Gypsum-Based Cements

The utilization of gypsum-based binary and ternary blended cements has been shown to provide the desired characteristics of early hardening strength with improved durability. This is illustrated in 

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Nonhydraulic cements were among the most common of the ancient cements. The relatively high solubilities of portlandite (Ca[OH]2) and gypsum means that they deteriorate rapidly in moist or wet environments. Many decades ago, the Romans used lime-based cements and mortars (cement plus sand) by ramming the wet pastes... 

Chem. Descrip. Olefin sulfonate, sodium salt Uses Surfactant air entraining agent, plasticizer for building materials, plasters, textured decorative coatings, masonry mortars, gypsum- and cement-based prods. 

Poly (2-hydroxyethyl, Et) ether Ethyl hydroxyethyl cellulose. Etulos. EMEC [9004-58-4] Useful in solvent coating applications, inks, paints and as an additive to cement and gypsum based plasters and mortars Laxative. 

Uitilization of FGD gypsum in cement-based material is feasible. It is not only for environmental uses, but also in construction and civil engineering. The results contribute to a greater understanding of how to sustainably and beneficially manage various industrial wastes and byproducts and suggest that there are also several important environmental and economic benefits that can be realized. 

Gypsum-based plaster >- Cement- or gypsum-based vermiculite >- Mineral or glass fibre > Ceramic-based products... 

In gypsum-less cement, a conduction calorimetric study showed that a strong retardation of hydration occurred in the presence of a lignosulfonate-based superplasticizer containing sodium carbonate. l... 

In normal portland cement, hydration leads to the formation of ettringite. In many instances, the formation of ettringite leads to expansion. To prevent the formation of ettringite, a gypsum-based material with 75% hemihydrate, 20% portland cement, 5% silica fume, and a superplasticizer was fabricated. The pastes were cured in water for 1 to 10 minutes and subjected to DTA. In Fig. 10, thermograms show the stepwise dehydration endothermal peaks (shown upwards) at 150° and 200°C as is typical of gypsum. There was no indication of ettringite or monosulfate, which normally are identified by peaks at 125-130° and 190-195°C. 

Uses Surfactant, consistency agent, stabilizer, water retention aid in aq. prods., cement-based tile fix and joint mortars, gypsum-based crack fillers thickener Features Improves workability, adhesion in mortars Regulatory Europe EINECS... 

Improved workability and open time of dispersion-based systems such as tape joint compounds and aqueous coatings, as well as mineral-bound building systems such as cement-based mortars and gypsum-based plasters... 

Construction Soil stabilization water absorber water retention aids in cements, grouts, and tiles improvement of mechanical properties of cement and gypsum plasters and water based paints... 

The uncontrolled variation in the gypsum-hemihydrate or soluble anhydrite ratio (G-H or A) that occurs during production, storage and transportation of cement can cause compatibility problems with certain superplasticizers, particularly a reduction in workability. The extent of the reduction on workability properties is dependent on the G-H ratio (ranging from 80 20% to 20 80%), level of C A and alkalis present in the cement and the fineness of the cement. For the most reactive type of cement with a high content of both C A and alkalis, a reduced G-H or A ratio affects the yield stress, while piastre viscosity is not much affected. These effects are much less pronounced for a less reactive cement, but with the lowest G-H or A ratio, false set can occur [130-132], An increased fineness of cement increases the effect of the G-H or A ratio. The effect has been found to be most pronounced with melamine-based superplasticizers [130, 133],... 

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