Self-healing Concrete with Fungi: An Exploration on Nutritional Sources to Sustain Fungal Growth in a Cementitious Environment

Concrete plays a central role as building material in the construction sector, however it is plagued by crack formation which leads to reinforcement corrosion and material degradation. To address these durability issues in a sustainable way, fungi have been introduced as self-healing agents to seal concrete cracks by promoting the precipitation of CaCO3 on their cell walls. In order to enable fungi to perform self-healing in concrete, nutritional sources need to be present that sustain the growth of the organism. This research therefore investigates potential nutritional sources to sustain the fungi Trichoderma reesei and Neurospora crassa in a cementitious environment. Samples with cotton, hay, hemp (lignocellulosic natural fibres), corn and oat (starch-based cereal grains) were prepared. Different grain sizes were considered by mixing the fibres and cereals. The influence of gelatinization of the starch-based cereals on the fungal growth was assessed. Additionally, the inoculation method was investigated by comparing a solid and liquid inoculation. Finally, a selection of fibres and cereals was combined with cement paste in three different ways: laid on cured cement paste, laid on fresh cement paste and mixed with cement paste. Results show that Trichoderma reesei thrives on cotton and (mixed) hay. Neurospora crassa thrives on starch but grows equally well on cotton and to a lesser extent on the other natural fibres. When combined with cement paste, fungal growth is mostly observed on corn, oat and cotton, however more experiments need to be conducted.