Research on the Hydration Properties of C4A3S-CSH2 Cement System at Different Temperatures

Abstract

Sulphoaluminate cement has the advantage of low-temperature application performance, but its hydration mechanism at low temperatures is not yet clear. Anhydrous calcium sulfoaluminate (C4A3S) is the main mineral in the composition of sulfoaluminate cement clinkers. In this paper, C4A3S mixed with gypsum (CaSO4∙2H2O) to form a C4A3S-CSH2 cement system; X-ray diffraction (XRD), thermogravimetric analysis (TG-DTG), scanning electron microscopy (SEM) and mercury intrusion analysis (MIP) to clarify the effect of temperatures on the hydration properties of C4A3S-CSH2 cement system. The results showed that hydration of the C4A3S-CSH2 cement system could carry on at low temperatures, even at −15 °C. The main hydration product was ettringite. Low temperatures did not change the types of the hydration products, but the low temperature of 0 °C was more favorable for the formation of ettringite. The early hydration of the C4A3S-CSH2 cement system was inhibited by the decrease in temperature. However, hydration of the cement at 0 °C continued at a high rate after one day. Morphologies of the ettringite for the C4A3S-CSH2 cement system at −15 °C were needle-like structures, while they were of columnar structure at 0 °C. The compressive strength of samples at 0 °C reached 82 MPa, which is significantly higher than that at 20 °C.

Influence of Granite Powder on Physico-Mechanical and Durability Properties of Mortar

“…In these temperature regions, four endothermal signals appeared. The first peak at 100 • C was attributed to the dehydration of calcium silicate hydrates (C-S-H) and ettringite (AFt) [14,21,23,38]. The second peak at 180 • C corresponded to the dehydration of the calcium alumina silicate hydrate (C-A-S-H) [39].…”

“…Figure 7 shows the temperature evolution during the hydration of control and GP mortars. It should be remembered that cement hydration is a thermoative phenomenon [38,43], so the degree or intensity of hydration is related to the evolution of temperature. The first 24 h are exothermic for all mixtures.…”

Preparation of Micro-Iron Ore Tailings by Wet-Grinding and Its Application in Sulphoaluminate Cement

“…Moreover, three weight loss peaks could be observed obviously from the DTG curve. According to previous literature [47][48][49], the mass loss peak at 100-150°C was ascribed to ettringite decomposition, and that at 250-280°C was mainly because of AH 3 dehydration. The peak at 600-800°C was assigned to calcium carbonate decomposition produced by carbonation during sample preparation or curing.…”

“…The peak at 600-800°C was assigned to calcium carbonate decomposition produced by carbonation during sample preparation or curing. Besides, the weak peak around 160-200°C could be ascribed to AFm [48].…”

Fire-Temperature Influence on Portland and Calcium Sulfoaluminate Blend Composites

“…The third sample, Z3, had intensive the first peak 149.1 • C 2.835 mW/mg, which was 34% more intense than Z2, but the second peak moved to 262.7 • C 0.69 mW/mg with almost 50% lower intensity than Z2. In paper [53], the second peak can be connected with the amorphous alumina trihydroxide (AH3) phase occurring, in which the origin is calcium sulfoaluminate cement hydration protocol. In accordance with previous samplers, a peak around 500 • C was absent, which means that portlantide phase was absent in this sample.…”