Effect of Gypsum on Hydration and Hardening Properties of Alite Modified Calcium Sulfoaluminate Cement

Abstract

Calcium sulphoaluminate cement (CSA) has the characteristics of quick hardening, high early strength and high impermeability, however its strength growth persistence in the middle and late stages (after the age of 3 days) is poor. In order to improve this disadvantage, the pilot production of alite (C3S) modified CSA (AMCSA) clinker was carried out by liquid phase manipulation and barium ion doping technology. The effects of different dosages of gypsum on the hydration and hardening properties of AMCSA, such as setting time, hydration rate, compressive strength and hydration products, were studied. The results show that the mineral content of ye’elimite, C2S, C3S and iron phase in the calcined AMCSA clinker are 48.5 wt.%, 32.6 wt.%, 11.7 wt.% and 7.2 wt.% respectively, which are close to the designed mineral composition. The stable coexistence of ye’elimite and C3S in the same clinker system is realized. The initial and final setting time of AMCSA are retarded with the increasing gypsum dosage. When the gypsum dosage is 15 wt.% under the experimental conditions in this study, the AMCSA mortar reaches the highest compressive strength at every age. The strength of AMCSA mortar at 28 days is still significantly improved compared with that at 3 days, which indicates that the shortcoming of the low strength growth persistence of CSA in the middle and late stages is improved.

Evaluation of Chloride Resistance of Early-Strength Concrete Using Blended Binder and Polycarboxylate-Based Chemical Admixture

“…the actual CaO content was similar. Previous studies reported that the development of early strength increased as the SO3 content increased in the range of less than 5% [36][37][38]. Figure 9a shows the chloride penetration depth of each concrete mix by age.…”

Effect of Flue Gas Desulfurization Gypsum on the Properties of Calcium Sulfoaluminate Cement Blended with Ground Granulated Blast Furnace Slag

“…Calcium sulfoaluminate cement (CSAC), which has been manufactured and used on a large scale in China since the 1970s, is considered environment-friendly with low CO 2 emissions [ 1 , 2 , 3 , 4 ]. Compared with Portland cement, CSAC exhibits a shorter setting time, faster hardening, higher early strength, better durability, etc., and is widely used in various special areas of engineering, such as rapid repair engineering, ocean engineering, winter construction and so on [ 5 , 6 ].…”

Effects of Accelerators and Retarders in Early Strength Development of Concrete Based on Low-Temperature-Cured Ordinary Portland and Calcium Sulfoaluminate Cement Blends

“…Klein and Metha reported that various hydrates can be produced depending on the molar ratios of Al 2 O 3 /SO 3 and CaO/SO 3 in the CaO-Al 2 O 3 -SO 3 system [23], where a high Al 2 O 3 component exhibits quick-setting and early strength, a high CaO component exhibits expandability, and a high SO 3 component exhibits high strength characteristics [24]. The key factors for the hydration of CSA cements vary according to the ingredients and composition of the hauyne clinkers, the reactivity of the externally incorporated gypsum, the type of mixture, and the mixing and curing conditions.…”