Kaolinite characterization-driven sustainability evaluation of limestone calcined clay cement (LC3) systems

This study presents a holistic sustainability evaluation of limestone calcined clay cement (LC 3 ) binders by integrating mechanistic performance validation with activity-based CO 2 emission assessment and cost analysis, and further demonstrating their practical feasibility through a building-level application framework. The LC 3 was prepared by partially substituting 30% and 50% of conventional cement with calcined clay and limestone, yielding two blends, LC 3 -30 and LC 3 -50, respectively. Three clay types with kaolinite contents of 25%, 55%, and 65% were used to produce six LC 3 formulations, which were subsequently assessed for their technical performance, including physicochemical properties, microstructure, quantification of hydration products, and strength up to 90 days. Sustainability performance, integrating technical, environmental, and economic factors, was also evaluated for residential and commercial units constructed with different concrete grades. The study found that LC 3 -30 and LC 3 -50 achieved strengths comparable to OPC at 90 days, attributed to additional hydration products (AFt/AFm phases), as confirmed by thermogravimetric analysis (TGA) and X-ray diffraction (XRD). LC 3 also reduced CO 2 emissions by up to 40% in residential applications and 38% in commercial construction, driven by differences in concrete grades. Cost analysis showed LC 3 -based residential units were $300 cheaper, while commercial units saved $11,000 compared to OPC-based counterparts. A sustainability score further underscores LC 3 's eco-friendly and cost-effective advantages, establishing it as a practical solution for modern construction.