Establishment of the special curve of rebound strength detection for C55 concrete based on method of least square

Based on a lot of experiments including rebound detection and compressive behaviors in site and in door, much investigation of relations between compressive strength and rebound detection value have been done in detail by means of the method of least square under the engineering background of the Yellow River Highway Bridge in Wuzhong Municipal, Ningxia Autonomous Region, whose upper continuous box girder is built of C55 concrete. The special curve of rebound detection strength for C55 concrete has been studied in this paper according to some regression equations with two variables, which related state codes recommend. The analysis of test data shows that the obtained curve has much better correlations, and its regression formulae could be used to getting concrete strength, whose relative error of accuracy and relative standard deviation are smaller and meet clearance norms. At the same time, comparing with sampled values of rebound detection strength of bridge structures, the results between detection values in site and deduced values are very corresponding. All these conclusions show that the special curve of rebound strength detection for C55 concrete has an important reference value for detection and acceptance of the Yellow River Highway Bridge in Wuzhong.