Bacteria-initiated self-healing concrete: Influence of chloride ions, carbonation and mechanical load

Under service conditions and because of environmental and climate changes, the concrete is at risk due to crack-induced durability problems. The consequences can be even more pronounced when concrete is exposed to specifically aggressive environmental conditions. This has been portrayed by rapid deterioration of relatively young concrete structures such as the ones no older than fifteen years, which obviously are much shorter than their estimated service life. As such, crack-closing ability is needed in these concrete constructions to prolong their service life.
Numerous studies have been reporting on the autogenous healing of cracks in cement-based materials. However, an active or rapid micro-crack healing is not always the case in the most critical parts of exposed structures. In this thesis, a new formulation of cement-based materials, by integrating selected bacteria and suitable organic mineral precursor compounds, was used to investigate its potential for enabling multiple crack healing events on load-induced cracked and pre-cracked concrete samples. For this purpose, chloride ingress in concrete subjected to compressive loading was investigated through laboratory experiments. Furthermore, investigation was also carried out on cracked mortar under chloride and carbon dioxide environments for healing-potential evaluation....