Characterization of Damage and Healing of Cement Matrices Based on Fly Ash under Repeated Loading

Abstract

This paper investigates damage and healing of cementitious materials based on fly ash (FA) with a special focus on the effect of repeated loading on the self-healing performance. In total, 90 prism specimens and 33 cylinder specimens were prepared and tested. Variables including the FA replacement ratio and preloading level were considered. Different methods were adopted to evaluate the self-healing performance, i.e., mechanical tests, acoustic emission (AE) analysis, water absorption measurement, and scanning electron microscope (SEM) observation. Test results revealed that an appropriate amount of cement replaced by FA was beneficial to the self-healing performance of the specimens subjected to a high level of repeated preloading, where the strength increased by 11% and the water absorption rate decreased by 12%, in comparison with that of the undamaged specimens. This was attributed to the active hydration of FA, which was confirmed by an energy dispersive X-ray spectroscopy (EDS) analysis. This study extends understanding of the self-healing performance when subjected to repeated loading and provides some useful suggestions for the self-healing technique based on mineral additives.