Assessing the self-healing capability of cementitious composites under increasing sustained loading

This study investigated the effects of progressively increasing sustained loading on self-healing behaviour of 180-d-old microcracked engineered cementitious composites (ECCs) incorporating different mineral admixtures. After introducing microcracks to the specimens with applied severe pre-loading, some were subjected to progressively increasing sustained loading. All of the specimens were then subjected to continuous moist curing for 150 d to evaluate selfhealing performance. Mechanical property (modulus of rupture (MOR) and mid-span beam deflection) characterisations and ultrasonic pulse velocity measurements were used to assess self-healing capability. Experimental results showed that even under progressively increasing sustained mechanical loading, MOR results greater than the original values could be obtained, depending on mineral admixture selection. Although deflection results were more adversely affected by progressive sustained loading compared to MOR results, even the lowest deflection value obtained from different ECCs was still more than 100 times that of conventional concrete after healing. Under continuous moist curing, there were minimal changes in ultrasonic pulse velocity results of all ECCs subjected to progressively increasing sustained loading, so that recovery results similar to those of specimens without sustained loading were obtained, despite the fact that ultrasonic pulse velocity testing was not that sensitive in capturing the effects of self-healing.