Research On The Performance Of Mechanics And Deformation Of Concrete With PVA Fiber

In recent years, fiber concrete becomes more and more important in research and application of modified concrete. At present, the steel fiber, polypropylene fiber and nylon fiber are widely used in practices. The polyvinyl alcohol fiber which has high tensile strength, high elastic modulus and resistance to acid, alkali and solarization, has been used as a new reinforced material in concrete.This paper focuses on the performance of polyvinyl alcohol fiber reinforced concrete. The main contributions of this dissertation are summarized as follows:1) The workability of polyvinyl alcohol fiber concrete is studied in this paper, and the results show that the polyvinyl alcohol fiber has no negative effect in a certain range. Water-washing method is used to detect the dispersion performance of the polyvinyl alcohol fiber, and the results show that the dispersion performance is improved by new production process.2) The polyvinyl alcohol fiber in concrete can improve its'mechanical performance slightly, such as compressive, flexural and split tensile strength according to the relevant test results.3) The mechanism model of settlement shrinkage is proposed, and cracking resistance mechanism is discussed. This paper suggests that the excellent performance of polyvinyl alcohol fiber concrete is related to its'hydrophilicity. The polyvinyl alcohol fiber in concrete can decrease the settlement shrinkage value obviously if the content is not more than 0.9 kg/m~3. However, the polyvinyl alcohol fiber exceeding this dosage can not improve the value further. The plastic shrinkage cracks of concrete with 0.9 kg/m~3 polyvinyl alcohol fiber can be controlled excellently, and the amounts of them are less than that of concrete with polypropylene fiber at the same dosage. 4) The broken characteristics and the crack resistance mechanisms of PVA fiber in concrete are discussed by SEM and optical micrograph. Through experiments, it is found that dry shrinkage values of concrete can be decreased by blending PVA fiber depending on the dosage of PVA fiber in concrete. It is noted that the dry shrinkage value of concrete with PVA fiber is less than that of concrete with PP fiber in the period of 28 days. The features of two or more cracking appear when the dosages are more than 0.64kg/m~3, and the initial cracking time of PVA fiber concrete in ring test is later than that of the concretes without fiber or with PP fiber. The cracking time of concrete is delayed when the dosage of fiber in concrete increased.5) The effects of PVA fiber on the practical project of concrete were investigated at the same time.