Reactive Aggregates
Reactive aggregates can be classified into naturally occurring siliceous minerals and artificially produced siliceous materials. Mineralogical composition of aggregates, their origin and texture of source rocks are considered responsible for the rate of reaction (i.e., rapid or slow) (Dolar-Mantuani, 1983; Stark, Morgan, Okamoto, & Diamond, 1993). Table 1 shows the details of reactive minerals based on ASTM C294 (standard descriptive nomenclature for constituents of natural mineral aggregates).
Researchers also investigated the use of waste clay bricks as coarse aggregates (Rashid, Hossain, & Islam, 2009). However, mortar bars incorporating clay brick aggregates showed expansion due to ASR along with presence of alkali silica gel (Bektaş, 2014). Waste glasses (commonly used as aggregates) also showed the presence of amorphous silica and resulted into formation of ASR gel, after dissolving under alkali attack (Rashad, 2014; Topçu, Boğa, & Bilir, 2008). It was found that different colors of glass showed different level of reactivity (Du & Tan, 2014; Topçu et al., 2008).