Experimental Study On Non-destructive Testing Technology Of High Performance Concrete Compressive Strength

With the wide application of high performance concrete,high performance concrete becomes one of the most important engineering materials in construction engineering.There has been built and many old and damaged water conservancy facilities in Harbin,and some are under construction.the actual needs of high performance concrete strength testing,evaluation of the quality of construction projects or for water conservancy facilities safety assessment to provide basic data.The most widely used method for nondestructive testing of concrete intensity method is ultrasonic method,rebound method and ultrasonic-rebound method,all of three methods given by the "Regulations" is the unified strength-measuring curve.In engineering practice,errors using national unified strength curve for high performance concrete may be obvious,the compressive strength of high performance concrete,especially the early age compressive strength,is obviously smaller than the actual measured value in Harbin.So in order to raise the detection precision to ensure the reliability of field detection,must be suitable for the establishment of strong local use curve.This paper selects the concrete materials commonly used in Harbin area.And adding fly ash,silica fume and other admixtures and superplasticizer and other chemical additives to make cube test block.The ultrasonic value,rebound value and compressive strength value were tested according to the requirements of the rules,and more than 290 groups of data were obtained.According to the principle of least squares method,using different analysis software such as Excel,SPSS and other forms of regression fitting,improve its fitting correlation coefficient,reduce relative error and relative standard deviation.Based on the laboratory test specimens,the springback of ultrasonic testing and ultrasonic rebound strength curve of high performance concrete has been preliminarilyformed.It can solve the problem that the error of the uniform curve is large.It can be used for nondestructive testing and evaluation of the compressive strength of high performance concrete used in the construction of water conservancy in Harbin area,which has an important guiding significance for the formation of local standards and norms.