Large-scale apparatus for the quantitative evaluation of biorepair in a cracked concrete slab

Biorepair of concrete uses microbial activity to repair cracks through the formation of calcium carbonate and biofilms. This new approach has already been demonstrated in the laboratory using small samples of cementitious paste or mortar. The objective of this research was to construct a large-scale laboratory apparatus to crack a reinforced concrete slab (2 m × 1 m × 0.15 m) and to quantify the performance and kinetics of an exo-biorepair method on two cracks with an opening of 430 ± 60 µm. Exo-biorepair was performed with two injections of nutrient media containing a consortium of indigenous bacteria, calcium lactate and mineral fillers. Quantitative assessment of water flow in the cracks showed a 99 % reduction in water flow after 11 weeks. Scanning electron microscopy and X-ray dispersive analysis of the products in the volume of the cracks indicate that they contain biobased calcium carbonate and biofilm. This research confirms that exo-biorepair can be used to seal cracks using a standard injection method. • Development of an apparatus to crack and repair cracks (430 µm) in a concrete slab. • Cracks were exo-biorepaired with an injection of a microbial consortium. • Quantification of crack sealing kinetics and analysis of the sealing products. • The exo-biorepair shows a 99 % reduction in water flow after 11 weeks. • The sealing material is a calcium carbonate-biological composite.