Bacteria-based self-healing mortar: A comparison of two studies

Self-healing concrete has drawn a lot of attention in recent years. There are numerous projects worldwide that work on the development of self-healing agents. Among those, bacteria-based self-healing concrete is a very promising solution to prevent durability problems in concrete that are related with cracking. Bacteria-based self-healing concrete not only provides sealing of open micro-cracks that endanger the structure's health, but it also has economical and environmental benefits, since it will extend the lifetime of the structure and reduce repair costs. In this study, the bacteria-based self-healing agent consists of alkaliphilic bacterial spores, organic mineral precursor compounds and Light Weight Aggregates (LWA). Although the success of the concept has been proven in previous research, in this study an optimized method for the incorporation of the organic compounds into the LWA has been developed. The method allows more of the organic compounds to be stored into the LWA. This paper focuses on comparing performance on mechanical properties and sealing efficiency of cracks of mortar samples from past and current research. The initial hypothesis of the study was that the lightweight mortar with the higher amount of healing agent will show faster and more efficient crack sealing capacity. The comparison revealed different results than expected. In fact, the sealing efficiency trend proved to be similar for the two studies which was speculated to be due to oxygen limitation rather than healing agent limitation in permanently water submersed specimens.