Influencing Factors And Mechanism Of Bonding Between New And Old Concrete Under The Action Of New Interfacial Agents

In the repair and reinforcement of concrete structure,the enlargement section method is the most commonly used method,but because the enlargement section method is related to the bond problem of the old and new concrete,in order to enhance the bond quality of the old and new concrete,the method often used in the old concrete surface is to brush the interface agent on the old concrete.Then the new concrete is poured [1].In order to optimize a new type of interfacial agent with good bonding performance,convenient construction and moderate price,this paper selects an optimum interface agent through 11 kinds of interfacial agents,which are unbounded surface agent(without any interface agent,direct pouring),cement paste interface agent and 9 kinds of modified epoxy interfacial agents.It is used in this test.According to the experimental results of interfacial agent optimization,the mechanical properties of old and new bonded concrete are studied with the influence of the old concrete age,the strength of the old concrete,the roughness of the old concrete bond surface and the new concrete pouring method,using the unbounded surface agent,cement paste interface agent and the optimized new epoxy interfacial agent.Test and compare the bonding effect of interface agent and analyze the bonding mechanism of new and old concrete.The results show that:1.Under the influence of old concrete age,the change rules of splitting tensile strength and shear shear strength of new and old bonded concrete are more complicated.On the whole,the bonding effect of new and old concrete with new epoxy interfacial agent under the same condition is better than that of cement paste interface agent and unbounded surface agent.2.Under the influence of old concrete strength,the strength of the old and new bonded concrete increases with the increase of the strength of the old concrete.Under the same conditions,the bonding effect of new and old cemented concrete with new epoxy interfacial agent is better than the use of cement paste interface agent and unbounded surface agent.3.Under the influence of the roughness of the old concrete bond surface and the new concrete pouring method,under the same condition,the bonding effect of new and oldcemented concrete with new epoxy interfacial agent is better than the use of cement paste interface agent and unbounded surface agent.4.Through microscopic microscopic analysis of the new and old cemented concrete specimens using cement paste and new epoxy interfacial agents,it can be seen that the gap is wide,the width of the seams is about 10 m,the penetration layer has obvious gap,the strong effect layer is very dense,and the gap of the new epoxy interfacial agent is used.It is narrow and almost invisible.The permeable layer is closely linked to the effective layer and has good bond properties.