Encapsulation Technology and Techniques in Self-Healing Concrete

Throughout concrete structures' service life span, deterioration inevitably occurs. A typical phenomenon of deterioration in concrete structures is cracking, which affects durability and integrity of these structures. Repair and maintenance of concrete structures are labor and capital intensive; it can also be difficult to access the degree of damage after the construction is completed. Self-healing is a possible solution. An encapsulation strategy is widely considered as a versatile and effective strategy for self-healing. In this review, attention is focused one valuation of different healing agents and encapsulation techniques. Eight key factors that affect the effectiveness of self-healing by encapsulation are discussed; these are (1)robustness during mixing, (2)probability of cracks encountering the capsules, (3)curing time and condition, (4)effect of empty capsules on concrete strength, (5)controllability of release of healing agent, (6)stability of healing agent, (7)sealing ability and recovery of durability and strength of concrete matrix (as a result of self-healing), and (8)repeatability of self-healing action. Finally, gaps in current research and important areas for future research are identified.