Study on the behaviors of fungi-concrete surface interactions and theoretical assessment of its potentials for durable concrete with fungal-mediated self-healing

Abstract

Abstract This study aims to investigate the feasibility of self-healing concrete with fungi. Fusarium oxysporum, a filamentous fungi strain that is capable of producing biomineralization was selected in the study. The growth behaviors of Fusarium oxysporum under the influence of concrete environment were studied under controlled conditions. The metabolism behaviors of Fusarium oxysporum that affect its self-healing capabilities, such as forming spores and growing mycelium were investigated with macroscopic observations as well as microscopic analytic instruments. The results show that Fusarium oxysporum was able to germinate on the surface of concrete and engaged in rapid mycelium development. The alkaline environment has an influence on the growth of fungal mycelium by slowing their growth. However, under favorable conditions, Fusarium oxysporum mycelium covered a surface area of mortar 86 times the area of the original fungi inoculum after 96 h. Such fast growth of Fusarium oxysporum could contribute to high efficiency in healing cracks. Microscopic characterization by SEM and FTIR further confirmed the metabolism activities of fungi produce biominerals inductive to self-healing performance. The fungal mycelium demonstrated hydrophobic nature. Analyses indicated that compared with bacteria-based self-healing, Fusarium oxysporum can potentially significantly increase the healing efficiency. Depending upon the pH value, fungi based healing time is 11.3%, 15.1% and 79.6% of the healing time required with MICP. Besides, the water repellency of mycelium would reduce the water infiltration rate to 17.22% of that of regular concrete surface, a benefit unseen in bacteria induced MICP. Fungi induced self-healing is environmental friendly than MICP process since no toxic gases are released. Overall, this study demonstrated fungi mediated self-healing mechanism via crack filling and improvement of water tightness as a novel strategy to significantly improve the durability concrete.