Assessment of Plain and Glass Fiber-Reinforced Concrete Under Impact Loading: A New Approach via Ultrasound Evaluation

Abstract

Impact loading leads to micro-crack formation that can compromise the performance of the concrete. The purpose of this paper is to evaluate plain concrete and fiber-reinforced concrete specimens using ultrasound methods under impact loading. These specimens were prepared and subjected to impact loading. Ultrasound tests were performed at different stages of impact loading on each specimen. The loading continued until cracks on the surface of the specimens were observed. Investigations were performed for both plain concrete and fiber-reinforced concrete to establish a correlation between ultrasound response characteristics, and the damage caused by impact loading due to the energy of blows transferred to the specimens. Analysis of signal records was based on the Fourier spectrum of signals and higher order harmonics. These investigations on the records improved the detection of damage on concrete, specifically micro-cracks. It was indicated that damage caused by impact loading deviates the predominant frequencies of diffused ultrasound waves from the excitation frequency. Finally, a new method was developed for detecting damage such as micro-cracks in concrete. The method was verified by using another impact mechanism for other specimens.