Judging method of incompactness defect in node of concrete structure by detection by ultrasonic method

The invention relates to a judging method of an incompactness defect in a node of a concrete structure by detection by an ultrasonic method. On the basis of the traditional method for detecting the concrete defect by the ultrasonic method, besides an acoustic velocity and a head wave amplitude, two variable acoustic parameters, namely a complex frequency difference and a cross-correlation coefficient, are added; each acoustic parameter is processed into an acoustic parameter judging factor and each acoustic parameter judging factor is processed into a normalized comprehensive acoustic parameter judging factor; a position detecting chromatogram is drawn out according to the comprehensive acoustic parameter judging factor; and the position and range of a suspicious defect are determined according to a red area in the chromatogram. By the method, the compactness quality distribution of concrete can be directly and accurately described; errors and judgment loss caused by adoption of a single acoustic parameter fo