Self-healing ability of Engineered Cementitious Composites (ECC) under different exposure environments

Engineered Cementitious Composite (ECC) normally contains large amount of cementitious materials (e.g. cement and fly ash), together with its self-controlled tight crack width (typically below 60 μm), it is considered of high self-healing potential. To further accelerate and enhance the self-healing process of ECC, 60 °C hot water and Ca(OH)2 solution can be used to condition the specimen. In this paper, the influence of the above-mentioned environmental conditions on the self-healing behavior of ECC was experimentally investigated. Specifically, compressive strength, fly ash reaction degree and non-evaporable water content of ECC cement-fly ash paste exposed to different environmental conditions were measured. The test results show that Ca(OH)2 solution and 60 °C hot water effectively increased the compressive strength, fly ash reaction degree and total amount of hydration product, thus have the potential of enhancing the self-healing ability of ECC mixtures. Direct water flow test and uniaxial tensile test were also conducted on ECC specimens exposed to different environmental conditions. The test results, together with ESEM observations, further confirmed that when exposed to 60 °C water and Ca(OH)2 solution, the self-healing process of ECC was accelerated and more self-healing product was formed. The findings of the present study can be used to promote self-healing of ECC infrastructures in the field.