US3785844A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Expansive cement additives and process for producing the same
Assignee: Taiheiyo Cement Corp
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Filing: 1972-11-08
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Granted: 1974-01-15
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Expires: 1992-11-08
Abstract
Abstract A finely pulverized expansive cement additive having an excellent chemical prestressing property, a clinker of which consists of alite crystals and calcium oxide crystals dispersed in a vitreous interstitial substance, wherein said alite and calcium oxide crystals have a size ranging from 50 to 100 microns and from 15 to 60 microns respectively, and the content of said calcium crystals and said interstitial substance are from 30 to 80 percent and from 2 to 27 percent by weight based on the clinker respectively.
Inventors
- 👤 T Kawano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 09:57
CPC Classifications
C; C04; C04B; C04B7/00; C04B22/00; C04B22/008
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
107 words
An expansive cement additive of pulverized clinker containing alite crystals and calcium oxide crystals dispersed in a vitreous interstitial substance consisting of substantially three phases of 4CaO.Al2O3.Fe2O3, 3CaO.Al2O3 and CaSO4, the ranges of crystal size of said alite and calcium oxide being 100 to 200 microns and 15 to 60 microns respectively, the content of the calcium oxide crystals in the vitreous interstitial substance being in a range of from 30 to 80 percent by weight based on the clinker, and the amount of said vitreous interstitial substance in the clinker being in a range of from 10 to 38 percent by weight based on the clinker.
Claim 2
Dependent Claim
22 words
The expansive cement additive of claim 1, wherein the size range of said calcium oxide crystals is from 25 to 60 microns.
Claim 3
Dependent Claim
22 words
The expansive cement additive of claim 2, wherein the size range of said calcium oxide crystals is from 25 to 60 microns.
Claim 4
Dependent Claim
32 words
The expansive cement additive of claim 1, wherein the pulverized clinker has such fineness that 1 to 40 percent by weight of said clinker is retained on a sieve of 88-micron mesh.
Claim 5
Dependent Claim
32 words
The expansive cement additives of claim 2, wherein the pulverized clinker has such fineness that 1 to 40 percent by weight of said clinker is retained on a sieve of 88-micron mesh.
Claim 6
Dependent Claim
32 words
The expansive cement additives of claim 1, wherein the pulverized clinker has such fineness that 15 to 30 percent by weight of said clinker is retained on a sieve of 88-micron mesh.
Claim 7
Dependent Claim
32 words
The expansive cement additives of claim 2, wherein the pulverized clinker has such fineness that 15 to 30 percent by weight of said clinker is retained on a sieve of 88-micron mesh.
Claim 8
Dependent Claim
166 words
A process for producing expansive cement additives which comprises; mixing raw materials of lime, clay and siliceous and ferrous substances, said mixing being so effected as to obtain a silica modulus, a weight percentage ratio of SiO2%/(Al2O3% + Fe2O3%), ranging from 1.0 to 4.0 and an iron modulus, a weight percentage ratio of Al2O3%/Fe2O3%, ranging from 0.5 to 4.0, and causing the mixture to contain a sufficient amount of calcium oxide for reaction with silicon oxide, aluminum oxide and ferric oxide in addition to the amount thereof to remain as free calcium oxide crystals; burning the mixture of raw materials long enough at a temperature ranging from 1300* to 1600*C to obtain a clinker having no belite crystals therein; whereby a vitreous interstitial substance and alite and calcium oxide crystals dispersed in said vitreous interstitial substance are formed in the clinker; and pulverizing the clinker to such fineness that 1 to 40 percent by weight of said clinker is retained on a sieve of 88-micron mesh.
Claim 9
Dependent Claim
46 words
The process according to claim 9, wherein, in the mixing step, the amount of calcium oxide to remain as free calcium oxide crystals to be dispersed in the vitreous interstitial substance formed in the clinker ranges from 30 to 80 percent by weight of the clinker.
Claim 10
Dependent Claim
53 words
The process according to claim 9, wherein the mixture of raw materials includes 10 to 20 percent of gypsum as converted to CaSO4 based on the total amount of calcium oxide contained in said mixture; and burning of said mixture is stopped before 20 percent by weight of the gypsum added is decomposed.
Claim 11
Dependent Claim
25 words
The process according to claim 9, wherein the gypsum is one selected from the group consisting of CaSO4.2H2O, CaSO4. 1/2 H2O and anhydrous calcium sulfate.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-14 | 1977-07-16 | 1978-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-14 | 1981-07-16 | 1982-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-14 | 1985-07-16 | 1986-01-15 | $7700.00 | Window Closed / Lapsed |