Combined Effect of Pressurized Water and Sustained Load on Self-Healing of Engineered Cementitious Composite Panels

Abstract

This paper presents an investigation on the water tightness/self-healing of engineered cementitious composite (ECC) elements subjected to direct tension cracking and exposed to the coupled effect of sustained loading and pressurized water. A setup was presented to simulate a wall segment of liquid containing structures subjected to direct tensile forces. The experimental program included ECC panels with different supplementary cementitious materials (SCMs), comprising fly ash Class-F, fly ash Class-C, and granulated blast furnace slag. Each panel was subjected to direct tensile load to induce full depth cracks and then a leakage test was carried out under sustained load and various water pressures. To consider the effect of ECC composition on the cracking/self-healing behavior of panels exposed to loading and pressurized water, the leakage rate was continuously studied until complete sealing. Additionally, a detailed microstructural analysis was completed on full depth drilled cores, in which the samples were taken from three layers of the healed cracks to investigate the influence of pressurized water on the self-healing products. The results of this study confirmed the high effect of water pressure and SCM type on the self-sealing capability of ECC, especially after the first 30 h of leakage. The fly ash-ECC panel was shown with lower crack opening and leakage rates, which also resulted in greater cracking/self-healing behavior under coupled sustained loading and high-water pressure. Different concentrations of CaCO3 and C-S-H/CH products were found in each crack mouth and elevation, indicating that self-healing under pressurized water likely developed from the core and bottom areas to the top layer of crack lines.