Experimental Study On Bonding Properties Between Steel Wire And Concrete Or Cement Slurry At Cryogenic Temperatures

The thesis is about experimental studies on bonding properties between steelwire and concrete or cement slurry at cryogenic temperatures. The project is a part ofexperimental studies on the mechanical properties of reinforced concrete at cryogenictemperatures, which is a project of National Natural Science Foundation ofChina(51078260).Testing equipments of low temperature refrigerator, liquid nitrogen ultra-lowfreezer which were designed in the earlier period and the specialized testing molds,anchorages which were designed temporarily help to finish the experimental studiessuccessfully. The detailed design of the experiment is as follows:1. The specialized testing molds were designed according to the demand of thefabricating of specimens, additionally, the appropriated anchorages were selectedaccording to the testing requirement.2. For the experimental researches of bonding properties between steel wire andconcrete: In order to analyze the bonding properties between steel wire and concreteat low and ultra-low temperature, specimens of4large groups named A, B, C, D weredesigned, which considered different parameter influences of temperature, concretestrength, relative anchorage length and relative concrete cover thickness. Selecting thetemperature of20℃,0℃,-40℃,-80℃,-120℃and-165℃, taking all parameterinfluences into account, specimens of32small groups were cast, which concluded3specimens in one group and amounted to96.3. For the experimental researches of bonding properties between steel wire andcement slurry: Considering the influence of temperature, specimens of6small groupswere fabricated, which concluded3specimens in one group and amounted to18.Some basic conclusions were obtained based on the experiment studies andanalysis, just as follows:1. The testing equipments and methods that our task group has owned cancomplete the central-pull-out test of the specimens of steel wire and concrete orcement slurry conveniently and efficiently.2. For the concrete specimens at low and ultra-low temperature: Both thecoefficient of bonding strength and the bonding strength when the slip between steelwire and concrete is1mm decrease with the increasing of relative anchorage lengthand increase with the increasing of relative concrete cover thickness. 3. For the concrete specimens At low and ultra-low temperature: both thecoefficient of ultimate bond strength and the ultimate bond strength decrease with theincreasing of relative anchorage length and increase with the increasing of relativeconcrete cover thickness.4. For the cement slurry specimens: At the temperature range of20~-120℃, theincreasing coefficient of bonding strength when the slip between steel wire andcement slurry is1mm raises with the decreasing temperature. However, the coefficienthas no significant changes at the temperature range of-120~-165℃.5. For the cement slurry specimens: the increasing coefficient of ultimate bondstrength raises with the decreasing temperature at the temperature range of20~-120℃.6. The calculation formula of bonding strength at low and ultra-low is putforward that can provide reference for the practical project.