Detecting the damage of concrete subjected to fatigue load coupled with freeze-thaw cycles using alternating current electric impedance spectroscopy

Abstract

The coupled effect of fatigue load and freeze-thaw cycles may cause damage to concrete structures. This paper explores the potential of alternating current (AC) electric impedance spectroscopy (EIS) technology to characterize the micro-damage of concrete under the mentioned coupled effect. Firstly, the mass loss rate (ML) and the relative dynamic elastic modulus (RDEM) evolution were employed to evaluate damage of concrete subjected to freeze-thaw cycles coupled with fatigue load. Comparatively, the degradation was also described in terms of ACEIS. The functional correlations between impedance parameters and concrete damage under the coupled effect were identified using the maximum entropy theory. The results show that the impedance parameters, RCCP and RCP, follow a consistent three-stage trend with ML and RDEM as the number of freeze-thaw cycles and fatigue load time increase. RCCP and RCP, however, are more vulnerable to early damage and can be used to faster recognize concrete damage caused by the coupled effect. Compared to RCP, RCCP is a more stable indicator for characterizing concrete damage, as it is less affected by external factors. The relationships between impedance parameters (RCCP and RCP) and traditional indicators (ML and RDEM) at stage II can be quantified as a third-order power function.