TERNESITE-YE'ELIMITE CEMENT: THE EFFECT OF TERNESITE CONTENT ON THE PERFORMANCE

A new type of ternesite-ye'elimite (TCSA) cement was prepared with different amounts of ternesite. The effect of the ternesite content on the mechanical properties and hydration products of cement pastes was studied. The influence of the added gypsum content on the performance of TCSA cement was also discussed. The results showed that increasing the contents of ternesite prolonged the setting times of the TCSA clinkers. Increasing the ternesite content promoted the strength development. The increase in the ternesite content caused the lower expansion of the TCSA clinkers. The formation of ettringite, stratlingite and monosulfate was observed in the hydrated clinker pastes. The amount of stratlingite and monosulfate decreased at 28 days, while the formation of ettringite continued to increase due to the hydration of ternesite. The higher added gypsum content increased the compressive strength between 1 and 28 d. However, 15% gypsum was not conducive to the strength development at later ages. In the presence of gypsum, the formation of stratlingite was not observed. A higher gypsum content favoured ettringite precipitation at 1 d, but excess gypsum hindered the ternesite hydration.