Influence of stress level in concrete constructions at ultrasound speed

Problem statement. Ensuring the reliable operation of buildings and structures relies on the determination of the physicomechanical characteristics of the material of their structures, which for most cases is possible only with the use of non-destructive methods of determining the physicomechanical characteristics. The reliability of non-destructive control methods is greatly influenced by the level of stress-strain state of structures, which is quite difficult to determine in the structures in use. Рurpose. To improve the accuracy of determining the physicomechanical characteristics of materials of construction, it is necessary to develop a technique that would allow to take into account the level of stress-strain state when conducting determinations in structures that are in operation. Methods. Comparison of measurements with the help of non-destructive testing methods with direct determinations of the level of stress-strain state and statistical processing of the results obtained (with visualization) was carried out using the EXEL software package. Results. Studies have confirmed the need to take into account the level of stress-strain state of the structure when assessing the strength of concrete using calibration dependencies. The difference between the ultrasound velocity in the concrete of the structure depending on the direction, in which the measurement device is located, is shown. The influence of the level of stress-strain state of the structure on the ratio of the propagation speeds of ultrasonic vibrations in concrete in two mutually perpendicular directions is determined. It is shown that for different types of concrete the nature of the dependencies does not change. Significant changes in the ratio between the results of measurements in two mutually perpendicular directions indicate the formation of structural defects of the structure. Conclusions. Studies have confirmed the effect of the stress-strain state on the results of measurements of the ultrasound velocity and allow to use the above mentioned method to determine the areas of the structure in which the formation of structural defects is possible.