The stability of supersulphated cement (SSC) is investigated. The hydration products of cement pastes prepared at a water
cement ratio of 0.27 were determined by thermogravimetry (TG) and X-ray diffraction (XRD). Ettringite, one of the initial
hydration products, is shown to be stable under conditions of storage at 25, 50 and 75°C and when subject to relative humidities
of 100, 53 and 11% of water vapour in each case. The effect of drying on ettringite stability at the higher temperatures is
discussed in relation to the relative humidity.
The stability of Supersulphated Cement (SSC) is investigated at 95°C when subjected to relative humidities of 100, 53 and
11% of water vapour. Previously  investigations at 25, 50, 75°C under the same conditions of humidity reported the stability
of ettringite, one of the initial hydration products. At 95°C, decomposition of ettringite, is found at all humidities and
is rapid at 100% relative humidity. The hydration products of cement pastes at a water cement ratio of 0.27 were determined
by thermogravimetry (TG) and X-ray diffraction (XRD).
The formation of the hydragarnet, plazolite is recorded during the decomposition/dehydration process enhanced by possible
carbonation. Rehydration studies on the products after storage for up to 9 months were carried out using distilled water and
the samples tested for ettringite content. It is concluded that ettringite in SSC is inherently unstable at 95°C.