Analytical study on mechanical properties of concrete containing crushed recycled coarse aggregate as an alternative of natural sand

摘要

Challenges of sand scarcity in construction and load built up on rivers for natural sand (NS) mining have generated an urgent requirement of sustainable alternative. Traditionally, recycled sand (RS) is the superfluous potential substitute of NS, obtained during production of recycled coarse aggregates from C&D waste. But, RS underperforms due to its variable composition and high water absorption, and thereby, has limited access to extensive utilisation. On the other hand, absolute utilization of RCA in structural concrete is also restricted by BIS-383 due to its declined properties as coarse aggregate. Recycled coarse aggregates have comparatively less amount of hydrated cement content than that of traditional RS, which is major cause of increased water absorption. Thus, the current study aimed to produce crushed recycled coarse aggregate (CRCA) and to investigate its technical feasibility as fine aggregate for NS replacement. X-ray diffraction of CRCA demonstrated its ability to be used against NS in concrete. The study demonstrated that a concrete with improved compressive strength is possible to be produced with 100% incorporation of specific CRCA as fine aggregate. Scanning electron microscopy (SEM) and electron diffraction spectroscopy (EDS) explained the strength development in concrete with CRCA. Empirical regression based models were formulated for evaluation of mechanical strengths of concrete at varying CRCA percentages following definite particle grades. (C) 2020 Elsevier Ltd. All rights reserved.