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1 Powered by TCPDF ( Swinburne Research Bank Author: Arulrajah, A., Piratheepan, J., Disfani, M. M. & Bo, M. W. Title: Resilient moduli response of recycled construction and demolition materials in pavement subbase applications Year: 2013 Journal: Journal of Materials in Civil Engineering Volume: 25 Issue: 12 Pages: URL: Copyright: Copyright 2012 American Society of Civil Engineers. This is the author s version of the work, posted here with the permission of the publisher for your personal use. No further distribution is permitted. You may also be able to access the published version from your library. The definitive version is available at: Swinburne University of Technology CRICOS Provider 00111D swinburne.edu.au

2 RESILIENT MODULI RESPONSE OF RECYCLED CONSTRUCTION AND DEMOLITION MATERIALS IN PAVEMENT SUBBASE APPLICATIONS A. Arulrajah 1, J. Piratheepan 2, M. M. Disfani 3 and M. W. Bo 4 A. Arulrajah 1 Associate Professor, Swinburne University of Technology, Melbourne, Australia. J. Piratheepan 2 Lecturer, Swinburne University of Technology, Melbourne, Australia. M. M. Disfani 3 Lecturer, Swinburne University of Technology, Melbourne, Australia. M. W. Bo 4 Senior Principal/Director, DST Consulting Engineers Inc, Thunder Bay, Ontario, Canada Corresponding Author: A/Prof Arul Arulrajah Faculty of Engineering and Industrial Science (H38), Swinburne University of Technology, P.O Box 218, Hawthorn VIC 3122 Australia. aarulrajah@swin.edu.au Phone : Fax :

3 Abstract Results of an extensive series of repeated load triaxial tests performed on three major recycled construction and demolition (C&D) materials at various moisture contents and stress levels were analysed to ascertain their performance in pavement subbases. The development of the resulting permanent deformation that accumulates with the repeated loading and the determination of resilient modulus by two phases of the test are described. The experimental study shows that the C&D materials perform satisfactorily at a moisture content of about 70% of their optimum moisture contents. Furthermore, the C&D materials also satisfy the two parameter and three parameter models. The results of this study indicate that, at a density ratio of 98% compared to maximum dry density obtained in the modified proctor test and with moisture contents in the range of 65%-90% of the optimum moisture content, most of the recycled C&D materials produce comparatively smaller permanent strain and greater resilient modulus than natural commonly used granular subbase materials in pavement subbase applications. Keywords: geotechnical; pavement; recycled materials; demolition; waste; resilient modulus; permanent deformation. 2

4 Introduction Construction and demolition (C&D) materials is the waste material collected from construction and demolition of buildings and structures. In recent years, C&D waste has become a valuable resource and is increasingly being used in various geotechnical engineering applications (Aatheesan, et al., 2010, Ali, et al., 2011). The amount of C&D waste materials is increasing annually and accounts for 40% of all waste going to landfill (Sustainability-Victoria, 2010). The increasing scarcity of natural resources and the soaring cost of waste disposal to landfills highlight the urgency of recycling and finding new ways to reuse C&D waste. Recycling and subsequent reuse of C&D materials will reduce the demand for scarce virgin natural resources as well as reduce the significant quantities of this waste material currently destined for landfill (Disfani, et al., 2011). The reuse of recycled C&D materials will have significantly lower carbon footprints compared to traditional quarried materials which will consequently lead to a more sustainable environment. C&D materials can be used as alternatives to quarry based products for road pavements and other civil works (Aatheesan, et al., 2010, Akbulut and Gurer, 2007, Arulrajah, et al., 2012, Jitsangiam and Nikraz, 2009, Poon and Chan, 2006, Tam and Tam, 2007). The usage of C&D materials in pavement bases and subbases is considered a viable and sustainable solution to minimise the C&D waste while reducing the demand for scarce virgin quarried materials. Assessment of resilient modulus and permanent deformation characteristics of C&D materials is an essential part in the process to adopt these materials in pavement base and subbase applications. In Australia for example, approximately 8.7 million tons of demolition concrete, 1.3 million tons of demolition brick and 3.3 million tons of excavated waste rock are stockpiled annually and these stockpiles are growing. These figures are the authors estimate obtained by applying the figures for the state of Victoria (Sustainability-Victoria, 3

5 2010) to the entire nation based on the ratio of Victoria s population to that of Australia. The resilient modulus and permanent deformation characteristics of three major C&D waste materials being recycled concrete aggregate (RCA), crushed brick (CB) and waste excavation rock (WR) is of particular interest in this study. Concrete waste is a by-product of construction and demolition activities of concrete structures. These concrete chunks are crushed into aggregates of variable sizes depending on the field of application, which are then termed as Recycled Concrete Aggregate (RCA). The nominal maximum diameter of 20 mm is the size commonly used as RCA for pavement base applications. Poon and Chan (2006), Tam and Tam (2007) and Arulrajah et al. (2012, 2012) have previously investigated the possibility of using RCA as unbound subbase materials. Brick rubble waste is another by-product of construction and demolition activities of buildings and other structures. Crushed brick (CB) typically consists of 70% brick and 30% other materials such as asphalt, concrete and rock, which were not removed (Arulrajah, et al., 2011). Several researchers have investigated the possibility of reusing CB in several civil engineering applications (Gregory, et al., 2004, Poon and Chan, 2006). Arulrajah et al. (2011); Arulrajah et al. (2012) and Aatheesan et al. (2010) have investigated the geotechnical properties and possibility of using CB as unbound subbase materials. Waste excavation rock (WR) originates from basalt floaters or surface excavated rock (basalt) which commonly occurs near the surface to the west and north of Melbourne, Australia (Aatheesan, et al., 2010). The rock is often encountered in excavation for residential sub divisional development and in the excavation works for drainage lines as well as other subsurface infrastructure (Ali, et al., 2011). Traditionally this material, excavated during site preparation, would have been disposed as waste, often into landfill. However, due to their 4

6 hardness, durability, and other desirable properties as a road aggregate they have been explored for usage in pavement and footpath applications (Aatheesan, et al., 2010, Akbulut and Gurer, 2007, Ali, et al., 2011, Arulrajah, et al., 2012, Arulrajah, et al., 2012, Jitsangiam and Nikraz, 2009, McKelvey, et al., 2002, Nunes, et al., 1996, Rodgers, et al., 2009). Other common recycled aggregates used in pavement base and subbase applications include reclaimed asphalt pavement (Hoyos, et al., 2011, Piratheepan, et al., 2012, Puppala, et al., 2011, Taha, et al., 2002) and recycled crushed glass (Ali, et al., 2011, Arulrajah, et al., 2012, Disfani, et al., 2012, Grubb, et al., 2006, Imteaz, et al., 2012, Wartman, et al., 2004). C&D materials account for half of the solid waste generated worldwide with an environmental impact at every step of the building process. Challenges of low-carbon economies and resource depletion are major factors in pushing toward reuse of C&D material in roadwork applications (DSEWPC, 2012). Landfill cost (which ranges from AUD$42 to $102 per ton in Australia) is a major driver for reuse of C&D waste materials. Sometimes there are additional levy charges introduced by state and local governments which add up to the landfill cost. In Australia, furthermore the cost implications of the newly introduced carbon tax and rising energy prices also need to be considered. These considerations suggest that reusing C&D waste in most cases will be a more economical solution compared to using natural virgin aggregate (DSEWPC, 2012). The cost of C&D products, based on the authors experience, is competitive compared to that of traditional quarry aggregates. The C&D products also tend to have lower densities than traditional quarry products and often more C&D products can be obtained for the equivalent unit weight. In addition to potential cost savings, there are also significant carbon savings in the usage of recycled materials in Civil Engineering applications. The haulage distance and cost are often the main dominating factor 5

7 in the final decision making process of whether to use a C&D product or a traditional quarry product. Testing Procedure The experimental investigation involved the study of the resilient modulus and permanent deformation characteristics of recycled C&D waste materials. Samples of these materials were obtained from several recycling sites in the state of Victoria, Australia. RCA, CB and WR aggregates used in this research had a maximum aggregate size of 20 mm. Modified compaction tests were conducted following the Australian standard AS (2003), which is similar to the ASTM-D1557 (2009). It is noted that the sample was compacted in five layers in a 105 mm diameter by 115 mm high mould with the application of 25 blows per layer for the compaction testing and the moisture content-dry density relationships were determined for a compaction effort of 2700 kn-m/m3. The specimens for the repeated load triaxial (RLT) tests were prepared in split moulds 100 mm in diameter and 200 mm in height. The recycled C&D materials were oven dried over 24 hours at around 105 C and allowed to cool down before the sample preparation. Water was subsequently added to bring the sample to appropriate a moisture content equal to optimum moisture content obtained in modified compaction test. The mixture was kept for 12 hours in a closed container to make moisture uniformity throughout the sample. Test specimens were prepared for RLT testing using the dynamic compaction method (AS, 2003) into the split mould. The automatic (mechanical) compaction apparatus, which permits a continuous and even compaction mode, was used to produce uniform specimens to specified density. The specimens were compacted to the target density of 98% maximum dry density (MDD) while the target moisture content was 100% of optimum moisture content (OMC). Test specimens 6

8 were then allowed to dry back to the target moisture content. Generally, it was possible to prepare the specimens within the tolerance of 0.5% for density ratio using the dynamic compaction method at 100% OMC. However, it was more difficult to achieve moisture contents within the tolerance of 0.5% of the optimum moisture content using the dry-back method. Table 1 summarises the dry densities and moisture contents of the tested samples. However, some of the target moisture contents varied by high percentages due to the uncertain nature of air drying. For each material, 3 samples were prepared and air dried back to target moisture contents of 90 %, 80 % and 70 % of the optimum moisture contents, to simulate the possible field moisture contents of subbases. Repeated Load Triaxial (RLT) test was conducted to determine the resilient modulus and permanent deformation responses of the recycled C&D materials. The resilient modulus determination characterises the vertical resilient strain response using combinations of applied dynamic vertical and static confining stresses (Austroads, 2004). In this investigation, the RLT test was performed according to the test method proposed by Vuong and Brimble (2000). The RLT test consists of two phases of testing, permanent strain testing (Phase 1) followed by resilient modulus testing (Phase 2) on the same sample. Permanent strain testing (Phase 1) consists of three or four stages, each performed at different deviator stresses and a constant confining stress (Austroads, 2004). The permanent deformation determination characterises the vertical permanent strain with multiple loading stages (at different stress conditions) to enable quantification of the effects of vertical stress on permanent strain in a single test. This testing is specifically proposed for subbase material, in which the stresses are supposed to closely represent the actual stresses occurring in the pavement (Austroads, 2004). As such, this phase is more relevant for representing actual pavement material resilient modulus. Each of the stages consists of 10,000 repetitions and 7

9 which are more representative of real traffic loading. For the WR specimens, which appeared to fail quickly under the stress level of 350 kpa deviator stress and 50 kpa confining stress, three different loading stages (at specified deviator stresses of 150 kpa, 250 kpa and 350 kpa respectively) were used. For the RCA, which could carry the stress level of 450 kpa deviator stress and 50 kpa confining stress, four different loading stages (at specified deviator stresses of 150 kpa, 250 kpa, 350 kpa and 450 kpa respectively) were used. The resilient modulus testing (Phase 2) characterises the vertical resilient modulus of the materials at different stress conditions. The resilient modulus testing phase consists of sixtysix (66) loading stages with 50 repetitions, where confining stress varies between 20 kpa and 150 kpa and deviator stress varies between 100 kpa to 600 kpa and was conducted according to Austroads (2004). This process simulates the complicated traffic loading acting on a pavement. The Austroads (2004) resilient modulus testing method is very similar to AASHTO T307 (2003) except for differences in the stress conditions. In AASHTO T307 (2003), confining stress varies between 14 kpa and 42 kpa and deviator stress varies between 14 kpa to 69 kpa. The stresses and stress ratios are increased in small sizes to avoid early failure, which can occur at high stress ratios (Austroads, 2004). The specimens were compacted to 98% modified maximum dry density (MDD) and tested at three target moisture contents of 70%, 80% and 90% of the modified OMC. In the resilient modulus testing (Phase 2), both the confining and deviator stresses are varied over a preset wide range (Austroads, 2004). This phase is useful for examining the resilient modulus relationships with bulk stresses. The repetition of loading in each stage is less compared to permanent deformation test (Phase 1) and therefore, the resilient modulus achieved from permanent deformation test (Phase 2) is considered to be more reliable and has been used as the reported result. 8

10 Results and Discussion The particle size distributions of the three recycled C&D materials are shown in Figure 1. The grain size distribution parameters including D 10, D 30, D 50, D 60, C u, C c, percentage of gravel sized particles, percentage of sand sized particles, percentage of fines, USCS symbol and description are summarised in Table 2. RCA, CB and WR have approximately equal amount of sand and gravel sized particles, enabling them to be classified as gravelly sand or sandy gravel sized particles. The RLT test provides resilient modulus-permanent deformation parameters that uniquely describe the material response to traffic loading under prevailing physical conditions. These parameters are used as input to the design and analysis of pavement structures. The test results can also be used to establish a material selection criterion based on its ability to perform effectively in terms of permanent deformation sustained. Results of permanent strain testing (Phase 1) which consists of variations of permanent strain and resilient modulus against number of load cycles for the recycled C&D materials are plotted in Figure 2 and Figure 3. Results of resilient modulus testing as obtained from the resilient modulus tests (Phase 2) for these recycled C&D materials are plotted in Figure 4. RLT tests on recycled glass and reclaimed asphalt pavement were also attempted by the authors for this paper but these tests were unsuccessful due to their low cohesion which is attributed to lack of fines. Generally, the recycled C&D materials performed satisfactorily in the RLT tests for permanent strain testing (Phase 1) at 98% MDD and 70% of the OMC. However, some materials showed sensitivity to moisture and produced higher limits of permanent strain and lower limits of resilient modulus, particularly at higher target moisture contents in the range of 80%-90% of the OMC. It should be noted that the normal operating field moisture contents 9

11 for most pavement materials is generally below 75% of the OMC and consequently the performance at higher moisture contents of the OMC uniquely represents a worst case scenario. As expected the performance of the materials will be affected by increasing target moisture contents and the density level achieved in the compacted samples. The results in Table 3 indicate that, for a density ratio of 98% modified MDD and target moisture contents in the range of 65%-90% of the OMC, most of the recycled materials produced much smaller permanent strain and much higher modulus than natural granular subbases. Moreover, high level of the modulus values achieved for the recycled concrete aggregate suggests that residual cementing action is occurring in these samples. While this action may result in shrinkage cracks and possibly some reflective cracking, it is unlikely that it will significantly affect the performance of the pavement layer over time. This is because the hydration process due to residual cement in the RCA will be considerably slow as the residual cement is expected to have reached the final stage (diffusion-limited reaction period) long time ago. The slow hydration process will produce minimal shrinkage effects or reduce the shrinkage development (Chakrabarti and Kodikara, 2005). Results of permanent strain and resilient modulus for typical quarried granular subbases used in Australia are also provided as a comparison in Table 3. Permanent deformation results (Phase 1) can be presented in terms of the relationship between permanent strain rate and permanent strain (Dawson and Wellner, 1999). Figure 5 shows the permanent strain rate versus permanent cumulative strain for all the target moisture content cases investigated based on the results of permanent deformation tests (Phase 1). For RCA and CB, the responses were plastic in the first stage for a finite number of load applications, but after completion of the post compaction period, the response becomes entirely resilient, and no further permanent strain occurred. In the second stage, resurgence of 10

12 the permanent strain rate was observed for a number of load applications due to the increased deviator stress (i.e. deviator stress increased from 150 kpa to 250 kpa) and then the rate decreased, except for CB at 84% of the OMC. If the resurgence of the strain rate continues to increase, it is the indication of the failure. This happened for the CB samples with 80% and 84% of the OMC after first and second stages respectively. For WR, the responses were plastic with a higher level of strain rate during the first load cycles, and then the high level of plastic strain rate decreased to a low, nearly constant level. Because of the almost constant level of strain rate, in each stage a near-linear rise of permanent strain is observed (Figure 2) for all moisture content cases. The resilient modulus of the recycled materials from Phase 2 (Resilient modulus testing with 66 stages) were modelled as non-linear with respect to the magnitude of the applied stress (Hicks and Monismith, 1971) as shown in Equation 1: M k 2 r k 1 (Eq. 1) Where M r is resilient modulus (MPa), θ ( ) is bulk stress (kpa) and k 1 and k 2 are statistical regression parameters in this two parameter model. Figure 6 to Figure 8 show the results of the resilient modulus (Phase 2) of the recycled materials at different target moisture contents plotted against the bulk stress. It is noted that for WR and CB results, less than 3 moisture levels are presented. This is because the samples failed prior to completion of all loading stages at these higher moisture levels. These plots also show the results of the resilient modulus of the recycled materials modelled reasonably by using the K-θ model (Hicks and Monismith, 1971). Generally, higher values of k 1 and lower values of k 2 apply to good quality materials such as quarried stone (Gopalakrishnan, 2006, Rada and Witczak, 1981). 11

13 It is noted from Table 4 that the three recycled materials tested show high regression coefficient values of k 1 and lower values of k 2 for all the moisture content cases. Nevertheless, RCA at actual moisture content of 71% of the OMC shows the highest value of k 1 of 83.5 and lowest value of k 2 of 0.4 among the three recycled materials tested. This indicates that RCA at actual moisture content of 71% of the OMC, provides the best performance in the field. Similarly, CB at actual moisture content of 65% of the OMC shows the higher k 1 and the lower k 2 between the two samples at different moisture contents. As a result, it could be regarded as the best quality material among the materials tested. By and large C&D materials tested at actual moisture content of about 70% of the OMC, results in a lower resilient modulus and obtained the lowest value of k 1 and highest value of k 2. (Rada and Witczak, 1981) studied the resilient response of granular material on six different category material which added 271 samples and revealed a relationship between k 1 and k 2 on tested samples. A similar attempt was made to find the relationship between k 1 and k 2 in this investigation such that by knowing one parameter, the other can be determined. A unique relationship was derived for the recycled C&D materials and the relationship is shown in Figure 9. Uzan (1981) proposed a three parameter model which includes deviator stress based on laboratory measured resilient modulus as presented in Equation 2: M r k2 k1 pa p a d p a k3 (Eq. 2) Where, M r is resilient modulus (MPa), θ is bulk stress (kpa), σ d is deviator stress (kpa), p a is atmospheric pressure (100 kpa) and k 1, k 2, and k 3 are regression coefficients. Table 5 shows the regression coefficients (k 1, k 2, k 3 ) of the three parameter model for all the recycled materials using Uzan (1981) relationship. All the materials indicate positive values 12

14 for k 1 and k 2, and negative values for k 3 except CB. Most of the materials show higher k 1 values compared to k 2 values except WR. It appears that the coefficient values do not show any correlation with the target moisture contents for RCA and WR. It is noted that the sample with higher resilient modulus shows higher k 1 values. As the parameter k 2 is positive and related to bulk stress, the resilient modulus increases with bulk stress. As the parameter k 3 is negative and related to deviator stress, the resilient modulus decreases with deviator stress. When compared with bulk stress, the effect of deviator stress alone is minimal as the k 3 values are less than k 2 values. The C&D materials were found to satisfy both the two parameter and three parameter models. As the three parameter model has an additional required parameter, the authors would suggest that a higher level of requirement is required for the C&D materials to satisfy the three parameter model. Conclusions The experimental evaluation of three common recycled C&D waste materials for pavement base and subbase applications based on RLT tests were performed in this investigation. The evaluation was conducted in terms of the resilient modulus and the permanent deformation in an attempt to provide insight into the resilient and permanent deformation characteristics of recycled C&D waste under traffic loading conditions which will consequently help in bridging the knowledge gap on using recycled C&D in pavement applications The results of RLT experimental study, suggests that CB, RCA and WR would perform satisfactorily only around target moisture contents of 70% of the OMC. Even though, the normal operating moisture level of pavement is around 75% of the OMC, at higher moisture levels; strength of these materials will be reduced and would possibly lead to failure. CB, 13

15 RCA and WR satisfy the two parameter and three parameter models. All the models show that the resilient modulus increases with bulk stress. However, there is no clear variation with deviator stress or target moisture contents. The recycled C&D materials produced much smaller permanent strain and much higher modulus than natural granular subbases which is an indication of their superior performance under repeated loading of vehicles. The C&D materials were found to satisfy both the two parameter and three parameter models. As the three parameter model has an additional required parameter, the authors would suggest that a higher level of requirement is required for the C&D materials to satisfy the three parameter model. References AASHTO-T (2003). "Standard method of test for determining the resilient modulus of soils and aggregate materials."american Association of State and Highway Transportation Officials. Aatheesan, T., Arulrajah, A., Bo, M. W., Vuong, B., and Wilson, J. (2010). "Crushed Brick Blends with Crushed Rock for Pavement Systems." Proceedings of the Institution of Civil Engineers (UK), Waste and Resource Management, 163(1), Akbulut, H., and Gurer, C. (2007). "Use of aggregates produced from marble quarry waste in asphalt pavements." Building and Environment, 42, Ali, M. M. Y., Arulrajah, A., Disfani, M. M., and Piratheepan, J. (2011). "Suitability of Using Recycled Glass - Crushed Rock Blends for Pavement Subbase Applications." Geo-Frontiers 2011 Conference on Geotechnical and Foundation Design, March 13-16, 2011, American Society of Civil Engineers, Dallas, Texas, USA,

16 Arulrajah, A., Ali, M. M. Y., Disfani, M. M., Piratheepan, J., and Bo, M. W. (2012). "Geotechnical performance of recycled glass-waste rock blends in footpath bases." ASCE Journal of Materials in Civil Engineering, doi: /(ASCE)MT Arulrajah, A., Ali, Y. M. M., Piratheepan, J., and Bo, M. W. (2012). "Geotechnical properties of waste excavation rock in pavement sub-base applications." Journal of Materials in Civil Engineering, 24(7), Arulrajah, A., Piratheepan, J., Aatheesan, T., and Bo, M. W. (2011). "Geotechnical properties of recycled crushed brick in pavement applications." Journal of Materials in Civil Engineering, 23(10), Arulrajah, A., Piratheepan, J., Bo, M. W., and Sivakugan, N. (2012). "Geotechnical characteristics of recycled crushed brick blends for pavement sub-base applications." Canadian Geotechnical Journal, 49(7), Arulrajah, A., Piratheepan, J., Disfani, M. M., and Bo, M. W. (2012). "Geotechnical and geoenvironmental properties of recycled construction and demolition materials in pavement subbase applications." ASCE Journal of Materials in Civil Engineering, doi: /(ASCE)MT Arulrajah, A., Piratheepan, J., Y., A. M. M., and Bo, M. W. (2012). "Geotechnical properties of recycled concrete aggregate in pavement subbase applications." ASTM, Vol. 35, No. 5, pp AS (2003). "Soil compaction and density tests - Determination of the dry density/moisture content relation of a soil using modified compactive effort. Australian Standard " Australian Standard, Sydney, Australia. ASTM. (2009). "Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3(2,700 kn-m/m3)). ASTM Standard D1557." ASTM International, West Conshohocken, PA. Austroads (2004). "Guide to the Structural Design of Road Pavements." Austroads, Sydney, Australia. 15

17 Chakrabarti, S., and Kodikara, J. (2005). "Shrinkage behaviour of crushed basaltic rock and residual clay mixture stabilized with cementitious binders." International Journal of Pavement Engineering, 6(1), Dawson, A. R., and Wellner, F. (1999). "Plastic Behavior of Granular Materials, Report ARC Project 933 Reference PRG99014." University of Nottingham, United Kingdom. Disfani, M. M., Arulrajah, A., Bo, M. W., and Hankour, R. (2011). "Recycled crushed glass in road work applications." Waste Management, 31(11), Disfani, M. M., Arulrajah, A., Bo, M. W., and Sivakugan, N. (2012). "Environmental risks of using recycled crushed glass in road applications." Journal of Cleaner Production, 20(1), Gopalakrishnan, K. (2006). "Prediction of Airport Flexible Pavement Critical responses from Non-destructive Test Data using ANN-based Structural Models." Journal of Applied Sciences, 6(7), Gregory, R. J., Hughes, T. G., and Kwan, A. S. K. (2004). "Brick recycling and reuse." Proceedings of the Institution of Civil Engineers: Engineering Sustainability 157(3), Grubb, D. G., Gallagher, P. M., Wartman, J., Liu, Y., and III, M. C. (2006). "Laboratory Evaluation of Crushed Glass Dredged Material Blends." Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 132(5), Hicks, R. G., and Monismith, C. L. (1971). "Factors Influencing the Resilient Properties of Granular Materials." Transportation Research Record: Journal of the Transportation Research Board 345, Hoyos, L. R., Puppala, A. J., and Ordonez, C. A. (2011). "Characterization of cement fibertreated reclaimed asphalt pavement aggregates: Preliminary investigation." Journal of Materials in Civil Engineering, ASCE, 23(7),

18 Imteaz, M., Ali, M. M., Y., and Arulrajah, A. (2012). "Possible Environmental Impacts of Recycled Glass Used as a Pavement Base Material." Waste Management and Research, 30 (9), Jitsangiam, P., and Nikraz, H. (2009). "Mechanical behaviours of hydrated cement treated crushed rock base as a road base material in Western Australia." International Journal of Pavement Engineering, 10(1), McKelvey, D., Sivakumar, V., Bell, A., and McLaverty, G. (2002). "Shear strength of recycled construction materials intended for use in vibro ground improvement." Ground Improvement, Proceedings of the Institution of Civil Engineers, UK, 6(2), Nunes, M. C. M., Bridges, M. G., and Dawson, A. R. (1996). "Assessment of secondary materials for pavement construction: Technical and environmental aspects." Waste Management, 16(1-3), Piratheepan, J., Arulrajah, A., and Disfani, M. W. (2012). "Large scale direct shear testing of recycled construction and demolition materials." Advances in civil engineering materials, ASTM, (article in press, accepted November 2012). Poon, C. S., and Chan, D. (2006). "Feasible use of recycled concrete aggregates and crushed clay brick as unbound road sub-base." Construction and Building Materials, 20, Poon, C. S., and Chan, D. (2006). "Feasible use of recycled concrete aggregates and crushed clay brick as unbound road sub-base." Construction and Building Materials, 20, Puppala, A. J., Hoyos, L. R., and Potturi, A. K. (2011). "Resilient Moduli Response of Moderately Cement-Treated Reclaimed Asphalt Pavement Aggregates." Journal of Materials in Civil Engineering, ASCE, 23(7), Rada, G., and Witczak, M. W. (1981). "Comprehensive Evaluation of Laboratory Resilient Moduli Results for Granular Material." Transportation Research Record: Journal of the Transportation Research Board, 810,

19 Rodgers, M., Hayes, G., and Healy, M. G. (2009). "Cyclic loading tests on sandstone and limestone shale aggregates used in unbound forest roads." Construction and Building Materials, 23, Sustainability-Victoria (2010). "Victorian recycling industries annual report " Sustainability Victoria, Melbourne, Australia. Taha, R., Al-Harthy, A., Al-Shamsi, K., and Al-Zubeidi, M. (2002). "Cement stabilization of reclaimed asphalt pavement aggregate for road bases and subbases." Journal of Materials in Civil Engineering, ASCE, 14(3), Tam, V. W. Y., and Tam, C. M. (2007). "Crushed aggregates production from centralized combined and individual waste sources in Hong Kong." Construction and Building Materials, 21, Uzan, J. (1981). "Characterization of Granular Material." Transportation Research Record: Journal of the Transportation Research Board, 810, Vuong, B. T., and Brimble, R. (2000). "Austroads Repeated Load Triaxial Test Method: Determination of permanent deformation and resilient modulus characteristics of unbound granular materials under drained conditions, AG-PT/T053, Reprint of APRG 00/33 (MA) ", Austroads, Melbourne, Australia. Wartman, J., Grubb, D. G., and Nasim, A. S. M. (2004). "Select engineering characteristics of crushed glass." Journal of Materials in Civil Engineering, ASCE, 16(6),

20 List of Tables Table 1: Densities and moisture content of C&D materials RLT test specimens. Table 2: Resilient moduli response of recycled C&D materials. Table 3: Range of permanent strain and resilient modulus from permanent strain testing (Phase 1) for C&D materials at the end of each loading. Table 4: Regression coefficients of K-Theta model. Table 5: Regression coefficients of three parameter model (Mr, σ d, σ c ). 19

21 Table 1: Densities and moisture content of C&D materials RLT test specimens. Target Actual Material MDD (kn/m 3 ) OMC (%) Dry density ratio(% of MDD) Moisture content (% of the OMC) Dry density ratio(% of MDD) Moisture content (% of the OMC) RCA CB WR

22 Geotechnical Parameters Table 2: Resilient moduli response of recycled C&D materials Recycled Concrete Aggregate (RCA) 21 Crushed Brick (CB) Waste Rock (WR) D 10 (mm) D 30 (mm) D 50 (mm) D 60 (mm) C u C c Gravel content (%) Sand content (%) Fines content (%) USCS classification for particle sizes (ASTM, 2010) GW GW SW Compaction Max dry density (kn/m 3 ) (Modified) Optimum moisture content (%) Target Moisture Content: Resilient Modulus 90% of OMC (MPa) Target Moisture Content: Permanent strain 80% of OMC test (Phase 1) Target Moisture Content: % of OMC Target Moisture Content: Resilient Modulus Failed % of OMC (MPa) Target Moisture Content: - Resilient modulus Failed % of OMC test (Phase 2) Target Moisture Content: Failed 70% of OMC

23 Table 3: Range of permanent strain and resilient modulus from permanent strain testing (Phase 1) for C&D materials at the end of each loading Target Actual Stage1: Stage2: Stage3: Stage4: Moisture Moisture confining stress confining stress confining stress confining stress Material Permanent Strain Content (% Content (% = 50 kpa = 50 kpa = 50 kpa = 50 kpa Testing of the of the deviator stress = deviator stress = deviator stress = deviator stress = OMC) OMC) 150 kpa 250 kpa 350 kpa 450 kpa RCA CB WR Typical Quarry Material Permanent strain (micro-strain) Resilient modulus (MPa) Permanent strain (micro strain) Resilient modulus (MPa) Permanent strain (micro strain) Resilient modulus (MPa) Permanent strain (micro strain) Resilient modulus (MPa) Failed Failed Failed Failed Failed Failed > >

24 Table 4: Regression coefficients of k-θ model Material Target Moisture Content (% of the OMC) Actual Moisture Content (% of the OMC) k 1 k 2 RCA RCA RCA WR WR CB

25 Table 5: Regression coefficients of three parameter model (Mr, σ d, σ c ) Material Target Moisture Content (% of the OMC) Actual Moisture Content (% of the OMC) k 1 k 2 k 3 RCA RCA RCA WR WR CB

26 List of Figures Figure 1: Particle size distribution of C&D materials. Figure 2: Permanent strain testing (Phase 1) - Permanent strain determination for various C&D materials. Figure 3: Permanent strain testing (Phase 1) - Resilient modulus determination for various C&D materials. Figure 4: Resilient Modulus Testing (Phase 2) - Resilient modulus determination for various C&D materials. Figure 5: Permanent strain rate variations with permanent strain for various C&D materials. Figure 6: Resilient modulus variation with bulk stress for RCA (Phase 2). Figure 7: Resilient modulus variation with bulk stress for WR (Phase 2). Figure 8: Resilient modulus variation with bulk stress for CB (Phase 2). Figure 9: k 1 k 2 relation for all samples (Phase 2). 25

27 Figure 1 Percentage Passing (%) 100 Recycled Concrete Aggregate (RCA) 90 Crushed Brick (CB) 80 Waste Rock (WR) Particle Size (mm)

28 Figure 2 Permanent strain (microstrain) Stage 1: Static confining pressure = 50 kpa Dynamic deviator stress = 150 kpa Stage 2: Static confining pressure = 50 kpa Dynamic deviator stress = 250 kpa Stage 3: Static confining pressure = 50 kpa Dynamic deviator stress = 350 kpa Number of load cycles Stage 4: Static confining pressure = 50 kpa Dynamic deviator stress = 450 kpa RCA: 60% of OMC RCA: 71% of OMC RCA: 83% of OMC CB: 65% of OMC CB: 80% of OMC CB: 84% of OMC WR: 67% of OMC WR: 71% of OMC WR: 84% of OMC

29 Figure 3 Resilient Modulus (MPa) Stage 1: Static confining pressure = 50 kpa Dynamic deviator stress = 150 kpa Stage 2: Static confining pressure = 50 kpa Dynamic deviator stress = 250 kpa Number of Cycles Stage 3: Static confining pressure = 50 kpa Dynamic deviator stress = 350 kpa Stage 4: Static confining pressure = 50 kpa Dynamic deviator stress = 450 kpa RCA: 60% of OMC RCA: 71% of OMC RCA: 83% of OMC CB: 65% of OMC CB: 80% of OMC CB: 84% of OMC WR: 67% of OMC WR: 71% of OMC WR: 84% of OMC

30 Figure 4 Resilient Modulus (MPa) Stress Stage CC: 60% of OMC CC: 71% of OMC CC: 83% of OMC CB: 65% of OMC WR: 71% of OMC WR: 84% of OMC

31 Figure 5 Permanent Strain Rate (/cycle) E RCA: 60% of OMC RCA: 71% of OMC RCA: 83% of OMC CB: 65% of the OMC CB: 80% of the OMC CB: 84% of the OMC WR: 67% of the OMC WR: 71% of the OMC WR: 84% of the OMC Permanent Strain

32 Figure 6 Resilient Modulus (MPa) % of the OMC 71% of the OMC 83% of the OMC Mr, 60 = R² = Mr, 71 = R² = Mr, 83 = R² = Bulk Stress (kpa)

33 Figure 7 Resilient Modulus (MPa) % of the OMC 84% of the OMC Mr, 71 = R² = Mr, 84 = R² = Bulk Stress (kpa)

34 Figure 8 Resilient Modulus (MPa) % of the OMC Mr, 65 = R² = Bulk Stress (kpa)

35 Figure 9 Log k1 2 1 Log k1 = k R² = k2