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US 7,771,851 B2Granted
Gypsum-containing products containing alpha hemihydrate
AssigneeUnited States Gypsum Company
InventorsWeixin David Song, Qiang Yu, Qiangxia Liu
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Abstract
The invention provides gypsum wallboard, made from gypsum-containing slurries having outstanding hydration rate characteristics comprising alpha-hemihydrate ground to a particular particle size distribution range and having a Blaine surface area in the range from about 3100 cm2/g to about 9000 cm2/g, alone or in combination with beta-hemihydrate.
Claims25
A gypsum wallboard comprising:
- a set gypsum composition formed between two substantially parallel cover sheets, the set gypsum composition made using a gypsum-containing slurry comprising:
- water, and
- ground alpha-hemihydrate having a particle size distribution within the following range:
- d (0.1)=about 3μ-5μ,
- d (0.5)=about 14μ-50μ,
- d (0.9)=about 40μ-100μ,
- and a Blaine surface area in the range from about 3100 cm2/g to about 9000 cm2/g.
4 more elements
A gypsum-containing slurry comprising:
- water, and
- ground alpha-hemihydrate having a particle size distribution within the following range:
- d (0.1)=about 3μ-5μ,
- d (0.5)=about 14μ-50μ,
- d (0.9)=about 40μ-100μ,
- and a Blaine surface area in the range from about 3100 cm2/g to about 9000 cm2/g.
3 more elements
A method of making gypsum wallboard, comprising the steps of:
- (a) mixing a gypsum-containing slurry comprising
- water, and
- ground alpha-hemihydrate having a particle size distribution within the following range:
- d (0.1)=about 3μ-5μ,
- d (0.5)=about 14μ-50μ,
- d (0.9)=about 40μ-100μ,
- and a Blaine surface area in the range from about 3100 cm2/g to about 9000 cm2/g;
- (b) depositing the gypsum-containing slurry on a first cover sheet;
- (c) placing a second cover sheet over the deposited slurry to form a gypsum wallboard;
- (d) cutting the gypsum wallboard after the gypsum-containing slurry has hardened sufficiently for cutting;
- and
- (e) drying the gypsum wallboard.
9 more elements
A gypsum wallboard consisting essentially of:
- a set gypsum composition formed between two substantially parallel cover sheets, the set gypsum composition made using a gypsum-containing slurry of:
- water, and
- ground alpha-hemihydrate having a generally unimodal particle size distribution within the following range:
- d (0.1)=about 3μ-5μ,
- d (0.5)=about 14μ-50μ,
- d (0.9)=about 40μ-100μ,
- and a Blaine surface area in the range from about 3100 cm2/g to about 9000 cm2/g.
4 more elements
Dependencies are inferred from the claim text.