Healing performance of a self-healing protective coating according to damage width

Abstract

Although self-healing protective coatings have been widely studied, systematic research on healing performance of the coating according to damage width has been rare. In addition, there has been rare reports of self-healing of the protective coating having damage width wider than 100 μm. In this study, self-healing performance of a microcapsule type self-healing protective coating on cement mortar was studied for the coating with damage width of 100-300 μm. The effect of capsule-loading (20 wt%, 30 wt% and 40 wt%), capsule size (65-, 102-and 135-μm-mean diameter) and coating thickness (50-, 80-and 100-μm-thick undercoating) on healing efficiency was investigated by water sorptivity test. Accelerated carbonation test, chloride ion penetration test and scanning electron microscope (SEM) study were conducted for the self-healing coating with a 300-μm-wide damage. Healing efficiency of the self-healing coating decreased with increasing damage width. As capsule-loading, capsule size or coating thickness increased, healing efficiency of the self-healing coating increased. Healing efficiency of 76% or higher was achieved using the self-healing coating with a 300-μm-wide scratch. The self-healing coating with a 200-μm-wide crack showed healing efficiency of 70% or higher. The self-healing coating having a 300-μm-wide scratch showed effective protection of the substrate mortar from carbonation and chloride ion penetration, which was supported by SEM study.