Investigation of crack healing in concrete pavement using combined bacteria spray and filling solution method

Environmental and traffic conditions can significantly damage concrete pavement surfaces. Among the most common failures are plastic shrinkage cracks, which often appear within the first few hours after pouring. Loading and durability cracks are also frequently observed in concrete surfaces. In general, three approaches can be considered for addressing such cracks: (1) do nothing, (2) crack sealing, and (3) self-healing. In this study, Sporosarcina pasteurii bacteria in the form of spores were sprayed onto hardened concrete surfaces along with a filling solution (CaCl₂) in four weekly series. This approach was applied in two cases: (1) creating artificial cracks in the width range of 0.5 to 3 mm, and (2) on JPCP concrete parking lot surfaces. This innovative method promotes crack healing on the concrete surface. Microscopic and chemical analyses, along with the Crack Width Healing (CWH) and Crack Volume Healing (CVH) indices, were conducted to evaluate the degree of calcification and the effectiveness of crack healing. Laboratory samples with cracks up to 1.5 mm in width showed 100% healing after four weeks. For cracks with widths of 2 mm (12.6% and 32.1%), 2.5 mm (11.7% and 31.1%), and 3 mm (10.1% and 30.7%) based on the CWH and CVH indices, the effects of healing and calcite crystal formation were observed visually and confirmed through complementary SEM/MAP and EDS analyses. The crack healing performance of the parking slab matched that of the experimental specimens, showing a minimal difference of only 4% and 2% in the normalized CWH and CVH indices, respectively. It was determined that the CWH index is suitable for evaluating the self-healing performance of surface (shrinkage) cracks, while the CVH index should be used for deeper cracks caused by loading. • Using bacteria spray technology combined with filling solution. • Using Crack Width and Volume Healing indices (CWH and CVH) to evaluate the self-healing performance of surface and deep cracks of concrete pavement. • Investigating the self-healing performance of bacterial spray in experimental and parking lot slab.