Parametric study and alkali–silica reactivity-induced expansion model of ASTM C 1260

ASTM C 1260 (accelerated mortar bar test (AMBT)) is the most popular and time-effective method to evaluate the alkali–silica reactivity of an aggregate. In this study, the test specimens (mortar bars) of AMBT were prepared with six aggregate groups having six different rock mineralogies (limestone, dolomite, andesite, dacite, basalt and dolomitic limestone) and three dosages of cement alkalis (0·42, 0·84 and 1·26% equivalent sodium oxide (Na₂O_eq)). The bars were immersed in the three strengths (1·0, 0·5 and 0·25 N) of sodium hydroxide (NaOH) solution at 80°C and were tested for changes in length for the test duration of 98 d. This experimental study and analytical approach were used to (a) investigate the three factors of solution concentration, cement alkali and test duration of ABMT on mortar expansion, and (b) propose a model in predicting mortar expansion of each aggregate group. The study showed that the alkali solution contributed significantly to mortar expansion, followed by test duration, and then followed by cement alkali. The predicted mortar expansion evaluated by the proposed models showed a very good agreement with that obtained by the experimental procedure.