Relating LC3 microstructure, surface resistivity and compressive strength development

Concrete surface resistivity can be measured non-destructively, providing an indirect measurement of microstructural development which can be related to strength development. However, relating surface resistivity and strength can be challenging for limestone calcined clay cements (LC 3 ) since they contain mineral components of varying composition and reactivity. In this study of LC 3 formulations, concrete surface resistivity until 56 days of hydration and mortar compressive strength at 3, 7, and 28 days were investigated to explore the relationship between these properties while examining the influence of mixture proportioning, limestone particle size and gypsum dosage on LC 3 surface resistivity and strength development. Microstructural development of these blends was also assessed by thermogravimetric analysis and formation factor. The results suggest a strong logarithmic relationship between the resistivity and strength development, which can both be predicted by the portlandite consumption. These correlations can allow prediction of later-age strength based on early-age resistivity and portlandite consumption. • Microstructural differences due to the filler effect are more evident through surface resistivity (versus strength) • Both the surface resistivity and strength development of LC 3 can be predicted by the portlandite content. • Surface resistivity and strength development of LC 3 have a strong logarithmic relationship. • C-(A)-S-H formation can produce greater increases in surface resistivity than strength because of alkali binding