Research The Performance Of GFRP Reinforced Concrete Columns Under Seawater

With the FRP materials widely used in Civil Engineering,Many scholars have done a lot of research and experiment on FRP materials.Starting from different loading background,load condition,corrosion environment and multiple aspects,Many valuable experiences and conclusions have been drawn.The author believes that there are some limitations in the setting of some corrosion tests,It can not reflect the influence degree of corrosion environment on the component.Therefore,begin with a new point of view and more realistic corrosion conditions,to obtain the perfoemance of FRP material after corrosion,Make FRP material more scientific and reasonable to replace the traditional engineering materials applied in actual production,it lays a theoretical foundation for FRP bars replacing steel bars to solve the corrosion problem.In this paper,the concrete reinforcing bars of two kinds of material(steel bar and GFRP bar)has been corroded for different days,the corrosion solution is NaCl weak alkaline salt solution of 30%concentration,The corrosion days were 0 days,60 days,120 days and 180 days.After corrosion of concrete reinforcing bars,12 ordinary reinforced concrete columns and 12 GFRP reinforced concrete columns were made,divided into 4 groups according to the different days of reinforcement cage corrosion,each group has 3 GFRP reinforced concrete columns and 3 ordinary reinforced concrete columns.By observing the corrosion degree after reinforcement corrosion and studying the corrosion mechanism of reinforcement body.Then obtained an empirical formula suitable for reinforcement corrosion.At the same time,according to the axial compression test results of specially made concrete columns with two different reinforcement materials,comparing the ultimate bearing capacity,column failure mode,and the changes of concrete,GFRP bars,steel bars and stirrups of corroded concrete members before and after column reinforcement corrosion.The results of this experiment show that:In the experiment of whole reinforcement cage immersion test of artificial sea water solution,with the increase of corrosion time,the corrosion of reinforcing steel is more and more serious,the ribs on the bars become blurred and the surface is covered with rust.But it is difficult to see the corrosion degree of GFRP bars from the outside.After soaking for a period of time,there is crystal precipitation on the surface of reinforced body,at the same time,the concentration of the artificially prepared sea water solution increases slightly due to the evaporation of solvent in the solution,the concentration of the solution was determined and adjusted by a variety of concentration measurements,to maintain the test concentration of the solution;In axial compression test,The reinforced concrete column has obvious yield point with the increase of load,while the GFRP reinforced concrete columns increase with the increase of load,the constitutive relation is linear until failure and no definite yield point.The failure modes of reinforced concrete columns and GFRP reinforced concrete columns are both axial compression failure.Yet the longitudinal bars of the GFRP reinforced concrete columns are broken at the failure position of the columns,and some components made a great noise when column body failure.It can be seen from the experiment results:with the increase of soaking time,the decrease of ultimate load of reinforced concrete columns increases gradually,however,the compressive ultimate load of GFRP reinforced concrete columns has little change in the early stage of corrosion,and then decreases obviously in the later stage of corrosion.By means of making the component after the reinforcement corroded,can effectively avoid strength ascension of the concrete in the solution environment due to changes in curing conditions.Compared with the direct corrosion test method for concrete specimens,the test method in this paper reflects the working state of corroded reinforcement in concrete more realistically.To provide effective reference data for the prevention and repair of building corrosion problems in practical fields.Through the experimental research in this paper,it provides a realistic and reliable experimental basis for the corrosion test of GFRP reinforced concrete columns in the future,at the same time,it lays a solid theoretical foundation for the comprehensive and in-depth study of the corrosion resistance of GFRP reinforced concrete structures.