Fundamental Study on Crack Behavior of Bending Stress and on Improvement of Waterproof Properties of UHPFRC with Self-Healing Agent

Abstract

This study was carried out on UHPFRC for repairing concrete slabs that have suffered deterioration. Waterproof properties are required for decreasing LCC. Bending tests, bending fatigue tests and water penetration tests were carried out focusing on crack behavior, especially the microcrack restraint ability in the strain hardening zone of UHPFRC. Significant strain hardening was observed in UHPFRC with 3vol% steel fiber content, with effective crack dispersal and no visually detectable cracks until 1000 μ in bottom strain. Crack width was constrained to less than 0.07 mm in a 4,800,000 cycle bending fatigue test applying 15 N/mm² to 20 N/mm² in bending stress. Most cracks could be healed by the self-healing agent, indicating the possibility of achieving higher waterproof performance. In light of the above, the newly developed UHPFRC can be expected to be of use as a waterproof top layer for RC slabs in future.