Experimental studies are carried out to evaluate the self-healing capability of FRCC using different types of synthetic fibers that have different chemical properties, i.e. poly vinyl alcohol (PVA), ethylene vinyl alcohol (EVOH), polyacetal (POM) and polypropylene (PP). FRCC specimens were subjected to tension tests in order to generate a crack, and the cracked specimens were immersed in water. In order to evaluate the effect of self-healing phenomena, permeability tests and microscopic observation were carried out. Microscopic observation revealed that the high polarity of synthetic composite has high potential of self-healing precipitation around fibers bridging a crack. Moreover, the coefficient of water permeability was generally reduced with this chemical precipitation, especially in the PVA series. However, even when it was confirmed by microscopic observation that precipitation had appeared and filled a crack, we found there is no recovery of water tightness in some cases, i.e. in the EVOH and POM series. It is confirmed that not only the chemical properties of fibers but also the geometrical properties of the crack surface, such as roughness, complexity and continuity, affect the capability of self-healing for water tightness.

Even in case of conventional concrete, cracks width of about 0.1 mm or smaller is relatively safe due to self-healing autogenously achieved by immersing moisture. In this self-healing phenomenon, fiber reinforced cementitious composites (FRCC) that enable to keep the crack width smaller can be greatly effective. In order to investigate the self-healing capability of FRCC, some experiments were carried out that focused on the recovery of mechanical properties and chemical precipitation on the crack surface. Kinds and length of the contained fibers were adopted as the experimental parameters. These specimens, in which cracks were introduced by tension test, were cured in water after introducing cracks. The self-healing capability of the specimens was investigated by means of microscope observation, water permeability test, and re-tension test. It was found that a lot of very fine fibers were bridging over the crack and crystallization products became easy to be precipitated around such bridging fibers. Additionally, the increasing rate of the thickness of the crystallization products during the initial stage is higher than that of the latter stage. As a result, water permeability coefficient was recovered significantly. However, mechanical properties were restored slightly. Furthermore, it was shown that different types of fibers led a different performance of the self-healing effect.