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

Abstract

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.