In this research, lithium nitrite was injected into ASR-deteriorated concrete specimens made with reactive aggregates in order to suppress further deterioration. The amount of injected lithium nitrite was set to three different levels, and the subsequent expansion behavior and area of lithium permeation were investigated. The area of permeation was checked using the coloring reagent TDI. It was found that the prescribed amount of lithium cannot be injected fully into the non-deteriorated specimens. When the lithium was injected at an early stage of deterioration, the area of permeation was small and the ASR suppression effect was small regardless of the injection amount. Also, the expansion reduction effect was evident when the lithium was injected into the considerably cracked concrete
