Compositions with synthetic gypsum and methods
AssigneeUnited States Gypsum Company
InventorsDennis Mark Lettkeman, John Wesley Wilson, Mike L. Cloud, Brian K. Ball, Raymond A. Kaligian, Doug Blackburn
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Abstract
DTPA-coated synthetic calcined gypsum is provided with alpha-like properties and obtained by spray-coating the synthetic caclined gypsum with DTPA. Cementitious compositions comprising DTPA-coated synthetic calcined gypsum and low water demand are provided as well. Methods for controlling an open time of a cementitious slurry by increasing or decreasing the amount of DTPA-coated synthetic calcined gypsum in the slurry are provided as well.
Claims20
Synthetic calcined gypsum coated with diethylene-triamine-pentaacetic acid (DTPA), wherein the synthetic calcined gypsum is obtained by spray-coating the synthetic calcined gypsum with DTPA in a fluidized bed chamber at a temperature in the range from 190 degrees Fahrenheit to 340 degrees Fahrenheit.
A cementitious composition comprising DTPA-coated synthetic calcined gypsum and at least one natural calcined gypsum, and wherein the water demand for the composition is no more than 50 cc for 100 parts of all stucco combined.
A method of preparing a cementitious slurry with a predetermined open time, the method comprising controlling the open time of the slurry by increasing the amount of DTPA-coated synthetic calcined gypsum in the slurry from 0% to a value in the range from 0.1% to 25%, wherein increasing the amount of the DTPA-coated synthetic calcined gypsum in the slurry increases the open time.
Dependencies are inferred from the claim text.