The Influence of Mineral Additives on Aggregate Reactivity

In this article, the authors present the results of their research on assessing the effect of selected mineral additives on the alkaline reactivity of aggregates. The main objective of this research was to check whether the reactivity of aggregates that do not meet the standard requirements can be reduced. Due to the decreasing availability of crushed aggregates and the decreasing resources of sand used for cement concrete road surfaces, solutions should be sought that allow the use of lower-grade aggregates. Among the available mineral additives, dense microsilica, white microsilica, limestone flour, glass flour, basalt flour, and glass granulate were selected. Laboratory tests were carried out in accordance with the requirements for testing the alkaline reactivity of road aggregates in NaOH solution applicable in Poland. The tests included the use of mineral additives in the amounts of 10% and 20%. Based on the research conducted, it was observed that the most beneficial effect was obtained with the addition of white microsilica, for which a decrease in aggregate reactivity was observed by 76.7% for 10% of the additive and 95.8% for 20% of the content. The least beneficial effect, on the other hand, was the use of compacted microsilica, for which an increase in alkaline reactivity was observed by 9.3% for 10% of the additive and 20.9% for 20% of the additive. The research conducted shows that the alkaline reactivity of the aggregate can be reduced, due to which it is possible to use reactive aggregates for the construction of road surfaces made of cement concrete.