Characteristics of two types of fiber-reinforced mortar in four-point bending are discussed and compared in this paper. One is steel fiber-reinforced mortar that was introduced to Japan in 1960s. Another is PET (Polyethylene Terephthalate) fiber-reinforced mortar that was recently invented and right now information about its characteristics is still very limited.
Two types of fiber-reinforced mortar were tested in a servo-controlled testing machine to obtain a complete load-deflection curve or a curve in pre and post failure regions. Photographs of a sample were taken in the four-point bending test to evaluate the crack length and the crack opening displacement (COD).
Testing results indicated that the bending strength of two types of fiber-reinforced mortar was increased considerably compared with that of a plain mortar. Peak and residual strength of PET fiber-reinforced mortar was found to be slightly weaker than that of steel fiber-reinforced mortar, however, PET fiber elongated easily, therefore wider crack width was permissible. It was also shown that the peak strength can be theoretically estimated by the stress-strain curve obtained in uniaxial tensile test as pointed out formerly by Okubo et al.
Right now, usage of PET fiber-reinforced mortar is still very limited, however, the results obtained in this study indicate promising future of PET fiber-reinforced mortar. Especially, it is considered to be appropriate for usage under severe environmental conditions and construction in narrow space such as path through forest or winding road.
