evaluating the durability of two recycled aggregates to be ...€¦ · evaluating the durability of...

Evaluating the durability of two

recycled aggregates to be used in

basal drainage layer of landflills

Gonçalo Rodrigues (1, 2)

António José Roque (1)

Ana Paula da Silva (2)

(1) LNEC (2) FCTUNL

WASCON 2012, May 30 – June 1

SUMMARY

1. Introduction

2. Studied materials

3. Experimental program

4. Results and discussion

5. Conclusions

2

INTRODUCTION

Durabilty study of two recycled aggregates:

o Inert Siderurgical Aggregate for Construction (ISAC), processed from

electric arc furnace steel slag,

o Crushed concrete aggregate reclaimed from construction and demolition

waste (CCCDW).

Comparing to durability of two natural aggregates (reference material):

o Basalt (BA),

o Limestone (LIM).

Evaluating the technical feasibility of using recycled aggregates in the

construction of leachate collection and removal layer of basal

containment system of landfills.

Contribute to a Organized Market of Waste, a sustainable construction

and a reduction in natural aggregates exploitation.

WASCON 2012, May 30 – June 1 3

STUDIED MATERIALS

recycled aggregates

Electric arc furnace steel

slag (phase processing)

Inert Siderurgical Aggregate

for Construction (ISAC)


Construction and demolition

waste (phase processing)

Crushed concrete aggregate

(CCCDW)

STUDIED MATERIALS

recycled aggregates



Basalt quarry

(exploitation front)

Basalt aggregate (BAS) Crushed basalt

(phase processing)

STUDIED MATERIALS

natural aggregates

6


Limestone quarry

(exploitation front)

Limestone aggregate (LIM) Crushing of the limestone

(phase processing)

STUDIED MATERIALS

natural aggregates

7

RSU Leachate collection Pumping RSU leachate in a well

STUDIED MATERIALS

RSU leachate


STUDIED MATERIALS

Location of studied materials WASCON 2012, May 30 – June 1 9

EXPERIMENTAL PROGRAM

Petrographic

analysis

Macropetrographie

Micropetrographie

Physical

characterization

Density

Effective porosity

Water absorption

Durability

evaluation

Slake durability test with water and leachate

o without previous immersion

o with previous immersion (during 15 days)

Before and after slake durability test (SDT)


11 WASCON 2012, May 30 – June 1

RESULTS AND DISCUSSION

petrographic analysis (before SDT) ISAC

Macropetrographie

Dense material, vesicular texture, dark in

color and rough surface.

Minerals are not observable to the naked eye

Presence of small iron particles.

Micropetrographie

Material of vesicular and aphanitic texture,

and fine-grained particles.

Matrix composed of opaque minerals

(especially iron oxides) and unidentifiable

mineral species.



petrographic analysis (before SDT) CCCDW

Macropetrographie

Multiphase material, heterogeneous, non-

friable.

Cementitious matrix color gray and porous.

Crushed coarse and fine aggregates.

Micropetrographie

Material of complex structure composed of

three phases: cementitious matrix, transition

zone and crushed aggregates.

Fine aggregates corresponding to quartz

sand.



petrographic analysis (before SDT) BAS

Macropetrographie

Magmatic, compact, and melanocrata rock.

Aphanitic texture, very slightly porous.

There are no signs of alteration.

Micropetrographie

Porphyritic texture, fine-grained particles, and

composed by two stage of crystallization:

aphanitic matrix (90%) with phenocrystals of

olivine (10%).

Matrix is composed by plagioclases, opaque

minerals, olivine and pyroxene.



petrographic analysis (before SDT) LIM

Macropetrographie

Sedimentary, carbonate and oolitic rock.

Presence of spherical nodules and veins of

calcite.

Micropetrographie

Matrix is composed by minerals of calcite and

some cemented elements (clasts and

oolites).

There are no signs of alteration in calcite.



physical characteristics (before SDT)

Specimen Bulk density

b (Mg/m3)

Real density

r (Mg/m3)

Ef. porosity

Pe (%)

W. absorption

wmax (%)

ISAC 3.77 3.28 12.40 3.83

CCCDW 2.58 2.14 16.88 7.89

BAS 3.02 3.00 0.45 0.14

LIM 2.72 2.58 5.40 2.20

ISAC is denser than CCCDW.

Effective porosity of the ISAC is identical to CCCDW.

Effective porosity of the ISAC (12.40%) is influenced by the

processing of steel slag.

ISAC is denser than BAS and LIM and with Pe and wmax also higher.

CCCDW is less dense than BAS and LIM and with Pe and wmax higher.


0

10

20

30

40

50

60

70

80

90

100

Mate

rial re

tain

ed

(%

)

Id1

Id2

Id5


durability

W L

ISAC

W W W L L L WI WI WI WI LI LI LI LI

CCCDW BAS LIM

• Very low durability

• Very high durability

• Low durability

• High durability

•Medium high

durability

• Medium durability

Durability index is greater than 95.0% in all specimens

Recycled and natural aggregates are classified as very high durability.

Gamble

classification



petrographic analysis (after SDT) ISAC

Macropetrographie

Deposition of organic matter of the leachate on the surface of the

specimens, in particular in the alveolus.

Oxidized iron particles.

initial specimen specimen after SDT

(ISAC_SDTI_L)



petrographic analysis (after SDT) ISAC

Micropetrographie

Higher concentrations of opaque minerals, especially iron oxides.


(ISAC_SDTI_L)

18



petrographic analysis (after SDT) CCCDW

Macropetrographie

Alterations in the color of the cementitious matrix as a result of

deposition of organic matter of the leachate on the surface of the

specimens.


(CCCDW_SDTI_L)

19



petrographic analysis (after SDT) CCCDW

Micropetrographie



(CCCDW_SDTI_L)

20



petrographic analysis (after SDT) BAS

Macropetrographie

Slight alterations in color of the basalt as a result of deposition of

organic matter of the leachate on the surface of the specimens.


(BAS_SDTI_L)

21



petrographic analysis (after SDT) BAS

Micropetrographie

Partial or total alteration of phenocrystals of olivine (alteration of the

color and partial loss of mass of the phenocrystals).


(LIM_SDTI_L)

22



petrographic analysis (after SDT) LIM

Macropetrographie

Alterations in color of the limestone as a result of deposition of

organic matter of the leachate on the surface of the specimens.


(BAS_SDTI_L)

23



petrographic analysis (after SDT) LIM

Micropetrographie



(LIM_SDTI_L)

24



physical characteristics (after SDT)

Specimen b (Mg/m3) r (Mg/m3) Pe (%) wmax (%)

ISAC_SDT_W 3.98 3.58 10.00 2.88

ISAC_SDT_L 3.71 3.28 11.65 3.77

ISAC_SDTI_W 3.77 3.28 12.32 3.77

ISAC_SDTI_L 3.78 3.29 12.61 3.90

CCCDW_SDT_W 2.62 2.22 15.34 6.93

CCCDW_SDT_L 2.63 2.27 13.59 5.99

CCCDW_SDTI_W 2.65 2.24 15.27 6.82

CCCDW_SDTI_L 2.62 2.27 13.59 6.00

BAS_SDT_W 3.01 2.99 0.48 0.16

BAS_SDT_L 3.01 3.00 0.38 0.13

BAS_SDTI_W 3.04 3.02 0.45 0.15

BAS_SDTI_L 3.00 2.99 0.41 0.14

LIM_SDT_W 2.74 2.57 6.15 2.41

LIM_SDTI_L 2.72 2.57 5.33 2.09

LIM_SDT_W 2.72 2.59 4.70 1.82

LIM_SDTI_L 2.72 2.56 5.99 2.38

3.7

7

3.2

8

12.4

0

3.8

3

2.5

8

2.1

4

16.8

8

7.8

9

3.0

2

3.0

0

0.4

5

0.1

4

2.7

2

2.5

8

5.4

0

2.2

0

No significant quantitative changes have occurred on physical

characteristics of the specimens after SDT tests.

The use of water and leachate had no significant influence on physical

characteristics of the specimens.

The exception was observed for the porosity accessible to water (Pe)

and water absorption under vacuum conditions in CCCDW_SDT_L and

CCCDW_SDTI_L specimens. Pe and wmax decreased of about 3.3% and

2.0%, respectively, relating to these properties in CCCDW specimen.

These differences most likely have resulted from the deposition of

organic matter of the leachate on surface of the specimens,

particularly in the pores accessible to water.


physical characteristics

CCCDW specimen

(before SDT)

CCCDW_SDTI_L specimen

(after SDT)



CONCLUSIONS

According to Gamble classification, either the recycled aggregates (ISAC and CCCDW), or the natural aggregates (BAS and LIM), belong to the category of materials of very high durability, even when subjected to mechanical and chemical conditions more aggressive than those provided in the SDT test proposed by ISRM.

Previous immersion of specimens in tap water and in the acidified RSU leachate for 15 days and carrying out three slake-durability cycles did not affect the durability of the materials studied, except, though insignificant, in the case of CCCDW_SDTI_L specimen.

The results of petrographic study (macro- and microscopic) and physical characterization are consistent with the classification achieved for the four types of aggregates, recycled and natural, since no significant changes occurred in their initial petrography and physical properties.

The results obtained with the recycled aggregates, CCCDW and ISAC, as well as the natural ones, BAS and LIM, have showed their technical feasibility to be used in the proposed application, as well as in the most of the transportation infrastructure and geotechnical works, from the point of view of durability.

27

ACKNOWLEDGEMENTS

The authors would like to thank to:

Demotri Company (Ambigroup Group), for providing crushed

concrete aggregate;

Iron and Steel Company, for providing Inert Siderurgical

Aggregate for Construction;

Alves Ribeiro Company, for providing basalt aggregates;

Agrepor Company, for providing limestone aggregates;

Amarsul Company (AdP Group), from providing RSU leachate.


THANK

YOU ALL!


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