Comparing belite-rich and calcium sulfoaluminate cements: physico-mechanical properties

This study focuses on the development of two alternative cements by using respectively kaolin and bauxite as main alumina sources to produce belite-rich (CSAB) and calcium sulfoaluminate (CSA) cements. So, two types of clinkers were prepared, mixed with 15 wt.% of distilled water, pressed at 2 MPa, oven-dried at 105°C for 24 h, thermally treated at 1200°C for 4 h with a holding time of 60 min and cooling. The as-obtained clinkers were milled again and mixed together with 15 wt.% of gypsum to produce CSA and CSAB cements. The samples were characterised by X-ray fluorescence, X-ray diffraction and environmental scanning electron microscopy analyses as well as physico-mechanical tests. The results showed that CSAB cement promotes the formation of belite as the main crystalline phase whereas CSA cement instead promotes the formation of ye’elimite. Furthermore, CSAB specimens were endowed with long setting times (68–91 min) compared to those obtained for CSA ones (12.5–22 min). After 28 days of curing in water, CSAB specimens exhibited a homogeneous features with lower performance compared to those of CSA ones. These CSA cements endowed with enhanced physico-mechanical properties can be suitably used as sustainable cements for the production of mortars and concretes employed in several industrial applications.