Experimental Study On Strength Curve Of Concrete Compressive Strength Based On Pull-off Method

In recent years,with the development of the civil engineering industry,the form of building structures has become more diversified,and the application of concrete materials has become more and more widely.At the same time,the industry has paid more attention to the quality inspection of concrete engineering.At present,in actual engineering,there are many types of concrete component strength testing technologies.The testing methods mainly include non-destructive and non-destructive testing,and several currently used testing technologies have certain limitations in engineering testing.The characteristics and limitations of these testing technologies have been proposed in recent years.A new testing technology,pull-off method,has been established to test the compressive strength of concrete.A unified national strength curve has been established.However,due to the differences in raw materials across the country,errors may occur in the strength estimation using the unified strength curve.The situation is relatively large,so it is necessary to carry out the study of regional strength curve in combination with the actual situation in the region.This subject consults and summarizes the influencing factors of the pull-off strength test in domestic and foreign literatures,conducts some influencing factor tests,and analyzes the influence of different factors on the pull-off strength value;selecting concrete materials,mix ratios,and the production process of concrete is to make concrete test blocks.For this test,the design strength level of concrete test blocks is C15 ~ C80,the size of concrete test blocks is 150mm×150mm×150mm,and the test age is 1 ~ 360 d.The concrete samples of the same age were subjected to the pull-off test to obtain the test data,and the least square method regression and support vector machine were used for data analysis to establish the pull-off strength measurement curve(side)for the Hebei area with a design strength level of C15 ~C80,the comparison and analysis of the obtained strength curve with the existing unified curve and the established curves in other regions can be obtained: the accuracy of the strength curve obtained in this test is higher,which is more suitable for the use of the pull-off method for the strength of concrete in Hebei inference;At the same time,the support vector machine intelligent model is introduced,and some test data are trained to predict the strength,and the results are compared with traditional regression fitting.The accuracy is found to be slightly higher than the traditional regression fitting method.During the establishment process,the dataprocessing provides a new way,at the same time,the numerical simulation of the strength of the concrete by the pull-off method is carried out,and the model is established to analyze the stress distribution of the pull-out test specimen under the tensile state.Based on the experimental research,the pull-off strength measurement curve(side)suitable for Hebei area was finally established and verified.Compared with the national unified strength measurement curve in the industry standard,the accuracy of the pull-off strength measurement curve established in this paper is more it is high and provides an important basis for the establishment of the pull-off strength measurement curve in Hebei region,and provides technical support for the development of detection technology in this region.