Bonding Behavior Of CFRP-clay Brick Interface Study Under Sulfate And Wetting-drying Cycle

Carbon fiber reinforced polymer(CFRP)is widely used in the reinforcement and repair of existing structures because of its high strength,light weight,non-magnetic,good durability,and easy construction.Using CFRP to strengthen the masonry structure is to achieve the stress transmission between the two materials through the adhesive force in the CFRP-clay brick interface,so that the two materials combine to work together.Therefore,pros and cons of bonding performance at CFRP-clay brick interface is the key to the external CFRP reinforcement masonry structure technology.However,in actual engineering,many CFRP-reinforced masonry structures are often exposed to harsh natural environments.The durability of CFRP-clay brick interfaces in harsh natural environments directly determines the long-term mechanicalproperty of CFRP-reinforced masonry structures.Nowadays,there is not much research on the durability of the bonding performance of the CFRP-clay brick interface.In this paper,a sulfate and drying-wetting cycles accelerated erosion test is used to simulate a specific harsh natural environment.The mechanical performance parameters were experimentally studied to explore the degradation mechanism and degradation law of the bonding performance of the CFRP-clay brick interface under harsh natural environments.The main research contents and results of this article are as follows:(1)Experimenting longitudinal tensile test of CFRP sheet under the effects of sulfate and drying-wetting cycles at room temperature,and exploring the effect of the damage form,stress-strain relationship,tensile strength,elastic modulus and elongation of CFRP sheets under the action of sulfate and drying-wetting cycles.It can be known from the test results that the mechanical properties of CFRP sheet after sulfate and drying-wetting cycles was basically unchanged.(2)Based on the sulfate and drying-wetting cycle test of clay bricks,the degradation of compressive strength of clay bricks with the number of drying-wetting cycles was studied.The results show that the compressive strength of clay brick specimens increases first and then decreases with the increase of erosion times.(3)The single-shear test was used to experimentally study the interfacial adhesion properties of CFRP-clay bricks under the effects of room temperature and sulfate wet-dry cycle.Influence of mechanical properties parameters such as interfacial stress and strain distribution and effective bonding length of the interface.It is known from the test that: a)With the number of sulfate and drying-wetting cycles increasing,the interface failure form gradually changes,and it from the shear failure of the clay brick layer to the peel failure at the CFRP-clay brick interface;b)After the sulfate and drying-wetting cycles,the interface performance parameters such as the ultimate bearing capacity of the interface,the maximumstrain at the measurement point,and the maximum shear stress of the interface show an upward trend first and then a decrease with the increase of the number of drying-wetting cycles,and the rate of decline with the times of cycles increasing further.