Direct-tensile and flexural strength and toughness of high-strength fiber-reinforced cement composites with different steel fibers

Abstract

The main purpose of this study is to investigate effects of the type and volume fraction of steel fibers on the mechanical behaviors of fiber-reinforced cement composites (FRCCs) with high strengths. Various FRCC mix cases were designed and tested in two steps. At the 1st step, two types of steel fibers (straight and hooked) were examined with two different fiber volumes (1.0 and 1.5%). The test variables of the 1st step included the type and volume fraction of steel fibers, and the inclusion of coarse aggregate. At the 2nd step, ultrahigh strength FRCC mix cases using hooked steel fibers only were tested with two different fiber volumes (1.0 and 1.5%). Various mechanical tests were performed to evaluate the stress-strain behaviors of the FRCCs subjected to uniaxial compression, direct tension, and third-point bending. The test results reveal that the use of hooked steel fibers improved the tensile and flexural capacities of FRCCs more effectively than did the straight steel fibers. Also, the FRCCs generally demonstrated greater direct-tensile and flexural toughness compared with ordinary fiber reinforced concretes (FRCs).