Hydration and strength development of low-clinker (<50 %) factor limestone calcined clay cements (LC3): A comparative study with natural pozzolans

This study investigates the hydration kinetics and strength development of low-clinker (50–35–25 %) limestone calcined clay cements (LC 3 ) in comparison with Portland pozzolanic cements (PPC) incorporating natural pozzolans (NP). Using a combination of experimental analysis and thermodynamic modeling, the study examines phase assemblage evolution, sulfate requirements, and strength/porosity development. Results indicate that LC 3 cements exhibit enhanced hydration kinetics, increased precipitation of carboaluminates, and superior porosity reduction compared to PPC, owing to the higher reactivity and alumina content of calcined clays. This leads to a phase assemblage that yields a higher volume of solids at comparable degrees of reaction. The improved phase development enables additional clinker savings of 40–46 % while maintaining strength performance within PPC standard requirements. These findings highlight LC3 as a viable low-carbon alternative, particularly in markets where PPC is commonly used, offering significant CO₂ reduction potential while ensuring adequate mechanical performance. • Calcined clay reactivity enables additional reductions of clinker content as compared to NP. . • The higher alumina content in metakaolin yields a larger volume of hydrates than NP at equal degrees of reaction. • Replacing NP with calcined clays enables clinker reductions of up to 40–46 %. • Sulfate requirement is directly proportional to clinker factor in LC 3 formulations.