Abstract

Cracks increase permeability affecting the durability of concrete. As they develop gradually, it is difficult to determine when to repair them. Self-healing materials can repair themselves gradually as cracks form. In this study, the isolated and combined effect of two self-healing agents for concrete, both based on calcium carbonate precipitation, was studied. Lightweight aggregates were impregnated with chemical and biological solution to be added as healing agents in concrete mixtures. The influence of two common chemical admixtures on the performance of the self-healing agents was also studied. All self-healing agents were able to seal cracks between 0.08 and 0.22 mm in width. The estimated effect of chemical agents on the mean healing was higher than that of biological agents. In addition, thermogravimetric analysis suggests the precipitates are different. Admixtures had no significant influence on the performance of self-healing agents. (C) 2014 Elsevier Ltd. All rights reserved.