Belitic calcium sulfoaluminate as mineral admixture in limestone-calcined clay cement and low carbon dioxide binders

This study investigates blending belitic calcium sulfoaluminate (BCSA) cement with Portland limestone cement (PLC) and calcined clay (CC). Two blends, PLC-BCSA and PLC-BCSA-CC, were tested using different proportions of BCSA cement, PLC and calcined clay (CC). Workability was assessed using a flow test, and mechanical properties were evaluated through compressive strength and shrinkage tests. The hydration process was analysed using thermogravimetric analysis, scanning electron microscopy and X-ray diffraction. The global warming potential (GWP) of the blends was calculated, and the ‘carbon intensity’ was estimated as carbon dioxide (CO2) equivalent per unit of compressive strength, a first for BCSA and BCSA blends. Although the PLC-BCSA and PLC-BCSA-CC blends showed slower strength development compared to BCSA, they achieved similar compressive strengths at 28 days while improving the early-age compressive strength of PLC and limestone-calcined clay cement. BCSA blends can significantly reduce carbon dioxide intensity, highlighting their potential as more sustainable concrete alternatives.