Time shift method, a new method for early detecting alkali-silica reaction (ASR) damages in concrete structures

摘要

While a wide variety of methods are available to detect Alkali-Silica Reaction (ASR) damages, recent studies have indicated that nonlinear acoustic techniques appear to be promising for the detection and characterization of early cracks and/or micro-cracks produced by ASR in structural concrete elements. A new method based on nonlinear acoustics, which has been validated in the laboratory, has been developed for the characterization of damages associated with ASR in concrete structures. This method consists in quantifying the influence of an external mechanical disturbance on the propagation of an ultrasonic wave in a solid medium. This paper presents a laboratory test set-up involving three large reactive and nonreactive concrete slabs used to study the nonlinear behaviour of concrete using the recently proposed method. Experimental test results show that this method is suitable for recognizing the ASR damages at early stages.