Self-healing soil: Biomimetic engineering of geotechnical structures to respond to damage

The concept of self-healing, whereby materials such as polymers, composites and cementitious construction materials are able to sense damage or deterioration and regulate, adapt and repair themselves automatically, is applied here to natural and anthropogenic soil structures. Damage in such structures can be difficult to detect and monitor, and will have significant consequences, but maintenance and repair are costly and disruptive. This paper presents an overview of the self-healing concept, its potential within geotechnical engineering and results from preliminary experiments exploring the potential for self-healing through the actions of living organisms such as bacteria. We report a simple experimental example, which demonstrates the potential for bacterial activity in microbially induced calcium carbonate precipitation of coarse-grained soils to persist and heal damage. Sands stabilized through calcium carbonate precipitation effected by Sporosarcina pasteurii were sheared and rehealed with only additional supply of nutrients, recovering a proportion of the original strength. This example is a simple demonstration of the ability of living organisms to adapt and respond to damage, and suggests the potential for this ability to be harnessed by engineers to design structures that can heal themselves.