Study On The Durability Of CFRP Reinforced Concrete Structure Under Chloride Environment

Carbon fiber reinforced polymer (CFRP) is widely used in building, bridge repairand reinforcement of concrete structures, Due to its light weight, high strength, simpleand quick construction, small impact on the original structure, good corrosion resistance,good fatigue resistance performance, and widely application. The durability of theReinforced concrete structure is starting to be more widely appreciated. Due to the longsuffering of seawater (or salt) and deicing salt erosion to CFRP reinforced concretestructure, the reinforcement effect may be affected to a certain extent even damage inChina’s coastal regions and the northern cold areas. This dissertation aims to furtherstudy on the durability of the concrete structure strengthened with CFRP under chlorideenvironment, including the interfacial bonding performance of CFRPsheet, concrete, CFRP-concrete and the whole bending durability of concrete beamsreinforced by CFRP under chloride environment, providing experimental basisand theoretical reference for the practical engineering. The main research workincludes the following aspects:(1) Carrying out the longitudinal tensile performance test of CFRP sheet underchloride environment, studying on the influence on the durability of CFRP erosion ofchloride. The results show that: the chlorine salt erosion have little effect on the elasticmodulus CFRP, but tensile strength and elongation decrease slightly; After the erosion,the stress-strain curve of CFRP sheet is still linear under the action of load, showinggood linear elastic characteristics.(2) Through the double shear test, studying on the interfacial bonding performanceof CFRP-concrete under the chlorine salt erosion. Through the analysis of test-pieces’failure pattern, bearing capacity, the end slip and the shear stress distribution etc. beforeand after chloride erosion, discussing on the influence and interaction mechanism on theinterfacial properties of CFRP-concrete under chlorine salt erosion. The results showthat: the results show that: when the number of chlorine salt erosion days is less, theinterfacial bonding performance of CFRP-concrete changes little, or even slightly increased; when reaches a certain number of times, the interfacial bondingperformance decreased rapidly, with the changing of failure pattern, decreasing ofbearing capacity and the end slip.(3) By the four point bending test of reinforced concrete beam, studying on effectof the overall performance of strengthening concrete beams reinforced by CFRP underthe chlorine salt erosion. The results show that: Chlorine salt erosion will change thefailure mode of concrete beam, reducing the ultimate load and the maximum deflectionof mid-span and Influencing the development of steel and CFRP strain to a certainextent.