The hydration and strength evolution of two multi-phase ternesite-based cements with 15 and 29 wt% ternesite are reported. The synthesis and hydration properties of single phase ternesite, nominally Ca5(SiO4)2SO4, are also reported including both chemically-pure ternesite and preparations doped with sodium, potassium, phosphorous, magnesium, manganese, strontium, zinc and titanium oxides. Hydration of the samples at 25 °C was studied by calorimetry and quantitative X-ray diffraction. Unconfined compressive strength development was determined for up to 1 year. Single-phase chemically activated ternesite hydrated rapidly at 25 °C achieved compressive strengths of ≈30 and ≈65 MPa at 28 and 90 days respectively, with C-S-H and gypsum as hydration products. The multi-phase ternesite-based cements reached 7 day strengths of ≈30 MPa. It is concluded that ternesite reacts with water, exhibiting strength gain. The future of calcium sulfoaluminate and sulfosilicate cements is discussed and it is suggested that a considerable, and as yet unrealised scope exists for simultaneously optimising cementing properties while lowering production costs and reducing CO2 emissions.
Bibliographical noteThe authors would like to thank the financial support provided by the Gulf Organisation for Research and Development (GORD) through the research grant number ENG016RGG11757. The authors would like to thank Dr. Marianna Kourouzidou for all the meaningful discussions about the strength evolution of PC systems and Vassiliko Cement Works Plc that allowed me to use their equipment to obtain particle size distribution data. The authors would also like to thank Dr. Jo Duncan for insightful discussions regarding crystallography.
- Calcium sulfosilicate