Performance Of Cfrp Reinforced Concrete In Deicing Salt Environment Experimental Research

Reinforced concrete structures are often used for bridge construction.Most of the bridges are severely damaged after many years of use and need to be reinforced.In the cold regions,deicing salt is used in winter.The chloride ion-containing brine will flow along the beam-slab joints and directly penetrate the bridge pier beam,the end of the beam and the abutment cap and the ear wall,causing different degrees of damage.This paper mainly studies the performance of CFRP-reinforced concrete structures under the dual action of deicing salt(chlorine)and freeze-thaw cycles,and provides some guidance and reference for practical engineering.In this paper,the CFRP sheet tensile test,CFRP-concrete double shear test and CFRP-reinforced concrete prism compression test were carried out to study the mechanical properties of carbon fiber reinforced concrete under the dual action of deicing salt erosion and freeze-thaw cycle.The curing environment of the test pieces was divided into three groups,which were freeze-thaw at normal temperature,freezing and thawing in water and chloride solution.After 25,50,75,and 100freeze-thaw cycles,the durability of CFRP sheets in chloride salt erosion and freeze-thaw environment was analyzed.The bond interface failure characteristics of CFRP-concrete double shear specimens and tensile load The law of force and strain change at different bond locations,and the variation of strength of CFRP-reinforced concrete columns.The following conclusions were obtained:1.The CFRP specimens after single freeze-thaw cycle and salt-freezing cycle have no obvious change in tensile strength and elongation.CFRP specimens have good durability in chloride salt freezing environment.2.The mechanical properties of CFRP sheets actually produced in the laboratory cannot meet the manufacturer's calibration values.This shows that the tensile properties of CFRP sheets are related to the environment and production process at the production site.When applying it to an actual project,an approach inspection is performed and construction is performed based on the test data.3.In the northern region,the use of carbon fiber cloth should be used to reinforce the beam and slab structure.(1)When the CFRP-reinforced concrete bonding interface is subjected to shearing force,the main failure mode is the concrete layer damaged on the side of the carbon fiber cloth.The decrease of concrete strength at the bonded interface caused by salt erosion is the main factor for the decrease of CFRP-concrete interface bonding performance.The degradation of rubber layer is a secondary cause.As the freeze-thaw cycle and the chloride salt erosion time increase,the destruction interface has a tendency to transfer to the rubber layer.(2)Through the calculation of the relative value change range ? of ?,after50,75,and 100 times of double-shear specimens after freezing and thawing in water,the shear bond performance decreased by 3.08% and 15.38,respectively,compared with the normal temperature curing test piece.%,30.31%.After 50,75,and 100 times of the double-shear test piece in the freeze-thaw cycle of the salt solution,the bond performance decreased by 9.23%,29.62%,and 31.15%,respectively,compared with the normal temperature curing test piece.4.The reinforcement form of CFRP-reinforced concrete columns can be promoted and used in cold areas in the north.The durability of CFRP-reinforced concrete prisms is less affected by environmental factors.This is mainly because CFRP has better durability in freeze-thaw environment and salt-free environment,and the reinforcement performance of CFRP-reinforced concrete column structure depends on the axial binding force of CFRP on the column,that is,depends on the mechanical properties of CFRP itself.