Physicochemical properties of limestone calcined clay cement (LC³) concrete made using Saudi clays

Using calcined clays and limestone powder for clinker substitution to make a tertiary blend, known as limestone calcined clay cement (LC³), is a promising emerging technology. This study explored the viability of using local Saudi clays to prepare LC³ concrete. Two Saudi (white and yellow) and one Ukrainian (for comparison) clays were used for clinker substitution at three levels (i.e., 30%, 50% and 70%). The clay and LC³ samples were characterized using X-ray fluorescence, X-ray diffraction, and thermogravimetric analyses. Paste and concrete specimens were prepared to investigate the phase assemblage, fresh (water demand, setting time, and flowability), and hardened (compressive strength, shrinkage, and chloride ingress) properties. The results revealed that the clays contained about 53%, 30%, and 35% kaolinite, respectively. The incorporation of clays resulted in increased water demand to achieve normal consistency. The setting time of LC³ mixtures also increased, while the flowability decreased compared to the control mixture. The 28-day compressive strength was more than 28 MPa up to 50% clinker substitution. LC³ mixtures also exhibited relatively low shrinkage and high resistance to chloride ingress.