Mineral fillers are used in concrete for a number of reasons, which include achieving self-consolidation properties. Different fillers are available depending on the type of the original rock. Alkali-silica reaction might occur if the filler is produced from a reactive rock. The present research focuses on evaluating the applicability of the current accelerated mortar bar test, described in ASTM C1260 and CSA A23.2-25A, in evaluating their reactivity. Three different fillers are used: a calcium-carbonate filler, a carbonate silica filler with 27% SiO2, and a siliceous filler produced from reactive aggregate. Two different gradations of the filler obtained from reactive aggregate are tested: 1) Gradation finer than 75 µm; 2) Gradation with 30% passing 150 µm sieve but is retained on 75 µm sieve and remaining 70% passing 75 µm. Results showed that the calcium-carbonate filler and the carbonate silica filler did not show any expansion higher than the non-reactive sand, while the filler obtained from reactive aggregate did not show expansion higher than the control at 14 days for both gradations, with the expansion showing at later age. This might be due to the high surface area of fillers and the reduced permeability affecting the rate of expansion. Hence, the need to extend the testing period beyond the 14-day specified in the standard to be able to see the expansion.
Full Text (PDF)