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First International Conference on Construction In Developing Countries (ICCIDC–I) “Advancing and Integrating Construction Education, Research & Practice” August 4-5, 2008, Karachi,, Pakistan

Aggregate Characterization - An Important Step towards Addressing Construction Issues in Pakistan

S. M. Zaidi

Research Assistant, Department of Civil Engineering, NED University of Engineering & Tech., Karachi, Pakistan

memadiha@neduet.edu.pk

S. F.A. Rafeeqi Professor & Dean, Faculty of Civil Engineering and Architecture, NED University of Engineering

&Tech., Karachi, Pakistan

M. S. Ali Professor & Chairman, Department of Urban and Infrastructure Engineering, NED University of

Engineering & Tech., Karachi, Pakistan

A. M. Khan Professor & Chairman, Department of Petroleum Engineering, NED University of Engineering & Tech.,

Karachi, Pakistan Abstract Aggregate is a material vastly used in the construction industry related to concrete structures, asphalt bases and pavement. To achieve required dimensional stability, durability and strength of structures, aggregate characteristics and related engineering properties is one of the main issues needed to be addressed. The city of Karachi is receiving massive quantities of aggregates supplied by several sources present within and along its periphery, however, no concerted effort has been witnessed to document aggregate characteristics, leading to all sort of durability problems and threatening service life of structures. There is a dire need to develop a data-base that contributes to the suitability of material in asphalt and concrete mix. Aggregate characterization technique is a forefront vision to enhance the quality of HMA and concrete along side being a pioneering move to select construction materials. It focuses on quality and performance in roads and buildings and determines suitability of their use in Hot Mix Asphalt and Concrete Mix Design, thus addressing issues related to applicability in given situation, strength, durability and maintenance and monitoring and rehabilitation. This paper aims to present a methodology for aggregate characterization based on their physical properties, petrography examination and engineering properties. Visits of construction sites in all eighteen towns of Karachi city revealed that Hub River is the major source of raw material. Based on experimental design formulated to evaluate the physical properties and engineering behaviour of rocks and crushed rock respectively, statistical techniques have been applied to ascertain significance of relationships between various properties governing aggregate characterization. Conclusions are drawn regarding suitability of characterization of aggregates in relation to their construction application and ability to address construction related problems. The aggregate characterization model thus developed has the capacity and potential to be utilized and extended for various scenarios.

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Keywords Aggregate Characterization, Engineering Properties, Petrographic Studies. 1. Introduction Understanding construction material and its behaviour in asphalt and cement applications has always been a challenge to construction industry. It is of utmost importance to assess and evaluate the properties at material level and as part of the mix for durability and monitoring point of view. Aggregate characterization is the first step needed to facilitate construction industry which focuses on quality and performance issues related to their application in cement concrete, asphalt and other construction. Being a high seat of learning, NED University has assumed the responsibility to take up the task of developing a comprehensive mechanism of aggregate characterization which would cover all aspects of variation in aggregate. These variations include aggregate physical and engineering properties as well as their chemical and reactivity considerations. All this calls for attempting aggregate characterization based on source rock, inherent variation, crushing plants limitations and brought down to laboratory testing of various properties. Bringing all this into one framework is the major objective of the research reported in this paper. It aims to provide a methodology for characterization of aggregates which can encompass various construction issues pertaining to Pakistan. The scope of the current research is limited to coarse aggregate as they possess major variability as well as they are required in large volume. This paper dwells upon a conceptual framework which visualizes the aggregate characterization as a comprehensive endeavour covering all major causes of variation in the aggregate properties. This way the conceptual framework may be considered as a step towards addressing construction issues including aggregate availability, aggregate quality and aggregate functionality. The paper provides the details of a conceptual framework envisaged as part of a comprehensive research agenda. The methodological aspects of converting concept into applicable targets are identified. The workability of the methodology is presented by carrying out field and laboratory examination of aggregates collected from Hub, the largest source supplying aggregates for the construction industry, prevalent in the mega city of Karachi. The conceptual frame work presented here will eventually lead to mapping out all related sites; crushing plant as well as quarries across Pakistan. 2. Aggregate Characterization And Understanding Of Construction Issues 2.1 Aggregate Characterization Attempts and Aspects Studied Documentation of aggregate resource area provides a semi-quantified estimate of construction aggregates available in the area to satisfy construction needs (Division of Mines and Geology, 2000). Aggregate characterization is the process of classification of aggregate resources on the basis of its rock source, properties and performance in various construction applications. It includes the cataloguing of the quarry and evaluation of its functional properties by laboratory testing so that it can be utilized according to its required property. California Geological Survey (CGS) reported general information about the current availability of California’s permitted aggregate resources on a Map having a scale of 1:1,100,000.All aggregate data and any reference to aggregate on the map pertain to construction aggregate that meets standard specifications for use in Portland Cement Concrete (PCC) or Asphalt Concrete (Kohler, 2006). Every potential deposit

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must be tested to determine how much of the material can meet the specifications for a particular use, and what processing is needed to work with it. This is of major importance when planning for future availability of aggregate commodities because of their versatility, value and relative scarcity. The aggregate resource map of Colorado-Wyoming developed in 1997 predicts the location of potential source of aggregate with understanding of geology which is utilized for regional planning and land use management (Langer et al., 1997). Correlation of textural properties were reported (Liu et al., 2004), which were studied through microscopic imaging, and mechanical properties, obtained from laboratory tests. The following tests were conducted, and properties of aggregate affecting the asphalt concrete performance were evaluated. I) Resistance of an aggregate to fragmentation by Los Angeles test; II) Measurement of rock aggregate resistance by Aggregate Abrasion Value; III) Determination of the resistance to wear by Aggregate Impact Value (AIV) test and brittleness test; IV) Determination of aggregate geometry by Length-Thickness (LT) index test and flakiness index test and V) Evaluation of the plasticity characteristic of fine aggregate sand equivalent value. In view of long term aggregate resource planning, the location and classification of sand, gravel and bedrock deposits is an essential first step in managing the resources. If one valuable aggregate deposit is identified in conjunction with other resources value then reserve area can be established for preservation and future use (Baker et al., 2005). As aggregate demand is increasing day by day, the quarries producing aggregate are depleting fast and the future production is bound to be decreased if the identification of new resources is not carried out. To fulfil the continually changing demand of construction aggregate and satisfaction of target market, exploration of new quarries is imperative. 2.2. Construction Issues 2.2.1 Durability of Aggregates The preliminary need of the aggregates is its inherent durability against natural and man created disturbances. The aggregate provide volume, stability, resistance to weathering and other physical properties to the building and road structures. There are common issues in construction related to characteristic of material such as; suitable aggregate gradation, shape, density and source. Deterioration of construction aggregates loses the durability requirement and progressive performance of structure. Prediction of aggregate characteristic before placement and starting the construction activity can manifest the un-expected happening and can prevent the post construction material problems. In this regard, keeping in view other construction requirement, aggregate sampling and testing is needed to make the construction workable and long-lasting. 2.2.2 Quality assurance The construction industry needs to move toward material laboratories in order to ensure quality and establish adequate confidence regarding the material used to satisfy given requirement and quality during the service life. Quality assurance of materials, therefore, as a first step needs testing of materials on the basis of specifications that should ensure and increase the confidence regarding fitness for the purpose of product and services. 2.2.3 Hauling, availability and supply of material The deposits supplied to the construction sites must be technically and economically effective to be used for the construction work. The aim of the construction site needs to grasp the quarry where maximum aggregate quantity is available at required rate of production with lowest possible cost. Aggregates resource map is a comprehensive and advisory indication to provide the occurrence of rock/aggregates that can be used in construction industry for various applications.

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2.3 Research Potential for Pakistan Literature search reveals that no such attempt has been witnessed in Pakistan which shows the evidence of aggregate characterization, technique to achieve this target and mapping of aggregate resources (Rafeeqi, 2007). It is, therefore, imperative that a concerted effort should be carried out for characterization of aggregates serving the construction industry; by integrating all possible sources affecting their performance in concrete, HMA and other related construction materials. The current study, therefore, would not only resolve the issue of regional resource planning, tempro-spatial dynamics of the area but would also possess the potential to resolve major construction issues. 3. Conceptual Framework Aggregates reaching construction sites possess variability in properties caused at-least at three stages. The first stage right at the bed rock, as bed rock is formed under natural phenomenon and inherits mineralogical and chemical properties. Gravel and boulders obtained from these bed rocks become the second stage where the shape, size and weathering of these stones results in redefining the properties of aggregates inherited from the bed rocks. The next stage causing variation in aggregate properties is at the crushing plants as gravels and boulders when turned into crushed aggregates possess further variation in their properties. The aggregate characterization attempt, therefore, must include variation caused at each of these stages. The Conceptual Framework for characterization of aggregates is presented through Figure 1. It comprises of three stages; stage 1 incorporates the evaluation process in which material is collected from the quarry and crusher. The sampling of material is to be done according to the prescribed procedure established by the standards for petrographic studies and carrying out engineering tests. Stage 2 consists of the quality evaluation of material in the light of standards and specifications for their use in various applications, such as cement concrete, HMA and others, so as to use it for various purposes. Stage 3 defines the development of aggregate resource map as a ready reference for the use of material that can be utilized for the selection and availability of material in relation to the construction site. 4. Methodology Aggregate characterization is the process of indication of source, evaluation of aggregate properties and designation of material sources so as to generate a data bank of construction material that can be utilized for instant reference in construction industry. To achieve this process, as a pilot study, field visits to the construction sites located in 18 towns were carried out in order to identify the sources of material coming within the city of Karachi. It has been found that Hub Naddi remains to be the major source supplying construction aggregates to these areas. The gravel of hub river basin is predominantly limestone inclusive of minor elements of other rocks which in the presence of water alters the representative characteristic of the main rock. Further basic contents (carbonate of Ca and Mg) of the material due to the exposure of water are removed and leads to the higher concentration of alumina, iron oxides, hydroxide and formation of clay minerals, where as the hot climatic condition disintegrate the rock to weathered condition (West et al., 1970). The methodology is primarily focused toward developing a conceptual framework which deals with aggregate characterization on the basis of physical properties, petrographic examination and engineering properties, eventually leading to the development of Adaptive Aggregate Characterization Model (AACM). The study, therefore, comprises of field investigation which includes reconnaissance field survey and the material collection for aggregates sampling from quarry and crusher plants of Hub Naddi for characterization (Ali et al., 2008). Further the gravels colleted from Hub Naddi were utilized for

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petrographic examination while the crushed material was utilized for engineering tests. Correlation charts have been developed to illustrate the mechanical behaviour of aggregates with the raw gravels and further the behaviour of aggregates in asphalt and cement was also observed to prioritise its usage in the two binders. These charts, however, are not made part of this paper.

Quarry

Sampling (Area, Material, Number)

Evaluation Process

Petrographic Studies

Study of Engineering Properties

Cutting Crushing

Acceptable Quality

Suitability of Aggregate

Conveyor Route to

Construction Sites

(Hauling Distance)

Sufficient Amount (Availability and Storage)

Distribution to Construction Sites (Supply to how many sites)

Aggregate Resource Map

Geological Structure and Tectonic Features

Hydrology of the Area

Lithology of Rock Type

GPS and Area

Ready Reference

Standards and Specification

Stage 1

Stage 2

Stage 3

Application in

Pavement Structure

• Wearing Course

• Base Course

Building and Bridges

• Cement Concrete

• Mortar

Other • Railway

Track Ballast

• Filter Media

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Figure 1: Conceptual Framework for Aggregate Characterization

4.1. Surveys and Sampling Initially 18 towns of Karachi were visited to determine the source of aggregates being used. Based on this information, the survey of the quarries and crushers installed at the Hub Naddi was conducted to collect the samples from quarries and crushers and distinguished as Hub Naddi gravel and crushed aggregate. The material was sampled according to the experimental design and estimated numbers of samples were prepared to perform petrographic examination and engineering properties. Keeping in view the appearance of material, the gravel were sorted out according to colour in three (03) categories; red, yellow and grey along with its condition of being either fresh or weathered. The percentages of each colour and condition were estimated so as to check intensity of each gravel in a representative sample collected from a quarry (Ali et al., 2008). According to the sample size four (04) gravels were randomly picked from each colour and condition to study the physical properties. Each sample was labelled according to its source, location and property. From the entire Hub Naddi initially two (02) quarries were chosen for the evaluation of properties. The coarse aggregates from the crushed rock of each quarry were also separated on the basis of colour (red, yellow, grey) to conduct engineering tests, and samples of each colour with required sizes were separated and labelled. Figure 2 illustrates the sampling of rock and crushed rock (aggregates).

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Figure 2: Study of Engineering and Petrographic Examination of the Sample

4.2.1. Petrographic examination Petrographic testing is a microscopic examination that evaluate the aggregate material (French, 1991) and is used to examine the Alkali-Aggregate-Reaction (AAR) risk in carbonate aggregates which remains to be one of the major cause of damage in concrete (Lopez-Buendia et al., 2006). The petrographic examination, therefore, included the description and systematic classification of rock and studying thin sections by means of microscope. The gravels after physical description were cut into thin slices, trimmed and reduced to 0.03mm thickness and pasted on glass slide to be studied under microscope and then compiled in the form of designed data table. 4.2.2 Engineering tests The sets of engineering tests for evaluation of aggregate in relation to its behaviour in asphalt and cement concrete were identified and conducted according to ASTM and BS standards (Dhir et al., 1971; Akbulut et al., 2006; Pan et al., 2006 and Brandes et al., 2006). The list of selected tests for the current study were: a) Flakiness Index; b) Elongation Index; c) LA Abrasion; d) Specific Gravity and Absorption; e) Crushing Value and f) Impact Value. The samples utilized for conducting these tests, however, remained confined to crushed aggregates obtained from crushing plants.

Hub Naddi Selection of Quarries on the basis of Variation in Material

Quarry1 (Maru Dakka)

Quarry 2 (Hasan Pir Hill)

Crushing of Rock

Physical Properties

Petrographic Studies

Aggregate

Engineering Properties

Rock Samples

Crushed Rock Samples

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As said earlier, the coarse aggregates were sorted out on the basis of colours; red, yellow and grey, while engineering tests were performed to check the mechanical behaviour. The results were then compiled and the qualitative analysis of the engineering and petrographic studies is presented through Table 1a & 1b. 5. Preliminary Results And Discussion Table 1 (a & b) show the qualitative analysis of engineering properties of aggregate collected from crushers and petrographic studies of rock collected from quarries, according to the variation observed within the aggregates. Table 2 shows the evidence of methodology being adopted for evaluating engineering properties of aggregates in terms of allowable limits needed for asphalt and cement concrete. It has been found that both the quarries supplying these aggregates have satisfactory quality and may be recommended to be utilized for roads and building application. 6. Conclusion The paper presents a conceptual framework which puts forwarded a vision for aggregates characterization. It integrates three major facets of characterization viz. the aggregate source, the crushing plant and the basic properties obtained through physical and engineering testing. The above three facets are linked with application side where the standards come in place to define suitability of the aggregate for a given application such as concrete, asphalt etc. The output of the characterization is an aggregate resource map which can provide geographically referenced database for ready utilization. It may be concluded that the ongoing study would provide results which would be highly beneficial to the construction industry in Pakistan.

Table 1 a: Qualitative Analysis of Engineering Properties and Petrographic Studies of Rock Quarry: Maru Dakka Crusher: Rais Goth

Sample Engineering Properties Petrographic Studies RED AGGREGATE Flakiness Index: High Texture: Grain supported

Texture Elongation Index: Low Sphericity of grains: Medium Absorption: Low Intensity of Fossils: Medium Crushing Value: Low Impact Value: Medium LA. Abrasion: Medium Sample Engineering Properties Petrographic Studies YELLOW AGGREGATE Flakiness Index: High Texture: Mixed Elongation Index: Low Sphericity of grains:

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Medium Absorption: Low Intensity of Fossils: High Crushing Value: Low Impact Value: Medium LA. Abrasion: Low Sample Engineering Properties Petrographic Studies GREY AGGREGATE Flakiness Index: High Texture: Mixed Elongation Index: Low Sphericity of Grains: Low Absorption: Low Intensity of Fossils: High Crushing Value: Low Impact Value: Medium LA. Abrasion: Low

Table 1 b: Qualitative Analysis of Engineering Properties and Petrographic Studies of Rock Quarry: Hasan Pir Hill

Crusher: Hasan Pir

Sample Engineering Properties Petrographic Studies RED AGGREGATE Flakiness Index: Low Texture: Matrix Supported

Texture Elongation Index: Medium Sphericity of Grains: Low Absorption: Low Intensity of Fossils: High Crushing Value: Medium Impact Value: Medium LA. Abrasion: Low Sample Engineering Properties Petrographic Studies YELLOW AGGREGATE Flakiness Index: Low Texture: Mixed Texture Elongation Index: Medium Sphericity of Grains: Low Absorption: Low Intensity of Fossils: Medium Crushing Value: Medium Impact Value: Low LA. Abrasion: Low Sample Engineering Properties Petrographic Studies GREY AGGREGATE Flakiness Index: Low Texture: Grain Supported

Texture Elongation Index: Low Sphericity of Grains: Low Absorption: Low Intensity of Fossils: High Crushing Value: Medium Impact Value: Low LA. Abrasion: Low

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Table 2 a: Aggregate suitability analysis results

Table 2 b: Aggregate suitability analysis results

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7. Refrences Akbulut, H., and Gu¨ rer, C. (2006). “Use of Aggregates Produced from Marble Quarry Waste in Asphalt

Pavements”. Building and Environment, Vol. 42, pp 1921-1930. Ali, M.S., Khan, A.M., and Zaidi S.M. (2008), “Sampling Techniques for the Characterization of Hub

River Aggregates, Sindh, Balochistan Area, Pakistan”. 1st International Conference of Transportation and Infrastructure, Beijing, China.

Baker, D., and Hendy, B. (2005). “Planning for Sustainable Construction Aggregate Resources in Australia”. The Queensland University of Technology Research Week International Conference, Brisbane, Australia.

Brandes, H.G., and Robinson C.E. (2006). “Correlation of Aggregate Test Parameters to Hot Mix Asphalt Pavement Performance in HAWAII”. Journal of Transportation Engineering ASCE, Vol. 132, pp 86-95.

Dhir, R. K., Ramasy, D. M., & Balfour, N. (1971). “A Study of the Aggregate Impact and Crushing Value Tests”. Journal of the Institute of Highway Engineers, pp 17-27.

Division of Mines and Geology (2000). “Guidelines for Classification and Designation of Mineral Lands”. California Surface Mining and Reclamation Policies and Procedures, Special Report 51, California, US.

French, W.J. (1991). “Concrete Petrography”. Quarterly Journal of Engineering Geology, Vol. 3, pp 17-48.

Kohler, S. (2006). “Aggregate Availability in California”. Department of Conservation, California Geological Survey.

Langer, W.H., Green G.N., Knepper, D.H., Lindsey, J.D.A., Moore, D.W., Nealy, L.D., and Reed, J.C. (1997). “Distribution and Quality of Potential Sources of Aggregate Infrastructure Resources Project Area, Colorado-Wyoming”.

Liu, H., Kou, S., and Arne, P. (2004). “Microscope Rock Texture Characterization and Simulation of Rock Aggregate Properties”. SGU Project 60-1362.

Lopez-Buendia, A.M., Climent, V., Verdu, P. (2006). “Lithological Influence of Aggregate in the Alkali-Carbonate Reaction”. Cement and Concrete Research, Elsevier Ltd. Valencia, Spain, Vol. 36.

Pan, T., Tutumluer, E., and Carpenter, S.H. (2006). “Effect of Coarse Aggregate Morphology on Permanent Deformation Behaviour of Hot Mix Asphalt”. Journal of Transportation Engineering ASCE, pp 580-589.

Rafeeqi, S.F.A. (2007). “Proceedings of International Workshop on Cement Based Materials and Civil Infrastructure”. Karachi Pakistan, pp 91-102.

West, G., & Dumbleton, M.J. (1970). “The Mineralogy of Tropical Weathering Illustrated by Some West Malaysian Soils”. Quarterly Journal of Engineering Geology, Vol. 3, pp 25-40.