Effect of PVA fibres and crystalline admixtures on the self-healing efficiency under long-term aconstant loading

Cracks in cement-based materials affect the strength and durability. This study explored the synergistic effect of polyvinyl alcohol (PVA) fibres and crystalline admixtures on the self-healing properties under long-term constant loading conditions. First, specimens with varying degrees of pre-damage were obtained. The pre-damaged specimens were then cured with and without constant applied load. The self-healing efficiency was evaluated based on the compressive strength, and the self-healing mechanism was analysed based on the changes in porosity. When curing was performed without a load, the compressive strength increased to different extents. Conversely, when cured under constant loading conditions, the compressive strength increased under low-load conditions, and the compressive strength decreased under high-load conditions. The porosity exhibited a similar pattern of variation. The self-healing efficiency was found to be dependent on both the damage caused by long-term constant loading and the repairing effects achieved during the curing process. When subjected to external forces, PVA fibres inhibited crack propagation, and crystalline admixtures repaired the cracks after they appeared. This demonstrates the successful integration of "control-repair" in cracks. The curing conditions involving long-term constant loading better simulated real engineering scenarios, which distinguishes this work from those performed under no-load curing conditions. This study represents a valuable exploration of self-healing technology.