Test Research On Concrete Strength Survey By Rebound Method And Ultrasonic Rebound Synthetic Method In Kunming Area

Concrete is the one of important materials in construction,and especially its quality would make an immediate impact on the security of civil engineering structure.There are many damaged buildings including new,under construction,the existence and old building in Kunming district.Therefore,it is vital to detect the practical strength of concrete and provide the basic data for assessing the quality or security of engineering construction.Non-destructive methods are the widely applied in practical,specially rebound method and ultrasonic rebound synthetic method. And the two ways are as common means of supervising construction and quality.Vast engineering practice indicates the errors of unitary strengthen-measuring curves are bigger, but the derived values are lower than the measured values.To enhance the detection precision, it’s necessary to build up the specific regional strengthen-measuring curve. So this paper gathered more than ten of thousands data, involving the supersonic wave value, rebound value, and compressive strength. Analyze and deal with the measured values according to the least square method, then build the regional strengthen-measuring curve in the many forms of regression function by several analysis software.Based on the experimental results, the strengthen-measuring curves is fcuc= (0.00227Rm2+1.4978Rm-15.65)10-0.0173dm by using rebound method in Kunming district,including its average relative error δ=8.60% and relative standard deviation er=10.54%.Moreover,the strengthen-measuring curves is fcuc=0.1151vm0.635Rm13671 with ultrasonic rebound synthetic method,including including its average relative error δ=9.91%,relative standard deviation er=12.08% and the relative coefficient r=0.91.It’s worth mentioning that the above two curves meet the accuracy of the strengthen-measuring curves in JGJ/T23-2011 and CECS 02:2005.To make sure the reliability of strengthen-measuring curves, several companies have applied and verified the new strengthen-measuring curves in practice, and the results suggest that the accuracy of the regional curve is higher and it is more adaptable for the local condition, so the regional curve is fit to measure the nondestructive testing and assessment of the concrete strength in Kunming area. Moreover, it’s efficient to reducing the error of unitary strengthen-measuring curves.