Breaking strength-ductility trade-off dilemma for Engineered Cementitious Composites (ECC) through filler effect

Abstract

The outstanding strain-hardening and multiple cracking behavior of Engineered Cementitious Composites (ECC) is favored by maintaining a low fracture toughness (Km) in its matrix. However, limiting Km comes at the cost of diminished compressive strength (fc), owing to their intrinsic positive correlation in general cementitious binders. Here, we explore the feasibility of decoupling the Km-fc relationship by applying the filler effect, aiming to improve the composite fc and tensile ductility simultaneously. Our results show that Km and fc can be adjusted independently by manipulating the use of fillers with different cementitious reactivities, and incorporating the inert-particle-packing effect produced a densified matrix with increased fc but nearly unchanged Km. Micromechanical analyses revealed favorable changes in the fiber/matrix interfacial bond and pseudo-strain-hardening index, accompanied by an improved tensile strength, ductility, and crack control capability in the composite. These findings inform a cost-effective design strategy for ECC across wide-ranging applications.