Mechanical properties of engineered cementitious composites incorporating high-volumes of fly ash

Engineered Cementitious Composites (ECC) containing high volumes of fly ash (HVFA) as a partial replacement of Portland cement (PC) at different replacement levels (0.8, 1.2, 1.6 and 2) by weight of cement, incorporated either with silica fume (ECC-SF) or with carbon black (ECC-CB) powders have been studied. Physical properties (bulk density, water absorption and ultrasonic pulse velocity [UPV]), furthermore, mechanical properties (splitting tensile strength and compressive strength), were measured at different curing ages (7, 28 and 90) days. In addition, Scanning Electron Microscopy (SEM) were measured. For comparison, control mixture was produced, which was free from any mineral additives. Results showed when utilizing FA instead of PC in mortars at proportions (0.8 & 1.2) can achieve good sustainability material as well as gain the consistency and mechanical strength of ECC. While, when the replacement ratio was raised to (2.0), the ECC mortar becomes heterogeneous and crumble subsequently that lead to giving poor mechanical and durable properties of mortar. Utilizing of FA as cement replacement in mortars at appropriate level, leading to decrease PC consumption as well as providing an economic and friendly environmentally advantages.