Behavior of Steel-Polypropylene Hybrid Fiber Reinforced Concrete

ABSTRACT: Since ancient time, fiber reinforced concrete has been replaced with plain concrete which is brittle material. Although, the inclusion of single type fiber may improve mechanical properties of concrete, the hybridization can compensate the disadvantages of two fiber types and represent their advantages. This thesis explores the effect of using steel fiber and polypropylene fiber for reinforcing the concrete to quantify the mechanical properties of concrete matrix. For this purpose, 45 specimens of fiber reinforced concrete which contains different fibers dosage were casted. All mixes were tested for slump and VeBe test in fresh state, and 28 days compressive strength, flexural strength and impact resistance tests were carried out in hardened state. According to the test results, the regression analysis was carried out to predict the value of compressive strength, flexural strength and impact resistance. The experimental results show that the hybrid form of fiber has slight effect on compressive values, while it causes increase in modulus of rupture, toughness and impact resistance values. Keywords: Fibers, hybrid fiber reinforced concrete, compressive strength, flexural toughness energy and impact energy. …………………………………………………………………………………………………………………………