Evaluation of alkali-silica reaction damage in concrete by using acoustic emission signal features and damage rating index: damage monitoring on concrete prisms

Alkali-Silica Reaction (ASR) occurs between cement alkalis and some aggregate types and causes expansion and damage in concrete. The most common and effective way to rate the severity of ASR damage in structural members is to conduct crack imaging and microstructural analysis on the core samples taken from the structures. However, it is also essential to monitor the damage with non-destructive testing methods to identify them without damaging the structure and taking necessary precautions. In this context, Acoustic Emission (AE) is of great benefit for this purpose as an effective method of monitoring active damage. The limited number of studies in the literature to assess alkali-silica reaction by AE are conducted on mortar specimens containing only reactive fine particles as aggregate under RILEM AAR-2 (80 degrees C, 1 N NaOH) test conditions. In this regard, this paper includes findings of a study in which progress of cracking due to ASR damage monitored by AE during fourteen weeks under RILEM AAR-4 (60 degrees C, over water in sealed containers) conditions, which allows testing combinations of fine and coarse aggregates. In addition to AE monitoring during the exposure period, expansion and damage rating index (DRI) were determined at different time intervals. This study was further from the existing studies in the literature; DRI identified the type and extent of cracking in either cement paste or aggregate, and AE parameters such as amplitude, energy, duration, and count were associated with the data obtained by DRI analysis. Besides, correlations between expansion, non-destructive and microstructural results were analyzed.

Automated summary

This study monitored the progress of cracking due to alkali-silica reaction (ASR) using Acoustic Emission (AE) technology for 14 weeks under RILEM AAR-4 test conditions. In addition to AE monitoring during the exposure period, expansion and damage rating index (DRI) were determined at different time intervals. The study showed that DRI could identify the type and extent of cracking in either cement paste or aggregate, while AE parameters were associated with the data obtained by DRI analysis.