US3852081A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cement compositions containing alpha gypsum having improved long-term durability
Assignee: United States Gypsum Co
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Filing: 1973-07-30
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Granted: 1974-12-03
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Expires: 1993-07-30
Abstract
Abstract Cementitious mixtures of alpha calcium sulfate hemihydrate, a portland cement and a dispersing agent are provided with improved long-term durability by the use of particular portland cements which are very low in tricalcium aluminate content.
Inventors
- 👤 C Lehman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:37
CPC Classifications
C; C04; C04B; C04B7/00; C04B7/02; C04B28/00; C04B28/14; C04B28/145; C04B28/146; C04B2103/00; C04B2103/40; C04B2103/408
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
61 words
A CEMENT COMPOSITION WHICH WHEN SET IS RESISTANT TO SUBSEQUENT DETERIORATION BY SUBSTANTIAL EXPANSION, WEIGHT GAIN, AND LOSS OF COMPRESSIVE STRENGTH COMPRISING A MIXTURE OF, BY WEIGHT, ABOUT 40-94 PERCENT OF ALPHA CALCIUM SULFATE HEMIHYDRATE; ABOUT 49-5 PERCENT OF A PORTLAND CEMENT CONTAINING NOT MORE THAN ABOUT 7 PERCENT BY WEIGHT TRICALCIUM ALUMINATE; AND ABOUT 0.5-0.8 PERCENT OF A DISPERSING AGENT.
Claim 2
Dependent Claim
61 words
A CEMENT COMPOSITION WHICH WHEN SET IS RESISTANT TO SUBSEQUENT DETERIORATION BY SUBSTANTIAL EXPANSION, WEIGHT GAIN, AND LOSS OF COMPRESSIVE STRENGTH COMPRISING A MIXTURE OF, BY WEIGHT, ABOUT 40-94 PERCENT OF ALPHA CALCIUM SULFATE HEMIHYDRATE; ABOUT 49-5 PERCENT OF A PORTLAND CEMENT CONTAINING NOT MORE THAN ABOUT 7 PERCENT BY WEIGHT TRICALCIUM ALUMINATE; AND ABOUT 0.5-0.8 PERCENT OF A DISPERSING AGENT.
Claim 3
Dependent Claim
33 words
The cement composition of claim 1 in which the amount of tetracalcium aluminoferrite plus twice the amount of tricalcium aluminate content of the portland cement does not exceed about 20 percent by weight.
Claim 4
Dependent Claim
16 words
The cement composition of claim 1 in which the portland cement is a Type V cement.
Claim 5
Dependent Claim
41 words
The cement composition of claim 1 containing, by weight, about 49 percent of alpha calcium sulfate hemihydrate; about 49 percent of a portland cement having not more than about 5 percent tricalcium aluminate content; and about 0.5-0.8 percent of dispersing agent.
Claim 6
Dependent Claim
14 words
A settable, plastic mass comprising an aqueous slurry of the composition of claim 1.
Claim 7
Dependent Claim
52 words
A process for imparting long-term durability, to alpha calcium sulfate hemihydrate-portland cement compositions that contain minor amounts of a dispersing agent, and resistance to subsequent expansion, weight gain and loss of compressive strength of the set cement, comprising the step of incorporating portland cements which are very low in tricalcium aluminate content.
Claim 8
Dependent Claim
52 words
A process for imparting long-term durability, to alpha calcium sulfate hemihydrate-portland cement compositions that contain minor amounts of a dispersing agent, and resistance to subsequent expansion, weight gain and loss of compressive strength of the set cement, comprising the step of incorporating portland cements which are very low in tricalcium aluminate content.
Claim 9
Dependent Claim
22 words
The process of claim 6 in which the portland cement contains not more than about 7 percent by weight of tricalcium aluminate.
Claim 10
Dependent Claim
22 words
The process of claim 6 in which the portland cement contains not more than about 5 percent by weight of tricalcium aluminate.
Claim 11
Dependent Claim
33 words
The process of claim 6 in which the amount of tetracalcium aluminoferrite content plus twice the amount of tricalcium aluminate content of the portland cement does not exceed about 20 percent by weight.
Claim 12
Dependent Claim
15 words
The process of claim 6 in which the portland cement is Type V portland cement.
References Cited (Backward Citations)
US3582376A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-02 | 1978-06-03 | 1978-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-02 | 1982-06-03 | 1982-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-02 | 1986-06-03 | 1986-12-03 | $7700.00 | Window Closed / Lapsed |