The main component forming concrete is cement, and one of the major problems in cement production worldwide is the high amount of CO2 emissions. This issue has been deemed significant to the extent that the United Nations Environment Programme (UNEP) highlighted it in their 2016 report, urging countries to consider necessary measures towards sustainable development by contemplating actions for reducing CO2 emissions. One of the proposed strategies in this report is the use of blended cement, including LC3.

In recent years, the use of calcined clays such as metakaolin (highly pure calcined clay of kaolinite) has shown promising results as a pozzolanic additive in mortar and concrete. In this research, four types of clay soils with varying kaolinite percentages from mines in Iran were collected and, after calcination and transformation into calcined clays, were utilized to produce LC3 cement. To determine the physical and chemical properties of the materials, TG, XRD, XRF, and PSD tests were conducted. Additionally, for identifying the structural shape of kaolinite-containing clay samples, Fourier-transform infrared spectroscopy (FTIR) was employed.

Finally, the produced cements were used in the preparation of mortar and concrete samples. Tests were conducted on the normal consistency of cement, cement setting time, compressive and flexural strength of mortars, concrete air content, and concrete compressive strength. The results indicate that LC3 cement samples, in general, despite having approximately 50% less clinker, exhibit comparable compressive strength to control samples in concrete specimens and higher compressive strength than control samples in mortar specimens. The influential factors affecting the mechanical properties and durability of LC3 cement-containing samples include the amount of available kaolinite, the structure's regularity and irregularity in terms of form, and the particle size distribution and specific surface area.