Concrete can be susceptible to expansive reactions between alkalis in the Portland cement and reactive forms of silica in the aggregates, which can ultimately reduce the lifespan of the concrete used in pavements and other structures. When this occurs, it can result resulting in costly repairs or even replacement of infrastructure. While alkali-silica reactivity (ASR) has been documented as an issue in many states, little work has been conducted to determine the presence/potential of ASR in Montana. The primary objectives of the proposed research are to evaluate the potential for ASR in the state of Montana, and to develop a testing protocol for identifying potential reactive aggregates. This research will also identify/document existing ASR damage in the state and investigate the potential underlying geological features that may contribute to the presence of reactive aggregates. Finally, this research will evaluate potential techniques used to mitigate the damaging effects of ASR.

This research will provide MDT with a better understanding of reactive aggregates (including severity) and a better understanding of potential ASR issues in the state of Montana. This information will be helpful in promoting sustainability and extending the service life of Montana concrete pavements and structures.