Proposed Concrete Section Repair Techniques for Crack Reduction

Deteriorated concrete bridges undergo periodic repairs such as section repairs. However, cracks frequently occur after these repairs. This study evaluated the performance of repair materials based on the inclusion of coarse aggregate and the maximum aggregate size, as well as to assess the effects of crack reduction during each stage of section repair. Breaking and water jetting were applied to assess the effect of different deteriorated area removal techniques. In addition, the saturated surface dry (SSD) condition of the substrate was compared between the applied and unapplied methods, and the effect of coarse aggregate was checked by incorporating aggregates of 3, 10, and 13 mm sizes. The results showed that the inclusion of coarse aggregate in repair materials helps suppress drying shrinkage, thereby leading to fewer cracks. Field experiments confirmed that, during section repair, the combination of using a water jet for deteriorated part removal, applying the SSD condition to the parent concrete, and using polymer cement concrete with a maximum aggregate size of 10 mm as the repair material resulted in the fewest cracks.