Mitigation of ASR by the use of LiNO3—Characterization of the reaction products

• Detection of lithium in ASR product by ToF-SIMS
• Relation between composition of pore solution and ASR product
• Identification of ASR suppressing mechanisms of LiNO3

The influence of the LiNO3 on the ASR product was studied both in a model system and in mortars. In the model system, the addition of LiNO3 decreases the dissolution rate and the solubility of silica. Lithium changes the 2-dimensional cross-linked (Q3 dominated) network of the ASR product into a less structured, Q2 dominated product, likely by adopting the role of calcium. In the mortar samples the addition of LiNO3 decreases expansion and significantly influences the chemical composition and the morphology of the reaction product. Lithium decreases the calcium, sodium and potassium content and changes the relatively porous plate-like reaction product into a dense one without texture. The findings in the mortars indicate that the ASR-suppressing effect of lithium is caused by the lower potential of the reaction product to swell. Furthermore, it forms a protective barrier after an initial reaction slowing down ASR.