Feasibility of self-healing in cementitious materials – By using capsules or a vascular system?

• Healing agent released from capsules of various dosage and size was quantified.
• The effect of healing agent migration on self-healing was determined by modeling.
• Self-healing by using vascular systems to supply healing agent was evaluated.
• Self-healing realized by using capsules and vascular systems was compared.
• Ways to improve the efficiency of self-healing by using capsules were discussed.

Objective: The aim of this paper is to investigate self-healing in cementitious materials with saturated Ca(OH)2 solution as a healing agent, supplied by using capsules and a vascular system.Materials and methods: Numerical simulation was performed to determine the efficiency of the supply of saturated Ca(OH)2 solution by using capsules and consequently the efficiency of self-healing. The influence of capsule dosage and size was taken into account. Ultrasonic pulse velocity tests were conducted to evaluate the efficiency of self-healing of cracks with saturated Ca(OH)2 solution supplied via a vascular system.Results: The simulation results show that the efficiency of self-healing of cracks with saturated Ca(OH)2 solution supplied by using capsules is very low. This is due to the fast absorption of healing agent by the bulk matrix and the low efficiency of the supply of healing agent by using capsules. Increase of capsule dosage and size can improve the healing efficiency as the amount of healing agent supplied to crack linearly increases with the capsule dosage and diameter. In comparison, the efficiency of self-healing of cracks with saturated Ca(OH)2 solution supplied via a vascular system is much higher. This is because sufficient saturated Ca(OH)2 solution is supplied to cracks for healing via a vascular system.