Improving the physical and mechanical properties new concrete containing crushed dune sand and demolition waste as coarse aggregate

Résumé

Using concrete waste as aggregates in new concrete compositions brings numerous advantages. It helps in reducing the costs associated with managing demolition waste and contributes to the preservation of natural deposits and mountains by minimizing the demand for new quarries. However, when completely substituting natural aggregates (NA) with recycled concrete aggregates (RCA) in concrete, it directly affects the fundamental properties of the material, particularly its physical and mechanical characteristics. This is primarily due to the inferior qualities exhibited by RCAs in comparison to natural coarse aggregates, primarily stemming from their increased porosity and water absorption. In the experimental study conducted, the focus was on investigating the influence of substituting cement with crushed dune sand (CDS) at different replacement levels (5%, 10%, and 15%) on the mechanical and physical properties of self-compacting concrete (SCC) incorporating 100% RCA. The findings from this study indicated that the substitution of cement with CS resulted in improved mechanical and physical behavior of the self-compacting concrete containing 100% RCA, particularly when CS was present at 5% and 10% levels. Overall, the study suggests that incorporating CS as a partial substitute for cement in SCC containing 100% RCA can positively affect the properties of the concrete mixture, enhancing its mechanical and physical performance.