Evaluate Rationality Of Cement Content Of Concrete According To Carbonation Resistance And Reinforcement Corrosion

As the development of admixture technologies in concrete production, cement content inthe concrete is reduced gradually. The strength property and carbonation resistance ofconcrete is also increasingly widespread concerned. Because of existing non-standardconstruction curing, the effect of the reducing cement content on the carbonation resistance ofconcrete still needs to be further studied. Furthermore, reinforcement corrosion in concrete isrelated to the durability of concrete, whether the reducing cement content have effect on thecorrosion behavior of steel bars, and thus have effect on the durability of concrete, which isproblem that should not be neglected during energy saving, sustainable development.This thesis studied the carbonation resistance and the steel protection performance ofconcrete with different amounts of cement and different strength grade. As for partialcarbonation zone issues, a new pH indicator was used to measure the carbonation depth,which was compared with phenolphthalein. We found that concrete carbonation depth wasmuch greater than results obtained by conventional method. So our new test method fordetecting the carbonation depth provides an effective way for future awareness of concretecarbonation problem. Through open circuit potential and electrochemical impedance spectrum,we studied the changes of the steel protection property concrete with different cement content,under standard curing conditions.The results show that under dry and hot climate, the wetter curing days results in smallercarbonation depths and better carbonation resistance. To ensure concrete carbonationresistance (carbonation depth<25mm when accelerated carbonated28days), the concrete inwhich cement content is less than66%of cementing material, needs to be wet cured for atleast16days. This paper using F value to evaluate concrete carbonation resistance conform toexperimental results and theoretical analysis, can characterize the carbonation resistance moreaccurately. Electrochemical experiments showed that the concrete with fewer cement contentwhen was carbonated after3days showed poor steel protection performance. The concretewith medium cement content when was carbonated7days showed poor steel protectionperformance. The concrete without fly ash showed best steel protection performance. All theexperimental results show that under standard curing condition, the concrete with few cementcontent can just meet the strength properties, the concrete with medium cement content canjust meet the strength properties and carbonation resistance but cannot meet the steelprotection performance. If being under non-standard curing condition, the performancesrelated to concrete with inadequate cement content will be worse...