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AGGREGATE PROPERTIESOF SOME

HONG KONG ROCKS

GEO REPORT No. 7

T.Y. Irfan, A. Cipullo, A.D. Burnett & J.M. Nash

ORDINANCEChapter 142

5

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© Hong Kong Government

First published, January 1992First Reprint, April 1995

Prepared by:

Geotechnical Engineering Office,Civil Engineering Department, A ORCivil Engineering Building, X 3 l101 Princess Margaret Road, " j \ \Homantin, Kowloon, ,_.~ , _ ^ ^Hong Kong. 1.. ^

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Government Publications Centre,Ground Floor, Low Block,Queensway Government Offices,66 Queensway,Hong Kong.

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Cheques, bank drafts or money ordersmust be made payable to HONG KONG GOVERNMENT

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PREFACE

In keeping with our policy of releasing information ofgeneral technical interest, we make ayailable some of our internalreports in a series of publications termed the GEO Report series.The reports in this series, of which this is one, are selected from awide range of reports produced by the staff of the Office and ourconsultants.

Copies of GEO Reports have previously been madeavailable free of charge in limited numbers. The demand for thereports in this series has increased greatly, necessitating newarrangements for supply. In future a charge will be made to coverthe cost of printing.

The Geotechnical Engineering Office also publishesguidance documents and presents the results of research work ofgeneral interest in GEO Publications. These publications and theGEO Reports are disseminated through the Government'sInformation Services Department. Information on how to purchasethem is given on the last page of this report.

A. W. MalonePrincipal Government Geotechnical Engineer

April 1995

EXPLANATORY NOTE

This GEO Report consists of eight Technical Notes on selected aggregateproperties of various granitic and volcanic rocks in Hong Kong. TheseTechnical Notes were prepared by the Planning Division of the formerGeotechnical Control Office as part of the Fresh Rock Testing Programme whichwas initiated in 1985.

The Technical Notes are presented in separate sections in this Report.Their titles are as follows :

Section Title Page No.

1 Aggregate Properties of Medium-Grained 5Granite from Turret Hill Quarry.T.Y. Irfan & J.M. Nash (1987)

2 Aggregate Properties of Monzonite from 25Turret Hill Quarry.T.Y. Irfan (1987)

3 Aggregate Properties of Coarse-Grained 47Granite from Lai King.T.Y. Irfan (1987)

4 Aggregate Properties of Fine-to Medium- 69Grained Granite from Ma Yau Tong.T.Y. Irfan (1987)

5 Aggregate Properties of Fine- and Fine- 91to Medium-Grained Granites fromAnderson Road.T.Y. Irfan & A. Cipullo (1987)

6 Aggregate Properties of Medium-Grained 123Granite from Diamond Hill.A. Cipullo & T.Y. Irfan (1988)

© Aggregate Properties of Fine-, Medium-, and 147

Megacrystic Granites from Lamma Island.T.Y. Irfan (1989)

8 Aggregate Properties of Volcanic Rock Types 179from 'Spun1 Sites at Mount Davis and Chai Wan.A.D.. Burnett (1989)

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SECTION 1 :AGGREGATE PROPERTIES OFMEDIUM-GRAINED GRANITEFROM TURRET HILL QUARRY

T.Y. Man & J.M. Nash

This report was originally produced as GCO Technical Note No. TN 2/87

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FOREWORD

In order to help provide the Materials Division andthe Hong Kong Geological Survey with much needed data onthe characterization and possible usage of each of theTerritory's major rock types the Office initiated theFresh Rock Testing Programme in 1985.

This report forms part of the Fresh Rock TestingProgramme and is one of a series of reports which presentsthe results of selected aggregate and index laboratorytesting carried out on fresh block samples of discreterock types.

The rock type described in this report is a medium-grained, inequigranular, megacrystic, GRANITE from theTurret Hill Quarry, Shatin.

The authors wish to acknowledge the role played inthe field sampling and sample preparation by TO's W.C. Leeand M«K. Chan and in the laboratory testing by K,H. Leeand other laboratory staff. The cooperation andassistance of the Quarry Management and the MaterialsDivision is also acknowledged.

(A.D. Burnett)Chief Geotechnical Engineer/Planning

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CONTENTS

PageNo.

Title Page 5

FOREWORD 6

CONTENTS 7

1 . INTRODUCTION 8

2. SITE DESCRIPTION AND SAMPLING 8

3. GEOLOGY 8

3.1 Site Geology 8

3.2" Description of Test Sample 8

4. AGGREGATE TESTING AND CHARACTERIZATION 9

4.1 Sample Preparation and Testing Methods 9

4.2 Classification and Characterization of Aggregate 9

4.3 Test Results 9

5. DISCUSSION ON TEST RESULTS 10

5.1 Suitability of Rock as an Aggregate 10

6. CONCLUSIONS 10

7. REFERENCES 11

LIST OF TABLES 13

LIST OF FIGURES 20

LIST OF PLATES 22

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1. INTRODUCTION

One of the objectives of the Fresh Rock Testing Programme outlined in theTechnical Note "Laboratory Characterization Testing of Fresh Rock (Irfan &Purser, 1985) is to determine the aggregate properties of rocks commonly usedin Hong Kong for concrete and roadstone aggregate and to recommend alternativerock types based on the results of testing. Major rock types recently mappedduring the course of the new Geological Survey of Hong Kong are sampled andsubjected to limited selected physical index and aggregate tests. It wasdecided to publish the results of the agregate testing at each samplinglocality in the form of technical reports at the request of CGE/M and onrecommendation of the Aggregate Working Group. This Technical Note on theaggregate properties of medium-grained granite from Turret Hill Quarry formsthe first report in the series.

This report gives the results of selected aggregate and rock index testscarried out on fresh granite samples from a particular locality in the quarryand discusses the results and suitability of the rock as aggregate incomparison with the typical aggregate acceptance values. Only the selectedrock material properties are considered when assessing the suitability of therock. Other rock factors as well as environmental, operational and haulagefactors will be the dominant factors in determining the suitability fordevelopment of a particular source of suitable material.

2. SITE DESCRIPTION AND SAMPLING

The sampling site is the disused Turret Hill Quarry located on thesouthwestern flank of Turret Hill (Nui Po Shan), east of Shatin (Figure 1).The site was originally used as a borrow area in the mid-1960's and 70fs whichwas then turned into an aggregate quarry in the late-1970fs. Rock extractionceased at the quarry at the end of 1984 when the contractor had completed theformation of rock slopes (Plate 1) in accordance with the Contract. Thissampling site was chosen for Fresh Rock Testing Programme bacause of its easeof access and nature of fresh rocks present. The sampling locality issituated at the estern end of the quarry on third bench from the toe (Plate2). Block samples of easily manageable size were collected from the face ingranite for testing.

3. GEOLOGY

3.1 Site Geology

The quarry is shown to be located in medium-grained granite, (gm), on thenew 1:20 000 geological map (Figure 1). Addison (1986) reported that thisgranite is intruded by thin sheets and dykes of fine-grained granite in thequarry area. A monzonite intrusion is present at the eastern end of thequarry. A northwest-southeast trending fault traverses granite near thenorthern side of the quarry. At the sampling locality, the medium-granite isfresh and moderately to widely jointed. Some major joints are reddish brownstained. Occasional vugs of quartz and mica occur in the rock.

3.2 Description of Test Sample

Engineering geological description (c. BS 5930 ; 1981)* The rock is very

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strong, light pinkish grey, crystalline, fresh, medium-grained GRANITE withan average grain size of 3 to 5 mm and inequigranular texture.

Detailed description. The rock consists of subhedral grains of quartz,alkali feldspar, plagioclase feldspar and biotite. Quartz forms about 35$of the rock and biotite less than 5%. Alkali feldspars are generally lightpink in colour. No modal analysis was carried out. Detailed description ofthe medium-grained granite is given in1 Addison (1986). The minimum andmaximum sizes of grains are 1 mm and 7 mm respectively (average size of 3 to5 mm) .

4. AGGREGATE TESTING AND CHARACTERIZATION

4.1 Sample Preparation and Testing Methods

The block samples collected from the site were broken by using a sledgehammer and rock breaker into smaller size specimens. These were then fed intoa laboratory jaw crusher (Plate 3) to prepare 10-14 mm and nominal 20 mm sizeaggregates (Plate 4).

Selected physical rock index tests were performed on the irregular lumpsof rock using the methods recommended by ISRM (1978). These included thedetermination of bulk density (dry and saturated), mineral grain specificgravity, porosity (total and effective) and water absorption. Point loadindex testing (ISRM, 1985) was carried out on irregular lumps to determine thestrength of the rock.

The aggregate testing included aggregate crushing value, ACV, aggregateimpact value, AIV, water absorption, flakiness index, Ip, and elongation indexIg, on standard size (10-14 mm) aggregates according to the methodsrecommended in BS 812 (BSI, 1975) and Los Angeles abrasion value, LAAV, on 20mm nominal size aggregates according to ASTM C-131 (ASTM, 1981).

4.2 Classification and Characterization of Aggregate

Numerous classification and descriptive schemes exist to characterizeaggregates. A number of commonly used schemes were critically reviewed andfound unsatisfactory from many points of view by the Geological SocietyWorking Party on Aggregates (Collis & Fox, 1985). This Working Partyrecommended a new classification system called CADAM (Classification andDescription of Aggregate Materials) to be used for both commercial andcontractual purposes. This CADAM scheme is adopted here to describe andclassify the Hong Kong aggregates. Table 1 shows the classification ofaggregate in this study by the proposed CADAM scheme. A more detailedpetrographic evaulation of the aggregate is given in Table 2.

4.3 Test Results

The results of standard tests carried out on irregular specimens aregiven in Table 3, The results of tests carried out on laboratory crushedaggregates are shown in Table 4. Limited test results are available on 10 mmand 20 mm nominal size aggregates from the quarry carried out in 1979 and1980. These are given in Table 5.

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5. DISCUSSION ON TEST RESULTS

The rock index tes ts given in Table 3 show that the fresh, medium-grainedgranite from the Turret Hill Quarry s i t e is a very strong rock with a pointload strength value of over 10 MPa (or uniaxial compressive s t rength of over250 MPa using a conversion factor of 25; ISRM 1985) and has very low waterabsorption and porosity propert ies .

The t e s t resu l t s given in Tables 3 and 4 are those of the t e s t s carr iedout on a few block samples chosen from one loca l i ty in the quarry. The t e s tresults may therefore not be representative of the whole rock type occurringin the quarry or the Territory, With th i s in mind, a comparison of theaggregate t e s t resul t s carried out on laboratory crushed specimens (Table 4)is made with the limited t e s t resul ts avai lable on the quarry run mater ia l(Table 5) . The resul ts are similar in terms of aggregate impact value, waterabsorption, elongation index and re la t ive density except in the f lakinessindex where a lower value was obtained on laboratory crushed specimens.

5.1 Sui tabi l i ty of Rock as an Aggregate

The t e s t methods adopted and their l imiting values for determining thesu i tab i l i ty of rock for various aggregate uses, both vary considerably fromspecification to specification in response to appl ica t ion , c l imate ,ava i lab i l i ty of mater ia ls , e t c . In Hong Kong, both the t e s t methods andacceptance values for aggregates to be used in concrete and as roadstone aregenerally those recommended in the Bri t ish Standards (Government of Hong Kong,1977), namely BS 882, BS 1621, BS 812. In general , fresh g r an i t i c rocks havebeen t rad i t iona l ly used for both concrete and as roadstone in Hong Kongalthough volcanic rocks have occasionally been used for some special aggregatepurposes ( e .g . as f r ic t ion course for Kai Tak Airport runway extension) .

A comparison of the t e s t resul ts in Tables 4 and 5 with typical UKaggregate acceptance values (Table 6) indicates that the aggregates producedfrom the medium-grained granite in the quarry are within the acceptable l imi t sfor use in concrete and as roadstone. However, in terms of both aggregateimpact value (or aggregate crushing value) and Los Angeles abrasion value,they have rather high values making the aggregate from the medium-grainedgranite less desirable , compared to the fine-grained grani tes or ba sa l t i crocks, for wearing courses and some special purposes such as heavy dutyconcrete f loor.

No soundness tes t s to determine the durabi l i ty of the aggregate have beencarried out for the reasons that the rock tested was fresh and the aggregatesfrom fresh granites are known to-be durable. However, i t i s recommended thatthe soundness t e s t s should be carried out i f the proportion of discoloured(weathered) rock is s ignif icant .

No t e s t s have been carried out to determine potent ia l a l k a l i - s i l i c areact iv i ty since this is not expected to be a problem in the case of aggregatefrom coarsely crys ta l l ine grani t ic rocks.

6. CONCLUSIONS

The laboratory t e s t resul ts carried out on aggregate produced from fresh,medium-grained granite samples collected from the Turret Hill Quarry are

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within the commonly accepted limiting values for general use in concrete andas roadstone.

The aggregate impact value (or crushing value) and the Los Angelesabrasion value test results are rather high and near to the specified limitingvalues thus making the aggregate from this rock type less desirable forspecial uses such as wearing courses and heavy duty concrete floors comparedto aggregates from the fine-grained granites or basaltic rocks.

In this investigation, the tests were all carried out on fresh rocksamples. Aggregates produced from slightly weathered granite grade are,however, also generally suitable for various uses (see Choy'& Irfan, 1986 andCollis & Fox, 1985), but they may have lower strength and abrasioncharacteristics. Their suitability, particularly in-service performance,should also be assessed for particular aggregate use by durability andsoundness tests and petrographic examination.

The test results for the current laboratory crushed sarnies are comparableto the documented test data for quarry run aggregates available from thequarry when it was operational. However, for the latter case the state ofweathering of the samples tested and their exact geological characteristicsare not known.

7. REFERENCES

Addison, R. (1986). Geology of Sha Tin, 1:20 000 Sheet 7, GeotechnicalControl Office, Hong Kong, 85 p. (Hong Kong Geological Survey MemoirNo. 1).

American Society for Testing Materials (1981). Specification for ConcreteAggregates (ASTM C33-81). American society for Testing Materials.

American Society for Testing Materials (1976). Test for soundness ofaggregates by use of sedium sulphate or magnesium sulphate. TestDesignation C88-76. American Society for Testing Materials»

American Society for Testing Materials (1981). Test for resistance toabrasion of small size coarse aggregate by use of the Los Angelesmachine. Test Designation C131-81. American Society for TestingMaterials.

British Standards Institution (1983). British Standard Specification forAggregates from Natural Sources for Concrete (BS 882 : 1983)* BritishStandards Institution, London, 7 p.

British Standard Institution (1975). Methods for Sampling and Testing ofMineral Aggregates, Sands and Fillers (BS 812 : Parts 1 to 3). BritishStandards Institution.

British Standard Institution (1976). Code of Practice for the Structural Useof Concrete for Retaining Aqueous Liquids (BS 5337 : 1976). BritishStandard Institution.

British Standard Institution (1981). Code of Practice for Site Investigations(BS 5930 : 1981). British Standards Institution, London, 147 p.

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British Standard Institution (1960 . Bitumen Macadam with Crushed Rock orSlag Aggregate (BS 1621 : 1961)* British Standards Institution.

Choy, H.H. & Irfan, T.Y. (1986). Engineering Geology Studies for the Extensionof the Anderson Road Quarries. GCO Report No. ADR 12/86, 71 p.

Collis, L, & Fox, R.A. (1985). Aggregate : Sand, Gravel and Crushed RockAggregates for- Construction Purposes. Geological Society EngineeringGeology Special Publication No. 1, Geological Society, London, 220 p.

Department of Transport (1976). Specification for Road and Bridgeworks, 5thEdition. H.M.S.O., London.

Government of Hong Kong (1977). General Specification for Civil EngineeringWorks, Public Works Department. Hong Kong Government Printer.

Higginbottom, I.E. (1976). Section 11.1. General requirements for rocks andaggregates. In Applied Geology fpr Engineers, H.M.S.O., 378 p.

Hosking, J.R. & Tubey, L.W. (1969). Research on Low Grade and UnsoundAggregates. Road Research Laboratory Report L.R* 293* Road ResearchLaboratory, Crowthorne, 30 p.

Irfan, T.Y. & Purser, P.J. (1985). Laboratory Characterization Testing ofFresh Rock. Unpublished Technical Note in folio (7) in Planning DivisionFile GCP 1/10/145.

ISRM (1978). Rock Characterization Testing and Monitoring. ISRM SuggestedMethods (ed. E.T. Brown). Commission on Testing Methods, InternationalSociety for Rock Mechanics, Pergamon Press, 211 p.

ISRM (1985). Suggested method for determining point load strength.International Society for Rock Mechanics Commission on Testing Methods.International Journal of Rock Mechanics and Mining Sciences &Geomechanics Abstracts, vol. 22, No. 2, pp. 51-60. ~~~

Shergold, F.A. (1948). A review of available information on the significanceof road-stone tests. Road Research Technical Paper 10, DSIR, H.M.S.O.,London.

Standards Association of Australia (1985). Aggregates and Rock forEngineering Purposes. Part 1 -Concrete Aggregates (Australian Standard"2758.1 - 1985)* Standards Association of Australia, 16 p.

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LIST OF TABLES

Table PageNo. No.

1 Description and Classification of Aggregate 14by the CADAM System

2 Petrographic Evaluation of Aggregate 15

3 Rock Index Properties of Medium-Grained Granite 16from Turret Hill

4 Test Results on Laboratory Crushed Aggregates 17from Turret Hill

5 Aggregate Test Results from Turret Hill Quarry, 181979-1980

6 British Standard and Other Acceptance Values for 19Test Results on Roadstone and Concrete Aggregates

Table 2 - Petrographie Evaluation of Aggregate

PETROGRAPHIC EVALUATION OF AGGREGATESSAMPLE REF

LOCATION/GRID REF

SAMPLING DATE

AGGREGATE PROPERTIES

Particle Shape (BS 812:1975)

Surface Texture (BS 812:1975)

Coating

Cleanliness (Dust etc)

GEOLOGICAL PROPERTIES

Rock Type (GSS Classification)

Mineralogy

Major Constituents

Minor Cons t i tuen t s

Cementing Materials

Expansive Minerals

Weathering of Particles

Organic Material Content

GENERAL COMMENTS

ADDITIONAL INFORMATION

HK 3663 EG 003Turret Hill Quarry, Shatin84020E 82760N16.5.1985

SAMPLE SIZE/WEIGHT

Bulk sample 50 kgSub-sample 1 kg flO - 14 mm)

Mainly i rregular , some angular shaped, small percentage of elongated par t ic les

Crystalline

None

Some dust result ing from aggregate crushing

Medium-grained GRANITE (gm)

Quartz, Alkali Feldspar, Plagioclase Feldspar, some Bioti te (5%)

Chlorite, muscovite

Crystalline, no cementing minerals

Chlorite (?), small amount

Fresh, no staining

None

Granite i s inequigranular and megacrystic Compiled by JMN/TYI

Date

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Table 3 - Bock Index Properties of Medium-Grained Granitefrom Turret Hill

Rock Index Property

Mineral Grain Specific Gravity, (g/cm3)

Bulk Density Dry (g/cm3)

Saturated (g/cm3)

Water Absorption (%)

(Saturation Moisture Content)

Porosity Total (%)

Effective (%)

Point Load Strength (MPa)

AverageValue

2.64

2.60

2-62

0.52

1.76

1.34

10.1 +

Range

2.60 - 2.66

2.58 - 2.61

2.60 - 2.63

0.51 - 0.52

1.73 - 1.78

1.33 - 1.35

Legend :

+ Limited test results on 4 irregular lumps

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Table 4 - Test Results on Laboratory Crushed Aggregates (10-14 mm)from Turret Hill

Aggregate Property

Aggregate Crushing Value,

Aggregate Impact Value,

Los Angeles Abrasion Value,

Water Absorption

Flakiness Index,

Elongation Index,

Legend :

* 14 - 20 mm aggregate

ACV (%)

AIV {%)

LAAV {%)

<»

i E <j)

Test Value

23

24

29

0.5

7(20)*

(30)*

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Table 5 - Aggregate Test Results* from Turret HillQuarry, 1979-1980 (20 mm aggregate)

Aggregate Property

10JC Fines Value

Aggregate impact Value,

Aggregate Abrasion Value,

Water Absorption

Flakiness Index,

Elongation Index,

Relative Density

Legend :

+ Test results from

n.d. Not determined

AIV

AAV

IF

IE

(kN)

(?)

(?)

(?)

(?)

(?)

Cg/cm3)

Materials Division ]

Test Value

1979

140

n.d.

5

n.d.

14

33

2.61

File Q 3/2/8

1980

110

27

n.d.

0.5

28

42

2.61

Table 6 - British Standard and Other Acceptance Values for Test Results on Roadstone and Concrete Aggregates

Test



10$ Fines Value


Los Angeles Abrasion Value,(ASTM C-131)

Water Absorption (Porosity)

Bulk Density

Flakiness Index,

ACV (%)

AIV (%)

(kN)

AAV (%)

LAAV

(g/cm3)

I F

Magnesium Sulphate Soundness (%)

Sodium Sulphate Soundness

Test Value

Maximum 30

Maximum 45+

Maximum 30*

Minimum 50*More than 100*More than 150*

Maximum 10 (diff. condMaximum 12 (av. cond.)

Maximum 30 (diff. condMaximum 40 (av. cond.)Maximum 35*

Less than 3+

More than 2.60

Less than 35***

Maximum 18 (5 cycles)

Maximum 12 (5 cycles)Maximum 12 (5 cycles)

Legend : R - Road aggretates, C - Concrete aggregates,** For heavy duty concrete floor, *** For C20 and

Use

C.R.

C.R.

R.C.R.C.

R.

C.C.R.

C.R.

C.R.

C.R.

C.R.

C.R,C.

Authority

Higginbottom (1976)

BS 882:1983

Hosking & Tubey (1969)BS 882:1983BS 882:1983

DoT (1976)

Australian Standard 2758.1 (1985)

Shergold (1948)

Higginbottom (1976)BS 5337:1976

Higginbottom (1976)

BS 882:1983

ASTM C33-81

ASTM C33-81Australian Standard 2785.1 (1985)

* For wearing surfaces,over concrete grade, + General use

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LIST OF FIGURES

Figure PageNo. No.

1 Location Map Showing Geology of the Site 21and the Adjacent Areas

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LIST OF PLATES

Plate Page

No. No.

1 General View of Turret Hill Quarry 23

2 Sampling Site 23

3 Laboratory Jaw Crusher 24

4 Crushed Rock Aggregate from Medium-Grained 24Granite

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SECTION 2 :AGGREGATE PROPERTIES OFMONZONITEFROM TURRET HILL QUARRY

T.Y. Man


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FOREWORD

In order to help provide the Materials Division andthe Hong Kong Geological Survey with much needed data onthe characterisation and possible usage of each of theTerritory1s major rock types the Office initiated theFresh Rock Testing Programme in 1985.


The rock type described in this report is a quartz-monzonite from the Turret Hill Quarry, Shatin.

The author wishes to acknowledge the role played inthe field sampling and sample preparation by GE J.M. Nashand TOfs W.C. Lee and M.K. Chan and in the laboratorytesting by GE K.H. Lee and other laboratory staff. Thecooperation and assistance of the Quarry Management andthe Materials Division is also acknowledged.

(K.A. Styles)Atg. Chief Geotechnical Engineer/Planning

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CONTENTS

PageNo.

Title Page 25

FOREWORD 26

CONTENTS 27

1. INTRODUCTION 28


3. GEOLOGY 28

3.1 Site Geology 28

3.2 Description of Test Sample 28


4-1 Sample Preparation and Testing Methods 29


4.3 Test Results 29


5.1 Rock Index and Aggregate Properties 29


6. CONCLUSIONS 31

7. REFERENCES 31

LIST OF TABLES 34

LIST OF FIGURES. ^2

LIST OF PLATES ^

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1. INTRODUCTION

This Technical Note on the aggregate properties of fresh monzonite formsthe second report in the series of aggregate properties of selected Hong Kongrocks and is part of the Fresh Rock Testing Programme, the aims of which areexplained in the unpublished Technical Note by Irfan & Purser (1985).

The monzonite samples under discussion were collected from the TurretHill Quarry and were subjected to selected laboratory physical index andaggregate testing. This report presents the results of these index andaggregate tests and discusses the results and suitability of monzonite fromthis locality as aggregate in comparison with the typical aggregate acceptancevalues. In assessing the suitability of the rock as aggregate, only theselected rock material properties are considered. Other rock properties suchas jointing, weathering and overburden, as well as environmental, operationaland haulage factors should also be considered in determining the overallsuitability for development of a particular source of material.


The sampling site is the disused Turret Hill Quarry (Plate 1) located onthe southwestern flank of Turret Hill (Nui Po Shan), east of Shatin (Figure1). The site was originally used as a borrow area in the mid-1960fs and 70Tswhich was then turned into a granite aggregate quarry in the late-1970's.Rock extraction ceased at the quarry at the end of 1984.

The sampling location is situated near the western end of the quarry onthe fourth face from the base of the quarry (Plate 2). Block samples ofeasily manageable size and weight were collected from the fresh monzonite silloccurring on the face for testing. While this sill material is thus clearlynot of sufficient size to form an economic source of monzonite it does providea typical representative of this rock type for testing and assessment.

3. GEOLOGY

3.1 Site Geology

The main rock type in the quarry is medium-grained granite (gm) intrudedby thin sheets and dykes of fine-grained granite (Addison, 1986). Monzoniteoccurs as a relatively thin sheet (sill) of 0.8 to 1.2 a width, near thewestern end of the quarry dipping at about 35° towards southeast (Plate 2 ) .The extent of the sill is not known and on the 1:20 000 geological map it isshown as a discontinuous outcrop. The sill is irregular in shape and thecontact with granite is fused. No obvious alignment of feldspar megacrystsis present. The joints are generally medium-to widely-spaced and tight.


Engineering geological description (c.BS 5930:1981). The rock isextremely strong, medium grey coloured, crystalline, fresh, medium- to coarse-grained, quartz-MONZONITE with an inequigranular and porphyritic texture.

Detailed description. The rock consists of phenocrysts of both alkaliand plagioclase feldspars (up to 45?O in a medium-grained matrix of feldspars,

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biotite and quartz. Quartz forms about 13% of the roek and biotite andhornblende about 4.3?, the rest being feldspars. Modal analysis was carriedout on one thin section only. The results are given in Table 1. Phenocrystsof feldspars are up to 20 mm but generally 5 to 10 mm in size. Some of theplagioclase feldspars show slight alteration to sericite in thin section(Plate 3)» Detailed description of quartz-monzonite occurring in the Shatinarea is given in Addison (1986).



Standard (10-14 mm) and nominal 20 mm size aggregates (Plate 4) wereprepared using a laboratory jaw crusher. Selected physical rock index testswere also performed on the larger irregular lumps of rock using ISRMrecommended methods. Aggregate testing was carried out according to themethods recommended in BS 812 (BSI, 1975).

The rock index tests included the determination of bulk density, mineralgrain specific gravity, porosity and water absorption (ISRM, 1978) and pointload testing (ISRM, 1985). The aggregate tests included aggregate crushingvalue, aggregate impact value, water absorption, flakiness and elongationindices (BSI, 1975) and Los Angeles abrasion value (ASTM, 1981).


The CADAM scheme recommended by the Geological Society Working Party onAggregates (Collis & Fox, 1985) is used to describe and classify the aggregate(Table 2). A more detailed petrographic evaluation of the aggregate is givenin Table 3.

4.3 Test Results

The results of rock index tests are given in Table 4. The test resultson laboratory crushed monzonite aggregate are tabulated in Table 5. Limitedaggregate test results from the material quarried between 1979 and 1980 areavailable0but these results are highly likely to be for granite rather thanmonzonite as the latter has very limited outcrop in the quarry.


5.1 Rock Index and aggregate Properties

The rock index tests given in Table 4 show that the fresh monzonite fromTurret Hill Quarry site is an extremely strong rock with a point load strengthvalue of about 12 MPa (or uniaxial compressive strength of about 300 MPa usingthe normal conversion factor of 25) and has very low water absorption andporosity properties.

In terms of rock index properties including bulk density, the monzonitehas very similar properties to the medium-grained granite occurring in thequarry (Table 3 in Irfan & Nash, 1987). The rock specimens tested wereisotropic in nature with no apparent alignment of feldspar megacrysts. Therock type tested was not therefore typical of monzonite occurring in the

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Territory since the thicker intrusions are generally known to have a well-defined and characteristics feldspar orientation. This usual anisotropy islikely to result in strength differences in directions perpendicular andparallel to the feldspar alignment. Aggregate mechanical properties are alsolikely to be influenced by this anisotropy and also the presence of feldsparmegacrysts.

A comparison of the aggregate test results on the monzonite (Table 5)with those of medium-grained granite from the same locality (Table 6) showthat the monzonite has lower and hence more desirable aggregate properties interms of aggregate crushing value, aggregate impact value and Los Angelesabrasion value. The results in terms of water absorption, flakiness andelongation indices are similar in being better than granite.

No test results are available from the Quarry (or elsewhere in theTerritory) to make a comparison between the aggregate properties of laboratorycrushed and plant crushed rocks.

5.2 Suitability of Rock as Aggregate

The existing aggregate quarries in Hong Kong are all in granite. Nocommercial monzonite aggregate test results are available and the in-serviceperformance of this aggregate is not known. Aggregate test results and in-service performance records from overseas sources are also not readilyavailable to make a general assessment of the suitability of monzonite as anaggregate source rock. However, monzonite is similar to granite in terms ofcomposition and grain size, except it has a lower quartz content of less than20$. The monzonite has similar mechanical and physical properties to thoseof granite and is therefore expected to have similar aggregate properties.Monzonite aggregates may, however, have lower resistance to abrasion due toa lower free silica content. Acid crystalline rocks including monzonitegenerally show relatively poor performance in relation to adhesion propertieswith bitumen (p. 170, Collis & Fox, 1985).

In Hong Kong, both the test methods and the acceptance values foraggregates to be used in concrete and as roads tone are generally thoserecommended in the British Standards (Government of Hong Kong, 1977). Acomparison of the test results in Table 5 with typical UK aggregate acceptancevalues (Table 7) indicates that the aggregates produced from the monzonite inthe Quarry are well within the acceptable limits for use in concrete and asroadstone as far as the properties determined in Table 5 are concerned. Theyare also comparable to those of granite aggregates which are commonly used inHong Kong.

No polished stone values, PSV, were determined. Soundness tests were notcarried out to determine the durability of the aggregate because of the freshstate of the rock. Chemical decomposition generally results in higher PSV'sin igneous rocks (Collis & Fox, 1985). However, a considerable degree ofresistance to weathering including resistance to disintegration with cyclesof wetting and drying or freezing and thawing, during the service lifetime isrequired for both roadstone and concrete aggregates. Some of the severestcases of failure of roadstone in unbound bases have been associated withphysical breakdown of rock already subjected to some degree of chemicalweathering (Turner & Wilson, 1956; Day, 1962). Monzonite contains a higherpercentage of feldspars (lower quartz) compared to granites and is likely tobe more susceptible to further decomposition and disintegration if the rock

- 31 -

has already weathered to some degree. I t i s , therefore, recommended thatsoundness t e s t s should be carried out and abrasion and polished stoneproper t ies be determined i f anything but fresh monzonite i s to be used asaggregate.

6. CONCLUSIONS

The laboratory t e s t r e s u l t s carried out on aggregate produced from freshquartz-monzonite col lec ted from Turret Hill Quarry are well within thecommonly accepted l imi t ing values for general use in concrete and asroadstone. In terms of cer ta in properties such as aggregate impact value,aggregate crushing values and Los Angeles abrasion value, the monzoniteaggregates have lower and hence s l igh t ly more desirable properties than thoseof medium-grained g ran i t e from the same quarry. The polished stone valueswere not determined.

Although the mechanical and physical t e s t r e su l t s indicate that monzonitemay be su i t ab le for aggregate production, the monzonite intrusion at thiss i t e , however, i s not considered as a sui table source rock since i t occurs asa very thin shee t - l i ke form of less than 1.5 m thickness and underconsiderable overburden of g r an i t i c rock.

The rock t e s t ed in t h i s invest igat ion i s also atypical of monzoniticin t rus ions occurring in the Shatin area and elsewhere in the Territory. I tdoes not show the t yp i ca l and cha rac te r i s t i c fabric anisotropy resulting fromthe alignment of feldspar megacrysts. Further tes t ing i s therefore requiredon samples col lec ted from other parts of the Terri tory, part icularly from themore common aniso t ropic var ie ty to determine the overall aggregate potentialof monzonite in Hong Kong.

The t e s t s in t h i s invest igat ion were carried out on laboratory crushedfresh rock samples. No t e s t r e su l t s are available on plant crushed monzoniteaggregates for a comparison, since monzonite i s rare ly used as an aggregatein Hong Kong. In -se rv ice performance of monzonite aggregates from outsideHong Kong i s a l so not read i ly available to the author. They are, however,expected to show s imi la r performance records to those of grani tes being ofs imilar composition and gra in s i ze , except that due to lower quartz contents,the aggregates produced from monzonite may have higher and hence moredesirable PSVfs but lower res is tance to abrasion.

7. REFERENCES

Addison, R. (1986). Geology of Sha Tin, 1 ;20 OOP Sheet 7, GeotechnicalControl Office, Hong Kong, 85 p . (Hong Kong Geological Survey MemoirNo. 1) .

American Society for Testing Materials (1981). Specification for ConcreteAggregates (ASTM C33-8O. American Society for Testing Materials.

American Society for Testing Materials (1981). Test for resistance toabrasion of small s ize coarse aggregate by use of the Los Angelesmachine. Test Designation C131-81. American Society for TestingMater ia ls .

Br i t i sh Standards I n s t i t u t i o n (1983). Bri t ish Standard Specification for

- 32 -

Aggregates from Natural Sources for Concrete (BS 882 : 1983). British

Standards Institution, London, 7 p.

British Standards Institution (1975). Methods for Sampling and Testing ofMineral Aggregates, Sands and Fillers (BS 812 : Parts 1 to 3). BritishStandards Institution,

British Standards Institution (1976)- Code of Practice for the Structural Useof Concrete for Retaining Aqueous Liquids (BS 5337 : 1976), BritishStandards Institution.

British Standards Institution (1981). Code of Practice of Site Investigations(BS 5930 : 1981). British Standards Institution, London, 147 p.

Collis, L. & Fox, R.A. (1985). Aggregates : Sand, Gravel and Crushed RockAggregates for Construction Purposes. Geological Society EngineeringGeology Special Publication No. 1. The Geological Society, London,220 p.

Day, H.L. (1962). A progress report on studies of degrading basalt aggregatebases. Highway Research Board Bulletin No. 334, p. 8-16.


Government of Hong Kong (1976). General Specifications for Civil EngineeringWorks, Public Works Department. Hong Kong Government Printer.

Higginbdttom, I.E. (1976). Section 11.1. General requirements for rocks andaggregates. In Applied Geology for Engineers, H.M.S.O., 378 p.

Hosking, J.R. & Tubey, L.W. (1969). Research on Low Grade and UnsoundAggregates. Road Research Laboratory Report L.R. 293, Road ResearchLaboratory, Crowthorne, 30 p.

International Society for Rock Mechanics (178). Rock Characterization Testingand Monitoring. ISRM Suggested Methods (edTE.T. Brown). Commission onTesting Methods, International Society for Rock Mechanics, PergamonPress, 211 p.

International Society for Rock Mechanics (1985). Suggested method fordetermining point load strength. International Society for RockMechanics Commission on Testing Methods. International Journal of RockMechanics and Mining Sciences and Geomechanics Abstracts, vol. 22, No.

2, pp. 51-60. ' ~~"~ "

Irfan, T.Y. & Purser, p . j . (1985). Laboratory Characterization Testing ofFresh Rock. Unpublished Technical Note,

Irfan, T.Y. & Nash, J .M. (1987). Aggregate Properties of Medium-GrainedGranite from Turret Hill Quarry. GCO Report No. TN 2 /81 . 23 p .

Standards Association of Australia (1985). Aggregates and Rock forEngineering Purposes. Part t - Concrete Aggregates (Australian Standard"

'• 2758.1 - 1985). Standards Association of Austral ia , 16 p . ' ~ ' ""

Turner, R.s. & Wilson, J.D. (1956). Degradation study of some Washington

- 33 -

aggregates. Washington State Institute Technical Bulletin No. 232.

. 34 -

LIST OF TABLES

Table PageNo. No.

1 Modal Analysis of Monzonite 35

2 Description and Classification of Monzonite 36Aggregate by the CADAM System

3 Petrographic Evaluation of Monzonite Aggregate 37

4 Rock Index Properties of Monzonite from Turret 38Hill

5 Test Results on Laboratory Crushed Monzonite 39Aggregates from Turret Hill

6 Test Results on Laboratory Crushed Monzonite 40from Turret Hill


- 35 -

Table 1 - Modal Analysis of Monzonite

Mineral

%

Feldspars

80.9

Quartz

13.0

Biotite Hornblende

0.9

Others

0.6

Note : Modal analysis carried out on one thin section.

Table 2"- Description and Classif icat ion of Monzonite Aggregate by the. CADAM System (Collis & Fox, 1985)

AGGREGATE

FORM

CLASS[OK

MISCELLANEOUS)

Pz&iologJjiaZ name[<ii known)

GEOLOGICAL AGE/COLOUR/

GRAIN SHEFISS1LITV

Conmejtt[11 any)

Cmuhed Rock G*l£LV*£

Neub^hsJt

G*n*htd Sand

SltlaaXe Clcu6

Ignzou6

~L'€Lnd.~tVOTl

[cofiAtct name tobe qiven betocv)

GRANITE

Mesozoic/Medium grey/Fresh/Medium to coarse-grained, porphyritic/No fissibili ty (seenote).

Large crystals up to 30 mm in a medium- to coarse-grained matrix.

CompUZed by : T. Y. Irfan Vote : 13.2.87

SGE/EG

CADAM - CLASSIFICATION a n d DESCRIPTION o f AGGREGATE MATERIAL

I

LOCATIONANVSAMPLEVET AILS

QuaAAij/PJJ: add*&64> : Tu r re t H i l lQuarry, Shatin, N.T.QpehaioK .'Disused (Contract Qu.)Sample : Type Blocks

Size 50 k^?KepaAa£u)n Lab. crushedSuppded bif E.G. Sec t ion

GrUd Re{.

Vote oi6ajnpLLnq16.5.85"

Vote Redd

Samp&jxqCeAX. No.

3662 EG002

Table 3 - Petrographic Evaluation of the Monzonite Aggregate

P E T R O G R A P H I C E V A L U A T I O N O F A G G R E G A T E S

SAMPLE REFLOCATION/GRID REF

SAMPLING DATE




Coating




MineralogyMajor Constituents

Minor Constituents

Cementing Materials

Expansive Minerals



GENERAL COMMENTS


HK3662 EG002

Turret H i l l Quarry, Shatin84020E 82T6ON16.5.1985

SAMPLE SIZE/WEIGHT

Bulk sample 50 kg aggregatesub-sample 1 kg (10-14 mm)

Mainly i r regular to angular with sharp corners, some percentage of elongated part ic les

Crystal l ine

None

Clean

Quartz-MONZONITE (mq)

Plagioclase feldspars and a l k a l i feldspars in equal proportions ( to ta l 81%), b i o t i t e

Quartz (13%), hornblende

Crysta l l ine, no cementing materials

None

Fresh, no staining

None

Rock in the quarry occurs as a th in s i l l . Very lowquartz content. The texture is porphyri t ic with f e l d -spar crystals up to 20 mm, set in a medium-grained(less than 2 mm) groundmass.

Compiled by TYI/JMN

D a t e 17.2.1987

I

- 38 -

Table 4 - Rock Index Properties of Monzonite from Turret Hill

Rock Index Property

Mineral Grain Specific Gravity (g/cm3)

Bulk Density Dry (g/cm3)

Saturated (g/cm3)

Water Absorption (%)

Porosity Total (%)

Effective {$)


Legend :

Average

2,65

2.62

2,63

0.48

.1.31

1.26

12.0+

+ Limited test results on 6 irregular lumps

Range

2.65

2.62

2.63

0.45-0.51

1.23-1.39

1.18-1.33

- 39 -

Table 5 - Test Results on Laboratory Crushed MonzoniteAggregate from Turret Hill

Aggregate Property




Water Absorption

Flakiness Index,

Elongation Index,

Note : Numbers in brackets

ACV

AIV

LAAV

IF

IE

««

(*)

(%)

(%)

for 14-20 mm aggregate.

Test Value

18

12

(21.5)

0.5(0.4)

20(25)

39(36)

Table 6 - Test Results on Laboratory Crushed Medium-Grained GraniteAggregates (10-14 mm) from Turret Hil l

Aggregate Property




Water Absorption

Flakiness Index,

Elongation Index,

Legend :

• 14-20 mm aggregate

ACV

AIV

LAAV

IF

IE

(*)

(3)

(*)

(*)

(*)

(%) •

Test Value

23

24

29

0.5

(20)*

41(30)*


Test



10$ Fines Value



(ASTM C-131)

Water Absorption (Porosity)

Bulk Density

Flakiness Index,

ACV (JO

AIV (JO

(kN)

AAV (50

LAAV

(50

(g/cm3)

I F (JO

Magnesium Sulphate Soundness {%)

Sodium Sulphate Soundness (JO

Legend : R Road aggregates C -* For wearing surfaces **

Test Value

Maximum 30

Maximum 45+

Maximum 30*

Minimum 50+

More than 100*More than 150*

Maximum 10 (diff. condMaximum 12 (av. cond.)

Maximum 30 (diff. condMaximum 40 (av. cond.)Maximum 35*

Less than 3+

More than 2.60

Less than 35***



Concrete aggregatesFor heavy duty concrete

i j

»)

Use

C.R.

C.R.

R.C.R.C.

R.

C.C.R.

C.R.

C.R.

C.R.

C.R.

C.R.C.

floor ***

Authority

Higginbottom (1976)

BS 882:1983


DOT (1976)


Shergold (1948)


Higginbottom (1976)

BS 882:1983

ASTM C33-81


General useFor C20 and over concrete grade

I

-fcr

LIST OF FIGURES

Figure PageNo. No.

1 Locatioi* Map Showing Geology of the Site 43and the Adjacent Areas

. 44 -

LIST OF PLATES

Plate Page

No. No.

1 General View of. Turret Hill Quarry 45

2 Sampling Locality on Quarry Bench 45

3 Photomicrograph of Monzonite Showing 46Inequigranular and Porphyritic Texture

4 Crushed Rock Aggregate from Monzonite 46

SECTION 3 :AGGREGATE PROPERTIES OFCOARSE-GRAINED GRANITEFROM LAI KING

T.Y. Irfan


- 48 -

FOREWORD

In order to help provide the Materials Division andthe Hong Kong Geological Survey with much needed data onthe characterization and possible usage of each of theTerritory's major rock types the Office initiated theFresh Rock Testing Programme in 1985.

This report forms part of the Fresh Rock TestingProgramme and is one of a series of reports which presentsthe results of selected aggregate and index laboratorytesting carried put on fresh block samples of discreterock types.

The rock type described in this report is a coarse-grained granite from Lai King,

The author wishes to acknowledge the role played inthe field sampling and sample preparation by GE J. M. Nashand TO's W, C. Lee and M* K. Chan and in the laboratorytesting by GE K. H. Lee and other laboratory staff. Thecooperation and assistance of the Materials Division isalso acknowledged.


- 49 -

CONTENTS

PageNo,

Title Page 47

FOREWORD 48

CONTENTS 49

1 . INTRODUCTION 50


3. GEOLOGY 50

3.1 Site Geology 50





4.3 Test Results 51




6. CONCLUSIONS 52

7. REFERENCES 53

LIST OF TABLES 55

LIST OF FIGURES 63

LIST OF PLATES ' 65

- 50 -

1. INTRODUCTION

This Technical Note on the aggregate p roper t i e s of f r e sh , coarse-grainedgrani te from the Lai King area forms the th i rd repor t in the s e r i e s ofaggregate proper t ies of selected Hong Kong rocks . The repor t p resen t s theresul ts of selected laboratory physical index and aggregate t e s t i n g on freshgranite samples collected from a road cu t t ing at Ha Kwai Chung, Lai King, anddiscusses the resul ts and s u i t a b i l i t y of coarse-grained g ran i t e from thislocal i ty as aggregate in comparison with the typical aggregate acceptancevalues. The su i t ab i l i t y of the rock i s only assessed on the basis of a narrowrange of selected rock propert ies in th i s repor t .


The sampling s i t e i s a 30 m high road cutting (cut slope no. 11NW-A/C29)along Wah Yiu Road opposite Kwai Chung Methodist College, Ha Kwai Chung, LaiKing, Kowloon (Figure 1 and Plate 1) .

The location from which the sample was taken is s i tuated in the centra lportion of the cutting about 2 m above the toe (Plate 2 ) . Three block sampleswere collected from the fresh grani te for test ing (Plate 3 ) . While th i soutcrop of coarse-grained granite i s not of suff icient s ize to form aneconomic source for aggregate, i t does provide a typical representa t ive ofthis rock type in the Territory for tes t ing and assessment.

3. GEOLOGY

3.1 Site Geology

The rock type exposed and sampled in the road cutt ing is coarse-grainedgranite (gc) . I t is intruded by thin ap l i t e dykes and a 3 m widefeldsparphyric rhyolite (rf) dyke trending in an eas t -nor theas t d i r e c t i o n .The contact between the coarse-grained granite and a fine-grained gran i te canbe observed round the corner along Lai Chi Ling Road (Figure 1) . At thesampling s ta t ion , the granite i s s l ight ly weathered and moderately to widelyjointed (0,3-1.0 m). This i s overlain by moderately to highly weatheredgrani te in the upper portion of the slope. The rock is dissected by four setsof jo in ts forming a blocky to tabular fabric with mean jo in t o r i en ta t ions of60/350°, 75/066°, 67/156° and 10/085°.

3*2 Description of Test Sample

Engineering geological description (BS 5930:1981). The rock i s verystrong, l ight grey with pinkish patches, c rys t a l l i ne , fresh with slightstaining along joint planes, coarse-grained GRANITE with inequigranular andporphyritic texture.

Detailed description. The rock consists of subhedral grains of quartz,alkali feldspar, plagioclase feldspar and biotite. Alkali feldspars aregenerally light pink in colour and form the larger grains, up to 20 mm insize, m a groundraass of mainly quartz and plagioclase feldspars with anaverage grain size of 6 to 8 mm. Biotite generally occurs as pods, up to 6 mmm size. Modal analysis carried out on three thin sections (Table 1) gave ammeralogical composition of 36.3? quartz, 60.2* feldspars, and 3.0$ biot i te .

- 51 -

Detailed description of coarse-grained granite occurring in Sheet 11 area isgiven in Strange & Shaw (1986).



75 mm diameter cores were drilled from the block samples using a concretecoring machine and diamond bit in the Public Works Central Laboratory.Selected physical and rock index tests were performed on the cores. Theremainder of the samples were broken into smaller pieces using a sledge hammerand a laboratory rock breaker. Point load testing was carried out onirregular lumps of rock using ISRM recommended methods (ISRM, 1985). Standard(10-14 mm) and nominal 20 mm size aggregates (Plate 4) were prepared from thesmaller pieces of rock using a laboratory jaw crusher.

The rock index tests undertaken included the determination of bulkdensity, porosity, water absorption and sonic velocity using the PUNDIT (ISRM,1978). The aggregate tests included aggregate crushing value, aggregateimpact value, water absorption, flakiness and elongation indices (BSI, 1975)and Los Angeles abrasion value (ASTM, 1981).


The CADAM scheme recommended by the Geological Society Working Party onAggregates (Collis & Fox, 1985) is used to describe and classify the aggregate(Table 2 ) . A more detailed petrographic evaluation of the aggregate is givenin Table 3.

4.3 Test Results

The results of rock index tests on cores are given in Table 4. The testresults on laboratory crushed coarse-grained granite aggregate are tabulatedin Table 5.


5.1 Rock Index and Aggregate Properties

The rock index tests given in Table 4 show that the fresh coarse-grainedgranite from Lai King is a very strong rock with a point load strength valueof about 9 MPa (or uniaxial compressive strength of about 225 MPa using thenormal conversion factor of 25) and has very low water absorption and porosityproperties.

In terms of rock index properties, the coarse-grained granite from thislocality has very similar properties to the medium-grained granite from TurretHill quarry (Table 3, in Irfan & Nash, 1987) having slightly higher dry bulkdensity (2.62 g/cm3), lower water absorption (0.21 %) and effective porosity(0.55 50 values and lower point load strength (8.9 MPa). The test values forthe medium-grained granite are 2.60 g/c©3, 0.52 %, 1.34 % and 10.1 MParespectively.

A comparison of the aggregate test results on the coarse-grained granite

- 52 -

(Table 5) with those of medium-grained granite (Table 6) shows slightly higherand hence less desirable properties for the former rock type in terms ofaggregate impact and Los Angeles abrasion values and flakiness index.

The rock index and aggregate values presented in Tables 4, 5 and 6 arethose of limited tests carried out on a few block samples chosen fromparticular single localities for each rock type. Their test values may nottherefore be typically representative of the whole rock types occurring in theTerritory*

5.2 Suitability of Rock as Aggregate

The existing aggregate quarries in Hong Kong are all in fine- to medium-grained and medium-grained granites (Strange & Shaw, 1986; Choy & Irfan, 1986a, b). Commercial test results on coarse-grained granite are therefore notavailable to make a general assessment of the suitability of this rock typeas an aggregate source rock. Coarse-grained granites, particularlyporphyritic types, are generally less sought after for sources of aggregatebecause of their relatively low crushing strength which arises from fracturingalong cleavages or boundaries of coarse crystalline constituents*

A comparison of the limited laboratory test results in Table 5 withtypical, mainly UK, acceptance values (Table 7) indicates that the aggregatesproduced from the coarse-grained granite at Lai King are just within theacceptable limits for general use in concrete and as roadstone as far as theaggregate properties determined in this study are concerned. In terms of LosAngeles abrasion value, the test value of 31? although acceptable for generalconcrete purposes, is just outside the maximum value specified by theAustralian Standard AS 2748.1-1985 for concrete exposed to severe conditions.Aggregate crushing-value (or aggregate impact value) of the rock is alsorelatively high, making the aggregate from this type of granite less desirableas compared to the fine-grained granite for some special uses such as wearingcourse or heavy duty concrete floor.

Soundness tests, which are generally executed to determine the durabilityof aggregate to salt attack, have not been carried out because of the freshstate of the rock tested. It is, however, recommended that soundness testsare carried out if anything but fresh rock is to be used as aggregate.Polished stone values were not determined in this investigation*

6. CONCLUSIONS

The laboratory test results carried out on aggregate produced from thefresh coarse-grained granite collected from a road cutting at Lai King arejust within the commonly accepted limiting values for general use in concreteand as roadstone. The aggregate impact value (or crushing value) and LosAngeles abrasion value test results are rather high and near or just above thespecified limiting values. This makes the aggregate from this rock type lessdesirable for special uses such as wearing courses and heavy duty concretefloors compared to aggregates from fine-grained granites or basaltic rocks.No currently operating quarries in Hong Kong are extracting this type ofgranite and comparative test results are hence not available on plant-crushedaggregates. In-service performance of this granite type is therefore notknown. Coarse-grained granites are, however, generally less sought afterelsewhere in the world as an aggregate source because of their less desirable

- 53 -

properties•

7- REFERENCES

American Society for Testing Materials (1981). Specification for ConcreteAggregates (ASTM C33-8D. American Society for Testing Materials.


British Standards Institution (1983). British Standard Specification forAggregates from Natural Sources for Concrete (BS 882 : 1983). BritishStandards Institution, London, 7p*

British Standards Institution (1975). Methods for Sampling and Testing ofMineral Aggregates, Sands and Fillers (BS 812 : Parts 1 to 3). BritishStandards Institution.

British Standards Institution (1976). Code of Practice for the StructuralUse of Concrete for Retaining Aqueous Liquids (BS 5337 : 1976). BritishStandards Institution.

British Standards Institution (1981). Code of Practice for SiteInvestigations (BS 5930 :1981). British Standards Institution, London,147 p.

Choy, H.H. & Irfan, T.Y. (1986a). Engineering Geology Studies for theExtension of the Anderson Road Quarries. GCO Report No. ADR 12/86,71 p.

Choy, H.H. & Irfan, T.Y. (1986b). Engineering Geology Studies for theExtension of Pok Tung Wan Quarry, Lamma Island. GCO Report No.ADR 18/86, 60 p.

Collis, L. & Fox, R.A. (1985). Aggregates : Sand, Gravel and Crushed RockAggregates for Construction Purposes. Geological Society EngineeringGeology Special Publication No. 1. The Geological Society, London,200 p.


Higginbottom, I.E. (1976). Section 11.1. General requirements for rocks andaggregates. In Applied Geology for Engineers,, H.M.S.O., 378 p.

Hosking, J.R. & Tubey, L.W. (1969). Research on Low Grade and UnsoundAggregates. Road Research Laboratory Report L.R. 293, Road ResearchLaboratory, Crowthorne, 30 p.

International Society for Rock Mechanics (1978). Rock CharacterizationTesting and Monitoring. ISRM Suggested Methods (ed. E.T. Brown).Commission on Testing Methods, International Society for Rock Mechanics,Pergamon Press, 211 p.

. 5H -

International Society for Rock Mechanics (1985). Suggested method fordetermining point load strength. International Society for RockMechanics Commission on Testing Methods. International Journal of RookMechanics and Mining Sciences and Geomechanics Abstracts, vol . 22, No,"2, pp. 51-60. — —

Irfan, T.Y. & Nash, J.M. (1987). Aggregate Properties of Medium-GrainedGranite from Turret Hill Quarry. GCO Report No. TN 2 /81 , 23 p .

Shergold, F.A. (1948). A review of available information on the significanceof roadstone t e s t s . Road Research Technical Paper 10. DSIR, H.M.S.O.,London.

Standards Association of Australia (1985). Aggregates and Rock forEngineering Purposes. Part 1 -Concrete Aggregates (Australian Standard2758.1 - 1985). Standards Association of Austral ia , 16 p .

Strange, P . J . & Shaw, R. (1986). Geology of Hong Kong Island and. Kowloon.Geotechnical Control Office, Hong Kong, 134 p . (Hong Kong GeologicalSurvey Memoir No. 2 ) .

- 55 -

LIST OF TABLES

Table PageNo. No.

1 Modal Analysis of Coarse-Grained Granite from 56Lai King

2 Description and Classification of Coarse-Grained 57Granite Aggregate by the CADAM System

3 Petrographic Evaluation of Coarse-Grained 58Granite Aggregate

4 Rock Index Properties of Coarse-Grained Granite 59

5 Test Results on Laboratory Crushed Coarse-Grained 60Granite Aggregate

6 Test Results on Laboratory Crushed Medium-Grained 61Granite Aggregate from Turret Hill


- 56 -

Table 1 - Modal Analysis of Coarse-Grained Granite from Lai King

Mineral

Thin Section

Thin Section

Thin Section

Average

1

2

3

Feldspars

57.5

53.6

69.5

60.2

Quartz

39.6

41.8

27.3

36.3 -

Biotite

2.2

3.6

3.0

3.0

Others

0.6

0.7

0.0

Table 3 - Petrographic Evaluation of Coarse-Grained Granite Aggregate



SAMPLING DATE


Parttete Shape (BS 812:1975)


Coaling

CJeanRness (Dust etc)




Minor Constituents

Cementing Materials

Expansrve Minerals



GENERAL COMMENTS


3675 EG 015Wan Yiu Road Cutt ing, Lai King, Kowloon831500 E 823650 N12.11.1986

SAMPLE SIZE/WEIGHTBulk sample : 50 kgSub-sample : 1 kg (10-14 mm)

Mainly angular to i r regu lar

Crystal l ine

None

Some dust resu l t ing from aggregate crushing

Coarse-grained GRANITE (gc)

Quartz (36.3%), Feldspars (60.2%), B io t i t e (3-0%)

Magnetite, c h l o r i t e , zircon

Crysta l l ine , no cementing minerals

None

Fresh, very few par t i c les show s l igh t s ta in ing

None

Granite is inequigranular and porphyr i t ic with grainsize 1 to 10 mm, occasionally 30 mm

Compiled by

Date 16.11.1987

CD

I

- 59 -

Table 4 - Rock Index Properties of Coarse-Grained Granite from Lai Kins

Rock Index Property

Mineral Grain Specific Gravity (g/cm3)

Bulk Density Dry (g/cm3)Saturated (g/cm3)

Water Absorption {%)

Porosity Total {%)Effective {%)

Sonic Velocity (m/s)


AverageValue

n.d.

2-622.62

0.21

n.d.0.55

5008*

8.9+

Range

n.d.

2.61-2.622.62

0.21

n.d.

0.54-0.56

4890-5160

7.0-11.3

Legend :

n.d. Not determined

+ Mean of 16 tests on irregular lumps (ISRM, 1985)

* Determined on 75 mm diameter cores (ISRM, 1978)

- 60 -

Table 5 - Test Results on Laboratory Crushed Coarse-GrainedGranite Aggregate (10-14 mm) from Lai King

Aggregate Property



Los Angeles Abrasion Value

Water Absorption

Flakiness Index,

Elongation Index,

Legend :

+ Mean of two test

ACV (50

AIV (51)

LAAV (%)

<»

I F (?)

I E (?)

results

Test Value4-

23

25

31

0.3

11

3*

- 61 -

Table 6 - Test Results on Laboratory Crushed Medium-Grained GraniteAggregates (10-14 ram) from Turret Hil l

Aggregate Property




Water Absorption

Flakiness Index,

Elongation Index,

Legend :

* 14-20 mm aggregate

ACV {%)

AIV Cjf)

LAAV (55)

i P <»

IE ($)

Test Value

23

24

29

0.5

7(20)*

41(30)*


Test

Aggregate Crushing Value, ACV (%)

Aggregate Impact Value, AIV (%)

10% Fines Value (kN)

Aggregate Abrasion Value, AAV (%)

Los Angeles Abrasion Value, LAAV(ASTM C-13D

Water Absorption (Porosity) {%)

Bulk Density (g/cm3)

Flakiness Index, Ip

Magnesium Sulphate Soundness {%)

Sodium Sulphate Soundness {%)

Legend : R Road aggregates <* For wearing surfaces

Test Value

Maximum 30

Maximum 45 +

Maximum 30*

Minimum 50+More than 100*More than 150*

Maximum 10 (diff. cond.)Maximum 12 (av. cond.)

Maximum 30 (diff. cond.)Maximum U0 (av. cond.)Maximum 35*

Less than 3+

More than 2.60

Less than 35***



2 Concrete aggregates** For heavy duty concrete j

Use

C.R.

C.R.

R.C.R.C.

R.

C.C.R.

C.R.

C.R.

C.R.

C.R.

C.R.C.

floor

Authority

Higginbottom (1976)

BS 882:1983


DoT (1976)


Shergold (1948)


Higginbottom (1976)

BS 882:1983

ASTM C33-81


+ General use*** For C20 and over concrete grade

i

- 63 -

LIST OF FIGURE

Figure PageNo. No.

1 Location Map Showing Geology of the Site and 64the Adjacent Areas

1 : 2 0 0 0 0

LEGEND:

SOUD GEOLOGY

I QG [

I Qb

; Qd

I ms

JHHH

I b

I rf

I rq

QuaternarySuperficialDeposits(Onshore)

QuaternarySuperficialDeposits(Offshore)

Basalt

Feldsparphyric Rhyolite

Quartzphyric Rhyolite

Aplite

Pegmatite

Coarse-grained Granite,> 6mmFine-grained Granite,<2mm

Medium-grained Granite,2-6mm

Megacrystic

GEOLOGICAL LINES

Geological Boundary, Superficial Deposits

Geological Boundary, Solid Rock

Fault

Photogeological Lineament

STRUCTURAL SYMBOLS

Horizontal

Jointing -L.

Inclined

20

Vertical

NOTE :

The g e o l o g i c a l map is e x t r a c t e d f r o m t h e p u b l i s h e d s h e e t 1 1

of the 1 : 2 0 0 0 0 g e o l o g i c a l map s e r i e s o f H o n g K o n g , N o t a l l

t h e g e o l o g i c a l s y m b o l s a r e g i ven in t h e l e g e n d .

Figure 1 - Location Map Showing Geology of the Si te and the Adjacent Areas

PlateNo.

- 65 -

LIST OF PLATES

1 General View of Wah Yiu Road Cutting 66

2 Sampling Locality 66

3 Block Sample 67

H Crushed Rock Aggregate from Coarse-Grained Granite 67

- 66 -

SLOV

Plate 1 - General View of Wah Yiu Road Cutting

Plate 2 - Sampling Locality

- 69 -

SECTION 4 :AGGREGATE PROPERTIES OFFINE-TO MEDIUM-GRAJGRANITEFROM MA YAU TONG

T.Y. Man


- 70 -

FOREWORD

In order to help provide the Materials Division andthe Hong Kong Geological Survey with much needed data onthe characterisation and possible usage of each of theTerritory's major rock types the Office initiated theFresh Rock Testing Programme in 1985.


The rock type described in this report is a fine-to-medium-grained granite from Ma Yau Tong.

The author wishes to acknowledge the role played inthe field sampling and sample preparation by GE J. M. Nashand TO's W. C. Lee and M. K. Chan and in the laboratorytesting by GE K. H. Lee and other laboratory staff. Thecooperation and assistance of the Materials Division isalso acknowledged.

(Dr A,D. Burnett)Chief Geotechnical Engineer/Planning

- 71 -

CONTENTS

PageNo.

Title Page 69

FOREWORD 70

CONTENTS 71

1. INTRODUCTION 72


3. GEOLOGY 72

3.1 Site Geology 72





4.3 Test Results 73




6. CONCLUSIONS 75

7. REFERENCES . 75

LIST OF TABLES 77

LIST OF FIGURES 85

LIST OF PLATES 87

- 72 -

1. INTRODUCTION

This Technical Note on the aggregate properties of fine- to medium-grained granite from Ma Yau Tong area forms the fourth report in the seriesof aggregate properties of selected Hong Kong rocks. The report presents theresults of selected laboratory physical index and aggregate testing on freshgranite samples and discusses the results and suitability of fine- to medium-grained granite as aggregate in comparison with typical aggregate acceptancevalues. The suitability of the rock is only assessed on the basis of a narrowrange of selected rock properties in this study.


The sampling site is a new road cutting, northeast of Lam Tin Estate,Phase II and below Ma Yau Tong Controlled Tip, Kowloon (Figure 1 and Plates1 and 2)•

The rectangular shaped granite samples were collected from the rockexcavated during the construction of the new road. Four fresh granite blocksamples were selected for testing (Plate 3). While this outcrop of fine- tomedium-grained granite is not a suitable site to form an economic source foraggregate because of its location, it is, however, of the same rock type as.that being quarried in the lower faces of the Anderson Road quarries (Choy &Irfan, 1986). The granite outcropping in this area is considered typical andrepresentative of fine- to medium-grained granite in the Territory except forits counterpart cropping out in Central and Northern Lamma Island which hasa distinctly modified texture (Strange & Shaw, 1986).

3. GEOLOGY

3.1 Site Geology

The road cutting is dominantly composed of f ine- to medium-grainedgranite (gfm) with fine-grained granite (gf) occupying a small portion of thewestern end of the slope. The contact between the two types of g ran i te isshown to be passing just below the controlled t i p , east of the road cutt ingon the recently published geological map of Hong Kong and Kowloon (GCO, 1986).A number of basalt dykes, each approximately 1.0 to 1.5 ra wide, cross theroad cutting in a ENE-WSW direct ion. The granite exposed in the cut t ing istypical of the fine- to medium-grained granite type cropping out in EastKowloon having a generally equigranular texture and uniform charac ter .

The road cutting is in mainly fresh to s l igh t ly weathered grani te withmore weathered granite zones near the crest and southern end of the cut face.The basalt dykes are parallel to the most dominant subver t ica l j o in t set inthe grani te , and trending ENE-WSW. Sub-horizontal sheeting jo in t s are alsopresent in the cut slope. The jo int spacing as displayed on the cut facevaries from widely spaced (0.6 - 2 m) to medium spaced (0.2 - 0.6 m) .

3-2 Description of Test Sample

. ( 1 ) Engineering geological description. The rock i s an extremelyP W ? ; ^ t Pinkish grey, c rys ta l l ine , fresh, f ine- to medium-grainedGRANITE with equigranular texture .

- 73 -

(2) Detailed description. The major granite constituents are quartz,plagioclase and alkali feldspars and biotite. Quartz forms about 30% of therock and biotite less than 5%. The results of modal analysis on threesections is given in Table 1, Small amounts of muscovite are also present.Alkali feldspars are generally light pink in hand specimen while someplagioclases show slight greenish discoloration at their centres indicatingslight alteration. The rock is equigranular and non-megacrystic with anaverage grain size of 1 to 2 mm. Occasional quartz and feldspar grains up to4 mm in diameter are also present.

In thin section (Plate 5), some of the plagioclases show slightalteration in the form of either partial replacement by or growth ofindividual muscovite flakes (hydrothermal alteration ?). In addition, someplagioclases show slight alteration to minute kaolinite-like minerals at theircentres. The amount of feldspar alteration is about 3.3$ of the rock(Table 1). A few tight microcracks are present traversing quartz andfeldspars grains.



75 mm diameter cores were drilled from the block samples using a concretecoring machine and diamond bit in the Public Works Central Laboratory.Selected physical and rock index tests were performed on the cores. Theremainder of the sample were broken into smaller pieces using a sledge hammerand a laboratory rock- breaker. Point load testing was carried out onirregular lumps of rock using ISRM recommended methods (ISRM, 1985). Standard(10-14 mm) and nominal 20 mm size aggregates (Plate 4) were prepared from thesmaller pieces of rock using a laboratory jaw crusher.

The rock index tests undertaken included the determination of bulkdensity, porosity, water absorption, and sonic velocity using the PUNDITequipment (ISRM, 1978). The aggregate tests included aggregate crushingvalue, aggregate impact value, water absorption, flakiness and elongationindices (BSI, 1975) and Los Angeles abrasion value (ASTM, 1981).


The CADAM scheme recommended by the Geological Society Working Party onAggregates (Collis & Fox, 1985) is used to describe and classify the aggregate(Table 2 ) . A more detailed petrographic evaluation of the aggregate is givenin Table 3.

4.3 Test Results • ; • . . ' . •• ' • • • • : •.•-'.

The results of the rock index tests on cores are given in Table 4. Thetest results on laboratory crushed fine- to medium-grained granite aggregateare tabulated in Table *5,.

- 71 -



The fresh fine- to medium-grained granite from Ma Yau Tong is a verystrong rock with a point load strength value of about 8.2 MPa (or uniaxialcompressive strength of about 210 MPa using the normal conversion factor of25) and has very low water absorption and porosity properties (Table k).Although the density, water absorption, porosity values of this rock type isvery similar to the coarse-grained granite from Lai King (Irfan, 1987a), andthe medium-grained granite and monzonite from Turret Hill (Irfan, 1987b; Irfan& Nash, 1987), it has a lower strength than all the rocks tested so far inthis project. The sound velocity is also very much lower than the valueobtained on the coarse-grained granite; 3585 m/s against 5008 m/s for thelatter.

A comparison of the aggregate test results of the fine- to medium-grainedgranite (Table 5) with those of medium- and coarse-grained granites andmonzonite (Table 6) show significantly higher and hence less desirableproperties for the former rock type in terms of aggregate impact value(AIV = 31), aggregate crushing value (ACT = 27) and Los Angeles abrasion value(LAAV = 41). This result is rather unexpected since finer grained granitesgenerally have more favourable aggregate properties when compared with coarsergrained equivalents.

The lower than expected strength and velocity values determined on intactrock and the slightly poorer aggregate strength properties of this rock typefrom Ma Yau Tong road cutting may be the result of slight hydrothermalalteration it has undergone, which can only be detected in thin section onpetrographic examination (see Section 3.2).

The lower production platforms of both Pioneer and particularly K. Wahquarries are in fine- to medium-grained granite passing into more finergrained granite near the contact with the volcanics. A comparison of the testresults-on samples from Ma Yau Tong (Table 5) is therefore made with the testresults available (1973-1985) on the quarry run material from both thesequarries (Table 7). The results are similar in terms of aggregate crushingvalue, aggregate impact value, water absorption, density, flakiness andelongation indices. No Los Angeles abrasion values were determined for theAnderson Road quarry materials.

•5.2 Suitability of Rock as an Aggregate

A comparison of the limited laboratory test results with typical, mainlyUK, aggregate acceptance values (Table 5) indicates that the aggregatesproduced from the fine- to medium-grained granite at Ma Yau Tong are justwithin the acceptable limits for general use in concrete and as roadstone, interms of aggregate crushing and impact values, water absorption value andflakiness index. However, in terms of Los Angeles abrasion value, the testvalue of 43 is outside the maximum value specified by the Australian StandardAS 2758.1-1985 for concrete exposed to even average conditions. The aggregateimpact value of 31 is just outside the maximum value specified by BS 882 whichmakes the aggregate tested in this study less desirable for special purposessuch as wearing surfaces or heavy duty concrete floors. No polished stonevalues or 10$ Fines values were determined for Ma Yau Tong granite samples.

- 75 -

I t i s to be noted tha t the rock index and aggregate values presented inTables 4 to 6 are those of limited tes t s carried out on few block sampleschosen from one pa r t i cu la r loca l i ty for th i s rock type, which appears to haveundergone s l i gh t hydrothermal a l t e r a t i on . The t e s t values may not thereforebe fully representa t ive of the f ine- to medium-grained granite occurring inTerr i tory.

6. CONCLUSIONS

The r e s u l t s of laboratory t e s t s carried out on aggregate produced fromfresh f ine- to medium-grained granite from a road cutt ing at Ma Yau Tong arejust within the commonly accepted limiting values for general use in concreteand as roadstone, except in terms of Los Angeles abrasion value where a higherthan acceptable value of 43 was obtained. This value together with ratherhigh (near or above the specified limiting) aggregate impact and crushing tes tvalues make the aggregate from th is par t icu la r loca l i ty less desirable forspecific uses such as wearing courses and heavy duty concrete floors comparedto f iner grained g ran i t e s and basal t ic rocks. The rock appears to haveundergone s l i g h t hydrothermal a l t e r a t i on . The lower than expected strengthand other proper t ies of the in tac t rock as well as the aggregate propertiesare therefore attributed to this slight alteration.

The aggregate properties of the rock determined on laboratory crushedspecimens is very similar to the test values available on quarry run graniticmaterial of similar grain size from the Anderson Road quarries, and theaggregates from these quarries have been satisfactorily used in concrete forgeneral building purposes in the Territory.

Further tests on samples from other localities are however necessary toassess more accurately the typical aggregate properties of the fine- tomedium-grained granite occurring in the Territory.

7. REFERENCES

American Society for Testing Materials (1981). Test for resistance toabrasion of small s ize coarse aggregate by use of the Los ° Angelesmachine. Test Designation C131—81• American Society for TestingMaterials .

Bri t ish Standards Ins t i tu t ion (1983)- Bri t ish Standard Specification forAggregates from Natural Sources for Concrete (BS 882 :1983)» Bri t ishStandards In s t i t u t i on , London, 7 p.

Bri t ish Standards Ins t i tu t ion (1975). Methods for Sampling and Testing ofMineral Aggregates, Sands and Fi l le rs (BS 812 : Parts 1 to 3) . Bri t ishStandards I n s t i t u t i o n .

Choy, H.H. & Irfan, T.Y* (1986). Engineering Geology Studies for theExtension of the Anderson Road Quarries. GCO Report No. ADR 12/86, 71 p*

Col l ls , L. & Fox, R.A. (1985)- Aggregates : Sand, Gravel and Crushed RockAggregates for Construction Purposes. Geological Society Engineering

• Geology Special Publication No. 1. The Geological Society, London,200 p .

- 76 -

Higginbottom, I .E. (1976). Section 11.1. General requirements for rocks andaggregates. In Applied Geology for Engineers, H.M.S.O., 378 p .

International Society for Rock Mechanics (1978)- Rock CharacterizationTesting and Monitoring. ISRM Suggested Methods (ed. E.T. Brown).Commission on Testing Methods, International Society for Rock Mechanics,Pergamon Press, 211 p .

International Society for Rock Mechanics (1985). Suggested method fordetermining point load strength. International Society for RockMechanics Commission on Testing Methods. International Journal of RockMechanics and Mining Sciences and Geomechanics Abstracts , vo l . 22, No. 2,pp 51-60.

Irfan, T.Y. (1987a). Aggregate Properties of Monzonite from Turret HillQuarry. GCO Report No. TN 3/87, 24 p .

Irfan, T.Y. (1987b). Aggregate Properties of Coarse-Grained Granite from LaiKing. GCO Report No. TN 4/87, 23 p .

Irfan, T.Y. & Nash, J.M. (1987). Aggregate Properties of Medium-GrainedGranite from Turret Hill Quarry. GCO Report No. TN 2 /81 , 23 p .

Shergold, F.As (1948). A review of available information on the significanceof roadstone t e s t s . Road Research Technical Paper 10. DSIR, H.M.S.O.,London.

Standards Association of Australia (1985). Aggregates and Rock forEngineering Purposes. Part 1 - Concrete Aggregates (Australian Standard2758.1 - 1985). Standards Association of Australia, 16 p .

Strange, P.J . & Shaw, R. (1986). Geology of Hong Kong Island and Kowloon.Geotechnical Control Office, Hong Kong, 134 p . (Hong Kong GeologicalSurvey Memoir No. 2) .

- 77 -

LIST OF TABLES

TableNo. No<

1 Modal Analysis of Fine- to Medium-Grained 78Granite from Ma Yau Tong

2 Description and Classification of Fine- to 79Medium-Grained Granite by the CADAM System

3 Petrographic Evaluation of the Ma Yau Tong 80Aggregates

i| Rock Index Properties of Fine- to Medium- 81Grained Granite from Ma Yau Tong

5 A Comparison of Aggregate Test Results from 82Ma Yau Tong with British Standard and OtherAcceptance Values

6 Test Results on Laboratory Crushed Granitic 83Aggregates (10-14 mm)

7 Aggregate Test Results from Anderson Road 84Quarries, 1975-1985 (from Choy & Irfan, 1986)

- 78 -

Table 1 - Modal Analysis of Fine- to Medium-GrainedGranite from Ma Yau Tong

Mineral

Thin Section 1

2

3

Average

Note : Thethin

Feldspars%

68.4(3.1)

68.5(3.4)

65.1(3.4)

67.3(3.3)

number in bracketssection

Quartz%

27.8

27-3

33.6

29.6

Biotite, MuscoviteChlorite

%

3.6

4.0

1.3

3.0

is the percentage of altered

Others%

0.2

0.2

0.0

0.1

feldspars per

Table 2 - Description and Classification of Fine- to Medium-Grained Granite by theCADAM System (Collis & Fox, 1985)

AGGREGATE

FORM

CLASS

{oxMISCELLANEOUS)

Pz&iotogJJicdL name[JLI known)


GRAIN SIZEriSSlLlTV

[l{ any)

CAuAh&d Rock

Ccu*iboncut(L>

NatiLKal

Chii^hdd

HJYOA

O r-l

hllxtd—

SJUUXMJUL Cla&i,

Igneous ^zcumzntaxyii / -MctamoxphsLC

Land won

[cofiAe.ct name, toh.z QAjv<in boXcM)

GRANITE

Mesozoic/Light p ink i sh grey/Fresh/Medium to Coarse-grained, equigranular/No fissibility

CompJJLzd by : T.Y. Irfan VaU : 21.8.1987SGE/EG, GCQ

CADAM - CLASSIFICATION a n d DESCRIPTION o f AGGREGATE MATERIAL

LOCATIONANVSAMPLEVETAILS

addh.QJ>h : Road Cut t ingbelow Ma Yau Tong Cont ro l led T ip ,

KowloonSampla : Typn

SlzaBlocks

kgVKHpaAcvUcn Lab. crushedSupp-tced bu -EG SectioT)

GnXd

Vata o&complyin17.9-85

VOJL<L Radd

SamplingCeAt. No.

Table 3 - Petrographic Evaluation of the Ma Yau Tong Aggregate

PETROGRAPHIC EVALUATION OF AGGREGATESSAMPLE REFLOCATION/GRO REF

SAMPLING DATE


Particle Shape (BS812;1975)

Surface Texture (Bo8i2;1975)

Coating

CleanRoess (Dust etc)




Minor Cons t i tuents

Cementing Materials

Expansive Minerals



GENERAL COMMENTS


3677EGO17Road Cutt ing below Ma Yau Tong ControlledTip 8**281O£ 8i9MfON17.9.1985

SAMPLE SIZE/WEIGHT

Bulk Sample ; 50 kg

Sub-sample : 1 kg (i0-1*f mm)

Mainly angular to i r regular , very few flaky and elongated

Crystalline

None

Clean

Fine- to Medium-grained GRANITE (gfra)

Quartz (29-6#)f Feldspars (67.390, Biotite ( 3.0%)

Chlorite, muscovite

Crystalline t no cementing minerals

None

Fresh

None

Granite i s equigranular, with grain size 0,5 to3.0 mm

Compiled by T.Y. Irfan

Date 21.8.1987

- 81 -

Table H - Rock Index Properties of Fine- to Medium-GrainedGranite from Ma Yau Tong

Rock Index Property

Mineral Grain Specific Gravity,

Bulk Density DrySaturated

Water Absorption

Porosity TotalEffective

Sonic Velocity

Point Load Strength

Legend :

n.d. Not determined.

+ Mean of 15 tests on

* Determined on 75 mm

g/cnH

g/cm^g/cm^

m/s

MPa

irregular lumps

diameter cores

Average

Value

n.d.

2.602.60

0.32

n.d.

0.83

3585*

8.2

Range

n

2.592

0

n.0.82

3540

5.1 -

(ISRM, 1985).

(ISRM, 1978)•

.d.

- 2.60.60

.32

d.- 0.84

- 3620

- 10.2

- 82 -

Table 5 - A Comparison of Aggregate Test Results from Ma Yau Tongwith British Standard and Other Acceptance Values

Aggregate PropertyTest Acceptance

Value* ValueUse Authority

Aggregate Crushing Value, ACV %

Aggregate Impact Value, AIV %

Los Angeles Abrasion Value, LAAV %

Water Absorption

Flakiness Index

Elongation Index

27 Max. 30

31 Max. 451

Max. 302

43 Max. 303

Max. 401*

Max. 35"*

0.4 Max. 3 1

13 Max. 3 5 :

28

C.R.

C.R.C.R.

C.C.

R.

C.R.

C.R.

Higginbottom(1976)

BS 882:1983BS 882:1983

AustralianStandard2758.1 (1985)

(1948)

Higginbottom(1976)

BS 882:1983

Notes :

1 - General use

2 - For wearing surfaces

3 . - Difficult conditions

C - Concrete aggregate

4 - Average conditions

5 - For C20 and over concrete grade

+ « Average of two t e s t r e s u l t s (10-14 mm)

R - Road aggregate

- 83 -

Table 6 - Test Results on Laboratory Crushed GraniticAggregates (10-14 mm)

AggregateProperty

Aggregate Crushing %Value

Aggregate Impact %Value

Los Angeles Abrasion %Value

Water Absorption %

Flakiness Index

Elongation Index

Medium-GrainedGraniteTurret Hi l l 1

23

24

29

0.5

7

41

Notes :

1. Test r e s u l t s from Irfan & Nash (1987)

2. Test r e s u l t s from Irfan (1987a).

3. Test r e s u l t s from Irfan (1987b).

Coarse-GrainedGraniteLai King2

23

25

31

0-3

11

34

•

Monzonite

Turret H i l l 3

18

12

22

"0.5

20

39

- 84 -

Table 1 - Aggregate Test Results from Anderson Road Quarries1975-1985 (from Choy & Irfan, 1986)

Aggregate Property



10? Fines kN

Water Absorption %

Relative Density g/crar

Flakiness Index, I %

Elongation Index, I %hi

Na?SGv Soundness %

K. WanQuarryGranite

30**(24-34)

28

(19-33)

145(120-200)

0.6(0.3-0.8)

2.60(2.58-2.62)

17(10-27)

35(26-41)

n.d.

PioneerQuarry-Granite

28**(23-30)

29(25-34)

126(100-150)

0.7(0.5-0.8)

2.60(2.57-2.61)

17(13-22)

34(22-42)

n.d.

Legend :

n.d. Not determined, number in parentheses indicate ranges of values.

** Test results from 1975 to 1977, all other test results 1980-1985-

- 85 -

LIST OF FIGURE

Figure pfge

No. N o -

1 Location Map Showing Geology of the Site 86and Adjacent Areas

- 86 -

- 87 -

LIST OF PLATES

plate PageNo. No•

1 General View of Sampling Locality (Road Cutting 88below Ma Yau Tong Controlled Tip)

2 Jointing Pattern in Fine- to Medium-Grained 88Granite

3 Block Sample 89

4 Crushed Rock Aggregate from Fine- to Medium-Grained 89Granite

5 photomicrograph 90

- 88 -

Plate 1 - General View of Sampling Locality (Road Guttingbelow Ha Yau Tong Controlled Tip)

Plate 2 - Jointing Pattern in Fine- to Medium-Grained Granite

- 91 -

SECTION 5 :AGGREGATE PROPERTIES OFFINE- AND FINE-TO MEDIUM-GRAINED GRANITESFROM ANDERSON ROAD

T.Y. Man & A. Cipullo

This report was originaUy produced as GCO Technical Note No. TN 11/87

- 92 -

FOREWORD

In order to help provide the Materials Divisionand the Hong Kong Geological Survey with much neededdata on the characterisation and possible usage ofeach of the Territory's major rock types the Officeinitiated the Fresh Rock Testing Programme in 1985.

This report forms part of the Fresh Rock TestingProgramme and is one of a series of reports whichpresents the results of selected aggregate and indexlaboratory testing carried out on fresh block samplesof discrete rock types.

The rock types described in this report are fine-and fine- to medium-grained granites from the PioneerQuarry, Anderson Road.

The authors wish to acknowledge the role playedin the field sampling and sample preparation by GEJ.M. Nash and TO M,K. Chan, in the laboratory testingby GE K.H, Lee and in the report production by M*W»Yuen (STO/EG). The cooperation and assistance of theMaterials Division is also acknowledged.

(Dr A.D# Burnett)Chief Geotechnical Engineer/Planning

- 93 -

CONTENTS

PageNo.

Title Page 91

FOREWORD 92

CONTENTS 93

1. INTRODUCTION 9*1


3. GEOLOGY 94

3.1 Site Geology 94


3.2.1 Fine-Grained Granite 95

3.2.2 Fine- to Medium-Grained Granite 96




4.3 Test Results 97




6. CONCLUSIONS 98

7. REFERENCES "

LIST OF TABLES 101

LIST OF FIGURES 112

LIST OF PLATES 115

1. INTRODUCTION

This report presents and discusses the results of selected physicalIndex and aggregate testing on laboratory crushed fine- and fine- tomedium-grained granite samples from the Pioneer Quarry, Anderson Road.The results are compared with the routine test values available on quarryrun material from the Pioneer Quarry and the suitability of both rocktypes as aggregate is assessed in comparison with the typical acceptancevalues for various uses.


The sampling site is at the northwestern part of the Pioneer Quarryalong Anderson Road, Kowloon (Figure 1, Plate 1). Quarrying operations atboth the Pioneer Quarry and the adjacent Ka Wah Quarry started as a numberof permit quarries pre-1960fs on the southwestern flank of an elongatehill (Tai Sheung Tok) rising up to 420 mPD (Figure 1). Large scale quarryoperation started at the western part of the site in 1962 by Ka Wah andthe contract for quarrying the eastern part of the site was let to Pioneerin 1974 by the Government. The current combined annual production is 3.0million tonnes.

Fine- and fine- to medium-grained granite block samples werecollected from the newly excavated rock stockpile on the 245 mPD platform(Plates 2 and 3). The exact location of the samples on the quarry face isnot known, but the majority of the rock in the stockpile is considered tocome from the faces above the platform (Plate 2).

The samples collected appeared to be typical and representative ofboth granite types occurring throughout the quarry• The currently workedfaces of the Pioneer Quarry are dominantly in fine-grained granite (Figure2) with fine- to medium-grained granite outcropping in the lower faces andthe quarry platform.

3. GEOLOGY

3.1 Site Geology

A detailed account of the geology and engineering geology of bothquarry sites is given in the Advisory Report ADR 12/86 "EngineeringGeology Studies for the Extension of Anderson Road Quarries" (Choy &Irfan,^ 1986) • The site is underlain by granite with volcanic rocksoccupying the summit region of Tai Sheung Tok. The granite-volcaniccontact crosses the uppermost quarry face in the Ka Wah Quarry (Figure 2).

The granite is grey to pinkish grey, equigranular, and generally ofgrain size of 1 to 4 ram along the lower reaches of the quarries* It isshown on the new geological map of Hong Kong and Kowloon (GCO, 1986) asfine- to medium-grained granite (gfta). This grades into a finer grainedI leas than 2 mm in grain size), inequigranular granite with scatteredporphyritic feldspar crystals (fine-grained granite, gf) towards thecontact with the pyroclastics. The granite generally contains smallamounts of muscovite and less than 5% biotite.

Two sets of faults cross the quarry sites in NHW-SSE and NE-SW

- 95 -

directions. Kaolin veins and. pyrite mineralization is present along thefault zones which indicates hydrothermal alteration of the granite alongthese lines of weakness prior to weathering (Choy, Earl, irfan & Burnett,1987). The joint spacing is variable over the site in the Ka Wah Quarrywhere the NNW-SSE trending major fault zone passes very close to thecurrent working quarry faces and the spacing is generally 0.5 to 1.5 m.In the Pioneer Quarry, the major faulted zone is well outside the currentworking limits or to the south and the discontinuity spacing is much widerexcept along the minor fault/shear zones where the spacing can be lessthan 0.3 m (Figure 2 ) .

At the northwestern corner of the Pioneer Quarry, from where thesamples were selected, the rock is generally slightly weathered. Pyritemineralization was observed along some faults and joints with pyritecrystals also occurring in the rock some distance from the faults.

Strange and Shaw (1986) described the geology of both granite typesoccurring in the Territory.


3.2.1 Fine-Grained Granite

(1) Engineering geological description. The rock is a very strong,light grey, crystalline, fresh to slightly decomposed, fine-grained (lessthan 2 mm) GRANITE with inequigranular and slightly megacrystic texture.

(2) Detailed description. The joint surfaces are stained lightyellowish brown with some migration of discoloration, up to 10 mm, intothe rock from the joint surface. Yellowish brown staining is also presentaround pyrite crystals scattered throughout the rock indicating slightdecomposition of pyrite.

The major constituents of the granite are quartz, plagioclase andalkali feldspars. Small amounts of biotite and muscovite and pyrite arealso present. Feldspars are milky white except near joint surfaces wherethey may be light pink in colour. Quartz forms about 32% of the rock and,biotite and muscovite less than 3%. The results of modal analysis carriedout on three thin sections are given in Table 1. The rock isinequigranular and slightly megacrystic. The finer groundmass has asgrain size of 0.1 to 1.0 mm with quartz and feldspar megacrysts up to 3mm. Occasional feldspar raegacrysts are up to 8 mm in grain size.

In thin section (Plates 4 and 5). some plagioclase and alkalifeldspars show slight alteration in the form of either partial replacementby or growth of individual muscovite flakes (muscovite also occurs as aprimary constituent). In addition, most plagioclases show slightalteration to minute serieite and clay minerals. Calcite was seen to beforming as decomposition product in one or two plagioclase grains. Thetotal amount of feldspar alteration is about 3.7* of the rock (Table 1).

The grain boundaries are tight and interlocking. Occasionalquartz-feldspar boundaries show iron-oxide staining. Microcracks are few(less than 1 per 10 mm) single, tight (less than 0.01 m in width) andgenerally intragranular in quartz and some feldspars. Very fewtransgranular mlcroeracks of longer length are present.

- 96 -

3.2*2 Fine- to Medium-Grained Granite

(a) Engineering geological description. The rock is very strong,light grey, crystalline, fresh to slightly decomposed, fine- tomedium-grained (1 to 4 mm) GRANITE with equigranular texture.

(b) Detailed description. The joint surfaces are stained lightyellowish brown with some migration (a few mm) of discoloration into therock from the joint surface. Slight decomposition of feldspars is evidentnear the joint surfaces. The feldspars are pink adjacent to one jointsurface in one of the block sanples indicating slight hydrothermalalteration.

The major rock constituents are quartz, plagioclase, alkali feldsparsand biotite. Quartz forms about 3Q% and biotite less than 555 of therock. The results of modal analyses carried out on three thin sections ofgranite are given in Table 2.

In this section (Plates 6 and 7) a few plagioclases and potashfeldspars show slight alteration in the form of either partial replacementby or growth of individual muscovite flakes, but the replacement is muchless intense than that of fine-grained granite (see Tables 1 and 2). Inaddition, most plagioclases show growth of minute flakes of sericite andclay minerals which may have formed as a result of weathering (Plate 7).The total feldspar alteration is about 6% of total feldspar content or3.6? of the rock.

Although most grain boundaries are tight, some quartz-feldsparboundaries are stained indicating movement of iron-oxide from biotitealteration along the slightly open grain boundaries. Transgranular aswell as intragranular microcracks exist with microcrack intensity being 2to 3 per 10 mm. Microcracks are simple, tight and generally less than0.02 mm in width; most are stained. Two thin micro-quartz veins wereobserved in one of the thin sections.



75 mm diameter cores were drilled from the block sanples using acoring machine in the Public Works Central Laboratory, Selected physicaland rock index tests were performed on the cores. The remainder of thesamples were broken into smaller pieces using a sledge hammer and alaboratory rock breaker. Point load testing was carried out on irregularlumps of rock using ISRM recommended method (ISRM, 1985)* Standard (10 to14 mm) and nominal 20 mm size aggregates (Plates 8 and 9) were preparedfrom the smaller pieces of rock using a laboratory jaw crusher.

The rock index tests undertaken included the determination of bulkdensity, porosity, water absorption, and sonic velocity using the PUNDITequipment (ISRM, 1978). The aggregate tests included aggregate crushingvalue (ACT) aggregate impact value (AIV), water absorption, flakiness(If) and elongation indices (I ) (BSI, 1975) and Los Angelas abrasionvalue (LAAV) (ASTM, 1981). **

- 97 -


The CADAM scheme recommended by the Geological Society Working Partyon Aggregates (Collis & Fox, 1985) is used to describe and classify theaggregates (Tables 3 and 4). A more detailed petrographic evaluation ofthe aggregates is given in Tables 5 and 6.

4.3 Test Results

The results of the rock index tests on cores and irregular lumps aregiven in Table 7. The aggregate test results are tabulated in Table 8.



The fresh to slightly decomposed fine-grained and fine- tomedium-grained granites tested from Anderson Road are both very strongrocks with point load strengths in excess of 7.5 MPa and 7.1 MParespectively corresponding to uniaxial strengths of 187.5 MPa and 177.5MPa using the normal conversion factor of 25. They both have very lowporosity and water absorption properties, less than 1.0/6 and 0.4?respectively (Table 7) and their densities are very similar. The slightdifference in their strength properties is also reflected in the seismicvelocities where a lower value of 3730 m/s was obtained on fine- tomedium-grained granite against 4518 m/s for fine-grained granite.

Strength and sonic velocity values of granites are both influenced toa great extent by the degree of microfracturing and decomposition of therock (Irfan & Dearman, 1978). The fine- to medium-grained granite in thisstudy has more raicrocracks (2 to 3 per 10 mm) compared to the fine-grainedgranite (about 1 per 10 mm) and consequently lower strength value; thedegree of decomposition measured by amount of feldspar alteration beingalmost the same for both granite types.

In terms of selected aggregate properties the fine-grained granitehas significantly lower and hence more desirable properties in comparisonwith those of the fine- to medium-grained granite (Table 8). Theaggregate properties of the latter rock are very similar to those of fine-to medium-grained granite from Mau lau Tong (Irfan, 1987a) in terms ofACV, AIV, LAAV, I. and water absorption value. The fine-grained granitefrom the Pioneer Quarry has the lowest and hence most favourable aggregatestrength and abrasion properties amongst the granitic rocks tested in thisstudy programme so far except for those of monzonite from Turret Hillwhere the rock tested was in fresh state (Table 9).

A comparison of the laboratory crushed aggregate test results withthe mean values of quarterly results available from PWC Laboratory onquarry run material from Anderson Road quarries (Table 10) show that thefine- to medium-grained granite has very similar properties in terms ofACV, AIV, I and water absorption whereas those of the fine-grainedgranite are superior* , •

- 98 -

5,2 Suitability of Rock as an Aggregate

A comparison of the limited laboratory test results with typical,mainly UK, aggregate acceptance values (Table 7) indicates that theproperties of aggregate produced from the fine-grained granite are wellwithin the acceptable limits for both general use in concrete and asroadstone. The low aggregate test values obtained in terms of AIV andLAAV suggest that this rock type may be suitable for some special purposessuch as wearing surface and high strength concrete whereas the fine- tomedium-grained granite has marginal values in terms of ACV, AIV and LAAVmaking it less desirable for special purposes when compared tofine-grained granite or basaltic rocks. A LAAV test value of 44 obtainedfor this granite type is just outside the maximum value of 40 specified bythe Australian Standard AS 2258 for concrete exposed to averageconditions.

Polished stone values, 10% fines values and chemical reactivity ofthe aggregates were not determined in this study.

The aggregates from Anderson Road quarries have been successfullyused for many years for general concrete purposes in Hong Kong, althoughfor some special uses volcanic rocks were considered (e.g. Kai Tak airportrunway). The aggregate test values reported in Table 10 are those of themean values of quarterly tests carried out in the PWC Laboratory for theyears from 1975 to 1985. In the original data no distinction was madebetween the various types of granites present in the quarry. Figure 2suggests that the bulk of the rock excavated for aggregate was from thefine-grained granite in the Pioneer Quarry. The majority of theproduction faces in the quarry are in the slightly weathered granite zonewith some moderately weathered granite along fault zones and higher levelsin the quarry (Choy & Irfan, 1986). The quarried material is thereforelikely to contain fresh and slightly decomposed granite as well as somemoderately decomposed granite (i.e. completely discoloured), which can besuitable if of high strength and low porosity. The rocks tested in thisstudy were fresh to slightly decomposed granite and came from the slightlyweathered zone in the quarry.

The samples collected from the fine-grained granite had pyritecrystals disseminated throughout the rock. Some forms of pyrites are ableto oxidise, with resultant expansion, when situated at or near concretesurfaces. This activity thus leads to the development or surface defectswith considerable staining of the surface by iron oxide• The surfacedeterioration is usually of no structural significance, but the unsightlyappearance may be undesirable (Collis & Fox, 1985).

6. CONCLUSIONS

The laboratory test results on laboratory crushed aggregates fromfresh to slightly decomposed fine-grained granite from the Pioneer Quarryare well within the commonly accepted limiting values for general use inconcrete and as roadstone, while those of fine- to medium-grained granitefrom the same locality are marginal in terms of ACV and AIV. The lowervalues make the fine-grained granite suitable for special uses such aswearing courses and heavy duty concrete floors. While the fine* tomedium-grained granite is still suitable for general concrete uses, high

- 99 -

aggregate strength test results near to the limiting values and a veryhigh LAAV value of 44 make the aggregates produced" from this rock typerather undesirable for some specific uses.

Although the bulk excavation for aggregate came from the fine-grainedgranite in the quarry, the average values obtained on quarry run materialare higher and near to the limiting acceptance values than thosedetermined on the samples chosen from the same granite type in this study.This is attributed to the fresher state of the rock used for laboratorytesting in this study than those normally used for producing aggregate inthe quarry. There is also variation in grain size even within the rockunit mapped as fine-grained granite in the vicinity of the quarry withgrain size becoming finer towards the contact with the volcanic rocks.

Field observations indicate that the quality of granite near thefault zones is affected by more intense differential weathering andearlier hydrothermal alteration. Pyrite is present in the rock adjacentto such zones of alteration. Pyrite may cause staining if oxidized at ornear concrete free surfaces; the surface deterioration is usually of nostructural significance.

7. REFERENCES


British Standards Institution (1983). British Standard Specification forAggregatesfromNatural Sources for Concrete (BS 882 : 1983)*British Standards Institution, London, 7 p.

British Standards Institution (1975). Methods for Sampling and Testing ofMineral Aggregates, Sands and Fillers (BS 812 : Parts 1 to 3).British Standards Institution.

Choy, H.H. & Irfan, T.Y. (1986). Engineering Geology Studies for the

Extension of the Anderson Road Quarries* GCO Report No. ADR 12/86,

71 p.

Choy, H.H,, Earle, Q.G., Irfan, T.Y. & Burnett, A.D. (1987). Studies forthe extension of a major urban quarry in Hong Kong. In : Culshaw,M.G., Bell, F.G., Cripps, J.C. & D. OrHara (eds). Planning andEngineering Geology. Engineering Geology Special Publication of theGeological Society, London, 4 (in press).

Collis, L. & Pox, R.A. (1985). Aggregates : Sand, Gravel and Crushed RockAggregates for Construction Purposes. ' Geological Society EngineeringGeology Special Publication No. 1. The Geological Society, London,

200 p*

Geotechnioal Control Office (1986). Hong Kong and Kowloon, Solid andSuperf ic ia l Geology (1 ; 20 000 map).• Hong Kong Geological SurveyMap Series HGM 20, Sheet 11, Geotechnieal Control Office, Hong Kong,1 map *

- 100 -

Higginbottom, I.E. (1976). Section 11.1. General requirements for rocksand aggregates." In Applied Geology for Engineers, H.M.S.O., 378 p.

International Society for Rock Mechanics (1978). Rock CharacterizationTesting and Monitoring* ISRM Suggested Methods (ed, E.T. Brown).Commission on Testing Methods, International Society for RockMechanics, Pergamon Press, 211 p.

International Society for Rock Mechanics (1985). Suggested method fordetermining point load strength. International Society for RockMechanics Commission on Testing Methods. International Journal ofRock Mechanics and Mining Sciences and Geomechanics Abstracts, vol.22, No. 2, pp 51-60.

Irfan, T.Y. (1987a). Aggregate Properties of Fine- to Medium-GrainedGranite from Mau Yau Tong. GCO Report No. TN 9/87, 24 p.

Irfan, T.Y. (1987b). Aggregate Properties of Monzonite from Turret HillQuarry. GCO Report No. TN 3/87, 24 p.

Irfan, T.Y. (1987c). Aggregate Properties of Coarse-Grained Granite fromLai King. GCO Report No. TN 4/87, 23 p.

Irfan, T.Y. & Dearman, W.R. (1978). The engineering petrography of aweathered granite in Cornwall, England. Quarterly Journal ofEngineering Geology, vol. 11, pp 233-244.

Irfan, T.Y. & Nash, J.M. (1987). Aggregate Properties of Medium-GrainedGranite from Turret Hill Quarry. GCO Report No. TN 2/81, 23 p.

Shergold, F.A. (1948). A review of available information on thesignificance of roadstone tests. Road Research Technical Paper 10.DSIR, H.M.S.O., London.

Standards Association of Australia (1985). Aggregates and Rock forEngineering Purposes, Part 1 - Concrete Aggregates (AustralianStandard 2758.1 - 1985). Standards Association of Australia, 16 p.

Strange, P.J. 4 Shaw, R. (1986). Geology of Hong Kong Island and Kowloon.Geotechnical Control Office, Hong Kong, 134 p. (Hong Kong GeologicalSurvey Memoir No. 2).

- 101 -

LIST OF TABLES

Table PageNo. No•

1 Modal Analysis of Fine-Grained Granite from the 102Pioneer Quarry

2 Modal Analysis of Fine- to Medium-Grained 103Granite from the Pioneer Quarry

3 Description and Classification of Aggregate 104from the Pioneer Quarry by the CADAM System(Fine-Grained Granite)

4 Description and Classification of Aggregate 105from the Pioneer Quarry by the CADAM System(Fine- to Medium-Grained Granite)

5 Petrographic Evaluation of Granite Aggregates 106from the Pioneer Quarry (Fine-Grained Granite)

6 Petrographic Evaluation of Granite Aggregates 107from the Pioneer Quarry (Fine- to Medium-GrainedGranite)

7 Rock Index Properties of Fine and Fine- to 108Medium-Grained Granites from the Pioneer Quarry

8 ' A Comparison of Aggregate Test Results from the 109

Pioneer Quarry with British Standard and OtherAcceptance Values

9 Test Results on Laboratory Crushed Granitic 110Aggregates

10 Aggregate Test Results from Anderson Road 111

Quarries, 1975-1985

- 102 -

Table 1 - Modal Analysis of Fine-Grained Granitefrom the Pioneer Quarry

Mineral

Thin Section 1

Thin Section 2

Thin Section 3

Average

Feldspars

%

60.3(2.1)

63.5(4.1)

69.6(4.9)

64.6(3.7)

Quartz

%

36.7

32.1

28.0

32.3

Biotite

%

0.8

0.6

1.3

0.9

Muscovite

%

2.1

3.5

0.7

2.1

Others%

0.1

0.2

0.3

0.2

Note : The number in brackets is the percentage of altered feldspars(kaolinite, sericite, etc.) per thin section.

- 103 -

Table 2 - Modal Analysis of Fine- to Medium-GrainedGranite from the Pioneer Quarry '

Mineral

Thin Section 1

Thin Section 2

Thin Section 3

Average

Feldspars%

56.8(3.7)

63.4(2.5)

59.5(4.7)

59.9(3.6)

Quartz

%

41.4

34.2

37.7

37.8

Biotite%

1.4

1.5

2.2

1.7

Muscovite

%

0.3

0.3

0.1

0.2

Others

%

0.0

0.3

0.3

0.2

Note : The number in brackets is the percentage of altered feldspars(kaolinite, sericite, etc.) per thin section.

Table 3 - Description and Classification of Aggregate from the Pioneer Quarry by the GADAM System (Fine-Grained Granite)

AGGREGATE

FORMCteuhzd Rock Cmuhad Ctu&lted

Itixtd

Lrt'JrT(*

CLASS[OK

MISCELLANEOUS)

Carbonate SUieata

Igneous Sadimiintan.il conAtctbe given

name to

'e£/iolog<icaZ name[<ll known) GRA1TITB


GRAIN SIZEFISS1L1TV

Mesozoic/Light grey/Fresh to slightly weathered/Medium grained/l?o fissili ty

Comment[i^ any] Contains pyrite crystals

CompUed by : . Irfan Vate : 5-11.1987

? GCO

CADAM - CLASSIFICATION and DESCRIPTION of AGGREGATE MATERIAL

LOCATIONkhfflSAMPLEVETA1LS

QuaHAiji

QpehakcSample

Kowloon'* : Pioneer: Typv

SizeVKepaSuppl

"Blocks50 kg

Koutwn h&1

led fat/ EG) • crusnedSection

8423103°82132011

Vote o&

Vate Rec'd

SamplingCenX. No.

Table 4 - Description and Classification of Aggregate from the Pioneer Quarry by the CADAM System (Fine-to Medium-Grained Granite)

AGGREGATE

FORMCmuhzd Rock Cmshtd

M-'C'X C.C!

Clashed

CLASS

MISCELLANEOUS)

CoAbonattClass Class

SUlcatzX name

be givtn below)

nam<il known]

GRASTTE

GEOLOGICAL AGE/COLOUR/GRAIW SIZE

Mesozoic/Light grey/Fresh to slightly weathered/Coarse grained, equigranular/ Wofissility

Commenti ij any)

Dhows sign of slight hydrothermal alteration

by : T.Y. Irfaai

SGE/EG, GCO

: 5*11*1987

CADAM - CLASSIFICATION and DESCRIPTION of AGGREGATE MATERIAL

LOCATIONAhlDSAMPLEPETAHS

: rioneer QuarryAnderson Road, .Kowldon

rioneerSample. :

Lao, crusnedSupplied by EG Section

34231OS

L sampling

Redd

SamplingCeM. Wo.

Table 5 -"Petrographio Evaluation of Granite Aggregates from the Pioneer Quarry (Fine-Grained Granite)

PETROGRAPHIC EVALUATION OF AGGREGATESSAMPLE REFLOCATION/GRID REF

SAMPLING DATE


Partfcte Shape (BS 812:1975)

Surface Texture CBS 812:1975)

Coating


'GEOLOGICAL PROPERTIES



Minor Cons t i tuen ts

Cementing Material

Expansrve Mine rate

Wsaifvering of Particles


GENERAL COMMENTS


3683 EGO23Pioneer Quany (Anderson Road)S4231OE 821320N

SAMPLE SIZE/WEIGHT

Bulk sample J 50 kgSub-sample s T kg (10-14 mm)

Angular to irregular

Crystalline

Hone

Slightly dusty

Pine-grained GHA1TITE (gf)

Quartz (33#)» Feldspars ( 6 ^ ) , Biot i te (<1^)

I^ r i t e ( 1#), Muscovite

Hone

I^rite may be deleterious

Generally fresh, some l i ^ i t l y discoloured (s l ight ly decomposed). Yellowish brown

Jfoneine^mgranular fabric, grain size 0.1 to 2 mm,occasional megaciysts up to 6 mm.

Compiled by T.Y. Irfan

D a t e 5.11.1987

TaT)le 6 - Petrographio Evaluation of Granite Aggregates from the Pioneer Quarry (Fine- to Medium-Grained Granite)

PETROGRAPHIC EVALUATION OF AGGREGATESSAMPLE REF

LOCATtOH/GRK) REF

SAMPLING DATE



Surface Texture {BS 812:1975)

Coating

CteanKness (Dust etc)

GEOLOGICAL PROPERTIESRock Type (GSS Classification)

Mineralogy

Major Constituents

Minor C o n s t i t u e n t s

Cementing Materials

Expansive Minerals



GENERAL COMMENTS


3680 BS020Pioneer Quarry (Anderson &oa&)84231OS 3213201?

SAMPLE SIZE/WEIGHTBulk Sample s 50 kgSub-sample % 1 kg (10-14 mm)

Angular to i r regular , ^ e w elongated

Crystal l ine

None

Clean

Fine- to medium-grained GRANITE (gfm)

Quartz (33$), Feldspars (6ofo), Biotite (c 2$>)

Muscovite

Ciystalline, no cementing minerals

NoneGenerally fresh, a few grains are lightly discoloured (slightly decomposed)• A fewshow signs of slight hvdrothermal alteration

ITone

Equigranular with g ra in s i me 1 t o 4 mm Compiled by T.Y. I r f an

Date 5.11»1987

- 108 -

Table 7 - Rock Index Properties of Fine- and Fine- to Medium-Grained Granites from the Pioneer Quarry

Rock Index PropertyFine-Grained

Granite(Range)

Fine- to Medium-Grained Granite

(Range)

Mineral Grain Specific Gravity, g/cnr

Bulk Density Dry g/cnr

Saturated g/cnr

Water Absorption

Porosity Total %Effective %

Sonic Velocity

Point Load Strength

m/s

MPa

n.d.

2.61(2.61-2-62)

2.62(2.62-2.63)

0.35(0.33-0.36)

n.d.0.90

(0.86-0.93)

4518*(4300-4700)

7.5+

n.d.

2.59(2.59)2.60(2.60)

0.37(0.37-0.38)

n.d.0.97

(0.97-0.98)

3730*(3660-3850)

7*10+

(4.5-11.5)

Legend :

n.d. Not determined.

+ Mean of 15 to 30 tests on irregular lumps (ISRM, 1985).* Determined on 75 mm diameter cores (ISRM, 1978).other index tests - average of 3 to 5 tests on cores*

Table 8 - A Comparison of Aggregate Test Results from the Pioneer Quarrywith British Standard and Other Acceptance Values

Aggregate Property+




Water Absorption %

Flakiness Index, Ip

Elongation Index, I p

Notes :

1 - General use2 - For wearing surfaces3 - Difficult conditions4 - Average conditions5 - For C20 and over concrete grade

Fine-GrainedGranite

21

15

28

0.58

26

31

+ .

C •R -

Fine- toMedium-GrainedGranite

29

27

44

0.65

13

44

- Average of

AcceptanceValue

Max 30

Max 451Max 30

Max 30^

Max 40Max 35

Max 31

Max 355

Use

C.R.

C.R.C.R.

C.C.R.

C.R.

C R .

2 test results- Concrete aggregate- Road aggregate

Authority

Higginbottom (1976)

BS882 : 1983BS882 : 1983

Australian Standard (1985)Australian Standard (1985)Shergold (1948)

Higginbottom (1976)

Higginbottom (1976)

oVO

- 110 -

Table 9 - Test Results on Laboratory CrushedGranitic Aggregates (10-14 mm)

AggregateProperty

Aggregate Crushing Value %

Aggregate Impact Value %

Los Angeles Abrasion Value %

Water Absorption %

Flakiness Index

Elongation Index

Fine- toMediumGrainedGraniteMau YauTong(Irfan,1987a)

27

31

43

0.4

13

28

Medium-GrainedGranite

TurretHill(Irfan &Nash, 1987)

23

24

29

0.5

7

41

Coarse-GrainedGranite

Lai King

(Irfan,1987c)

23

25

31

0.3

11

34

Monzonite

TurretHill(Irfan,1987b)

18

12

21.5

0.5

20

39

- 111 -

Table 10 - Aggregate Test Results from Anderson Road Quarries,1975-1985 (from Choy & Irfan, 1986)

Aggregate Property



10? Fines Value kN

Water Absorption, %

Relative Density g/cm

Flakiness Index, I_

Elongation Index, I_

Na SO. Soundness, %

' Ka WanQuarryGranite

30**(24-34)

28

(19-33)

145(120-200)

0.6(0.3-0.8)

2.60(2.58-2.62)

17(10-27)

35(26-41)

n.d.

PioneerQuarryGranite

28**(23-30)

29(25-34)

125(100-150)

0.7(0.5-0.8)

2.60(2.57-2.61)

17(13-22)

34(22-42)

n.d.

Legend :

n.d. Not determined, the number in brackets indicates

range of values.

** Test results from 1975 to 1977, all other test

results 1980-1985.

- 112 -

LIST OF FIGURES

Fifre PageN o - No.

1 Location Map Showing Geology of the Site njand Adjacent Areas

2 Engineering Geological map of the Anderson 114Road Quarries (from Choy & Irfan, 1986a)

- 115 -

LIST OF PLATES

Plate PageNo. No,

1 Anderson Road Quarries 116

2 The Sampling Locality 117

3 Block Samples Being Selected From the Stockpile 117

4 Photomicrograph of Fine-Grained Granite 118

5 Photomicrograph of Fine-Grained Granite 118

6 Photomicrograph of Fine- to Medium-Grained 119Granite

7 Photomicrograph of Fine- to Medium-Grained 120Granite

8 Fine-Grained Granite Aggregate 121

9 Fine- to Medium-Grained Granite Aggregate 121

- 123 -

SECTION 6 :AGGREGATE PROPERTIES OFMEDIUM- GRAINED GRANITEFROM DIAMOND HILL

A. Cipullo & T.Y. Man


- 124 -

FOREWORD

In order to help provide the Materials Divisionand the Hong Kong Geological Survey with much neededdata on the characterization and possible usage of eachof the Territory's major rock types, the Officeinitiated the Fresh Rock Testing Programme in 1985.

This report forms part of the Fresh Rock Testingprogramme and is one of a series of reports whichpresents the results of selected aggregate and indexlaboratory testing carried out on fresh block samplesof discrete rock.types.

The rock type described in this report is medium-grained granite from the Diamond Hill Quarry.

The authors wish to acknowledge the role played inthe field sampling and sample preparation by J,MU Nash(GE) and M,K. Chan (TO), and in the report productionby M.W. Yuen (STO/EG). The cooperation and assistanceof the Materials Division is also acknowledged.

A.D. BurnettChief Geotechnical Engineer/Planning

- 125 -

CONTENTS

PageNo.

123

124

125

126

126

126

126

127


4.1 Sample P repa ra t ion and Testing Methods 127

4.2 C l a s s i f i c a t i o n and Charac ter iza t ion of Aggregate 128

5. DISCUSSION ON TEST RESULTS 1 2 8

5.1 Rock Index and Aggregate Proper t ies 128

5.2 Suitability of Rock as An Aggregate 128

6. CONCLUSIONS 129

7. REFERENCES • 129

LIST OF TABLES 131

LIST OF FIGURES 139

LIST OF PLATES

1.

2.

3.

Title Page

FOREWORD

CONTENTS

INTRODUCTION

SITE DESCRIPTION AND

GEOLOGY

3.1 Site Geology

3.2 Description of

SAMPLING

Test Sample

- 126 -

1. INTRODUCTION

This report presents and discusses the results of selected physicalindex and aggregate testing on laboratory crushed medium-grained granitesamples from the Diamond Hill Quarry. The results are compared with theroutine test values available on quarry run material and the suitability ofthe rock as aggregate is assessed in comparison with the typicalacceptance values for various uses.


The Government quarry site was located on the west facing flank of anorthwest-southeast trending hill, rising up to 180 mPD. (Tsuen Shek Shan(Figure 1, Plate 1). Original quarrying operations started in 1952 on thesouthern side of the hill as a private permit quarry.

Government quarry operations at the western end (Plate 2) commenced in1962 and production of aggregates ceased by the end of 1986. The quarrysite has since been incorporated in a major redevelopment project whichwill result in the removal of most of the original hill and the formationof a number of platforms for residential purposes. Production ofaggregates from the excavated rock material will continue during siteformation works.

Medium-grained granite block samples were collected from the newlyexcavated lower quarry face and were typical and representative of the rockmaterial occurring throughout the quarry (Plate 2).

3. GEOLOGY

3.1 Site Geology

The new Sheet 11 of the geological map series of the Hong KongGeological Survey (GCO, 1986) shows the quarry area to be underlain bymedium-grained granite (gfta) of Mesozoic Age (Figure 2). The granite atthis site is light grey with average grain size of 3 to 5 mm, comprisingsubhedral interlocking grains of quartz, alkali feldspars, subordinatewhite plagioclase grains and with biotite generally making up only 2% to 3%of the rock (Strange & Shaw, 1986).

No major faults cross the site and joints are predominantly verticalto subvertical, striking mainly northwest-southeast and generally medium towidely spaced.

One large composite basalt dyke, about 7 m wide, cut subverticallythrough the granite in a ENE direction at the southern end of the site(Plate 1). The mostly subvertical narrow ehloritized veins observed inparts of the quarry faces (Plate 3) are thought to result from hydrothermalalteration which has also affected the basalt dyke. Strange 4 Shaw (1986)give a detailed description of the mineralogical composition and texture ofboth the medium-grained granite occurring in the" Kowloon area and thebasalt intrusion at the quarry site.

- 127 -


(a) Engineering geological description. The rock isvery strong, light grey, crystalline, fresh,medium-grained GRANITE, with average grain size of3 to 5 mm and inequigranular texture.

(b) Detailed description. The major mineralconstituents of the granite are quartz,plagioclase and alkali feldspars. Small amountsof biotite and occasional accessory pyrite grainsare also present. Alkali feldspars are 2.5 to 5mm in size, cloudy in polarized light and mostlymicroperthitic. The sodic plagioclase patches andlenticles are partly chloritized and altered tosericite and clay minerals. Plagioclases are 1.5to 2 mm in size, cloudy, some with partialalteration to sericite and clay minerals. Quartzgrains are, on average, 1.5 to 3 mm in size withoccasional individual grains up to 5 mm. Biotitegrains are 2 to 4 mm in size, partiallychloritized and with alteration rims and minorsegregation along cleavage planes. Isolated small(< 1 mm) grains of opaque mineral (magnetite ?)were observed in one thin section. Mineral grainsare subhedral with tight, mostly unstained andinterlocking boundaries. Hairline cracks arelimited to quartz grains, mostly intragranular,tight and unstained with occasional, partialextension into adjacent grains.

The results of modal analysis carried out on threethin sections are given in Table 1 and show thatfeldspars and quartz are the predominant mineralsforming, respectively, about 57? and 4035 of therock. Plates 4a and 4b are photomicrographsshowing typical mineral texture and extent ofalteration.



Cores of 50 mm and 75 mm diameter were drilled from the block samplesusing a coring machine at the Public Works Central Laboratory. Selectedphysical and rock index tests were performed on the cores. The remainderof the samples were broken into smaller pieces using a sledge hammer and alaboratory rock breaker. Standard (10 to 14 mm) and nominal 20 mm sizeaggregates were prepared from the smaller pieces of rock using a laboratoryjaw crusher*

The rock index tests undertaken included the determination of bulkdensity, porosity and water absorption. Sonic velocity using the PUNDITequipment (ISHH, 1978) and point load strength testing on irregular lumpsof rock (ISRM, 1985) were also carried out. The aggregate tests included

- 128 -

the determination of aggregate crushing value (ACV), aggregate impact value(AIV), water absorption, flakiness (Ip) and elongation indices ( Ig ) , tenpercent fines value, re la t ive density (BSI, 1975) and Los Angeles abrasionvalue (LAAV)USTM, 1981).


The CADAM scheme recommended by the Geological Society Working Partyon Aggregates (Collis & Fox, 1985) i s used to describe and c lass i fy theaggregates (Table 2) . . A more detailed petrographic evaluation of theaggregates is given in Table 3 .

5- DISCUSSION ON TEST RESULTS

5.1 Rock Index and Aggregate propert ies

The resu l t s of rock index t e s t s carried out on the selected samplesare presented in Table 4 and indicate that the medium-grained gran i te fromDiamond Hill i s a strong rock with an average point load s t rength value of6.5 MPa (corresponding to uniaxial strength of 162.5 MPa using a conversionfactor of 25) and very low porosity and water absorption p rope r t i e s . Thest rong nature of the rock i s also reflected in the high value of themeasured sonic veloci ty .

The"results of t e s t s on laboratory crushed aggregates are presented inTable 5* A comparison of these resu l t s with the mean values of resu l t sava i l ab l e from Public Works Central Laboratory on quarry run material(Table 6) show that AIV, ACV, Ip, Ig and water absorption determined inthe laboratory are s l igh t ly lower while re la t ive density and 1056 FinesValues are s imi la r . The PSV (polished stone value) shown in Table 6 refersto one t e s t only and i t does not allow for s ignif icant comments.

In terms of index properties the medium-grained grani te from DiamondHill has similar values to the medium-grained grani te from Turret HillQuarry (Irfan & Nash, 1987) only in terms of bulk density while exhibit inglower porosity and water absorption propert ies . However i n terms of bothlaboratory and quarry run t e s t s on aggregates the medium-grained grani tefrom Turret Hil l Quarry has generally superior cha rac t e r i s t i c s except forre la t ive density and water absorption where the t e s t values are s imi la r .This i s probably due to the r e l a t i v e l y higher s t a t e of hydrothermaldecomposition of the feldspars in the Diamond Hill g ran i t e ,

5 # 2 Sui tabi l i ty of Rock As An Aggregate

A comparison of the limited laboratory t e s t r e su l t s with typ ica l ,mainly UK, aggregate acceptance va lues (Table 7) i n d i c a t e that theproperties of laboratory produced aggregate are generally within or a t thel imit of the acceptable values for both general use in concrete and asroadstone. The lower than required 10* Fines Value and AIV suggest thatth is rock type i s not suitable for special purposes such as high strengthconcrete and heavy duty concrete floor f in ishes . The LAAV of 41, althoughjus t above the required value, may be acceptable for general concretepurposes but i t i s well outside the maximum values specified for concrete

a

- 129 -

exposed to severe conditions. However as the value is derived from *single test it would need to be confirmed by additional tests although theAIV would seem to be in agreement with the above limitation.

The aggregates from Diamond Hill Quarry have been successfully usedfor many years for general concrete purposes in Hong Kong. The as/resatetest values presented in Table 6 are mean values of tests carried out onquarry run material at the Public Works Central Laboratory over the periodfrom 1972 to 1985. The AIV is well below the maximum value acceptable ingeneral use concrete as is the ACV, but just above that for wearingsurfaces and well in excess of the maximum required for severe conditionsThe 10% Fines Value supports this limitation.

6. CONCLUSIONS

The laboratory test results on laboratory crushed aggregates fromfresh, medium-grained granite from the Diamond Hill Quarry are generallywithin the commonly accepted limiting values for general use in concreteand as roadstone.

The mean values of aggregate tests on quarry run material alsoindicate the suitability of this rock for general use and confirm thelaboratory test results which indicate that the near or above limitingvalues for ACV and AIV makes the aggregate produced from this rock typeless suitable for specific uses such as wearing courses and heavy dutyconcrete floors.

A comparison with the properties of laboratory produced and quarry runaggregates of medium-grained granite from Turret Hill Quarry indicatesthat the aggregate produced from Diamond Hill Quarry is of slightlyinferior quality. This is probably attributable to the relatively higherstate of alteration of the Diamond Hill granite and also slightly largergrain size revealed by the petrographic analysis.

No soundness tests to determine the durability of the aggregate werecarried out, for the reason that the rock tested was basically fresh andthe aggregates from fresh granites are known to be durable. However it isrecommended that soundness tests be carried out if the proportion ofdiscoloured and/or altered rock in significant.

7. REFERENCES

American Society for Testing and Materials (1981). Test for resistance toabrasion of small size coarse aggregate by use of the Los Angelesmachine* Test Designation C131-81. 1981 Annual Book of ASTMStandards. .American Society for Testing and Materials. '

British Standards Institution (1983). British Standard Specification forAggregates from Natural Sources for Concrete (BS 882 : 1983)* BritishStandards Institution* London, 7 p.

British Standards Institution (1975). Methods for Sampling and Testing ofMineral Aggregates, Sands and Filters (BS 812 : Parts 1 to 3), BritishStandards 'Institution* ' '" • ' ' ' • • ' ' •

- 130 -

Collis, L. & Fox, R.A. (1985). Aggregates : Sand, Gravel and Crushed RookAggregates for Construction Purposes. Geological Society EngineeringGeology Special Publication No. 1, The Geological Society, London,200 p.

Geotechnical Control office (1986). Hong Kong and Kowloon, Solid andSuperficial Geology (1 : 20 000 map). Hong Kong Geological Survey MapSeries HGM 20, Sheet 11, Geotechnical Control office, Hong Kong, 1map.

Higginbottom, I.E. (1976). Section 11.1. General requirements for rocksand aggregates. In Applied Geology for engineers, H.M.S.O., 378 p.

International Society for Rock Mechanics (1978). Rock CharacterizationTesting and Monitoring. ISRM Suggested Methods" (ed. E.T. Brown).Commission on Testing Methods, International Society for RockMechanics, Pergamon Press, 211 p.

International Society for Rock Mechanics (1985). Suggested method fordetermining point load strength. International Society for RockMechanics Commission on Testing Methods. International Journal ofRock Mechanics and Mining Sciences and Geomechanics Abstracts, vol.22, No. 2, pp 51-60.

Irfan, T.Y. & Nash, J.M. (1987). Aggregate properties of Medium-GrainedGranite from Turret Hill Quarry. GCO Report No. TN 2/81, 23 p.

Shergold, F.A. (1948). A review of available information on thesignificance of roadstone tests. Road Research Technical paper 10.DISIR, H.M.S.O., London.

Standards Association of Australia (1985). Aggregates and Rock forEngineering Purposes. Part 1 - Concrete Aggregates (AustralianStandard 2758.1 - 1985). Standards Association of Australia, 16 p.

Strange, P.J. & Shaw, R. (1986). Geology of Hong Kong Island and Kowloon.Geotechnical Control Office, Hong Kong, 134 p. (Hong Kong GeologicalSurvey Memoir No. 2).

- 131 -

LIST OF TABLES

Table PageNo. Mo.

1 Modal Analysis of Medium-Grained Granite 132from Diamond Hill Quarry

2 Description and Classification of Aggregate 133from Diamond Hill Quarry by the CADAM System

3 Petrographic Evaluation of Granite Aggregate 134from Diamond Hill Quarry

4 Rock Index Properties of Medium-Grained Granite 135from Diamond Hill

5 Test Results on Laboratory Crushed Aggregates 136from Diamond Hill

6 Aggregate Test Results from Diamond Hill Quarry, 137

1972-1985

7 A Comparison of Aggregate Test Results from the 138Diamond Hill Quarry with British Standard andOther Acceptance Values

- 132 -

Table 1 - Modal Analysis of Medium-Grained Granitefrom Diamond Hill Quarry

Mineral

Thin Section 1

Thin Section 2

Thin Section 3

Average

Note : The number in(sericite andchlorite)

Feldspars

%

61.(5.

60.(8

48(3

56(5

48)

.3

.1)

.3

.3)

.7

.7)

brackets is theclay minerals)

Quartz

%

36.3

35.6

48.9

40.3

percentageand altered

Biotite%

2(0.1)

4.1(0.4)

2.6(1.2)

2.9(0.6)

Others

%

0.1

0.2

0.0

0.1

of altered feldsparsbiotite (mainly

Table 2 — Description and Classification of Aggregate from Diamond Hill Quarrytry the CADAM System (Collis & Fox, 1985)

Table 3 - Petrographic Evaluation of Granite Aggregate from Diamond Hill Quarry



SAMPLING DATE



Surface Texture {BS 812:1975}

Coating



Rock Type {GSS Classffication)

Mineralogy

Major Constituents

Minor Cons t i tuen ts

Cementing Materials

Expansive Minerals



GENERAL COMMENTS


3696 20036Diamond Hill Quarry/83B8OOE, 822750K

May 1966

SAMPLE SIZE/WEIGHT

Bulk bample %) kg

Sub-Bample 1 kg (10-14 mm)

Kainly angular and irregular, few elongated and flaky

Crystalline

Hone

Clean

fcediuE - grained (2UKITE (gss)

Alkali and Plagioclose Feldspars (56«7/*)t ^uarts (40.3^)1 Biotite (2.9>)

Caaorite, Occasional fin© grains of magnetite

Crystalline| uo oecieating material

None

R*#sh, no staining

Kone

Graaite is inequigxanular with grain size j to 5 21; and occasionalindividual feldspars up to a maximum 10 mir.

Compiled by A. cipuiio

Date 21.4-1988

- 135 -

Table 4 - Rock Index Properties of Medium-GrainedGranite from Diamond Hill

Rock Index Property

Mineral Grain Specific Gravity g/cm3

Bulk Density Dry g/cm3Saturated g/cm3

Water Absorption %

Porosity Total %Effective %

Sonic Velocity m/s

Point Load Strength, Is(50) ^Pa

Legend :

+ Determined on 75 mm diameter cores (

AverageValue

n.d.

2.612.61

0.3

n.d.0.7

4420+

6.5*

1SRM, 1978).

Range

n.d.

2.60-2.612.61-2.62

0.2 - 0.3

0.6 - 0.7

3700-4800

5.2 -7.6

* Average of 17 tests on irregular lumps (ISRM, 1985).

n.d Not determined.

Other index tests - Average of three tests on cores.

- 136 -

Table 5 - Test Results on Laboratory Crushed Aggregates (10-14 mm)from Diamond Hill

Aggregate Property




Water Absorption

Flakiness Index,

Elongation Index,

1056 Fines Value

Relative Density (SaturatedSurface Dried)

Legend :

* Size fraction tested 10-4

+ One Test

ACV %

AIV %

LAAV* %

*

iv* %

and g/cm3

•75 mm - One Test

Test Value

29

29

«,

0.5

8

30

108

2.62

- 137 -

Table 6 - Aggregate Test Results from Diamond HillQuarry, 1972-1985 (20 mm aggregate)

Aggregate Property

"\0% Fines Value

Aggregate Impact Value, AIV

Aggregate Crushing Value, ACV

Aggregate Abrasion Value, AAV

Water Absorption

Flakiness Index, Ip

Elongation Index, Ig

Relative Density (Saturated andSurface Dried)

Polished Stone Value, PSV+

Legend :

+ One test on 10 mm aggregate

n.d. Not determined

kN

%

%

%

%

%

%

g/cm3

%

Test Value(Range)

104(90-110)

33(28-36)

31(28-36)

n.d.

0.73(0.6-0.8)

14(9-19)

52(39-64)

2.60(2.59-2.66)

52

Table 7 - A Comparison of Aggregate Test Results from the Diamond HillQuarry with British Standard and Other Acceptance Value

Aggregate Property

10% Fines Value KN




Water Absorption %

Flakiness Index, Ip

Elongation Index, I E

Notes :1 - General use2 - For wearing surfaces3 - Difficult conditions4 - Average conditions5 - For C20 and over concrete grade

Medium-GrainedGranite

108

29

29

41

0.5

8

30

AcceptanceValue

Min 1002

Min 1503

Max 30

Max 451

Max 302

Max 253

Max 303Max 40^Max 351

Max 31

Max 355

C - Concrete aggregateR - Road aggregate

Use

C.C.

C.R.

C.R.C.R.

C.C.R.

C.R.

C.R.

Authority

BS 882 : 1983

Higginbottom (1976)

BS 882 : 1983BS 882 : 1983BS 882 : 1983

Australian Standard (1985)Australian Standard (1985)Shergold (1948)

Higginbottoffl (1976)BS 5337 : 1976

BS 882 t 1983

OO

- 139 -

LIST OF FIGURES

Figure Page

No. No.

1 Location Map 140

2 Geology of the Site and the Adjacent Areas 141

- 141 -

- 142 -

LIST OF PLATES

Plate PageNo. No.

1 General View of the Former Quarry Area -j43Looking Southeast and Showing the BasaltDyke Intrusion

2 Sampling Locality Showing the General Joints 143Distribution

3 Close-up View of the Sampling Locality Showing 144Subvertical Chloritized Veins

4 Photomicrographs of Medium-Grained Granite 145

- 147 -

SECTION 7 :AGGREGATE PROPERTIES OFFINE-, MEDIUM-, ANDMEGACRYSTIC GRANITESFROM LAMMA ISLAND

T.Y. Man


- 148 -

FOREWORD

In order to provide industry and Government withreliable and high quality test data concerning the indexand aggregate properties and possible uses of each of theTerritory's major rock types, the Geotechnical ControlOffice initiated the Fresh Rock Testing Programme yi 1985.


The rock types described in this report are the fine-grained, medium-grained and megacrystic granites from thePok Tung Wan Quarry, Lamma Island.

The testing was carried out under the supervision ofDr T.I. Irfan when he was Senior GeotechnicalEngineer/Engineering Geology Section and the report waswritten after he moved to the Special Projects Divisionin April, 1981.

The assistance of the technical staff of theEngineering Geology Section with the field sampling andsample preparation and the staff of the Materials Divisionwith the testing is acknowledged.


- 161 -

Table 3 - Classification, Description and Petrographic Evaluation ofAggregate Produced from the Medium-Grained Granite

- 162 -

Table 4 - Classification, Description and Petrographic Evaluation ofAggregate Produced from the Megacrytic Granite

AGGREGATE

FOPM

CLASS[on.

MISCELLANEOUS)

Pz.tAolog.ical name[.Ifi known)


GRAIN SIZEF1SS1L1TV j

Corme.nl{i& any]

Ca,xbonaX:z jCfa-44

QiuuUCZa.64

Giavzt

HaXiiAat

C-nuAlizd

hlixzd

Sand

Natunat

Ciu-ihed

Uxzd

S-U-ica.Cz CLa.46

Igntoui J Szdbntn-taiu Mitamonphic

Land-voon

Vizdgzdy.iACZCkanilQuiiMatzxiaticotAzct name.bt qivzn bef

toowl

GRANITE

Mesozoic/Light pinkish grey to dark grey/Medium to coarse-grained/Megacrystic/Fresh to plightly Decomposed/No fissi'.ity.

Variable texture and grain size, contains over 10% of dark ferromagnesian minerals.

Compiled by T.Y. Irfan 6.9.1989

CADAM - CLASSIFICATION and DESCRIPTION of ACCRECATE .MATERIAL

LOCATIONAW

PETAUS

OuaAALj/P.lt adfazu .ypok Tung Wan.

IslandOptACLtoi :Sample. : Ttjpz Blocks

50 legb . crushedSection

Gtid

tempting

Vtutz Rcc'rf

SamptingC

EG042


SAMPLE REFLOCATION/GRtt) REF

SAMPLING DATE

/EGO 42Pok Tung Wan Q u a r r y , Lamma I s l a n d

1985

SAMPLE &I2E/WEIGHT

About 25 kg of bulk sample - processed toaggregate in laboratory (10-14 mm)


?artteto$hap« {BS 812:1975) Angular to irregular

Surface Texture (BS 812:1975) Crystalline

Coating

CleanQrmss (Dust etc) Clean


Rock Type (GSS Classification) Megacrystic fine- to medium-grained GRANITE (g£w)

Mineralogy Megacrysts of feldspars compose 20-30% of the rock

Major Constituents

Minor Constituents

Quartz (22 to 31%) , Feldspars (65 to 67%) , Siotit® (2 to 20%)

Magnetite, hornblende ( 28), sphere, se r i c i t e

Cementing Materials

Expansive Minerals

Weathering of Particles Generally fresh, some are slightly

Drgank: Material Content

GENERAL COMMENTS InequiciranuJiar and variable fabric with fold«p«rmegacrysts (up to 10 mm) set in a finer qraintd

ADDITIONAL INFORMATION Biotite rich areas are dark qrey coloured Andin composition

Compiled by T\Y.

Data fi.*).

- 163 -

Table 5 - Rock Index Properties of Granites fromPok Tung Wan Quarry, Lamina Island

Rock Index PropertyFine-GrainedGraniteEG040

Medium-GrainedGraniteEG041

MegacrysticGranite

EG042

Mineral Grain Specific Gravity, Mg/m^

Bulk Density Dry Mg/nH

Saturated

Water Absorption

Porosity

Sonic Velocity

Schmidt Hammer Value

Total %Effective %

m/s

1

Point Load Strength2 MPa

n.d.

2.60(2.59-2.61)

2.61(2.60-2.61)

0.25(0.23-0.29)

n.d.0.65

(0.59-0.76)

4605(4460-4710)

60(58-61)

11.2

n.d.

2.62(2.62-2.62)

2.63(2.62-2.63)

0.19(0.17-0.21)

n.d.0.50

(0.45-0.55)

5235(5050-5350)

57(57-58)

5.6

n.d.

2.60(2.60-2.62)

2.61(2.61-2.62)

0.16(0.10-0.25)

n.d.0.41

(0.26-0.65)

5020(4840-5220)

59(59-60)

7.8

Notes :1 Determined on blocks

2 Determined on irregular lumps, average of 20-35 tests

( ) Range of valuesOther index tests - average of 3 to 5 tests on cores.

Table 6 - A Comparison of Aggregate Test Results on Granites from Pok Tung Wan QuarryOther Granites and Acceptance Values

Aggregate Property



Los Angeles Abrasion Value, %LAAV

10$ Fines Value kN

Water Absorption %

Fiaklness Index, IF

Elongation Index, IE

Fine- Medium-Grained Grained MegacrysticGranite Granite Granite

16 25 19*

20 27 20

22** 33** n.d.

210 140 n.d.

0.8 0.6 0.5

26* 17* 21*

38* 26* 145*

OtherGranites(FRTP)

21-29

15-31

28-44

100-200

0.3-0.7

7-26

28-44

AcceptanceValue

Max 202

Max 301

Max 20^'5

Max 302

Max 402

Max 451

Max 305

Max 35*

Max 403

Max 351

Min 501

Min 1002

Min 1506

Max 31

Max 3Max I^* 5

Max 2511'5

Max 35

Max 3011'5

Use

C.C.R.

C.C.R.C.C.R.

C.

C.

C.

R.

C.c.c.

C.R.C.C.

c.C.R.

C.

Authority

Higginbottom (1976)Higginbottom (1976)

Fookes (1984)BS 882 (1983)ASTM C-131BS 882 (1983)

Australian Standard(1985)Australian Standard(1985)Australian Standard(1985)Shergold (1948)

BS 882 (1983)BS 882 (1983)BS 882 (1983)

Higginbottom (1976)BS 5337 (1976)Fookes (1984)

Fookes (1984)BS 882 (1983)

Fookes (1984)

Notes : C, = Concrete R, = Roadstonen.d, = Not determined* = One test result, others average of two tests** = On 5-10 mm aggregate, others on 10-1*1 mm aggregateFRTP = Fresh Rock Testing Programme (see references in this report for detailed results)1. = General use 4. = Moderate exposure2. = Wearing surfaces 5. = Severe exposure3. = Protected concrete 6. = Heavy duty concrete

- 165 -

Table 7 - Test Results on Quarry Crushed Aggregate (20 mmAggregate) from Pok Tung Wan Quarry, 1981-1986

Aggregate Property-



10% Fines Value

Water Absorption

Relative Density

Flakiness Index,

Elongation Index,

ACV

AIV

h

h

Notes :n.d. not determined1 6 series of tests, 19812 Average of 2 series of( ) Range of test values

%

%

kN

%

Mg/m3

%

%

PW CentralLaboratory

n.d.

17

215(190-260)

0.7(0.6-0.9) •

2.61(2.60-2.62)

11(6-16)

30(22-45)

to 1986tests carried out in 1986

Contractor'sLaboratory^

21

n.d.

180

0.7

2.63

15

19

- 166 -

LIST OF FIGURES

Figure p a g e

No. No,

1 Location Map Showing Geology of the Sampling 167Site and the Adjacent Areas

2 Engineering Geological Map of the Pok Tung Wan 168Quarry (from Choy & Irfan, 1986)

- 169 -

LIST OF PLATES

Plate Page

No. * No.

1 Pok Tung Wan Quarry 170

2 Hand Specimen of the Fine-Grained Granite 171

3 Hand Specimen of the Medium-Grained Granite 172

4 Hand Specimen of the Megacrystic Granite 173

5 Core Specimens of the Fine-Grained, the 174Medium-Grained and the Megacrystic Granites

6 photomicrograph of the Fine-Grained Granite 175

7 Photomicrograph of the Medium-Grained Granite 176

8 photomicrograph of the Megacrystic Granite 177

- 179 -

SECTION 8 :AGGREGATE PROPERTIES OFVOLCANIC ROCK TYPESFROM 'SPUN' SITES ATMOUNT DAVIS AND CHAI WAN

A. D. Burnett


- 180 -

FOREWORD

In order to help provide the Materials Divisionand the Hong Kong Geological Survey of the GeotechnicalControl Office with much needed data on thecharterisation and possible usage of each of theTerritory's major rock types the Office initiated theFresh Rock Testing Programme in 1985.

This report forms part of the Fresh Rock TestingProgramme and is one of a series of reports whichpresents the results of selected aggregate and indexlaboratory testing carried out on fresh block samplesof discrete rock types.

The two sites selected for sampling on thisoccasion were from the 'SPUN' Project which isinvestigating the potential use of underground space inHong Kong. These two potential cavern sites are bothvery likely to be within volcanic bedrock.

The rock types involved and described in thisreport are fine and coarse ash crystal tuffs andeutaxites from the two 'SPUN1 sites at Chai Wan andMount Davis.

The author wishes to acknowledge the role playedin the field sampling and sample preparation by GEP.G.D. Whiteside and TO C,C. Mak, in the laboratorytesting by GE T. Fung and in the report production byM.W. Yuen (STO/EG). The cooperation and assistance ofthe consultants for the fSPUNf Project, Ove Arup andPartners, is also acknowledged.


- 181 -

CONTENTS

PageNo.

Title Page 179

FOREWORD 180

CONTENTS 181

1. INTRODUCTION 182


2.1 Chai Wan 182

2.2 Mount Davis 183

3. GEOLOGY 183

3.1 Chai Wan 183

3.1*1 Site Geology 183

3«K2 Description of Bedrock Samples * 184

3*2 Mount Davis . 185

3.2.1 Site Geology 185

3.2.2 Description of Bedrock Samples 185




4.3 Test Results 187

5. DISCUSSION ON TEST RESULTS " l 8 7


5.2 Suitability of Rocks as Aggregate * 1 8 8

5*3 Recommendations for Further Tests 189

6. CONCLUSIONS 1 8 9

18Q

7. REFERENCES

LIST OF TABLES 1 9 1

LIST OF FIGURES 1 9 7

205LIST OF 'PLATES . • • • • . • ' : • • . . ;.' •

- 182 -

1. INTRODUCTION

The Geotechnical Control Office initiated the Fresh Rock Testingprogramme (FRTP) in 1985 in order to produce reliable and much needed highQuality data on the index and aggregate characterisation properties andpossible usage of each of the major rock types of the Territory.

The Programme, which is ongoing, involves selecting and sampling sitescontaining typical and representative members of a particular individualor suite of rocktypes. The fresh (unweathered) block samples are thencrushed to form aggregate or otherwise prepared for selected laboratoryindex and aggregate testing, A report is then prepared which presents theresults and discusses them in relation to other rock types and typicalaggregate acceptance standards.

Most of the reports in this Programme have dealt with granites butwith the increased usage of local and imported volcanic rocks as concreteaggregates in particular, it has become important to undertake studies ofthese rocks and their particular problems. Indeed the first report dealingwith volcanic rocks has recently been produced in the Planning Division byS.T. Gilbert and T.Y. Irfan. This useful, discussive report is numberedSPR 6/89 and is entitled, "Suitability of Volcanic Rocks for ConcreteAggregates in Hong Kong."

The current report is the second to cover volcanic rocks and theopportunity has been taken to link this FRTP work to a 'SPUN' Projectrequirement. The GCO 'SPUN7 Project is aimed at investigating thepotential use of underground space in Hong Kong where two of the potentialproject cavern sites are located in volcanic bedrocks• The purpose of thecurrent FRTP investigation is to assess whether the rock likely to beproduced in cavern excavation would be suitable for processing and sale asaggregate.

This report thus presents and discusses the results of selectedphysical index and aggregate testing on laboratory crushed fine ash andlapilli/coarse ash crystal TUFF samples from cavern sites at Chai Wan andMount Davis. The results are compared with typical granite values and thesuitability of the materials as aggregate is assessed in relation to normalacceptance values for various uses.


2.1 Chai Wan

The sampling at the Chai Wan site took place on the 16th March 1989and was carried out by staff from both GCO (Burnett and Whiteside) and OveArup and Partners (Fowler).

The general location of the site near Chai Wan is shown in Figure 1and the detailed positions of the alternative cavern sites and the actualsampling locations is given in Figure 2. It can be seen from the latterfigure and Figure 3 that the possible SPUN underground facilities lie tothe south of the new Siu Sai Wan construction platform deep in the hillsidebeneath Cape Collinson Road at a position midway between Pottinger Peak andCape Collinson.

As the proposed Government Supplies Store facility is likely to be

- 183 -

some 100 m underground, the surface outcrop sampling attempted to take intoaccount the known local geological structure and single regional rocktypeto obtain samples reasonably representative of the anticipated cavernmaterials* The general area was already covered by a spread of handspecimen sampling taken for the Hong Kong Geological Survey and whichconfirmed the presence of a single rocktype. Thus only three extra fSPUNf

hand specimen samples were taken (SPUN 1,2,3) plus one bulk sample (SPUN 4)comprising about 40 kg of broken fresh lumps. Figure 2 shows the actualsampling locations and Plates 1 & 2 illustrate the site and the bulksampling operations which comprised selecting large representative freshboulders of blasted rock from the site formation works at a portal positionand further breaking these by sledgehammer for bagging and labeling.

2.2 Mount Davis

The sampling operations at the Mount Davis took place on two separatedays, notably, the 16th March and the 6th April 1989 and again involved thesame GCO and Ove Arup & partners staff as for the Chai Wan site sampling.

Figures 1 and 4 show respectively the general and detailed locationsof the sampling and the proposed underground facilities. The elevation ofthe facilities is planned to be between about +10 and +40 mPD and itsposition to lie immediately beneath Mount Davis Path between the coast lineand Mount Davis.

At the Mount Davis locality surface geological mapping by Strange(1986) had shown two volcanic rocktypes to be present in the area of the'SPUN1 proposed underground Refuse Transer and Sewage Treatment facilities.

On the basis of the Hong Kong Geological Survey surface mapping andexisting hand speciman samples it was desided that two bulk samples (SPUN6 and 7) and four extra hand specimens (SPUN 5,8,9,10) were required andwere subsequently taken. Each bulk sample again comprised about 30-40 kgof sledgehammer broken fresh lumps of rock representative of the two majorrocktypes on the site, namely eutaxite and coarse ash crystal tuff. Plate3 shows the (SPUN 6 bulk sampling location on Victoria Road; Plate 4 showsthe Mount Davis Reservior SPUN 7 bulk sample location.

3. GEOLOGY

3-1 Chai Wan , • • -. " "

3*1*1 Site Geology

Description of the geology of the Chai Wan site falls into threecategories, namely Lithology, Intrusive History and Structure.

Lithologlcally the site comprises Upper Jurassic rocks of the RepulseBay Volcanic Group which are dominated by tuffs. In this region of theTerritory the Group has been divided into four formations, each of whichdisplays specific distinctive characteristics to the skilled observer andwhich has allowed their recognition and identification in the field. Thegeneralised sequences of the rocks comprising these formations is shown mFigure 6, (Strange & Shaw, 1986)- Essentially the formations compriseconsiderable thicknesses of structureless fine ash or coarse ash crystaltuff interspersed with minor, laterally impersisterit yet mappable, units of

- 184 -

eutaxite, tuff-breccia, siltstone and sandstone.

The Shing Mun Formation within which the Chai Wan site falls ischaracteristically a rather variable formation and on the hi l l slope to theeast of Siu Sai Wan bluish grey fine to coarse ash welded tuff withsubhedral plagioclase crystals (1-2 mm) are noted to included dark greylava lapi l l i . Southwards towards Cape Collinson Training Centre these verydark tuffs contain an increasing amount of subangular to angular blackaphanitic lapilli up to 40 mm in size.

A strong feature-forming welded tuff (eutaxite) layer forms theapproximately east-west trending Pottinger Peak ridge and many boulders ofwelded tuff and other impersistent layers of the same rocktype indicatethat eutaxites should not be unexpected in the proposed undergroundexcavation.

There is no evidence of granite intrusion outcrop in the Siu SaiWan/Pottinger Peak area and this fact together with a consideration of thegeneral disposition of this particular volcanic roof pendant leads to thebelief that even at the proposed +5 to +30 mPD underground elevations ofthe works, granite will not be encountered.

Structurally while no clear impression of the overall dip of thestrata can be ascertained the Shing Mun Formation at this locality isheavily fractured by closely spaced joint sets and probably also faults.The local drainage pattern clearly depicts this structural geologicalcontrol and illustrates the primary joint set directions of N~S, NW-SE andESE-WNW.

3.1.2 Description of Bedrock Samples

From an engineering geology viewpoint the main rock (JSM) a t th islocat ion as represented by the bulk sample SPUN 4 may be described as anextremely strong dark grey c ry s t a l l i ne f ine- to very f ine-grained TUFFoccasionally displaying welding and or volcanic l i t h i c l a p i l l i • Plate 5shows a close-up of a typical hand specimen example of t h i s m a t e r i a l .

The geological petrographic descr ipt ion of bulk sample SPUN 4 and assummarised in Table 5 i s as follows :

Hand Specimen - da rk g r e y t o b l ack , s l i g h t l y g r e e n i s h andaltered with abundant small (< 2 mm) feldsparsand dark greenish grey rounded l i t h i c fragmentsof < 20 mm s i z e .

Thin Section - feldspars (< 4 mm), embayed quartz (< 2 mm)andmafic (< 1 mm) c r y s t a l s s e t in an aphani t i cgroundmass. The quartz i s often bipyramidal ors h a r d i c ; a smal l patch comprising green-brownpleochroic hornblende with elongate c r y s t a l s ofsize about 0.7 mm ex i s t s in a groundmass showingsnowflake (devitrified) features. Feldspars,microcline and microperthite are present as ischloritized biotite and zoned oligoclase.

Final Identification - crystal coarse ash bearing, vitric TUFF,

- 185 -

3.2 Mount Davis

3.2.1. Site Geology

The Mount Davis underground facility site is likely to be more complexthan that at Chai Wan because two volcanic rocktypes are mapped at outcropas stradding the site and in addition the proximity of granite outcropindicates that it might also be encountered underground in the proposedexcavations.

Stratigraphically, as can be seen from Figures 4 and 6, the site lieslargely within the Upper Jurassic Tai Mo Shan Formation of the Repulse BayVolcanic Group of rocks. This comprises essentially a coarse ash crystaltuff of remarkably uniform and structureless appearance in outcrop apartfrom the interspersed occasional presence of dark angular lithic lapilli upto 30-40 mm in size. Abundant quartz and some biotite crystals can be seenin hand specimen as illustrated in Plate 6.

Epiclastic layers appear to be a common characteristic of theformation in this district (Strange & Shaw, 1986). These take the form ofmoderately steeply dipping sandstone lenses up to 25 m thick and extendinglaterally for 100 to 300 m.

To the west of Victoria Road, the Tai Mo Shan (JTM) rocks in thevicinity of the site are overlain by a thick band of eutaxite (flow bandedwelded tuff) dipping some 40-65° to the west. This rocktype is finer-grained and more vitric in appearance as shown in Plate 7 and displays aparataxitic fabric and is also thermally metamorphosed due to theproximities of the granite. This eutaxite, although not totallyrepresentative of the classic Ap Lei Chau Formation eutaxites wassufficiently distinctive to also warrant being sampled in bulk for testingas the SPUN 6 sample*

The likelyhood of encountering the top of the granite pluton in theproposed undergrained excavations cannot be discounted in this facility andshould not be overlooked.

The structural geology of the site is rather confusing and not easy topredict with any certainty. The schematic sections shown in Figure 5probably represent a reasonable estimate of the local structure based onthe dips of the main rocktypes as mapped (GCO 1986).

3*2.2 Description of Bedrock Samples •

The engineering geology description of the coarse ash crystal tuff(JTM) at this site and as represented by the SPUN 7 bulk sample is :extremely strong mid to greenish grey equigranular crystalline coarse ashto lapilli TUFF containing occasional well dispersed volcanic lithiclapilli, Plate 6 iullustrates this material in hand specimen.

The SPUN 6 bulk sample represents a material which can be described asextremely strong light greenish grey slightly flow banded in places fineash TUFF* Plate 7 shows a close-up view of a hand specimen of the SPUN bsample. , • . . ' •" ' • • ' - '

The petrographie descriptions of both these samples is summarized in

Table 5" and a fuller description is.given below. '. • • .

- 186 -

SPUN 6

Hand Specimen - Grey with white feldspars (< 3 mm), brown quartz (< 2 mm)and black mafic flakes (< 1 mm). The rock is dominated bycrystals in a fine groundmass.

Thin Section - Cloudy feldspars of < 3 mm size and quartz of < 4 mm sizeoccur in a fine matrix. Most crystals are subhedral withmuch dark mineral. Pleochroic biotite flakes of < 1 mmsize are noted as are perthitized potassium feldspar andzoned oligoclase. The matrix comprises recrystallisedquartz 85%; most quartz shows signs of granulation but isstill strained - indicating thermal metamorphism.

Final Identification - Thermally metamorphosed ash crystal TUFF.

SPUN 7

Hand Specimen - Light grey, speckled white and black, with white feldspars(< 3 mm), thin mafic flakes (< 2 mm) and dominated bycrystals.

Thin Section - Quartz (< 3 mm), feldspars (< 3 nun) and mafic minerals(about 0.5 mm) in a finely crystalline groundraass. Thequartz is subhedral and/or bipyramidal, embayed andshardic. The feldspar is subhedral and cloudy but theplagioclase is zoned and fresh. Zoned ser iz i t i sedmicrocline and mircoperthite is present. Muscovite andsmall pleochroic biot i te flakes are present. All aredominated by a fine (about 0.05 mm) crystal groundmass.

Final Identification - Ash crystal TUFF

*• AGGREGATE TESTING AND CHARACTERIZATION


All ten samples taken in this study i.e. both hand specimens and thebulk samples, were given TSPUNf numbers in the field and these temporarynumbers were then converted to fHKf numbers for permanent registration andcuration in the Hong Kong Rock Collection of the Hong Kong GeologicalSurvey.

Nine of the ten samples were submitted for thin sectioning; only SPUN9 (HK 8510) was not as it was slightly to moderately weathered and hencenot representative of the fresh rock anticipated in the proposedunderground excavations. All ten hand specimens and the nine thinsections together with the photomicrographs (In plane, crossed polarised,and 1/4 Lambda wavelength light) of the sections are available forinspection and reference in the Hong Kong Geological Survey*

The three field collected bulk samples, each comprising about 40-60 kgof bagged, broken fresh lumps, were converted into aggregate by processingthrough a small laboratory/field jaw crusher and hand sieving* Plate 11shows these operations by which standard 10-14 mm, and 10-20 mm sizeaggregates were prepared in preparation for testing.

- 187 -

The rock index t e s t s undertaken on each of the three bulk samples (14-10 ram s ize) included bulk density, grain specific gravity (< 150 mm), waterabsorption, effective porosity and to ta l porosity.

The aggregate physical t e s t s undertaken included aggregate crushingvalue (ACV), aggregate impact value (AIV), ten per cent fines value, LosAngeles abrasion value (LAAV), flakiness index ( I F ) , and elongation index( I E ) . All the above t e s t s were performed in the North Point Public WorksLaboratory of the GCO to fu l l Br i t i sh Standards Ins t i tu t ion (BSD(1975) andAmerican Society for Testing Materials (ASTM)(198D standards.

In order to make a preliminary assessment of the potential a lka l ireac t iv i ty of the aggregate, Test C289 of ASTM (1981) was also carried outin t r i p l i c a t e on 10 mm aggregate from each bulk sample.

4.2 Class i f ica t ion and Charaterization of Aggregates

The CADAM Scheme, as recommended by the Geological Society WorkingParty on Aggregates (Coll is & Fox, 1985), is used to describe and classifythe aggregates . In addit ion, a more detailed petrographic evaluation ofthe aggregates produced from three bulk samples has also been made. Theresul ts of these c l a s s i f i ca t ion techniques are presented in Tables 1 to 3 .

4.3 Test Results

The r e s u l t s of the rock index and aggregate laboratory tes t ing on theaggregates produced from the three representative SPUN bulk samples aresummarised in Table 5 which also shows the resul ts of a typical Hong Konggranite and the Br i t i sh Standard and other concrete acceptance values forcomparison*

5. DISCUSSION OF TEST RESULTS

5*1 Rock Index and Aggregate Properties

Table 4 shows that the grain specific gravi t ies of a l l three SPUNsamples volcanic rocktypes i s consistant and dense and averages about 2.70with a range 2.69 to 2,71 v The oven-dried density of these tuffs averages2.65 and va r i e s between 2*63 and 2.65 g/cc . These values are notically upon equivalent values for grani tes which tend to average 2.60 g/cc.

The considerable s trength and density of the tuffs lead to very lowand uniform water absorption and effective porosity values of 0A% and 1.ir-respec t ive ly . While these values are possibly only marginally bet ter thanequivalent fresh gran i te values they are very well within the 3% maximumusually specified for concrete aggregate.

As f a r as t he f lakiness and elongation indices are concerned thenormally required acceptance c r i t e r i a are 35 and 30$ maximum respectively.The average values for the three tuff samples of about 19 and 24 forf l ak lneas and elongation respectively are thus well within the usuallyspec i f i ed values, even bearing in mind the fact that the samples were"a r t i f i c ia l ly* ' produced using a small f ield/laboratory jaw crusher - thetype of which are thought to increase flakiness/elongation in comparison tocompetent fu l l scale quarry crushing. • . • • : ' *

- 188 -

Each of the mechanical test properties of the SPUN volcanicaggregates are consistantly and tightly grouped, better than the normalgranite spread of values and well within the general purpose concretespecification and even the heavy duty/wearing surface concrete acceptancecriteria as shown in Table 5.

These favourable mechanical test results as defined by the aggregatecrushing, impact, 10% fines value and Los Angeles abrasion values are notunexpected bearing in mind the high strengths determined by Irfan (1985)for the entire volcanic group of rocks, Irfan reported, after a reasonablycomprehensive point load testing programme, that for fresh, mainlypyroclastic, volcanic rocks an average (from 154 tests) point load strengthof 10.2 mPa with a standard deviation of 2,6 mPa resulted.

It is clearly concluded that the volcanic tuffs are distinctlymechanically superior to their typical granite equvalents and equallyclearly will provide very suitable concrete (and other) aggregates fromthe mechanical property viewpoint.

No polished stone value tests were undertaken on the three SPUNsamples in this study but other sources (Gilbert & Irfan, 1989) indicatethat volcanic rocks are slightly superior to Hong Kong granites in thisrespect. This data source also indicates that local volcanic rocks arealso far more resistant, i.e. sound to chemical attack weathering thanlocal granites and fall very well within the usual MgSOij and NaSOjjsoundness criteria. The durability of the volcanic tuffs thus appears tobe very favourable based on the results of the present and other laboratorytests undertaken to date.

Despite the fact that no clearly deleterious mineral phases orminerals appear to be present in the three SPUN tuffs tested it is wellknown that some doubt hangs over these volcanic rock types for reasons oftheir potential alkali-aggregate reactivity. For this reason the AmericanSociety of Testing Materials Potential reactivity of aggregate (ChemicalMethod) Test C289 was called for and undertaken. Table 4 presents theresults of this indicative chemical test which are also plotted on theusual dissolved silica (Sc) versus reduction xtx alkalinity (Re) graph inFigure 7.

The three SPUN sample results plot on the "innocuous aggregate" sideof the graph and thus provide an initial indication that the aggregates arenot deleterious. The few previous volcanic rock test results all plot inthe same general vicinity of the graph, thus apparently showing aconsiderable degree of consistancy throughout the volcanic suite of rocks.

^•2 Suitability of Rocks as Aggregate

The test results and petrographic examinations described above tend toindicate that the rock types sampled as being representative of thematerials likely to be excavated in the 'SPUN1 sites should be satisfactoryas normal or even special purpose concrete aggregates.

The physical and mechanical tests are clearly very satisfactory withonly a slight query hanging over the brittleness and hence crushed rockparticle shape of any future aggregate. The soundness (to salt attack) ofthe materials is also very good.

- 189 -

Regarding the a lkal i s i l i ca reactivi ty potential of the rock typestested, while the ASTM C289 quick chemical t e s t resul ts were encouragingi t i s known that no single tes t taken in isolation is foolproof or asubst i tute for long term serv ic ib i l i ty experience. These tuff rocks arealso known to contain (or certainly originally contained) the potent ial lyd e l e t e r i o u s subs tances of volcanic glass, crypto- to microcr ys t a l l ines i l i ca and strained quartz• While most of the former glass and s i l i caappear to have devitr i f ied th i s i s interpreted by diff icul t and imperfectobservational methods only (petrographic examination) and hence some doubtsmust remain, however s l i g h t , regarding the aggregate s u i t a b i l i t y .Reference i s made for a re levent and f u l l e r discussion on a l k a l ireact iv i ty to the Gilbert and Irfan (1989) report.

5.3 Recommendations for Further Tests

In the l i gh t of the importance of the use of volcanic rock aggregatesin general and from these samples/sites in part icular, i t is suggested thati t would be worthwhile for p a r t i e s i n t e re s t ed in the use of thesematerials to arrange for the remaining, and thus far untried, long termmortar bar t e s t s (ASTM C227) to be undertaken on these three SPUN samples.Confirmatory expert petrographic examination, as far as this pertains toappraisal of aggregate su i t ab i l i ty , would also be prudent.

6. CONCLUSIONS

The th ree SPUN tuff rock types sampled and relatively thoroughlytes ted have given everjr indication thus far of producing a perfectlysuitable aggregate for concrete purposes.

Confirmatory and additional testing and evaluation, in the form ofmortar bar tes ta and expert aggregate petrographic examination, shouldprovide the necessary confidence for full-scale use of these materials,whereafter long term, in - se rv ice monitoring wil l provide the finalconclusive proof of the materials su i t ab i l i ty .

7. REFERENCES

American Society for Testing Materials (1981). Test for resistance toabrasion of small size coarse aggregate by use of the Los Angelesmachine. Test Designation C131-81. American Society for TestingMaterials,

British Standards Institution (1983). British Standard Specification forAggregates from,Natural Sources for Concrete (BS 882 : 1983)*BritishStandards Institution, London, 7 p.

British Standards Institution (1975). Methods for Sampling and Testing ofMineral Aggregates, Sands and Fillers (BS 812 : parts 1 to 3).British' Standards Institution, ' . • • •

Collie, U & Pox, R.A.- (1985). Aggregates : Sand, Gravel and Crushed Rock

Aggregates for Construction Purposes. Geological Society EngineeringGeology •"Special Publication No, 1. The Geological. Society, London,200 p.

- 190 -

Fookes, P.G. (1984). An introduction to concrete in the Far East - Part 2.Concrete, July Edition, pp 38-41.

Geotechnical Control Office (1986) • Hong Kong and Kowloon, Solid andSuperficial Geology (1 : 20 000 mapfl Hong Kong Geological Survey MapSeries HGM 20, Sheet 11, Geotechnical Control Office, Hong Kong,1 map.

Higginbottom, I.E. (1976). Section 11.1. General requirements for rocksand aggregates. In Applied Geology for Engineer, H.M.S.O., 378 p.

Hindley, T. (1984). Quarrying in Hong Kong. Hong Kong Contractor.October Edition, pp 9-16.

International Society for Rock Mechanics (1978). Rock CharacterizationTesting and Monitoring. ISRM Suggested methods (led. E.T. Brown).Commission on Testing Methods, International Society for RockMechanics, Pergamon Press, 211 p.

Irfan, T.Y. (1985). Point Load Strength of Common Hong Kong Rocks. GCOReport No. TN 1/85, 49 p.

Shergold, F.A. (1948). A review of available information on thesignificance of roadstone tests. Road Research Technical Paper 10.DSIR, H.M.S.O., London.

Standards Association of Australia (1985). Aggregates and Rock forEngineering Purposes. Part 1 - Concrete Aggregates (Australian,Standard-2758 + 1 - 1985). Standards Association of Australia, 16 p.

Strange, P.J. & Shaw, R. (1986). Geology of Hong Kong Island and Kowloon.Geotechnical Control Office, Hong Kong, 134 p. (Hong Kong GeologicalSurvey Memoir No. 2).

Property Services Agency (PSA)(1979), Standard Specification Clauses forAirfield Pavements and Works Part 3, Concrete Appendix 3A. PropertyServices Agency, Department of the Environment.

Gilbert, S.T. & Irfan, T.Y. (1989)* Suitability of Volcanic Rocks forConcrete Aggregates in Hong Kong. GCO Report No. SPR 6/89, 54 p.

- 191 -

LIST OF TABLES

Table PageNo. No.

1 Classification, Description and Petrographic 192Evaluation of Aggregate Produced from theSPUN 4 Bulk Sample

2 Classification, Description and Petrographic 193Evaluation of Aggregate Produced from theSPUN 6 Bulk Sample

3 Classification, Description and Petrographic 194Evaluation of Aggregate Produced from theSPUN 7 Bulk Sample Aggregate

4 Petrographic Description of -Samples SPUN 4, 195SPUN 6 and SPUN 7

5 Laboratory Test Results for the SPUN Bulk 196Samples (Together with Typical GraniteResults and Normal Concrete AcceptanceCriteria for Comparison)

- 192 -

- 193 -

Table 4 -

- 195 -

Petrographic Description of Sample SPUN 4, SPUN 6 and SPUN 7

SPECIMENNUMBER

FINALIDENTIFICATION

Crystal Coarse Ash-bearingVitric Tuff

Thin SectionPhotomicrographModal AnalysisSilicate AnalysisPartial AnalysisNormative AnalysisPalaeontology

GEOLOGIST'S LOCALITY REF.S j P/L j D,f4 j | Chai Wan, HK

DATE

1:10 000 HK GRID EAST NORTH11FIELD NAME

|4 j 3j 9| Qj Ol I 1J3 JS J3 JO I [

1 [1 I 6l 0J3|8TiAERIAL PHOTO YEAR

ROCK UNIT

JSM

FIELD OCCURRENCE: Blas t boulders from cut slope formation works.Bulk sample a l s o taken for SPUN project .HAND SPECIMEN: Dark grey - black; slightly greenish altered,white fd<2 mm, abundant; rounded l i thic< 20 mm, darkgreenish grey;PETROGRAPHIC DESCRIPTION—St« back for details Feldspar < 4 mm; embayed quartzK 2 mm; maf icrs i mm; s e t in aphanit iz groundmass; qz b ipyra-midal or shardic ; small patch comprising green-brown p l e o -chroic hornblende; elongate crystals <v 0,7 mm; some snowflaketexture; feldspar microcline microperthxte; chloritizedbiot i te ; zoned oligoclase

GEOLOGICAL SURVEY 48

SPECIMENNUMBER

FINAL Thermally MetamorphosedIDENTIFICATION A s h C r y s t a l Tuff

Thin SectionPhotomicrographModal AnalysisSilicate AnalysisPartial AnalystsNormative AnalysisPalaeontology

GEOLOGIST'S LOCALITY REF. DATELj C/6| [Victoria Road, HK

1:10 000 HK GRID EAST NORTH11 1 SW 1 |3»OJ1 j6 jo] [I j 5j 2J3J0] [_

_ J M 16|O [ 3 T | 9- AERIAL PHOTO YEAR

FIELD NAME ROCK UNITme tamorphos ed

entaxite

FIELD OCCURRENCE: Rock ,,,jn road cut t ing , east; side of Victoria Road.Bulk sample a l so taken for SPUN project

HAND SPECIMEN: Grey? white fd < 3 mm; brown qz < 2 mm; maficblack, "̂ 1 mm; dominated by crystals in f ine ground—

JBflJ&SLPETROGRAPHIC DESCRIPTION—Sea back for rf»taii« Cloudy fd < 3 mm; Qz < 4 mm;fine matrix; most crystals subhedral; much dark mineral;

light-dark brown bi flakes < 1 mm; perthitiz K-fd;o^jgoc^ase; matrix recryst qz & bi 0.05 - 0.1 mm; most

fd cloudly; most qz showing signs of granulation; but still..strained; thermal metamorphism? greizenization

GEOLOGICAL SURVEY 48

SPECIMENNUMBER

8507 FINALIDENTIFICATION Ash Crystal Tuff

Thin SectionPhotomicrographModal AnalystsSilicate AnalystsPartial AnalysisNormative AnalysisPalaeontology

GEOLOGIST'S LOCALITY REF,S jp/fc C/|7 i I Mt. Davies, HK

DATEl2J6[0 |3

1:10 000 HK GRID EAST NORTH AERIAL PHOTO YEARi v p i T ] 1_31 o j e j o • o 1 h j sj oj 5j o| 19FIELD NAME ROCK UNIT

JTM

FIELD OCCURRENCE* Rock cutt ing forming part of west end of Mt.Paving Reservoir. Bulk sample a lso taken to SPUN projec t .

HAND SPECIMEN: Light grey, speckled white and black; white fd' < 3 mmy thin mafic f lakes < 2 mm; greenish fd < 3 mm;damiaat<fcd by, r c r y s t a l s

< 3 t d < 3 **'PETROGRAPHIC DESCRIPTION—Sit back lor <„«....• _ _ —-nz 0 5 mmi finely crystalline groundmass; some muscovxte qz

embayed or shardic; fd subhedral,fresh; y.oned serizitized microcline

—~ ' ——7™:—zz—r̂ ~_ -̂, T .muscovite 6 pieochroic bi flakes, small,

005 e opadomi rpundma33 0.05 mm; some opaque

GEOIOGICAL SURVEY

196

Table 5 - Laboratory Test Results for SPUN Bulk Samples (Together WithTypical Granite Results and Normal Concrete AcceptanceCriteria for Comparison)

Aggregate property

Mechanical Properties

Aggregate Crushing Value (ACV) %

Aggregate Impact Value (AIV) %

Los Angeles Abrasion Value (LAAV) %

10$ Fines Value kN

Polished Stone Value (PSV)

Physical Properties

Water Absorption

Effective Porosity

Flakiness Index (Ip)

Elongation Index (Ig)

Density (Oven dried)

Grain Specific Gravity

Chemical properties

Soundness

% loss (5 cycles)

Reactivity AggregateReactivity (AAR)m(millinoles/litre)

*

*

%

%

g/cc

with MgSOj,

with NaSOj,

Dissolved ScSilica

Reduction RcinAlkalinity

ChaiSPUN

13

14

15

290

-

0

1

17

21

2

2

-

16

505545

Note : a. Tests carried out by PWDTL.b. Results from Hindley (1984)c. Wearing surfaces,d. General purpose ooncrete.

Volcanic RocksWan4

.4

.1

.63

.69

.0

.0

.0

MountSPUN 6(VictoriaRd Site)

18

21

22

200

-

0.4

1.1

19

17

2.65

2.71

-

15.716.014.7

000

DavisSPUN 7(ReservoirSite)

15

16

16

280

-

•0.4

1.0

20

34

2.65

2.69

-

**

21.323.021,3 *

302020

T y p i c a lGranite"(FRTP)

21-29

15-31

28-44

100-200

5Qb

0.3-0.7

7-26

28-44

1G-I5b

-

e. Heavy duty ooncrete.f. Protected ooncrete.g. Moderate exposure.h. Airfield pavements.

(Coarse and fine aggregate).

AcceptanceCriteria for

Concrete

MaxMax

MaxMaxMax

MaxMaxMax

Max

MinMinMin

Max

Max

Max

MaxMax

MaxMaxMaxMax

( Seo

( See

20°

25C

OQC

jjcd

40c

30f25S

35d

100c

150e

50d

-

3

35

30

I8h

12io*

6̂

Figure 7

Figure 7

Reference

H i g g i n b o t t o m(1976)

B S : 8 8 2(1983)

ASTM C131A u s t r a l i a nS t a n d a r d2785.1 (1985)S h e r g o l d(1948)

BS 882 (1983)

-

H i g g i n b o t t o m(1976)BS5337 : 1976

BS882 (1983)

Fookes (1984)

PSA (1979)ASTM C33

ASTN C33A u s t r a l i a nS t a n d a r d2785.1 (1985)

ASTM C 289

1, • Vim aggregates,j . Coarse aggregatea.k* Severe exposure,ttu Triplicate analysesn, 3«© Gilbert & Irfan

(1989)

- 197 -

LIST OF FIGURES

Figure ' PageNo. No.

1 General Location and Geology Map 198

2 Geology and Sample Location Plan - 199Proposed Chai Wan Underground Facilities

3 Cross-sections - Proposed Chai Wan Underground 200Facilities

4 Geology and Sample Location Plan - Proposed 201Mount Davis Underground Facilities

5 Cross-sections - Proposed Mount Davis 202Underground Facilities

6 Generalized Sequences of Repulse Bay Volcanic 203Group Rocks

7 Potential Reactivity of the SPUN Sample 204Aggregates by the ASTM C28 Chemical Method

- 198 -

4- 4- 4- 4- 4- 4- 4-

Granitic rocksVolcanic / granite contact*

SPUN Sampio Site

Figure 1 - General Location and Geology Map (After Strange 4 Shaw, 1986)

- 203 -

- 204 -

- 205 -

LIST OF PLATES

Plate PageNo. No.

1 General View of SPUN 4 Bulk Sample Location 206at the Chai Wan Site

2 Sampling Operations for the SPUN 4 Bulk Sample; 206Chai Wan Site

3 General View of the SPUN 6 Bulk Sample Location 207on Victoria Road, Mount Davis

4 General View of the SPUN 7 Bulk Sample Location 207at Mount Davis Reservoir

5 Production of Aggregate for Testing by Field 208Crushing and Hand Sieving

6 Close-up of SPUN 4 Bulk Sample Fine Ash Tuff 208Lithology (HK 8504)

7 Close-up of SPUN 7 Bulk Sample Coarse Ash 209Tuff Lithology (HK 8507)

8 Close-up of SPUN 6 Bulk Sample Fine Ash/Eutaxite 209Tuff Lithology (HK 8506)

9 Photomicrographs of SPUN 4 Lithology .- Fine 210Ash Tuff (HK 8504)

10 Photomicrographs of SPUN 4 Lithology - Fine 211

Ash Tuff (HK 8507)

11 Photomicrographs of SPUN 4 Lithology - Fine 212Ash Tuff/Eutaxite (HK 8506)

GEOTECHNICAL ENGINEERING OFFICE PUBLICATIONS

Geotechnical Manual for Slopes, 2nd edition (1984),306 p. (Reprinted, 1994).

Guide to Retaining Wall Design, 2nd edition (1993),268 p. (Reprinted, 1994).

Guide to Site Investigation (1987), 368 p. (Reprinted1993).

Guide to Rock and Soil Descriptions (1988), 195 p.(Reprinted, 1994).

Guide to Cavern Engineering (1992), 159 p. (Reprinted,1994).

Model Specification for Prestressed Ground Anchors, 2ndedition (1989), 168 p.

Model Specification for Reinforced Fill Structures (1989),140 p.

Mid-levels Study : Report on Geology, Hydrology andSoil Properties (1982), 265 p. plus 54 drgs.

Prediction of Soil Suction for Slopes in Hong Kong, byM.G. Anderson (1984), 243 p.

(Superseded by GCO Publication No. 1/85)

(Superseded by Geospec 1)

Review of Superficial Deposits and Weathering in HongKong, by J.D. Bennett (1984), 58 p. (Reprinted, 1993).

Review of Hong Kong Stratigraphy, by J.D. Bennett(1984), 86 p.

Review of Tectonic History, Structure and Metamorphismof Hong Kong, by J.D. Bennett (1984), 63 p.

(Superseded by GCO Publication No. 1/88)

Groundwater Lowering by Horizontal Drains, by D.J.Craig & I. Gray (1985), 123 p. (Reprinted, 1990).

Geoguide 1

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Review of Design Methods for Excavations (1990), 193 p.(Reprinted, 1991).

Foundation Properties of Marble and Other Rocks in theYuen Long - Tuen Mun Area (1990), 117 p.

Review of Earthquake Data for the Hong Kong Region(1991), 115 p.

Review of Granular and Geotextile Filters (1993), 141 p.

Report on the Kwun Lung Lau Landslide of 23 July 1994,2 Volumes, 400 p. (Also available in Chinese)

(Hong Kong) Rainfall and Landslides in 1984, byJ. Premchitt (1991), 91 p. plus 1 drg. (Reprinted, 1995).



Hong Kong Rainfall and Landslides in 1987, byJ. Premchitt (1991), 101 p. plus 1 drg. (Reprinted, 1995).

Hong Kong Rainfall and Landslides in 1988, byJ. Premchitt (1991), 64 p. plus 1 drg. (Reprinted, 1995).

Hong Kong Rainfall and Landslides in 1989, by K.L. Siu(1991), 114 p. plus 1 drg. (Reprinted, 1995).

Aggregate Properties of Some Hong Kong Rocks, by T. Y.Man, A. Cipullo, A.D. Burnett & J.M. Nash (1992),212 p. (Reprinted, 1995).

Foundation Design of Caissons on Granitic and VolcanicRocks, by T.Y. Man & G.E. Powell (1991), 85 p(Reprinted, 1995).

Bibliography on the Geology and GeotechnicalEngineering of Hong Kong to December 1991, by E.W.Brand (1992), 186 p. (Superseded by GEO Report No.39)

Bibliography on Settlements Caused by Tunnelling byE.W. Brand (1992), 50 p. (Reprinted, 1995).



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Direct Shear Testing of a Hong Kong Soil under Various GEO ReportApplied Matric Suctions, by J.K. Gan & D.G. Fredlund No. 11(1992), 241 p. (Reprinted, 1995).

Rainstorm Runoff on Slopes, by J. Premchitt, T.S.K. GEO ReportLam, J.M. Shen and H.F. Lam (1992), 211 p. (Reprinted, No 121995).

Mineralogical Assessment of Creep-type Instability at TwoLandslip Sites, by T.Y. Man (1992), 136 p. (Reprinted,1995).

Hong Kong Rainfall and Landslides in 1990, by K.Y.Tang (1992), 78 p. plus 1 drg. (Reprinted, 1995).

Assessment of Stability of Slopes Subjected to BlastingVibration, by H.N. Wong & P.L.R. Pang (1992), 112 p.(Reprinted, 1995).

Earthquake Resistance of Buildings and MarineReclamation Fills in Hong Kong, by W.K. Pun (1992),48 p. (Reprinted, 1995).

Review of Dredging Practice in the Netherlands, by S.T.Gilbert & P.W. To (1992), 112 p. (Reprinted, 1995).

Backfilled Mud Anchor Trials Feasibility Study, by C.K.Wong & C.B.B. Thorley (1992), 55 p. (Reprinted, 1995).

A Review of the Phenomenon of Stress Rupture in HDPEGeogrids, by G.D. Small & J.H. Greenwood (1993),68 p. (Reprinted, 1995).

Hong Kong Rainfall and Landslides in 1991, by N.C.Evans (1992), 76 p. plus 1 drg. (Reprinted, 1995).

Horizontal Subgrade Reaction for Cantilevered RetainingWall Analysis, by W.K. Pun & P.L.R. Pang (1993),41 p. (Reprinted, 1995).

Report on the Rainstorm of 8 May 1992, by N.C. Evans(1993), 109 p. plus 2 drgs. (Reprinted, 1995).

Effect of the Coarse Fractions on the Shear Strength ofColluvium, by T.Y. Man & K.Y. Tang (1993), 223 p.(Reprinted, 1995).

The Use of PFA in Reclamation, by J. Premchitt & N.C.Evans (1993), 59 p. (Reprinted, 1995).

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Landslips Caused by the June 1983 Rainstorm, by E.B.Choot (1993), 124 p. (Reprinted, 1995).

Factors Affecting Sinkhole Formation, by Y.C. Chan(1994), 37 p. (Reprinted, 1995).

Classification and Zoning of Marble Sites, by Y.C. Chan(1994), 37 p. (Reprinted, 1995).

Hong Kong Seawall Design Study, by P.M. Aas &A. Engen (1993), 94 p. (Reprinted, 1995).

Study of Old Masonry Retaining Walls in Hong Kong, byY.C. Chan (1995), under preparation.

Karst Morphology for Foundation Design, by Y.C. Chan& W.K. Pun (1994), 90 p. plus 1 drg. (Reprinted, 1995).

An Evaluation of the Suitability of Decomposed Granite asFoundation Backfill for Gravity Seawalls in Hong Kong,by E.B. Choot (1993), 34 p. (Reprinted, 1995).

A Partial Factor Method for Reinforced Fill Slope Design,by H.N. Wong (1993), 55 p. (Reprinted, 1995).

Hong Kong Rainfall and Landslides in 1992, by P.K.H.Chen (1993), 201 p. plus 2 drgs. (Reprinted, 1995).

Methods of Test for Soils in Hong Kong for CivilEngineering Purposes (Phase I Tests), by P.Y.M. Chen(1994), 91 p.

Creep, Stress Rupture and Hydrolysis of PolyesterReinforced Geogrids, by J.H. Greenwood (1995), underpreparation.

Skin Friction on Piles at the New Public Works CentralLaboratory, by J. Premchitt, I. Gray & K.K.S. Ho(1994), 158 p. (Reprinted, 1995).

Bibliography on the Geology and GeotechnicalEngineering of Hong Kong to May 1994, by E.W. Brand(1994), 202 p. (Reprinted, 1995).

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Hydraulic Fill Performance in Hong Kong, by C.K. Shen& K.M. Lee (1995), under preparation.

Mineralogy and Fabric Characterization and Classificationof Weathered Granitic Rocks in Hong Kong, by T.Y.Man (1995), under preparation.

Performance of Horizontal Drains in Hong Kong, by R.P.Martin, K.L. Siu & J. Premchitt (1995), underpreparation.

Hong Kong Rainfall and Landslides in 1993, by W.L.Chan (1995), under preparation.

General Report on Landslips on 5 November 1993 atMan-made Features in Lantau, by H.N. Wong & K.K.S.Ho (1995), under preparation.

Gravity Retaining Walls Subject to Seismic Loading, byY.S. Au-Yeung & K.K.S. Ho (1995), under preparation.

Direct Shear and Triaxial Testing of a Hong Kong Soilunder Saturated and Unsaturated Conditions, by J.K.M.Gan & D,G. Fredlund (1995), under preparation.

Stability of Submarine Slopes, by N.C. Evans (1995),under preparation.

Strength Development of High PFA Content Concrete, byW . C Leung & WX. Tse (1995), under preparation.

AAR Potential of Volcanic Rocks from Anderson RoadQuarries, by W.C. Leung, W.L. Tse, C.S. Mok & S.T.Gilbert (1995), under preparation.

Geotechnical Area Studies Programme - Hong Kong andKowloon (1987), 170 p. plus 4 maps,

Geotechnical Area Studies Programme - Central NewTerritories (1987), 165 p. plus 4 maps.

Geotectmical Area Studies Programme - West NewTerritories (1987), 155 p . plus 4 maps. . • •

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Geotechnical Area Studies Programme - North Lantau(1988), 124 p. plus 3 maps.

Geotechnical Area Studies Programme - Clear Water Bay(1988), 144 p. plus 4 maps.

Geotechnical Area Studies Programme - North East NewTerritories (1988), 144 p. plus 4 maps.

Geotechnical Area Studies Programme - East NewTerritories (1988), 141 p, plus 4 maps.

Geotechnical Area Studies Programme - Islands (1988),142 p. plus 4 maps.

Geotechnical Area Studies Programme - South Lantau(1988), 148 p. plus 4 maps.

Geotechnical Area Studies Programme - Territory of HongKong (1989), 346 p. plus 14 maps.

Geology of Sha Tin, by R. Addison (1986), 85 p.

Geology of Hong Kong Island and Kowloon, by P.J.Strange & R. Shaw (1986), 134 p.

Geology of the Western New Territories, by R.L.Langford, K.W. Lai, R.S. Arthurton& R. Shaw (1989),140 p.

Geology of Sai Kung and Clear Water Bay by P.J.Strange, R. Shaw & R. Addison (1990), 111 p.

Geology of the North Eastern New Territories, underpreparation.

Geology of Lantau, under preparation.

Geology of Yuen Long by D.V. Frost (1992), 69 p.

Geology of Chek Lap Kok by R.L. Langford (1994), 61p.

San Tin : Solid and Superficial Geology (1:20 000 map)(1989), 1 map.

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GeologicalMemoir No. 1






Sheet ReportNo. 1

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Map HGM 20,Sheet 2

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Kat O Chau : Solid and Superficial Geology (1:20 000map) (1993), 1 map.

Tsing Shan (Castle Peak) : Solid and Superficial Geology(1:20 000 map) (1988), 1 map.

Yuen Long : Solid and Superficial Geology (1:20 000map) (1988), 1 map.

Sha Tin : Solid and Superficial Geology (1:20 000 map)(1986), 1 map.

Sai Kung Peninsula : Solid and Superficial Geology(1:20 000 map) (1989), 1 map.

Tung Chung : Solid and Superficial Geology (1:20 000map) (1994), 1 map.

Silver Mine Bay : Solid and Superficial Geology (1:20 000map) (1992), 1 map.

Hong Kong and Kowloon : Solid and Superficial Geology(1:20 000 map) (1986), 1 map.

Clear Water Bay : Solid and Superficial Geology(1:20 000 map) (1989), 1 map.

Shek Pik : Solid and Superficial Geology (1:20 000 map),under preparation.

Cheung Chau : Solid and Superficial Geology (1:20 000map), under preparation.

Hong Kong South and Lamma Island : Solid andSuperficial Geology (1:20 000 map) (1987), 1 map.

Waglan Island : Solid and Superficial Geology (1:20 000map) (1989), 1 map.

San Tin : Solid Geology (1 : 20 000 map) (1994), 1 map.

Lo Wu : Superficial Geology (1:5 000 map) (1990),1 map.

Lo Wu : Solid Geology (1:5 000 map) (1990), 1 map.

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Requests for copies of Geological Survey Sheet Reports and other reports which are free ofcharge should be directed to :

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