Self-healing of cracks in mortars using novel PVA-coated pellets of different expansive agents

摘要

The potential for fine aggregates, a basic constituent of any mortar or concrete mix, has not been sufficiently exploited in developing self-healing systems. This paper investigates the self-healing capability of mortar mixes that contain polymeric coated pellets containing several potential self-healing agents. The pellets replaced 10% of the sand by weight in mortar mixtures and mortar prisms were pre-cracked up to 0.3 mm crack width at seven days. It was demonstrated through microscopy and ultrasonic observations that the addition of the coated pellets resulted in an improvement of the crack mouth and depth sealing by similar to 20-60% over and above the healing observed in the control samples. Water sorptivity and gas permeability tests confirmed the capability of the formed healing products through the use of the pellets in preventing the ingress of water, gas and/or deleterious liquids. In addition, the samples containing the pellets showed a considerable regain of flexural strength and stiffness after two rounds of water curing of the cracked samples. The significant contribution of pellets in forming the healing products in the crack volume was clear from the microstructural analyses conducted. (C) 2020 Elsevier Ltd. All rights reserved.