Effect of exposure conditions on self-healing behavior of engineered cementitious composite incorporating limestone powder

Engineered cementitious composite (ECC) has superior self-healing potential compared to ordinary cement-based materials due to well controlled crack width. The effect of exposure conditions on self-healing behavior of ECC incorporating limestone powder (LP) was investigated in this paper. Four mixes with varying LP contents were used to prepare ECC. Pre-cracked specimens were subjected to three different exposure conditions, including water, Na₂SO₄ solution and saturated Ca(OH)₂ solution. The recovery of mechanical and transport properties was investigated by uniaxial tensile and sorptivity tests to characterize self-healing behavior. The experimental results show that ECC exposed to Ca(OH)₂ solution exhibits the best self-heling behavior among all four mixes. The addition of LP is conducive to improving the self-healing behavior of ECC. Further, it was observed by ESEM and XEDS that the cracks after healing were filled with healing products which were mainly composed of calcium carbonate, C–S–H, ettringite as well as carboaluminate, indicating a possible reaction between limestone powder and fly ash.