Abstract
Self-healing of cracks in cementitious materials using healing agents encapsulated in microcapsules is an intelligent and effective method. In this study, microcapsules were prepared by the melt–dispersion–condensation method using microcrystalline wax as the shell and E-51 epoxy resin as the healing agent. The effects of preparation process parameters and microcrystalline wax/E-51 epoxy resin weight ratio on the core content, particle size distribution, thermal properties, morphology, and chemical composition of microcapsules were investigated. The results indicated that the optimal parameters of the microcapsule were microcrystalline wax/E-51 epoxy resin weight ratio of 1:1.2, stirring speed of 900 rpm, and preparation temperature of 105 °C. The effects of microcapsules on pore size distribution, pore structure, mechanical properties, permeability, and ultrasonic amplitude of mortar were determined, and the self-healing ability of mortar with different contents of microcapsules was evaluated. The optimal content of microcapsules in mortars was 4% of the cement weight, and the surface cracks of mortar containing microcapsules with an initial width of 0.28 mm were self-healed within three days, indicating that microcapsules have excellent self-healing ability for cementitious materials.
Highlights
Cementitious materials are widely used in building construction materials and have excellent mechanical properties and workability [1]
The results indicated that the mass loss of microcapsules increased significantly with the decrease of shell/core weight ratio at temperatures from 280–396 °C, indicating that more E-51 epoxy resin was encapsulated into the microcrystalline wax
The results showed that the compressive strength recovery ratios of does not change much, which indicates that the self-healing limit of the microcapsules to the mortar increased with the increase of microcapsule content
Summary
Cementitious materials are widely used in building construction materials and have excellent mechanical properties and workability [1]. In order to ensure the safety of the building structure and prolong its service life, the building must be extensively overhauled or planned maintenance during the course of its use. Current manual inspection techniques make it difficult to locate internal cracks in buildings and to detect and repair internal microcracks in a timely manner, which can incur high maintenance costs [8,9]. It is imperative to develop new materials with low cost and high performance, especially for cementitious materials with self-healing ability, which can effectively reduce maintenance, extend service life, and improve safety [10,11]
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