Research Of The Properties Of Polyvinyl Alcohol Fiber Concrete

With the continuous improvement of fiber-reinforced concrete technology,steel fiber and polypropylene fiber have been recognized by people and obtained a certain scale of application in the engineering project.However,there is relatively little research on polyvinyl alcohol fiber-reinforced concrete,and the researches of this new synthetic fiber with high strength,high elasticity and acid and alkali resistance on the improvement of concrete performance and the reinforcing effect under different environments are of important significance in the application of polyvinyl alcohol fiber on concrete and the promotion in engineering practice.Therefore,this paper compares and analyzes the long-term mechanical properties of polyvinyl alcohol fiber concrete and reference concrete under five kinds of water/binder ratios,and uses wet-dry cycling test method,water penetration height method and quick-freeze method to explore the impact of polyvinyl alcohol fiber on the durability of coagulation,and combining with the acoustic emission detection system to characterize the damage during the uni-axial compression of concrete after high temperature,and the following main conclusions are drawed:Polyvinyl alcohol fibers increase the ratio of tension to compression and poisson's ratio of concrete,and improve the distribution relationship between tensile strain energy and compressive strain energy when the concrete is under compression.Compared with the failure pattern of reference concrete,it is clearly found that the fibers act as bridging and bonding in the concrete,which enhance the tenacity of the concrete.The mix of polyvinyl alcohol fibers can strengthen the compressive,flexural and splitting strength of concrete to a certain extent.The highest growth rates are 17.71%,16.04%,and 37.44%,respectively compared with the reference concrete.It was also found that the reinforcing effect of polyvinyl alcohol fibers on concrete with low water/binder ratio is more significant.Polyvinyl alcohol fiber inhibits the occurrence and development of concrete cracks,strengthens the bond between cementitious materials and aggregates,and has a good restraining effect on the deformation of concrete.After the fiber was incorporated,the concrete's corrosion resistance coefficient and relative dynamic modulus increased,and the water seepage height was lower than that of the reference concrete.It was found that the concrete's frost resistance,impermeability and resistance to sulfate wet-dry cycling were improved.The impermeability of high water/binder ratio concrete and the wet-dry cycling performance of sulfate resistance are more obvious,but the frost resistance of concrete with high water/binder ratio is limited.The axial compressive strength of polyvinyl alcohol fiber reinforced concrete rises with the increase of temperature and then decreases gradually.The critical point corresponding to the inflection point of strength is between 200? and 400?,and the mix of polyvinyl alcohol fiber can make the high temperature performance of concrete enhanced.The change of the acoustic emission energy count rate of concrete after high temperature is roughly divided into four stages:compaction,linear elasticity,plasticity and damage.The polyvinyl alcohol fiber concrete has a wider energy count rate distribution than the reference concrete.The peak energy count rate is relatively small,and the cumulative energy count is higher than the reference concrete.The mix of polyvinyl alcohol fibers improves the ductility of the concrete after high temperatures.