AUTOGENOUS SELF-HEALING OF POLYPROPYLENE FIBER REINFORCED ETTRINGITE-BASED COMPOSITE

This study intends to advance the poor knowledge on the ability of an ettringite-based binder to obtain autogenous self-healing and its relevant mechanism. We developed a high performance polypropylene fiber-reinforced cementitious composite based on the ettringite based binder and investigated the autogenous healing property under water-saturated conditions. Four-points bending loading of prismatic specimens was adopted to introduce cracks at different crack opening displacements (i.e., 0.5, 1, and 2 mm total crack opening). After different curing times, the retention and recovery of mechanical performance were compared with the uncracked composite. The material effectively heals micro cracks (i.e., under 100 μm) after 1 month of aging, while larger cracks could not completely close during the total curing times (up to 3 months). The healing product was mainly CaCO3 crystal, which was mainly resulted from the carbonation of ettringite in aqueous conditions. The strength retention slight reduced (about 10%) after healing, however, the composite still exhibited deflection hardening behavior. Findings show the high potential of ettringite-based binder to be a matrix for self-healing cementitious composites. Further improvements, nevertheless, are needed to increase the healing rate and strength recovery of the composite.