Self-compacting concrete with granite waste and recycled aggregate: A fresh, mechanical, and microstructural perspective

The significant by-products from the construction and granite industries have led researchers to investigate sustainable ways to integrate wastes into concrete, aiming to reduce their harmful environmental impacts. The current study focused on fresh, hardened, and microstructural properties of self-compacting concrete (SCC) made with recycled concrete aggregates (RCA) and granite-cutting waste (GW). Coarse aggregate was partially replaced with RCA at 50 % and 100 % levels, and GW was utilized as a replacement for fine aggregate at increments of 10 up to 50 %. The fresh properties of SCC were evaluated using slump flow, T500 mm flow time, J-ring, V-funnel, and L-box tests, while the hardened properties were assessed through compressive strength, flexural strength, and split tensile strength tests. Incorporating RCA at 50 % and 100 % reduced the compressive strength by approximately 15 % and 25 %, respectively, at 28 days. However, the addition of 30 % GW showed significant improvement in mechanical strength by 21 % and 13.5 %, for 50 % and 100 % RCA substitutions, respectively, at 28 days. In particular, the 50 % RCA with 30 % GW mix surpassed the compressive strength of the control mix at 28 and 90 days. Analyses using scanning electron microscopy (SEM), Energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) further validated the hardened properties. The findings showed that adding GW up to 30 % to RCA modified SCC mixes enhanced mechanical performance, successfully offsetting RCA's mechanical drawbacks, and can be recommended as a sustainable substitute in SCC.