Ultrasonic nondestructive evaluation of alkali-silica reaction damage in concrete prism samples

This paper presents a study that used ultrasonic techniques to nondestructively evaluate (NDE) the damage induced by alkali-silica reaction (ASR) in concrete. The study was conducted on concrete prism samples that contained reactive aggregates and were subjected to different ASR conditioning. The ultrasonic NDE techniques used in the study included measuring wave speed, attenuation and the amplitude of mixed wave in order to accurately calculate the acoustic nonlinearity parameter. Results of the study show that ASR damage reduces wave speed and increases the wave attenuation in concrete. However, neither wave speed nor attenuation is sensitive enough to ASR damage to be considered a good measure for the quantitative NDE of ASR damage in concrete. The acoustic nonlinearity parameter, on the other hand, shows a greater sensitivity to ASR damage, and can thus be used to nondestructively track ASR damage in concrete. However, due to the significant attenuation caused by ASR induced microcracks and scattering by the aggregates, attenuation measurements also need to be conducted in order to accurately measure the acoustic nonlinearity parameter. Finally, destructive tests were conducted to measure the compressive strength of the concrete prisms subjected to different ASR conditioning. It is found that the measured acoustic nonlinearity parameter is well-correlated with the reduction of the compressive strength induced by ASR damage.