Research On The Technique Of Quick Reinforced Short Concrete Columns With CFRP Under Cold Environment

The lifeline engineering is one of the most important infrastructures. In every disaster, once it’sdestroyed, the entire social life will be seriously affected. Xinjiang belongs to the earthquakeprone areas. Inrecent years, due to the seismic activity and regional earthquakes in xinjiang, the lifeline engineeringsystem and other public infrastructure have damaged in different degrees, they also caused huge economicloss. Concrete structures strengthened with carbon fiber reinforced plastic (hereinafter referred to as theCFRP) is a new, efficient and practical retrofit method in the field of civil engineering. Because of theconstruction environment temperature requirements, its application in low temperature is limited. Based onthe above issues, this article talks about experiments of the short palin concrete columns and shortreinforced concrete columns strengthened by CFRP with E-51/CAPCURE WR-6/DMP-30at lowtemperature levels, researching both the feasibility of fast curing EP and gelation time, and thestrengthening effect. With the comparing between axial compression of strengthened test pieces andordinary test pieces, this article also reasearches and analysises the fracture morphology, mechanicalproperty, etc. The technology of fasting repair and reinforce concrete structure construction at lowtemperature is discussed in the end of the paper. The major contents and conclusions are as follow:(1) The experimental results of pasting CFRP at the temperature levels of15(±3)℃,-15(±3)℃,-25(±3)℃show that using the epoxy resin curing system as above can achieved the purpose of fast curingepoxy resin at low outdoor temperature levels. Compared with other systems of normal or low temperaturelevels, the time of curing is shorter and the performance is more excellent.(2) Experiments of axial compressive strength which is conducted at the temperature level of20(±2)℃show when test pieces strengthening with CFRP sheets, the compressive strength of short plain concertecolumns and short reinforced concrete columns have improved to different degrees.(3) The specimens strengthened with CFRP, bearing capacity and ductility of which improvessignificantly, and provides significant improvements in deformation performance. Trends can be seen asthat the bearing capacity reduced as temperature decreases, and increased with the incressing of CFRPdosage.(4) For the specimens strengthened with CFRP, after the stress exceeds the stress, the stress may risesslowly and modestly, or maintians modestly, or it will drops down slowly thanks to stress developmentcomes from the constaint ability provide by CFRP on this situations. The axial strain will increase rapidlyas approaching the ruins of test pieces and the trends will end up with the rupture of the CFRP sheetssuddenly.(5) The low temperature will make the brittleness feature of EP exposed clearly, which affects thebonding performance of structural adhesive, but the influence will reduce after the temperature dropped toa certain degree. What’s more, the crease in the amount of CFRP can resist the negative impact oftemperature on the reinforcement effect to a certain extent.(6) Catalyst will improve structural adhesive curing rate, shorten curing time at large scale, but theaddition should be controled strictly according to the constrauction environment for the warranty ofeffective operation time and the quality and properties of structural adhesive.(7) Suggestions that selection of structural adhesive curing methods at low temperature and thereasonable ways of improving its performance are drawn. A simple state is elagorated for the reinforcementengineering of CFRP at low temperature level and the suggestive improvements of reinforcement projects’quality control and acceptance standard are proposed.