Evaluation of electrical resistivity, hydration, and durability against sulfate attack of limestone calcined clay cement (LC3) with various kaolinite content at high-replacement levels

Abstract

Cement and concrete play a crucial role in modern global infrastructure. The broad availability and low cost of cement production are the primary reasons for its widespread use in construction, contributing to approximately 5–8 % of CO₂ emissions. Using supplementary cementitious materials (SCMs) to substitute a portion of the clinker in cement has proven to be the most effective method for curbing CO₂ emissions in the international cement industry. Limestone calcined clay cement (LC³) permits the substitution of cement with calcined clay and limestone. This study compares the properties of LC³ samples at varying levels of clinker substitution using 11 different kaolinite clays with Portland cement. The results showed that the LC³ samples with high pozzolanic reaction, even with a kaolinite content of 14.96 %, reached a better strength than Portland cement from 7 days onwards. The electrical resistivity of LC³ samples increased with the increase of clinker replacement. At 60 % clinker replacement, the electrical resistivity of LC³ samples at 28 days was between 4.1 and 20 times that of the PC sample. The expansion rate of LC³ mortar samples under sulfate attack was significantly lower than that of the PC sample. These findings suggest that increasing clinker replacement in LC³ samples leads to refined pores, enhanced electrical resistivity, and improved durability against sulfate attack.