PSI - Issue 64

Rahma Dhemaied et al. / Procedia Structural Integrity 64 (2024) 343–351 Rahma Dhemaied/ Structural Integrity Procedia 00 (2019) 000 – 000

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factors like decreased carbon footprint and demand for natural resources (Behera et al., 2014; Muniz De Farias et al., 2019). To achieve sustainable infrastructure solutions, incorporating recycled concrete aggregates into pavement design requires a comprehensive strategy that strikes a balance between technical, financial, and environmental considerations. 5. Performance of recycled concrete aggregates in pavements 5.1. Case study 1 The study was conducted at the Queensland University of Technology in Australia by (Jayakody et al., 2019) to investigate the performance characteristics of recycled concrete aggregates (RCA) as an unbound pavement material. Repeated load tri-axial (RLT) tests were performed on compacted RCA specimens according to the standard test method of the Queensland Department of Transport and Main Roads. The RCA samples were obtained from a leading concrete recycling company in the region and their physical and strength properties were found to be within the specifications for high-quality pavement materials. The RLT test results revealed that the RCA exhibited a steady gain in stiffness (resilient modulus) with an increase in load cycles, especially at low moisture contents, high confining pressures and high vertical axial pressures. This indicated the RCA's high resistance to elastic deformation, comparable to that of conventional pavement materials, making it suitable for use as an unbound pavement material. Furthermore, the accumulation of plastic strain in RCA approached the "plastic shakedown limit", similar to high-quality pavement materials, demonstrating its high capacity to withstand repeated loads with minimal permanent deformation. The study also developed enhanced constitutive models that could accurately predict the resilient modulus of RCA by considering the effects of moisture content and stress conditions. 5.2. Case study 2 In another study, (Gabr and Cameron, 2012) investigated the resilient modulus and permanent deformation characteristics of RCA and compared them to conventional quartzite aggregates. This research was conducted at North Carolina State University in the United States. The researchers performed repeated load triaxial (RLT) testing on the aggregates under different moisture and stress conditions. The findings revealed that RCA exhibited higher resilient modulus and lower permanent deformation compared to quartzite aggregates, particularly at low moisture contents. The study also highlighted the importance of gradation and compaction in influencing the performance of RCA as a pavement material. 5.3. Case study 3 Additionally, (Zulkati et al., 2013) evaluated the performance of asphalt concrete mixtures incorporating RCA as a partial replacement for natural aggregates. This study was carried out at the Nanyang Technological University in Singapore. The researchers conducted laboratory tests to assess the rutting resistance, fatigue life, and stiffness of the asphalt concrete mixtures containing RCA. The results showed that the RCA-containing mixtures achieved comparable or even better performance than conventional asphalt concrete in terms of these performance indicators. The study emphasized the importance of proper mix design and RCA pre-treatment to achieve the desired performance in asphalt pavement applications. 5.4. Conclusion Overall, these case studies, conducted at various research institutions around the world, collectively demonstrate the potential of recycled concrete aggregates as a sustainable and viable alternative to conventional pavement materials. The consistent findings across these studies highlight the importance of material characterization, mix design optimization, and appropriate processing techniques to fully realize the benefits of RCA in pavement construction.