Abstract
Recycled concrete aggregate (RCA) collected from the demolition of old reinforced concrete structures can be reused to prepare structural and non-structural concrete, thereby protecting the environment by preserving natural resources. This study explores RCA’s use, collected from the crushed concrete of different building projects in Riyadh, to manufacture fresh self-compacting concrete (SCC) and investigate its properties in the fresh and hardened state. Four SCC mixes were prepared by replacing natural aggregate (NA) with RCA at 0%, 25%, 50%, and 75% replacement levels. The water-cement (w/c) ratio was maintained constant at 0.38 for all the mixes. Slump Flow, J-ring, and V-funnel tests were performed on the SCC mixes in the fresh state, and the compressive strength of hardened concrete was determined after seven, 14, and 28 days. Water absorption and split tensile tests were also carried out for all the mixes. The findings revealed that it is possible to reach compressive strengths higher than 40 MPa at 28 days for RCA replacement level of 75% by using a superplasticizer and low w/c ratio. The decrease in compressive strength concerning the SCC-NA mix was 25% for 75% replacement level. The highest split tensile strength at 28 days was around 3.3 MPa for a 50% replacement level. The lowest water absorption was 3.2% for SCC-NA, which was gradually increased and was highest at 5.6% for 75% replacement level.
Highlights
The main objectives of most environmental policies regarding waste are to prevent waste and promote reuse, recycling, and recovery to decrease the negative environmental impact
As the use of a high volume of recycled concrete aggregate (RCA) decreases the mechanical characteristics of concrete, those mixes are still considered suitable when superplasticizers are used [2], and this is the case of the produced concrete with a compressive strength of around 40 MPa, which is the range for mixes used in this research
Based on this literature review, it is observed that RCA is already a topic of research interest, and this study aims to develop self-compacting concrete (SCC) mixes using RCA obtained from locally demolished structures
Summary
The main objectives of most environmental policies regarding waste are to prevent waste and promote reuse, recycling, and recovery to decrease the negative environmental impact. When undertaking this issue, it is essential to consider that a key barrier for developing recyclable products is the lack of demand and clients’. GQFD-II integrated life cycle assessment (LCA) and life cycle costing (LCC) into QFD matrices and organized customer, environmental, and cost requirements through the complete product development process. This method integrates QFD (quality), LCA (environment), and LCC (cost) into one effective tool, which could be used to evaluate the diverse product concepts considering the quality, environment, and cost [3]
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