Experimental investigation of the lithium transport mechanisms in cementitious materials by NMR

Lithium hydroxide can help to reduce and control the expansion of concrete caused by Alkalisilica reaction. In new concrete structures the lithium ions can be introduced as admixture to prevent ASR deleterious expansion. In existing structures the lithium ions need to be transported into the cementitious matrix by diffusion or electromigration. In this study, NMR was applied to study lithium ion diffusion and electromigration in mortar sample. Lithium concentration profiles were measured at different times after treatments. The effective lithium diffusion coefficient was calculated using experimental data. After electromigration the concentration of ions within the specimen were analysed using an ion chromatograph (IC). The results of the present study show that NMR able to determine the lithium concentration and distribution in the pore solution in the mortar sample. The measurement technique is relatively quick and non-destructive. This capacity to define the distribution of lithium in the cement or concrete sample is suitable technique for monitoring the movement of lithium concentration within sample.