Experimental Study On Strength Measurement Curve Of High Strength Concrete By Rebound Method In Nanjing Area

In recent years,the application of high strength concrete technology in China’s civil engineering is more and more widely,in order to facilitate the promotion and application of high strength concrete technology,the state has established a unified strength measurement curve of high strength concrete rebound method,but this is for the establishment of the national scope,whether it is applicable to Nanjing area remains to be verified.Under the premise that the local testing standard of high strength concrete in our province has not been formulated,it is necessary to carry out the experimental research of testing the strength curve of high strength concrete by rebound method according to the actual situation of Nanjing area.This subject adopts the Nanjing area commonly used raw materials produce C50～C80high-strength concrete with different strength grade test block of different ages,through the determination of concrete block are two basic parameters:the rebound value and the compressive strength value,in this high strength concrete to verify the country the applicability of the unified strength curve in Nanjing area,and on the basis of the data fitting out of Nanjing area of high strength concrete strength curve.The experimental results show that the national unified strength measuring curve is not applicable in Nanjing area,and the relative standard deviation of the strength measuring curve of 4.5J and 5.5J high strength resilience instrument is 19.3%and 18.4%,respectively,which does not meet the requirement of no more than 15%in the current code.So you need to build strength curve of Nanjing area,the new Nanjing area 4.5 J high rebound hammer and 5.5 J rebound strength curve of high-strength rebound equation respectively:f^c_cu=0.1407 and f^c_cu=2.2716,relative standard deviation of the two curves are:2.1%and 1.8%,no greater than 17%meet the norms Then through the project entity rebound-core test to verify the accuracy of the test curves,the results show that using the new Nanjing area strength curve to predict the strength of high strength concrete is feasible.This study can provide a basis for the subsequent development of the strength measurement curve of the province’s high strength concrete rebound method,and also can provide a detection basis for the early detection of problems in the project site,which has a strong practical significance for the construction quality process control and quality acceptance.