This themed issue has as its focus calcium sulfolauminate cements (C$A). These cements have long evolutionary history but have recently attracted attention because their production emits less carbon dioxide than Portland cement. Of course a successful building material has to meet many criteria but the structural use of C$A cements in China has attracted much attention. The Chinese cements rely mainly on hydration of ye'elemite, ideally 4CaO.3Al2O3.SO3, for strength gain and thus differ in mineralogy from Portland cement. Despite their structural use in China C$A cements are used elsewhere mainly in special cement formulations, for example as adhesives and in repair materials, but the feeling has been that these cements have a bright future if only certain disadvantages can be overcome.
The papers in the themes issue were presented at the International Workshop on ‘Calcium Sulfoaluminate Cements’ organised by F. Winnefeld, B. Lothenbach, A. Telesca and M. Marroccoli in 4–6 June 2018 in Murten, Switzerland, which brought together more than 100 participants. This dedicated issue incorporates six papers invited by the Organising Committee. A further three papers will appear in the next issue.
Hanein et al. (2019) describe advances in clinkering. Experiment and thermodynamic calculation were combined and the development of an alite–belite–ye'elemite clinker made in a single step is described. Pisch and Pasturel (2019) uses density function theory to determine the enthalpy of ye'elemite. Telesca et al. (2019) shows how waste materials can be incorporated in C$A clinkers. Zajac et al. (2019) show how the hydration mechanisms contribute to mechanical properties in an optimised belite–ferrite–ye'elemite paste. Cuesta et al. (2019) use synchrotron methods as a tool to characterise the poorly crystalline state of the early-formed hydration products of C$A cements. C$A cements are often used in blends with Portland cement and Bertola et al. (2019) reports on the properties of the blended pastes.
It is apparent that basic and applied work on C$A cements is proceeding at a rapid rate: significant advances are occurring in our understanding of these ‘green’ binders. As editors, it has been our pleasure to coordinate the themed issues. We thank the referees for their timeous action and the contributors for their rapid and comprehensive response.
