Performance of self-compacting concrete incorporating wastepaper sludge ash and pulverized fuel ash as partial substitutes

The usage of cement is responsible for approximately 10% of anthropogenic CO2 emissions. Therefore, the use of supplemental cementitious materials in concrete was made possible by the demand for more affordable and environmentally friendly ingredients. Different cement-replacing alternatives are now often used in the construction sector. This study aims to investigate the possibility of using wastepaper sludge ash (WSA) and pulverized fuel ash (PFA) as partial substitutes for cement with different levels for the production of self-compacting concrete (SCC). Fourteen SCC mixtures with 0.4 and 0.45 water/binder (W/B) ratios, two controlled mixtures (i.e., without WSA and PFA), and two sets of six combinations with varying WSA and PFA replacement levels (5–30%) of cement were prepared and investigated. The characteristics of fresh concrete (slump flow and L-Box) and hardened concrete (compressive strength, tensile strength splitting, and modulus of elasticity) were examined. Results show that the WSA can substitute for up to 5% (optimal percentage replacement) of the weight of regular ordinary Portland cement (OPC) with an improvement in SCC’s fresh and hardened properties. The fresh and hardened properties of SCC containing WSA and PFA decrease as the replacement levels increase above 5%. Using WSA and PFA as construction materials is cost-effective because they may be used in place of OPC to produce good quality SCC.