Expeirmental Research On Detecting The Strength Of Cement Mortar By Pull-out Post-insert Method

Cement mortar is the most commonly used material in reinforcement of the brickmasonry walls at home and abroad. Currently there is no standard for testing thecompressive strength of cement mortar used for reinforcement in domestic. Thethickness of cement mortar used for reinforcement of the brick masonry walls isnormally25mm~35mm, it’s too thin to use the ordinary detection methods. But thePull-out Post-insert Method can meet the requirement.This thesis reports the work associated with using the Pull-out Post-insertMethod for experiment the compressive strength of cement mortar used forreinforcement of the brick masonry walls. The grade of cement mortar used in thisexperiment has M10, M15, M20, M25and M30. Based on the data of pull-out forceand cube strength of cement mortar, the pull-out force-compressive strength curve isbeen set up, and the regression equation parameters are calculated by using leastsquare method. The test results show that a good linear relationship exists between thecompressive strength of cement mortar and the pulling out post-insert force. Then, thequalities of linear regression equation of cement mortar have been examined byVariance Analysis. The significant differences for regression equation model areanalyzed by t test and F test. In addition, the credible section of regression coefficientunder95%probabilities was given. The differences about the regression equationamong cement mortar, concrete and Polyvinyl Alcohol-Engineered cement mortar arealso analyzed. At last, the destructive phenomenon of cement mortar in the test andthe failure mechanism are discussed，and the influential factors of Pull-out Post-insertMethod for detecting the compressive strength of cement mortar are analyzed. Forexample, factors such as test materials, experimental device, processing technology ofspecimen, test condition and improper operation that might affect the test results bothhave been considered.Pull-out Post-insert Method has been proved to have very high precision and itmuch cheaper and quicker than other methods. This method also was more convenientthan other methods because it requires much lighter machines and tools. It is shownthat Pull-out Post-insert Method can be an efficient and effective means in detectingthe strength of reinforcement materials, and it has optimistic outlook in detectionfields.