Experimental study on self-healing effect of FRCC with PVA fibers and additives

It has been confirmed that some types of fiber-reinforced cementitious composites (FRCCs), particularly the ones that use synthetic fibers (e.g. polyvinyl alcohol; PVA), have a great capability to self-heal the cracks by some previous research. In this study, self-healing capability of FRCCs with additives such as silica fume and excess PVA dosage was tested. Two experimental studies were carried out to evaluate the self-healing capability with different levels of cracks. As to Test I, freeze/thaw cycles (according to the JIS A 1148 (ASTM C 666-A) method) was subjected to specimens to introduce micro cracks. As to Test II, visible cracks up to 500 mu m width were generated by tensile loading test. The damaged FRCC specimens were exposed to several conditions to induce self-healing curing. In the case of Test I (freeze/thaw cycles), the self-healing capability was evaluated by measuring the number of cracks, relative dynamic Young's-modulus (RDYM) and pore structures. In the case of Test II (tensile loading test), the coefficient of watertightness was measured every certain period of time. Upon exposing to the curing conditions after the damage, the results showed a recovery by means of self-healing effect. In Test I, all of the cracks and RDYM recovered due to the densification of microstructures and filling up of the cracks. In Test II, the recovery of the coefficient of watertightness was confirmed after self-healing curing, which was proportionally consistent during the immersion in water. Moreover, the results showed that an admixture of PVA could be expected to enhance the self-healing capability of cracks without causing any negative impact on the properties of FRCC.