Rubber particle bridging effect on crack width control of low carbon Engineered Cementitious Composites (ECC)

Engineered Cementitious Composites (ECC) exhibit high tensile ductility and multiple cracking behaviors. The weak bonding between hydrophobic fiber and matrix tends to enlarge the crack width of ECC. This paper investigated recycled crumb rubber (CR) to tailor the crack width control of ECC as an artificial flaw. The experimental results show that CR can enhance the multiple cracking and reduce the crack width of ECC, which can be attributed to the CR weakened matrix and particle bridging effect. Micro-CT scanning revealed how CR influences the initiation and propagation of microcracks qualitatively. A constitutive model of CR particle bridging was developed to evaluate the quantitative contribution of CR particle bridging to the crack width reduction of ECC. Although the effect of bridging on crack width reduction is not as strong as that of the weakened matrix, the combined effect is consistent with the experimental magnitude of crack width reduction. Further parametric analysis indicates that small particle size, higher content, and narrower size distribution range of CR are preferred for better crack width control of ECC. The insights gained provide guidance on ECC composite design for a tight crack width with better durability properties.