Influence of micro-cracking on the composite resistivity of Engineered Cementitious Composites

Engineered Cementitious Composites (ECCs) are structural materials known for their excellent tensile ductility and damage tolerance. Previous experimental studies have shown a strong dependence of electrical resistivity of ECC on applied mechanical tensile strain (piezoresistive behavior), which can be potentially utilized for self-sensing mechanical damage for structural health monitoring. In this paper, the influence of micro-cracks on the composite electrical response of ECC under direct tension is investigated experimentally as well as analytically. For this purpose, the electrical–mechanical properties of two ECCs with different crack patterns are compared at macro (composite) and meso (single-crack) scales. An analytical model linking single-crack electrical response and crack pattern of an ECC to its composite electrical behavior is proposed in this study, and verified for both ECCs with experimental observations. Thus, a fundamental understanding of crack patterns and their effects on piezoresistivity of ECC is developed in this study.