USING ADVANCED LITHIUM TECHNOLOGY TO COMBAT ASR IN CONCRETE

Alkali-silica reaction (ASR) is a serious condition that can cause premature deterioration of structures such as concrete highways, runways, bridges, parking lots and garages. This paper examines the underlying causes of ASR and offers some viable solutions. Deterioration and expansion due to ASR is a two-step process. First, silica in the aggregate reacts with alkalis from the hydrated cement, forming a silica gel. The gel then absorbs water and swells, causing expansive pressures sufficient to crack the concrete. One way to avoid ASR is to use a non-reactive aggregate, and several tests and procedures have been developed to identify these potentially reactive aggregates. Pozzolans and mineral admixtures have been used to mitigate ASR with mixed success. Lithium-base admixtures are also a promising alternative. Lithium works by forming an alkali-silica gel that is non-expansive. Lithium is most effective when combined with pozzolans to manufacture concrete that is ASR resistant with enhanced durability. Lithium can also be applied to hardened concrete to mitigate further expansion.