Industrial-scale rotary kiln calcination of non-kaolinitic low-grade clays for LC 3 production

Abstract

While kaolinitic clay is central to Limestone Calcined Clay Cement (LC3), its uneven global distribution limits scalability and presents sustainability challenges, necessitating the need for alternative sources such as common low-grade clays. This study presents the LC3 investigation using a common non-kaolinitic low-grade clay (NKLC) from mine tailings (MT) deposits calcined in an industrial-scale rotary kiln. NKLC was calcined in a rotary kiln and compared with laboratory-scale muffle furnace calcination. A hybrid grinding approach based on the differing hardness of NKLC, limestone and gypsum was developed to optimize particle size distribution and blend uniformity. Comprehensive material characterization was performed and LC3 blends were benchmarked against a clinker-rich (85%) reference CEM II/A-LL 42.5 R (Ref/CEM II). Engineering tests confirmed that LC3 with industrially calcined NKLC met Ref/CEM II performance requirements. LCA results showed up to 32% lower global warming potential in the binder phase, demonstrating NKLC’s viability as a scalable low-carbon alternative.