Mechanical strength and compactness of bio self-compacting sand concrete containing granite industrial waste as fine aggregate

The sector of civil engineering has shifted towards the direction of sustainable development, with a focus on environmental protection as an important objective. This strategy is implemented by recycling and reusing polluted industrial by-products and waste. The manufacturing process of granite products generates huge quantities of granite waste (GW) worldwide, which causes environmental pollution when dumped. Self-compacting sand concrete (SCSC) is a novel, highly fluid, and durable concrete widely used as a construction material. In this work, the effect of using recycled waste granite (GW) and seashell powder (SSP) on the mechanical strength and compactness of eco-self-compacting sand concrete (SCSC) was studied. For this purpose, SSP has been used to substitute cement at levels of 5, 10, and 15% by weight, and GW replaced the natural sand at levels of 0, 10, 20, 30, and 40% by volume. The fresh properties of SCSC mixtures are evaluated by the mini-slump flow diameter. The compressive and flexural strengths and compactness of hardened SCSC were assessed. A SEM analysis was also used to examine the microstructure development of the hardened SCSC mixtures. The results indicate that using SSP for GW- based SCSC gives acceptable flowability with a low dosage of superplasticizer (SP). Moreover, an enhancement in compressive and flexural strengths and compactness of the SCSC mixtures was found by adding up to 40% GW combined with up to 15% SSP. 10SSP+40GW mix showed the highest mechanical strengths and compactness, with a denser microstructure after 90 days with an improvement of 30.61% and 35.82% in compressive and flexural strength, respectively, compared to control mixtures.