NONLINEAR ACOUSTICAL METHODS OF EVALUATING STRENGTH AND FRACTURE PARAMETERS OF CONCRETE

摘要

1. Although additional tests are needed for better statistical representation, presented data prove that compressive loading is one of the major sources of accumulating microcracks, affect considerably fracture parameters, and allow apply nondestructive methods for evaluating fracture parameters of concrete specimens at standard compressive tests. 2. Measuring the resonant frequency shift with an increase in the amplitude of impact loading allows assume the application of impact-echo method for predicting the strength of normal and high performance concrete in situ. 3. The phase method and equipment enabled to solve problems of evaluating strength for high performance concrete, when conventional ultrasonic and impact-echo methods, based on measuring only ultrasound velocity or resonant frequency, do not work.