Demonstration of microwave method for detection of alkali–silica reaction (ASR) gel in cement-based materials

Microwave methods have previously shown success in detecting changes in moisture content and binding (e.g., bound water vs. free water) in cement-based materials through extensive analysis of their reflection coefficient. Here, the novel use of microwave measurements is demonstrated to distinguish between mortars containing alkali–silica reactive (ASR) aggregate and non-reactive aggregate. The variations in measurements are linked to the production of ASR gel and its tendency to attract free water from its environment. This paper presents the analysis and results of the interaction of microwave signals with ASR gel-producing mortar samples and those without the ASR gel.