Experiment On Basalt Fabric Reinforcement Polymer-fiber Reinforced Cementitious Matrix Mechanical Property Considering Temperature Effect

Basalt fabric reinforced polymer-fiber reinforced cementitious matrix(BFRP-FRCM)has characteristics such as corrosion resistance,light weight,high strength,and fatigue resistance,and is widely used in various structural reinforcement.Its mechanical properties after temperature action have begun to attract widespread attention from scholars at home and abroad.The high-temperature effect has a relatively small impact on basalt fibers,but it has a certain impact on polyvinyl alcohol fibers(PVA).Therefore,further in-depth research is needed on the temperature action mechanism of BFRP-FRCM composite layers.Basalt fabric reinforced polymer-fiber reinforced cementitious matrix(BFRP-FRCM)has characteristics such as corrosion resistance,light weight,high strength,and good fatigue resistance,and is widely used in various structural reinforcement.Its mechanical properties after high temperature have begun to attract widespread attention from scholars at home and abroad.The effect of high temperature on basalt fibers is relatively small,but it has a certain impact on polyvinyl alcohol fibers(PVA).The temperature action mechanism of the composite layer needs further in-depth research.This article took Basalt fabric reinforced polymer-fiber reinforced cementitious matrix(BFRP-FRCM)composite layer as the research object,and explored the influence of different target temperatures and mesh ratios on the uniaxial tensile and overall bending mechanical properties of BFRP-FRCM composite layer through indoor experiments,theoretical research,and other methods.Based on experimental data,a temperature strength relationship equation was established.Combining SEM scanning electron microscopy experiments,article explored the micro morphology of the composite layer at different target temperatures,established the relationship between micro macro reactions and explained the changes in the macroscopic mechanical properties of the specimen.The main research contented and conclusions were as follows:(1)A total of 160 single doped PVA fiber BFRP-FRCM composite layer specimens with different distribution mesh ratios were designed and manufactured.Conduct heating tests at different target temperatures(20 ℃,200 ℃,400 ℃,600 ℃)investigated the changes in appearance morphology and mass loss of each group of specimens with temperature.Research showed that as the temperature increased,the color of the specimen gradually deepened and then became lighter.the surface of specimens degradation gradually became severe,and cracks appeared along the grid direction,and the mass loss rate gradually increased.(2)Conducting uniaxial tensile mechanical tests on the BFRP-FRCM composite layer after high-temperature testing,the effects of distribution mesh ratios and target temperature on the tensile properties of the composite layer was explored.Research showed that under the same temperature,the tensile mechanical properties of the composite layer were improved with the increase of distribution mesh ratios,but distribution mesh ratios had no moderating effect on the attenuation of the tensile mechanical properties of the composite layer after high temperature action(3)Four point bending mechanical tests were conducted on the BFRP-FRCM composite layer after high-temperature testing to explore the effects of distribution mesh ratios and target temperature on the overall bending mechanical performance of the composite layer.Indicators such as Load-displacement curve,bending strength,maximum mid span deflection,bending stiffness,and bending toughness coefficient were analyzed.Research had shown that under the same temperature,the overall bending mechanical properties of the composite layer were improved with the increase of distribution mesh ratios.The attenuation of the tensile mechanical properties of the composite layer after high-temperature action did not slow down due to changes in the distribution rate.(4)Scanning electron microscopy experiments were conducted on the BFRP-FRCM composite layer to investigate the micro morphology changes of the specimens under different target temperatures,and to elucidate the relationship between micro-structure changes and macroscopic mechanical properties.The results showed that at room temperature and 200℃,the internal structure of BFRP-FRCM composite layer was dense,the hydration products were arranged neatly,and the bonding properties of PVA fiber、basalt fiber mesh、and substrate have good adhesion.The mechanical properties of the composite layer were significantly improved.At 400℃,the density of the substrate significantly decreased,the structure became loose,the PVA fibers completely melt,and the residual pores reduced the probability of high-temperature cracking in the composite layer.The basalt fiber mesh slightly debonded,and the mechanical properties of the composite layer decreased.At 600℃,the basalt fiber mesh severely delaminated,and the mechanical properties of the BFRP-FRCM composite layer sharply decreased.