Research On Static And Dynamic Mechanical Behaviors Of UHMWPE Fiber Reinforced Concrete

As a kind of building material, concrete has been widespread used in various kinds of engineering structures and infrastructures. However, the shortage of low tensile strength, low toughness and easy to be spall and broken in the extreme conditions of explosion and impaction leads to the reduction in protective ability. Fiber develops the function of cracking resistance, reinforcing strength and reinforcing toughness, hence fiber reinforced concrete has better properties than plain concrete. The effect of enhanced strength is mainly determined by characterize of fiber, and it also relates to fiber fraction, fiber distribution in concrete basal body and the interface behavior of added fiber. Ultra high moleculer weight polyethylene(UHMWPE) fiber is a kind of ballistic fiber which has higher strength than steel fiber, high elastic modulus, low fineness and density. Therefore, the concrete reinforced by UHMWPE fiber is expected to have excellent mechanical properties to satisfy the requirements of blast-resistance and anti-impact protection. Based on above background, this paper researched the static and dynamic mechanical properties of UHMWPE fiber reinforced concrete. The main work and innovation achievements are followed:(1) Improved technique for preparation of fiber concrete. By means of improving dry mixing method and delaying the time to stir concrete properly, the problems of low elastic modulus fiber uneven dispersion and gathering into a mass were solved, the working performance of fiber concrete such as workability was improved, all of which lay a solid foundation for obtaining high performance concrete.(2) Researched the static strength of fiber concrete. It was found from this study that the fiber concrete cubic splitting tensile strength enhanced significantly with the increase of fiber fraction, whereas the compressive strength was improved not obviously compared with plain concrete, and the size effect of compressive strength of fiber concrete was similar to that of plain concrete. The twisted UHMWPE fiber researched in this paper improved the static mechanical properties of concrete more significantly than ordinary UHMWPE fiber which was not treatment researched in preliminary study.(3) Researched the compressive behavior. The results showed there is a positive correlation between peak strain, residual stress, poisson ratio, compressive toughness index and fiber fraction, and there is an opposite correlation between elastic modulus and fiber fraction, all of these demonstrated that fiber played a role which provided lateral passive confined pressure under uniaxial compressive loading, and improved the compressive deformation performance. Based on the experimental results, modified Guozhenhai model for unaxial compression was gotten.(4) Researched the dynamic compressive mechanical performance of fiber concrete. The results showed that fiber slowed down the degree of damage, delayed the time to damage and enhanced the impact toughness. Both the compressive strength and elastic modulus of fiber concrete were sensitive to strain rate, there is linear function relation between the dynamic strength increasing factor and strain rate logarithm.