Analysis of Acoustic Emission Signals Recorded during Freeze-Thaw Cycling of Concrete

Abstract

This manuscript deals with a complex analysis of acoustic emission signals that were recorded during freeze-thaw cycles in test specimens produced from air-entrained concrete. An assessment of the resistance of concrete to the effects of freezing and thawing was conducted on the basis of a signal analysis. Since the experiment simulated testing of concrete in a structure, a concrete block with the height of 2.4 m and width of 1.8 m was produced to represent a real structure. When the age of the concrete was two months, samples were obtained from the block by core drilling and were subsequently used to produce test specimens. Testing of freeze-thaw resistance of concrete employed both destructive and non-destructive methods including the measurement of acoustic emission, which took place directly during the freeze-thaw cycles. The recorded acoustic emission signals were then meticulously analysed. The aim of the conducted experiments was to verify whether measurement using the acoustic emission method during Freeze-thaw (F-T) cycles are more sensitive to the degree of damage of concrete than the more commonly employed construction testing methods. The results clearly demonstrate that the acoustic emission method can reveal changes (e.g., minor cracks) in the internal structure of concrete, unlike other commonly used methods. The analysis of the acoustic emission signals using a fast Fourier transform revealed a significant shift of the dominant frequency towards lower values when the concrete was subjected to freeze-thaw cycling.

Advanced Evaluation of the Freeze–Thaw Damage of Concrete Based on the Fracture Tests

“…The first is the F–T action, which proceeds continuously, and the second one is the fracture test performed after a selected number of F–T cycles. Considering that the F–T cycles act as a continuous loading and unloading process, failure occurs due to the progressive damage of the internal structure of concrete, which is reflected in a decrease in the acoustic signal amplitude or a shifting of the dominant frequency, as reported in [ 40 ]. This irreversible damage is then reflected in the AE parameters recorded during the fracture tests.…”

Testing of Materials and Elements in Civil Engineering

“…The paper by [ 57 ] deals with a complex analysis of acoustic emission signals that were recorded during freeze-thaw cycles in test specimens produced from air-entrained concrete. An assessment of the resistance of concrete to the effects of freezing and thawing was conducted on the basis of signal analysis.…”

“…The results clearly demonstrate that the acoustic emission method can reveal changes (e.g., minor cracks) in the internal structure of concrete, unlike other commonly used methods. The analysis of the acoustic emission signals using a fast Fourier transform revealed a significant shift of the dominant frequency toward lower values when the concrete was subjected to freeze-thaw cycling [ 57 ].…”

Assessment of Degradation Index in Freeze-Thaw Damaged Concrete Using Multi-Channel Contactless Ultrasound

“…The results confirmed that the method based on the nonlinearity of ultrasonic waves was able to more sensitively detect damage resulting from freeze-thaw cycles compared to methods using the relative dynamic elastic modulus or rebound hardness. Topoláˇr et al [19] applied the AE (acoustic emission) method to freeze-thaw cycle monitoring and measured dynamic modulus of elasticity to compare the results. The relative dynamic modulus of elasticity did not show a significant change according to the freeze-thaw cycle with a maximum decrease rate of 3 %.…”