Study On The Interface Mechanical Properties Of CFRP-concrete Under Sulfate Solution Immersion And Load Interaction

Concrete materials are widely used,concrete structure is one of the most commonly structural forms.Research on reinforcement of concrete structural is an important issue the construction industry faces.Carbon fiber reinforced polymer(CFRP)is widely used in reinforcement of concrete structures due to its advantages of high strength,high performance,light weight,durability,corrosion resistance,etc.However,the actual situation of reinforcement is directly affected by the interface durability of CFRP-concrete.In Northwest China where located inland and high altitudes areas with harsh weather have many saline and salt lakes.The rate of concrete damage is significantly higher than that in interior,the structure is heavily sulphate-degraded during service.Based on above all,the experimental study and analysis of mechanical behavior of CFRP-concrete interface under the joint action of sulfate and continuous load are carried out.The main research contents are as follows:(1)The CFRP tensile test was used to study the variation of elastic modulus,elongation and tensile strength of CFRP under the joint action of sulfate and continuous loading.The results show that CFRP has little effect on sulfate and loading.In practical applications,it can still be regarded as a stable material that can adapt to the sulphate and load-carrying coupling environment.(2)The effect of continuous soaking of sodium sulphate solution on the strength of concrete was investigated by the concrete strength test.The results show that the strength in the water has increased,and the strength in the sulfate environment has increased first and then decreased significantly.(3)The CFRP-concrete double shear test was used to study the change of the interface mechanical properties of CFRP-concrete under the joint action of sulfate and continuous loading.The distribution law of the interface strain and the stress distribution law were analyzed.The representative existing stripping bearing force model checking was collected.The test data indicates that the existing model is insufficient and proposes improvements.The experimental results show that as the immersion time of sodium sulphate solution prolongs,the initial peeling load,ultimate bearing capacity,ultimate end slip,the peak value of bond stress and the corresponding slippage of the specimens all show a downward trend,and the loading effect will increase the interface.Physical damage,increase the degree of decline,the higher the level of holding the more obvious.