Abstract
Abstract In the research program both longitudinal and transverse ultrasonic waves were applied to concrete specimens under uniaxial compression and tensile diametrical compression. A total of 45 concrete specimens with five (5) different mixes were loaded until failure. While load was being applied - in compression and split tension - ultrasonic pulses were recorded and velocities calculated for both shear and pressure waves. The results indicate that longitudinal or transverse ultrasonic waves can be applied in the evaluation of diffuse damage (microcracking in uniaxial compression) or concentrated damage (tensile microcracking by diametrical compression) imposed on the concrete mechanically through the application of loads.
Highlights
The need to investigate the structural behavior of concrete of different strengths, growing risk of the environment’s aggressiveness, aging of structures, understanding behavior of structures throughout their working life, requirements and performance criteria of structures, all contribute to the growing demand for easy-to-apply rapid and reliable test procedures, which are able to provide qualitative and quantitative information on the performance of concrete in conditions of use
The research considered the fact that the concrete was loaded, under unconfined compression and diametrical compression, when exposed to ultrasonic waves, allowing the capture of the ultrasonic wave propagation profile with the stress level applied to the specimen, both for longitudinal and transverse waves
Diametral compression stress level velocities close to the failure load of the tested specimens. This drop in velocities shows the capacity of ultrasonic pulses to detect the formation of tensile microcracking inside the samples when applying loads and detecting microcracking caused by uniaxial compression; the test is efficient for samples undergoing tensile and compressive loads, thereby evaluating the integrity of the material
Summary
The need to investigate the structural behavior of concrete of different strengths, growing risk of the environment’s aggressiveness, aging of structures, understanding behavior of structures throughout their working life, requirements and performance criteria of structures, all contribute to the growing demand for easy-to-apply rapid and reliable test procedures, which are able to provide qualitative and quantitative information on the performance of concrete in conditions of use. The cracking and degradation process of the elastic properties of concrete subjected to unconfined compression tests by emitting longitudinal and transverse ultrasonic pulses has led to a drop in amplitude with a heavier load level which the concrete element undergoes [2]. This finding could be a valuable tool for evaluating the degree of damage to the investigated element. When evaluating the change in ultrasonic pulse velocity as a measure of the damage to structural concretes subjected to unconfined compression, a sudden drop in the pulse velocity was noted from an 85% stress level of the tensile strength. The research considered the fact that the concrete was loaded, under unconfined compression and diametrical compression, when exposed to ultrasonic waves, allowing the capture of the ultrasonic wave propagation profile with the stress level applied to the specimen, both for longitudinal and transverse waves
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