| The Chinese construction industry has entered the phase of combining new construction with maintenance,reinforcement and reformation.The reinforcement method of pasting carbon fiber cloth has its own advantages and is widely used in the structural reinforcement.At present,epoxy organic adhesives are used for carbon fiber reinforcement,but their durability and high temperature resistance are poor,so the reinforced structural members have greater safety risks under high temperature fire.In order to improve the fire resistance of carbon fiber reinforced concrete structure,it is an important research direction to use high temperature resistant inorganic adhesive instead of epoxy organic adhesive.Based on magnesium phosphate inorganic adhesive,this thesis carried out high-temperature resistance modification of inorganic adhesive.The main research contents are as follows:1.Magnesium phosphate inorganic adhesive was modified with glass powder.The mechanical properties of magnesium phosphate inorganic adhesive were tested at 100～600℃with the content of glass powder as the key parameter.The addition of glass powder can improve the high temperature resistance of magnesium phosphate inorganic adhesive.By comparing the mechanical properties of magnesium phosphate inorganic adhesive containing0%,10% and 15% glass powder at 100～600℃,it is concluded that after high temperature resistance modification,its bending strength,compressive strength and tensile strength all show a gradual decrease trend with the increase of temperature.The decreasing range gradually decreases with the increase of temperature.At the same time,the flexural strength and tensile strength of the magnesium phosphate inorganic adhesive specimens at 600℃ were more than 50% of that at room temperature,and the compressive strength was more than 40%of that at room temperature.The magnesium phosphate inorganic adhesive with 10% glass powder replacement showed better mechanical properties in the range of 100～600℃.2.The internal shear performance test of magnesium phosphate inorganic adhesive carbon fiber cloth reinforced concrete structure at room temperature was carried out to investigate the feasibility of replacing epoxy organic adhesive to strengthen concrete structure,and to explore the effect of bond length on the internal shear performance of magnesium phosphate inorganic adhesive carbon fiber cloth reinforced concrete structure.At room temperature,the in-plane shear strength of the double-shear specimens using epoxy organic adhesive and magnesium phosphate inorganic adhesive as adhesive can reach 1.23 MPa,and the modified magnesium phosphate inorganic adhesive can replace epoxy organic adhesive to strengthen the concrete structure.As the magnesium phosphate inorganic adhesive did not fully infiltrate the carbon fiber cloth,the in-plane shear strength of the magnesium phosphate inorganic adhesive gradually decreased with the increase of bond length at room temperature.The main failure mode of the in-plane shear test was the failure of the bond layer,and few specimens were torn and peeled from the concrete base.3.The double shear test of magnesium phosphate inorganic adhesive carbon fiber cloth at100～600 ℃ was carried out to investigate the change of shear strength of magnesium phosphate inorganic adhesive carbon fiber cloth with temperature.The high temperature resistance of magnesium phosphate inorganic adhesive is obviously better than that of epoxy organic adhesive.When the temperature is 400℃,the in-plane shear strength is 0.44 MPa.When the temperature is 600℃,the shear strength of the base concrete is seriously reduced due to the deterioration of the material properties of the base concrete at high temperature,and the base concrete is torn and peeled off.After the high temperature of 100～600℃,the residual shear strength in the magnesium phosphate inorganic rubber surface shows a linear decrease trend. |
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