The water-to-binder (w/b) ratio is the prime factor governing the degree of hydration and composition of hydration products in cementitious composites. The hydrated phase composition consequently governs the performance of composites under different mechanical and environmental loadings. In this study,…
The water-to-binder (w/b) ratio is the prime factor governing the degree of hydration and composition of hydration products in cementitious composites. The hydrated phase composition consequently governs the performance of composites under different mechanical and environmental loadings. In this study, the effects of w/b ratios on the self-healing characteristics (under wetting- drying cycles) of carbonated reactive magnesia cement (RMC) based composites were investigated. This investigation focuses on the study of healed products and corresponding microstructure evolution. The study was conducted on RMC-based composites with w/b ratios of 0.30 and 0.40. The behavior was characterized on 7-day and 90-day matured composites to understand the effects on early-age crack mitigation and long-term performance simultaneously. The self-healing efficiency was characterized using crack width closure. The chemical characterization of the healing products was done using XRD and TGA analysis, and the morphology of the healing products was studied using SEM and EDS. The results demonstrate almost 100% crack closure in composites with a low w/b ratio than 80-90% crack closure at a high w/b ratio. The main healing product in low w/b RMC composite was amorphous magnesium-silicate-hydrate (MSH), whereas hydrated magnesium carbonates (HMCs) were observed in 0.40 w/b ratio RMC composite due to the increased porosity. The composition of healing products was different at the surface and core region of the healed matrix. The results will enable the tailoring of RMC-based composites to have desirable self-healing attributes.