Effect of gibbsite in lithomargic clay on the mechanical and physical properties of limestone calcined clay cement

Cement, a non-renewable yet essential commodity in the construction industry remains the most used material despite the high CO₂ emissions associated with the production. To address this, several attempts such as pozzolans have been used to replace cementitious materials. Currently, limestone calcined clay cement (LC³) has gained prominence as a solution to ensure sustainability in the construction industry. To this end, this work investigated the effect of gibbsite in lithomargic clay on the physical and mechanical properties of LC³. The gibbsite and kaolinite fractions in lithomargic clay were separated using the 90 µm mesh. Geotechnical analysis was performed on <90 µm clay to ascertain its suitability as supplementary cementitious material and further calcined at 800°C for 1 h. Paste cubes were produced from LC³ and cured at 7, 14, and 28 days. The compressive strength results for all gibbsite-containing formulations after 28 days were above 20 MPa; thus, can be classified as type M masonry cement. Furthermore, the density of LC³ cubes, which has a relationship with compressive strength was seen to increase as curing age increased, thus corresponding to an increase in compressive strength, which has the potential to enhance the resistance of LC³ paste cube specimens to harsh environmental conditions.