Tensile Behaviors and Self-Healing of Engineered Cementitious Composite under Sulfate Wet-Dry Cycles

This paper investigates the tensile behaviors and self-healing of engineered cementitious composite (ECC) under sulfate wet-dry cycles to reflect the durability. Four pretensile strain levels of 0%, 1%, 1.5%, and 2% were designed. The uniaxial tensile test, three-point bending test, and single-crack tensile test were performed, along with the microscopic characterizations of scanning electron microscope (SEM) and X-ray diffraction (XRD). The results indicated that the sulfate wet-dry cycle exposure had a positive effect on the tensile strength and initial cracking strength of the uncracked ECC, while that was negative on the tensile strain capacity. The insufficient margin of the sigma oc/sigma cr and Jb '/Jtip indices explained the lower tensile strain. The tensile strength and initial cracking strength of the cracked ECC with 1% pretensile strain surpassed those of the uncracked ECC after undergoing 80 sulfate wet-dry cycles (80 C), while that did not hold for the other cracked ECCs. All the cracked ECCs showed a similar tensile strain after undergoing 80 C. The crack with a width of less than 100 mu m achieved complete self-healing. The self-healing products of ECC under sulfate wet-dry cycle exposure may comprise of calcium (alumino) silicate hydrate [C-(A)-S-H] gel, calcite, ettringite, and gypsum. The current findings could offer reference points for applying ECC use in coastal regions.