Inorganic capsule based on expansive mineral for self-healing concrete

• Published in: Cement & concrete composites Vol. 144; p. 105305
• Main Authors: Li, Jinglu, Guan, Xinchun, Zhang, Chenchen
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2023
• Subjects: Inorganic capsule; Magnesium oxide expansive agent; Microstructure analysis; Permeability coefficient; Self-healing; Superabsorbent polymer; Inorganic capsule; Superabsorbent polymer; Magnesium oxide expansive agent; Self-healing; Permeability coefficient; Microstructure analysis
• ISSN: 0958-9465; 1873-393X
• DOI: 10.1016/j.cemconcomp.2023.105305

Expansive minerals are extensively used to promote the self-healing performance of the cracked concrete. Nonetheless, the expansive minerals will be consumed prematurely by participating in cement hydration. In this study, two types of inorganic capsules based on magnesium oxide expansive agent were developed by the techniques of granulation and encapsulation. The superabsorbent polymer was also embedded in inorganic capsules to enhance the healing ability. To investigate the healing potential and durability of the inorganic capsules in cement matrix, the mineralogy of inner core, granule strength and encapsulation effect were measured. The self-healing efficiency was evaluated by the tests of crack observation, water permeability and microstructure analysis. Results showed that the inner core of inorganic capsules remained stable during granulation, and the protective shell endowed the capsules with considerable strength and erosion resistance. Due to the addition of inorganic capsules, especially the capsules containing two-component healing agents, the effects of crack closure and impermeability recovery of the cracked mortar were significantly increased after healing in wet-dry cycles. The self-healing products consisting of calcite and Mg-rich phases were formed by the reaction of healing agents. The formation of the Mg-rich products was further accelerated owing to the continuous water supply by the superabsorbent polymer inside inorganic capsules. •Inorganic capsule with great healing potential and erosion resistance was developed.•Addition of capsules obviously improved crack closure and impermeability recovery.•Capsules enriched the composition and content of the healing products in cracks.•Healing process was further accelerated by the superabsorbent polymer in capsules.