Cracking and autogenous self-healing on the performance of fiber-reinforced MgO-cement composites in seawater and NaCl solutions

Abstract

MgO-cement is attracting increasing attention because of its ability to absorb CO2. In this study, the effect of cracking and autogenous self-healing on the performance of fiber-reinforced MgO-cement composites exposed to water, seawater and NaCl solutions were investigated. Moreover, changes in hydrates and microstructure as a consequence of cracking and different exposure were analyzed. It found that cracks cause significant deterioration in stiffness but 60% of the deterioration was restored by self-healing in seawater, while the load capacity was slightly affected by cracking and self-healing. Cracks in seawater were 100% self-healed by the fast precipitation of Mg(OH)2, decelerating the chloride penetration through cracks. However, the 100% crack closure achieved in NaCl solutions show no noticeable benefits for the mechanical properties and durability of cracked composites. This research provides a technical support for the use of MgO in reinforced composites to improve the sustainability of building materials.