The manufacture of CSA cements is more environmentally friendly than that of OPC as it releases
less CO2. This reduction depends on CSA composition and is due to three factors: i) less emissions
from decarbonation in the kilns; ii) lower clinkering temperature, consequently less fuel is needed, and
iii) it is easier to grind, implying a depletion in indirect emissions.
CSA cements are prepared by mixing the clinker with different amounts of calcium sulfate as a set
regulator. Their main performances are fast setting time (followed by a rapid hardening), good chemical
resistance and, depending on the amount of the added sulfate source they can work as
shrinkage controllers.
CSA cements present a wide range of phase assemblages, but all of them contain over 50 wt% of
ye'elimite (C4A3s) jointly with belite (C2S), tetracalcium aluminoferrite (C4AF) and other minor
components such as CA, Cs, CsH2 and so on [1]. Ye'elimite is also included (~25 wt%) in BYF (Belite-
Ye'elimite-Ferrite) or BAY (Belite-Alite-Ye'elimite) clinkers.
Ye'elimite has a sodalite type structure with general composition, M4[T6O12]X. Stoichiometric ye'elimite
crystal structure at room temperature will be described in detailed. The role of different amounts of
minor elements on the synthetic procedure and crystal structures will be also presented [2,3].
This keynote will be also focused on a revision of the effect of raw materials on the mineralogical
composition of CSA, BYF and BAY. Specifically, the role of main elements contents in the ye'elimite
formation in these systems will be described. Moreover, the effect of minor elements on the
polymorphism of both ye'elimite and belite, especially on BYF and BAY clinkers, will be presented
[4,5,6].Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Spanish MINECO and FEDER [BIA2017-82391-R] research project and I3 [IEDI-2016-0079] program
