Stucco Hydration

Calcined Anhydrite. Soluble anhydrite, or second-settle stucco, has physical properties similar to those of gypsum plaster. It hydrates to the dihydrate rapidly in water. Its outstanding property is its extreme affinity for any moisture, which makes it a very efficient drying agent (see Desiccants). In ambient moisture-laden air, it readily hydrates to hemihydrate. Soluble anhydrite, under the trade name Drierite, is widely used as a desiccant in the laboratory and in iadustry. A small amount is also used as an insecticide carrier. Small amounts of soluble anhydrite are unintentionally produced in most commercial calciners during hemihydrate production. 

ABSTRACT In gypsum board xoduction. the amount of water required for a stucco slurry with a suitable fluidity is considerably greater than the amount necessary for hydration of the stucco. Since excess water must be removed by drying, it is advantageous, from an energy point of view, to reduce the consistency or water demand of stucco. Constant board density is maintained thereby through increased addition of foam. 

All consistency measurements were conducted by adding 0.2-g sodium citrate to 100 mL of gaging water to prevent premature stiffening caused by hydration of the stucco. 

Uses Film preservative for highly alkaline systems such as masonry coatings, stuccos, constmction materials, and dry coalings hydrated at work site... 

Uses Dry film preservative, algicide, fungicide for acrylic stucco base coat mixes, mortars, and adhesives Features Rec. for prods, hydrated at site stable to 60 C solv.-free Properties Off-wh. powd. disp. 

Mortar m6r-tor [ME morter, fr. OF mortier, fr. L mortarium] (14c) n. (1) Material used in a plastic state which can be troweled, and becomes hard in place, to bond units of masonry structures Note — The word mortar is used without regard to the composition of the material, and is defined only with reference to its use as a bonding material as contrasted with the words stucco and plaster ). (2) A mixture of gypsum plaster with aggregate or hydrated lime, or both, and water is to produce a trowelable fluidity. 

Masonry cements These are used for preparing bricklaying mortars and stuccos, and must not be used in concrete. They are usually complex proprietary formulations containing Portland clinker and a number of other ingredients that may include limestone, hydrated lime, air entrainers, retarders, water proofers and colouring agents. 

C desiccation of semi-hydrated calcium sulphate (stucco)... 

The hydration mechanism described accounts for the main features of the European Roman cements— quick setting, combined with high initial and long-term strength. These features made them favored materials for economic and easy manufacture of the renders and stuccos for the exterior of buildings in the... 

The practices for use of natural cement in the mid-19th Century are concisely summarized in an excerpt from thel857 Handbook of Railroad Construction. It provides a formulary for natural cement mortars, concretes, stucco, grout and coatings, and includes a clear reference to the early practice of using hot-mixed hydrated lime in American engineering construction. 

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