| Polyvinyl alcohol fiber (PVA) is a kind of ideal environmental protection cement reinforced materials, good dispersion, easy construction, and cement has good compatibility. And it can be improved its durability, crack resistance and toughness in concrete composite, It has a wide range of applications in civil engineering structure now. Different kinds of external factors such as salt corrosion, temperature change and mechanical vibration can be caused internal damage and concrete material performance degradation significantly, and shorten the service life. Therefore, the research and analysis of characteristics and master concrete structure state are very necessary for PVA fiber-reinforced concrete material. This paper put forward by use of the acoustic emission monitoring the damage evolution process. In this paper, the work for study is carried out as follows:First, Realistic Failure Process Analysis (RFPA-2D) software is developed by Chunan Tang professor's group. RFPA software is used to simulate the process of gradual damage of cement mortar material. Numerical model of concrete material in three-point bending load conditions is established, and then analyze the influence of flexural strength and toughness using qualitative results of numerical analysis of concrete PVA fiber. Furthermore, numerical model of cement mortar is used to analyze the action of PVA fiber in the frost resistance and cement resistance crack under thermal effect.Second, failure mechanism of injury for the mixed with polyvinyl alcohol (PVA) fiber concrete samples is researched through to three point bending test by acoustic emission monitoring. Through the three point bending test, strengths for uncorroded and corroded PVA fiber-reinforced concrete are obtained. Based on acoustic emission signal characteristics during the loading process, according to the acoustic emission amplitude, count and energy related figure, and through comparison for corrosion PVA fiber reinforced concrete acoustic emission signal, the flexural strength decline reason and damage mechanism for corroded PVA fiber-reinforced concrete is revealed. Qualitative evaluation of PVA fiber-reinforced concrete samples damage is cumulated by using NDIS-2421 quantitative evaluation standard, clearance index, Kurtosis index, b-value index. The function of uncorroded and corroded PVA fiber-reinforced concrete is analyzed. It is found that PVA fiber-reinforced concrete bending damage obviously divided into three stages and uncorroded PVA fiber-reinforced concrete specimens of clearance value is more homogeneous. Finally, damage evolution mechanism is studied through to temperature fatigue test by acoustic emission for the cement mortar specimen mixed with polyvinyl alcohol (PVA) fiber. Through the temperature fatigue test, real-time acoustic emission monitoring data of PVA fiber-reinforced cement mortar specimen is obtained. Based on the test of the acoustic emission characteristic signal process, according to the acoustic emission signal related figure, and through comparing the different proportion of PVA fiber cement grinding acoustic emission signal, the damage evolution process of PVA fiber-reinforced cement mortar is revealed. Using clearance index analysis acoustic emission signal of cement mortar, and the damage degree of qualitative evaluation is made. Otherwise, through calculation Kurtosis index and b-value index of acoustic emission characteristic signal, it is found that temperature of fatigue damage of PVA fiber-reinforced cement mortar has three obvious stages.The research has been obtained characteristics and durability of the effects of injury for PVA fiber on cement mortar material. This paper gives acoustic emission monitoring and evaluation methods under salt fog corrosion and temperature fatigue conditions for PVA fiber-reinforced concrete damage, and provide reference for the further study of performance. The application of PVA fiber-reinforced concrete has certain directive significance. |
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