Bond-slip Behavior Between GFRP Bar And High Strength PE Fiber Reinforced Seawater Sea-sand Concrete

Reinforcement corrosion is a common durability problem of buildings in coastal areas of China.In order to avoid the construction quality problems caused by the corrosion of Steel Bar,in recent years,researchers put forward the application of Fiber reinforced polymer(FRP Bars)in seawater and sea sand concrete.FRP rebar has the advantages of low weight,high strength and corrosion resistance,and the bond performance between FRP rebar and seawater sand concrete is one of the important performances of the cooperation of the two.Adding fiber into concrete can restrain the development of cracks in concrete and strengthen the bond between FRP bars and concrete.From the point of view of comprehensive utilization of high strength sea water sea-sand concrete,this paper selected Polyethylene Fiber(PE Fiber)and Glass Fiber reinforced composite plastic bars(GFRP Bars),which are widely used and have high corrosion resistance,to analyze the bond-slip behavior and the influence law of GFRP bars and high strength PE fiber reinforced sea water sea-sand concrete.By controlling the variables of sea sand and River Sand,concrete strength,PE fiber content,diameter and bond length of GFRP bars,pull-out tests were carried out,the influence of GFRP bars on the bond-slip behavior of high strength PE fiber reinforced marine sand concrete is studied,and the bond-slip constitutive model is analyzed.It provides a reference for the application of GFRP rebar and PE fiber in high strength sea water sand concrete.In the aspect of theoretical research,this paper summarizes the research status of bond action between FRP bars and concrete in recent years,compares the main design codes and bond-slip constitutive model,and collects 1413 experimental data,an experimental database of bond-slip behavior between FRP rebars and concrete(Appendix 1)is established to analyze the main factors affecting bond behavior between FRP bars and concrete.In the aspect of experimental research,96 pull-out tests were used to carry out experimental research.The main variables are: sea water sea sand concrete and fresh water river sand concrete;concrete strength grade C80,C120;PE fiber content 0%,0.5%,1%;The diameter of GFRP rebars is 6 mm,10 mm,16 mm;the bond length between GFRP rebars and concrete is 2.5,5 and 10 times.It is found that the addition of PE fiber can effectively enhance the bond performance of concrete.At the same time,the fluidity of concrete decreases obviously,which requires full stirring and vibrating.The bond strength decreases with the increase of the diameter and bond length of GFRP bars.Because the pullout failure occurs partly in the spalling of surface sand layer of GFRP bars,the increase of concrete strength has limited effect on bond strength.The influence of seawater sea-sand and fresh water river sand on the bond behavior of concrete and GFRP bars in the short term is minimal.Based on the bond mechanism and bond-slip curve,the applicability of m BPE model and CMR model in high strength PE fiber seawater sea-sand concrete is also verified.According to the experimental data,a modified CMR model for high strength PE fiber seawater sea-sand concrete is proposed.Finally,by comparing the experimental results with the existing design codes,it is found that the bond strength and anchorage length of GFRP bars are conservative in high strength PE fiber reinforced seawater sea-sand concrete.