A self-healing approach to cement-based materials with crystalline admixtures in normal and accelerated environmental conditions

Abstract

Cracks in cement-based materials can be a source of significant problems in civil works, especially those exposed to the action of harmful agents and moisture. Its occurrence may be associated with various physical, chemical, or mechanical factors. Self-healing phenomenon can promote cracks repair, contributing to a useful life increase through the sealing by cracking closure. This work aimed to evaluate the self-healing phenomenon in cementitious matrices with different crystalline admixtures. Mortars were produced using high initial strength cement, quartz sand, three types of crystalline additives, and 0.4 as w/c ratio. Compressive strength tests were performed at 3 days (crack opening age), 28 days, and 45 days. The environmental conditions were wet/dry cycles in controlled and accelerated climate chambers. Ultrasonic pulse and optical microscopy with image editing techniques were used to evaluate the self-healing phenomenon. The results indicate that the samples in accelerated chamber (CAR) presented the highest mechanical strength at 45 days, and the most significant crack closure to samples with Z crystalline admixture. The ultrasonic wave propagation speed analysis showed that crystalline admixtures-based samples (X, Y and Z) had the highest matrix densification. Additionally, special attention should be given to the samples preparing steps and images editing to identify the healed area for the techniques being used.