Structural And Mechanical Properties Of Carbon Fibers Mesh Reinforced Cement Matrix Composites

Carbon fiber mesh has been widely concerned by researchers due to its excellent mechanical properties and unique physical properties.The outstanding advantages of high tensile strength and elastic modulus,excellent corrosion resistance and two-way force make it an ideal reinforcement phase for composite materials in the field of cement-based reinforced composite engineering repair and reinforcement especially.However,carbon fiber mesh reinforced cement matrix composite materials(CMCCs)still have the unavoidable problems such as low interface bond strength between carbon fiber mesh and cement matrix at present.Therefore,exploring new ways of interface modification to break through the prior technology is of great significance for obtaining cement matrix composites with excellent comprehensive mechanical properties.In this paper,the high-performance CMCCs were successfully prepared by surface modification process.Firstly,the surface of the carbon fiber mesh was modified by epoxy resin and silane coupling agent(SCA),which enhanced the chemical activity of the surface of the composite.Then,hydroxymethyl cellulose(HMC)was added to the polymer mortar to enhance the wettability between the cement and the modified carbon fiber fabric.It made that the uniform transfer of the internal load of the mortar matrix was effectively promoted.The effects of coating on the surface morphology and chemical activity of carbon fiber mesh before and after treatment were studied.The effects of HMC on cement matrix and interface bond strength were investigated.The flexural behavior of carbon fiber mesh on concrete beams and the impact of the load transfer mechanism at the interface were discussed.The purpose of this study was to ensure that the final interface optimization.Meanwhile,internal optimization of the reinforcement system was achieved.The results showed that the longitudinal shear strength of the composite with SCA and HMC increased by 28.2% and 53.9%,respectively,compared with the composite prepared by the carbon fiber mesh treated with epoxy resin.The failure model and synergistic enhancement mechanism of the interfacial bonding properties of composites were discussed.The experimental results of composite material flexure showed that the best reinforcement parameters for the flexural behavior of carbon fiber mesh reinforced concrete beam were obtained: the optimal reinforcement position of the carbon fiber mesh was the bottom of the concrete beam;the optimal reinforcement layer was one layer;the end anchoring could effectively suppress the generation of the end crack,which strengthened the flexural behavior of the concrete beam.Compared with the sample of composite without carbon fiber mesh reinforcement,the bending resistance of the sample strengthened by the single carbon fiber mesh layer on the bottom of concrete beam was improved by 174.6%.Compared with the sample strengthened by the double carbon fiber mesh layers on the bottom and middle of concrete beam,the bending resistance of the sample with end anchoring was increased by 28.3%.The interface optimization method of carbon fiber mesh reinforced cement-based composites proposed in this study has passed the mid-term trial production verification.It also has been successfully applied in actual reinforcement projects,which had brought considerable economic benefits to enterprises.It was awarded “International Advanced” in the appraisal of the results organized by the Science and Technology Achievement Transformation Center of Tianjin Science and Technology Commission.The scheme provided in this study had guiding significance for the industrialization and practical application of carbon fiber composite reinforcement materials.