ASR prevention — Effect of aluminum and lithium ions on the reaction products

In spite of the recent progress in the understanding of the mechanisms enabling aluminum-containing SCM like metakaolin and added LiNO₃ to limit the extent of ASR in mortar and concrete, some gaps still remain. They concern mainly the effect of aluminum-containing SCM on the formed ASR products and the influence of aggregate characteristics on the effectiveness of LiNO₃. In this study, a model system, concrete and mortar were investigated by pore solution analysis, TGA, XRD, NMR, SEM combined with EDX and ToF-SIMS to address these questions. The amount of aluminum present in the pore solution of concrete and mortar is only able to slow down SiO₂ dissolution but not to alter morphology, structure and composition of the reaction products. LiNO₃ can suppress ASR by forming dense products protecting reactive minerals from further reaction. But its effectiveness is decreasing with increasing specific surface area of the reactive minerals in aggregates. - Highlights: • Aluminum of SCM slows down SiO₂ dissolution. • Aluminum of SCM does not alter morphology and structure of ASR product. • ASR suppressing effect of LiNO₃ depends on specific surface area of the aggregates