Strätlingite formation in high-alumina cement — zeolite systems

Reaction mechanisms of strtitlingite formation in high-alumina cement (HAC)—zeolite systems were studied. A component separation method that made it possible to study individual reactions involving hydrated HAC and zeolite was employed. Different sodium salts, e.g. sodium silicate, sodium carbonate, sodium sulphate and sodium nitrate, were used to promote statlingite formation in the HAC paste. Strtitlingite forms preferentially to the cubic hydrogarnet phase in hydrated HAC systems in the presence of zeolite. A sufficiently high silicate concentration, arising from the dissolution of silicabearing materials such as zeolite, is required. A high pH environment is also conducive to stratlingite formation. The thermochemical stability of CAH₁₀, the normal precursor to hydrogarnet formation, is apparently increased under the condition of high microsilica content.