Standard Research On Field Test Of Compressive Strength Of Cement Mortar By Pull Out Method

Taking the steel mesh cement mortar to reinforce bearing wall or brick column is a widely used method in masonry structure reinforcement engineering. The strength of the cement mortar thin layer directly embodies the reinforcement effect of this method.In industry, there has neither field test method or technical means which is aimed specially at compressive strength of cement mortar layer, nor the corresponding technical specifications or standards.By inspecting the reinforced wall with cast-install and post-install pullout method in actual project site, this thesis analyzs the feasibility of testing compressive strength of cement mortar layer by pullout method. Reinforcement materials of field test used cement mortar the strength grade of which includes M10, M15, M20, M25,M30, M35, M40, M45, and M50. There are 54 cast-install pullout method groups and54 post-install pullout method groups are set. Using the least square method to linearly fitting the cube compressive strength data and the corresponding pullout force,and reaching the regression formula of cast-install and post-install pullout method,testing the overall model and coefficient of the regression formula, and giving the interval estimation for individual actual strength of the cement mortar under constraint conditions.At the same time, the possible failure mode to pull out method of field test configuration is summarized. Finally, in the same experimental conditions,researcher compares not only the regression curve of cement mortar and three kinds of fiber mortar, but also the regression curve of cast-install and post-install pullout method, in order to contrast the differences and correlation between various regression curves.In this thesis, innovative improvements were proposed on the test device of field detection of pullout method, detection is conducted at the scene of the actual engineering conditions, and operation procedure of pullout method under the scene of test conditions is detailed.In this thesis, conditions and factors such as test device, processing technology of specimen, test environment, instrument operation method, the cement mortar layer thickness, distance from the center of measuring point to steel mesh have been determined, it can accurately reflect the change law of pullout force with different strength grade of cement mortar layer, in order to establish the measured curve.Pullout method is an accurate, convenient and economy field detection technique.The research content in this thesis stipulated the operation process and test content of the field test, expanded the application scope of pull-out method on testing compressive strength of cement mortar layer.The research results can provide important basis for the establishment of relevant technical standards, it will obtain a wide range of social benefits.