Experimental Study On The Strength Of Cement-based Grouting-concrete Mixture By Rebound Method

With people’s increasing living standards and the needs of social development,as well as natural disasters or human factors,some existing buildings gradually can not meet the requirements of functions designed initially.At the moment,it would be too long and costly to demolish these buildings directly,therefore,local reinforcement and reconstruction are generally selected.Cement-based grouting material has been widely used in structural reinforcement projects for its advantages of high early strength,good liquidity,small shrinkage and no vibration,but its construction will face the problems of quite high cost,strength redundancy and high difficulty.Therefore,taking the mixture specimen made of grouting material and C30 ordinary concrete mixed together as the study object,mixing proportion,age and curing method of grouting material as the variables,216 standard cube test specimens of mixture,72 cubic test specimens of Class-III grouting materials and 18 standard prism test specimens were prepared for experimental study.The specific research contents and results are as follows:Rebound test and compressive strength test were conducted on 216 cube test specimens of mixture,followed by the carbonation depth test,the impact of rebound value and pressure strength of different ratios and maintenance methods were analyzed and calculated according to the development rules of strength and age.Carbonation depth experiment showed that the carbonation depth of mixture specimen was zero at 28 d,so the influence of carbonation depth does not need to be considered.Finally,according to the test data,the rebound strength curve suitable for the mixture was established,indicating that the error between the measured strength and the estimated strength is small,which can meet the specification requirements.Compressive strength test was conducted on 72 cubic test specimens of Class-III grouting materials,and the results were compared with the strength of the mixture.Economic analysis showed that the strength of the mixture could meet the actual reinforcement needs and the cost was greatly reduced compared with the grouting material,which has practical value.Six standard prism test specimens were prepared for the axial compressive strength test and the elastic modulus test.The conversion formula of the mixture cube compressive strength was then established.Through the analysis of the test results,the elastic modulus of the mixture specimen is lower than that of the concrete with the same strength.