Mechanical Properties Research For Steel-PVA Hybrid Fibers Reinforced Concrete

With the rapid development of modern concrete application and research，high-risebuildings，large-scale bridge structure increasingly，the requirements of concrete strength arealso increasing. But excessive strength will inevitably lead to the brittleness of concreteincreasing, increase the toughness of concrete and make the concrete develop towards lowbrittlement and high strength is the inevitable trend. Currently, an effective way to improvethe toughness of concrete is adding fiber.This thesis is study on the influence of hybrid polyvinyl alcohol fibers and steel fiberson the strength and toughness of concrete. By setting three different water-binder ratio:0.30,0.35,0.40,and three different fiber volume fraction:0,1.0%,1.5%, to make up the fiberreinforced concrete, compared the compressive strength and flexural tensile strength ofconcrete and analysis the toughness index and toughening mechanism, research the threefactors of water-binder ratio, fiber type, fiber content influence on the strength and toughnessof concrete separately, lay the foundation for future study on the fiber reinforced concretedurability.The fiber reinforced concrete compressive and flexural tensile test results show that:themost important factor affecting the compressive strength is the water-binder ratio, theconcrete compressive strength increased with the increasing fibre volume fraction; thecompressive strength of PVA fiber reinforced concrete is superior than the PVA/steel hybridfiber; the most important factor affect the flexural tensile strength is fiber volume fraction;under the same water-binder ratio, the same fiber volume fraction, the flexural strength ofPVA/steel fiber reinforced concretes is superior than PVA fiber reinforced concrete.The results of Two types fiber-reinforced concrete toughness analysis showes that:thefibre volume fraction is the main impact factors of fiber reinforced cement concretetoughness, the more fiber content,the deformation hardening of fiber reinforced concrete ismore obvious,and the toughness index is greater, the load-deflection curve showed that thedeformation hardening phenomenon of the PVA/steel fiber reinforced concrete is significantcompared to the PVA fibers.The analysis of the toughening mechanism showed that the most important factor ofaffecting the fiber toughening effect is the fiber spacing, the fiber spacing is smaller, the toughening effect is more obvious; other important factor affecting the fiber toughness is thebond strength between the fiber and the matrix, improve the cohesive force can postpone thefiber reinforced concrete cracking time and improve the bearing capacity of the structure.