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US4036657A
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High iron oxide hydraulic cement
Assignee: University of California
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Filing: 1975-07-23
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Granted: 1977-07-19
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Expires: 1995-07-23
Abstract
Abstract Hydraulic cements having higher (about 5%) iron-oxide content and lower (43-57%) than the usual calcium-oxide content of Portland cements are disclosed. These high iron-oxide cements have normal setting times, but high early strengths that develop without resorting to fine grinding or steam curing. The cements can be produced with considerably less expenditure of energy than required for conventional Portland cements due to lower burning temperatures and reduction in the amount of calcium-oxide which requires the greatest energy input for preparation of the cements.
Inventors
- 👤 Povindar K. Mehta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 01:17
CPC Classifications
C; C04; C04B; C04B7/00; C04B7/22
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
37 words
High iron-oxide hydraulic cement compositions comprising from about 15 to about 65% by weight tetracalcium aluminoferrite, from about 10 to about 20% by weight tetracalcium trialuminosulfate, and from about 10 to about 15% by weight calcium sulfate.
Claim 2
Dependent Claim
37 words
High iron-oxide hydraulic cement compositions comprising from about 15 to about 65% by weight tetracalcium aluminoferrite, from about 10 to about 20% by weight tetracalcium trialuminosulfate, and from about 10 to about 15% by weight calcium sulfate.
Claim 3
Dependent Claim
19 words
The hydraulic cement composition of claim 1 wherein tetracalcium aluminoferrite is present in the form of dicalcium aluminate-dicalcium ferrite.
Claim 4
Dependent Claim
18 words
The hydraulic cement compositions of claim 1 further including from about0 to about 50% by weight dicalcium silicate.
Claim 5
Dependent Claim
68 words
The composition of claim 3 wherein the iron is present essentially in the form of tetracalcium aluminoferrite; calcium is essentially in the form of tetracalcium aluminoferrite, tetracalcium trialuminosulfate, calcium sulfate, and dicalcium silicate; aluminum is essentially in the form of tetracalcium aluminoferrite and tetracalcium trialuminosulfate; and sulfate is essentially in the form of tetracalcium trialuminosulfate and calcium sulfate; and silicon is present in the form of dicalcium silicate.
Claim 6
Dependent Claim
16 words
The composition of claim 4 wherein dicalcium silicate is present essentially in the beta crystalline structure.
Claim 7
Independent Claim
79 words
A method for producing high iron-oxide hydraulic cement clinker comprising mixing predetermined amounts of iron-oxide, aluminum-oxide, calcium oxide, and sulfate raw materials, subjecting said raw materials to a heat treatment at temperatures of about 2,200°-2,300° F. for a period of time sufficient to form clinkers comprising an admixture of from about 15 to about 65% tetracalcium aluminoferrite, from about 10 to about 20% tetracalcium trialuminosulfate, and from about 10 to about 15% calcium sulfate, and thereafter cooling the clinker.
Claim 8
Independent Claim
79 words
A method for producing high iron-oxide hydraulic cement clinker comprising mixing predetermined amounts of iron-oxide, aluminum-oxide, calcium oxide, and sulfate raw materials, subjecting said raw materials to a heat treatment at temperatures of about 2,200°-2,300° F. for a period of time sufficient to form clinkers comprising an admixture of from about 15 to about 65% tetracalcium aluminoferrite, from about 10 to about 20% tetracalcium trialuminosulfate, and from about 10 to about 15% calcium sulfate, and thereafter cooling the clinker.
Claim 9
Dependent Claim
22 words
The method of claim 6 wherein silicon containing raw materials are used and the clinker includes up to about 50% dicalcium silicate.
Claim 10
Dependent Claim
25 words
The method of claim 6 including the further steps of grinding the clinker to a fineness of about 3500 to 4200 cm 2 /g Blaine.
Claim 11
Independent Claim
50 words
A method for reducing the energy required to produce an hydraulic cement clinker comprising reducing the amount of CaO required in the cement composition and replacing the reduced amount of CaO with additional amounts of iron-oxide, alumina and sulfate in the form of tetracalcium aluminoferrite tetracalcium trialuminosulfate and calcium sulfate.
Claim 12
Independent Claim
50 words
A method for reducing the energy required to produce an hydraulic cement clinker comprising reducing the amount of CaO required in the cement composition and replacing the reduced amount of CaO with additional amounts of iron-oxide, alumina and sulfate in the form of tetracalcium aluminoferrite tetracalcium trialuminosulfate and calcium sulfate.
References Cited (Backward Citations)
US3251701A
Cited
US3677781A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-18 | 1981-01-17 | 1981-07-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-18 | 1985-01-17 | 1985-07-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-18 | 1989-01-17 | 1989-07-19 | $7700.00 | Window Closed / Lapsed |