Mechanical Performance and Shear Behavior of Synthetic Fiber Reinforced Concrete Beam

Abstract

The potential use of fiber reinforcement for enhancing the mechanical properties and shear capacity of fiber reinforced concrete beams had been clearly established and recognized that fiber reinforcement is an effective way to enhance the mechanical performance, shear behavior and fracture toughness of concrete in all modes of failure. An experimental study was performed to investigate effect of two different types of fibers: micro and macro synthetic fiber on the workability, compressive strength, splitting tensile strength, flexural strength and shear behavior of synthetic fiber reinforced beam with concrete strengths,25and 40 MPa, and fiber volume fractions,0.2,0.35 ,0.50, and 0.65% of concrete volume. The test results showed that the workability of concrete decreases as the volume of fibers and concrete strength increases. The micro SNFRC beams with a strength of 25MPa at 0.2,0.35,0.5, and 0.65% volume fractions decreases the compressive strength by 12,12.31,23.96, and 44.6%, while macro synthetic fibers improved the compressive by at least 3.87, 5.16,5.3 and 5.39%, respectively compared to the control specimen. Likewise, the compressive strength of fiber reinforced concrete with 40MPa decreases by 2.17 % for 0.35%fiber content and, 72% for 0.65% fiber content and 10.48 % for 0.65% of both micro and macro SNFRC beam respectively. As the volume of micro synthetic fibers increases the tensile strength of micro SNFRC beam constantly decreases up to 14.93% and 61.33% for 0.65%fiber content in both 25 and 40MPa concrete strength respectively. However, macro SNFRC beam with a strength of 25MPa at 0.20,0.35, and 0.50% volume fractions enhanced the tensile strength by 4.75,5.88 and 7.0% respectively and in the same way it increases by 10.47% at 0.35% fiber content and by 5.71% at 0.65% fiber content in concrete with 40MPa strength. The micro SNFRC with a concrete strength of both 25 and 40 MPa showed a decreases in flexural strength particularly for a fiber volume fraction of greater than 0.35%. With the addition of macro synthetic fiber, the flexural strength of concrete with 25 MPa increases by 0.46,2.77,2.3 and 7.39% at 0.20,0.35,0.50, and 0.65% fiber content and decreases by 35.1at 0.35%and 38.9% at 0.65% fiber content in SNFRC with strength of 40MPa. Average shear strength of micro and macro synthetic FRC greatly enhanced as the fiber volume content of the concrete increases. The flexural and shear toughness behavior of the SNFRC is highly boosted and more effective in higher strength concrete (40 MPa) than in normal strength concrete (25 MPa).