Effect of material composition on the mechanical behavior of engineered cementitious composites (ECC)

Abstract

Engineered cementitious composites (ECC) are designed to show high ductility, multiple cracking, and enhanced crack control, while providing strength suitable for structural applications. Achieving a balance of compressive strength, flexural performance, and crack-control capacity requires careful optimization of mixture composition. This study investigates the influence of material composition on the mechanical behavior of ECC, focusing on variations in sand-to-binder (S/B) ratio, fly ash-to-cement (FA/C) ratio, PVA fiber volume fraction, and the incorporation of silica fume slurry (SFS). Compressive strength and flexural load–deflection behavior were evaluated at 28 days, along with residual crack widths. Increasing the FA/C ratio improved flexural deflection and reduced residual crack widths, while compressive strength decreased but remained suitable for structural use. Maintaining a 2.0% PVA fiber content provided consistent flexural performance, whereas higher fiber content slightly increased peak load but introduced more variability. Incorporating 10% SFS enhanced compressive strength and improved post-peak flexural response without compromising the overall flexural performance. All ECC mixtures exhibited residual crack widths below 100 μm, with the higher FA/C mixtures showing the tightest cracks. Overall, the findings demonstrate that systematic optimization of binder composition, fiber content, and SFS incorporation enables ECC with improved flexural performance, crack control, and structural applicability.