Investigation of self-healing behavior of Engineered Cementitious Composites (ECC) materials

▸ ECC has many characteristics that contribute to self-healing behavior. ▸ Longer age and high fly ash leads to many more cracks of smaller width. ▸ Wet/dry cycles contribute to self-healing of ECC. ▸ Mechanical capacity of majority re-healed ECC are higher than control samples. ▸ Self-healing products may be including C–S–H and CaCO3. Crack characteristics of M45-ECC and HFA-ECC specimens pre-loaded to strain levels of 0.3%, 0.5%, 1.0% and 2.0% were investigated in this paper. This was done at different ages, resonant frequency and mechanical recovery behavior of re-healed ECC materials, new crack paths after reloading and the chemical analysis of healing products. Based on the experimental results, ECC with multiple micro-cracks benefits self-healing behavior. Longer aged samples and high fly ash contribute to create more cracks of smaller width. Wet/dry conditioning cycles aid self-healing, most of which occurs before 4–5 cycles. After 10 wet/dry cycles, RF recovery due to self-healing exceeds 75% for M45-ECC, 85% for HFA-ECC of different ages even at a 2.0% imposed pre-loaded damage. The tensile strain capacity of the major re-healed ECC is almost 2.0% for M45-ECC and 3.0% for HFA-ECC. Most of new cracks follow through the previous crack location after reloading. Self-healing products mainly include C–S–H and CaCO3.