Concrete is the most used construction material worldwide for infrastructure projects. Due to deterioration, regular maintenance works are necessary to seal the concrete cracks and restore durability. In Europe, infrastructures such as tunnels, bridges and earth retaining walls alone cost approximately 5 billion EUR per year. Self-healing strategies (particularly bacterial-based self-healing) are regarded as a promising solution to reduce the high maintenance and repair cost of concrete infrastructures. The research to date has tended to focus on the self-healing process in air or water environment. However, infrastructures are built on or in the ground, where part of their concrete structures are inevitably embedded in soil environment. It is not clear if the process of self-healing is efficient within concrete elements exposed to ground conditions.
The article aims to explore the possibility of the bacterial-based self-healing in underground concrete structures. By using a novel interdisciplinary approach, the research combines state-of-the-art technologies applied in materials/concrete, geotechnical engineering, and microbiology to conduct a seriews of lab-scale experiments on mortar specimens incubated within soil environment under water saturation regime. Filled cracks are observed under Electron Scanning Microscope supported by image analysis. The results are analysed and presented in this paper. The outcomes of this research work are highly relevant to the construction industry and the knowledge produced by the present and the near future perspectives will have an economic, financial and societal impacr in EU and other regions of the world.