Experimental Study On Strength Curve Of Long-lived Pumped Concrete By Rebound Method

Due to its excellent working performance,concrete has been an indispensable building material since its invention and has been widely used in many kinds of buildings.So it has been a long time for delivery time of the concrete structure,in its working environment also can continue to provide design allows the strength of the structure,as well as the safety of the structure is there enough reserves continue to complete its use function,it becomes very important.Nondestructive testing cannot be used to determine the compressive strength of structural concrete over 1000 days old.Therefore,there are some errors in the detection of long-lived buildings.Therefore,some regions have developed corresponding research results,established special curves suitable for local use,and published corresponding procedures.In this paper,the imitated structure solid model is used to study the springback method for the detection of long-lived structures.This article main content is: with full size 12 long age structure model as the research object,through to the end of December,in early October and made two C20 strength grade and size of the same imitation structure entity model for actual research.In this paper,the differences between the strength of solid model in winter construction and that of non-winter application are studied.Model structure of 12 different age corresponds to the rebound value,carbonation and the rebound strength of core samples from test area are collected,and two different mixture ratio of imitated entity of C30 strength analysis structure model,verify the difference of mixture ratio has a certain influence on strength;Test the springback value,the use of energy springback and digital meter two instrument for the same strength testing is part of the surveyed area,explores the different types of hammer to strength testing instrument;The data were divided into long age,short age and whole age,and the relevant data were analyzed.Linear function,quadratic function,power function and exponential function were used to carry out regression,and the fitting function was obtained by the regression coefficient of least square method.By comparing the correlation coefficient,relative standard deviation and average relative error,the power function of the four function models has the highest degree of fitting,so it is used as the final strength curve.In this paper,the strength curves of the three age ranges of the long age are obtained by the springback method,which is applicable to the langfang area.Through the comparison and analysis of the fitting results with the uniform curve in the industry standard,the long-life strength curve obtained in this paper has higher precision.For the future to perfect the relevant national regulations applicable scope to provide important reference basis.And realize the nondestructive testing methods for ages range from 1000 days to 11 years of solid strength of pumped concrete structure detection.