A blending of construction and demolition and agricultural wastes for efficient circularity: A sustainable approach for ceramic tile coarse aggregates and rice husk ash in M20 concrete

Abstract The present study evaluates a sustainable approach of blending ceramic tile coarse aggregates (CTCA) and rice husk ash (RHA) to produce M20 concrete. In the first step, CTCA was used to replace natural gravel stones by weight with the percentage replacements of 0% (C00 and control), 10% (C10), 20% (C20), 25% (C25) and 30% (C30) in M20 concrete. The best CTCA replacement result was used as the control for the second step. In the second step, ordinary Portland cement (OPC) was replaced by RHA in the range of 0% (C00R = C20 = control), 5% (C05R), 10% (C10R), 15% (C15R) and 20% (C20R). The replacements in each step were done at a constant water/cement ratio of 0.64 and without a plasticizer. The workability of fresh concrete, compressive strength at 7, 14 and 28 days, bulk density and water absorption were tested for each step. When blending CTCA in concrete, 20% CTCA replacement showed the maximum compressive strength of 22.43 ± 0.01 MPa on the 28th day. An increased compressive strength of 23.30 ± 0.02 MPa and relatively low water absorption (3.13%) resulted when blending C20 and C05R. This was a 9.9% increase of strength when compared with M20 concrete. The bulk density of concrete increased gradually as curing age increased, while showing an inverse relationship with RHA. The study recommends the replacement of 20% natural gravel stones and 5% OPC with CTCA and RHA, respectively, in M20 concrete for efficient circularity.