Effects Of Artificial Seawater Immersion On The Long Term Properties Of Basalt And Glass Fibers Reinforced Bars

The reinforcing bar is very easy to be corroded when the reinforced concrete structures are used in the ocean engineering, resulting in the structural performance and service life degradation. Fiber reinforced composite materials reinforcement(FRP bars) is used to replace reinforcing bar with the advantages of light weight, high strength, excellent corrosion resistance, which is considered to be one of the feasible scheme to solve the problem of the long-term durability of reinforced concrete. In recent years, the long-term durability of FRP bars used in various engineering conditions has been widely concerned, and deep studies is going on. But in recent years the studies about the basalt fiber and glass fiber reinforced FRP reinforcement used in seawater are relatively less, influencing the safe and economic design and application in marine engineering.Therefore, this paper adopts a test method of heating acceleration aging. By contrast, the properties degradation of basalt fiber and glass fiber and its reinforced epoxy resin matrix composite reinforcement in simulating seawater immersion environment was studied. The research contents and main results are as following:The performance degradation and mechanism of basalt fiber and glass fiber in simulating seawater environment was studied. The results show that the strength retention rate of basalt fiber and glass fiber reduced with the soaking temperature and time increasing. The initial strength of basalt fiber was higher than that of glass fiber’, but its performance resistance to the seawater immersion was poor. The water molecules will react with the silica skeleton in the glass fiber into the silanol bonds, destroying the structure of the fiber, decreasing the fiber strength. The salt ions in seawater will also destroy the fiber structure, causing a reduction in the fiber strength.The water absorption and diffusion of basalt fiber and glass fiber reinforced FRP reinforcement (BFRP、GFRP) in sea conformed to the Fick law. The maximum absorption increased with the time and temperature increasing. Because the initial pore inside the BFRP bar was more, resulting in the water absorption is greater than GFRP bars’. Compared with the distilled water, the water absorption rate of FRP bar decreased because of the salt ions in sea.The BFRP bars were immersed in seawater solution. In the first three months, the strength was decreasing by approximately linear form, then maintained at a stable level. The GFRP bars were immersed in seawater solution at20℃,40℃for6months, the strength retention stayed above95%. But the first two months of seawater immersion at60℃, the tensile strength decreased slowly, then decreased rapidly, and the decline rate slowed down again after3months’ immersion. The final reduction of tensile strength of BFRP bars was greater than that of GFRP bars owing to the greater water absorption. The durability in seawater of the two kinds of bars was better than in distilled water’. Water molecules caused matrix resin swelling, degrading, led to the interface of fiber and resin debonding, which led to the strength decrease of FRP bars. After BFRP bars and GFRP bars were dried, the tensile strength increased in different degree, and the higher the temperature was, the smaller the degree of improvement was. The interlaminar shear strength of BFRP bars and GFRP bars in seawater bothdecreased, and the reduction of BFRP bars was more than GFRP bars’.