Establishment of in-situ ultrasonic-rebound strength curve for nondestructive testing of concrete structure

The ultrasonic-rebound comprehensive method is one of the most used methods for in-situ testing concrete strength, it can remedy the single test´s unperfected of the rebound method and the ultrasonic method, improve the detection precision. The in-situ strength curve of traditional method is obtained most from test blocks of the laboratory, which isn´t coincident with the practical engineering because the differences between the blocks and the architecture structure are comparatively great. Fusing the generality information provided with plenty of data in the laboratory and the personality information obtained from in-situ sample and the test blocks of the same condition, the in-situ rebound strength curve and in-situ ultrasonic strength curve is got by two-way regression method. The in-situ ultrasonic rebound strength curve which fuses both in-situ rebound strength curve and in-situ ultrasonic strength curve is given by using the theory of the maximum likelihood. It is shown from engineering practice that the strength curve of this paper can reach a higher precision than the traditional one. Moreover, this method is used not only in testing concrete strength but also in the fields.