Hydrated high alumina cement
OwnerShamim A. Sheikhinventor
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Abstract
A hydraulic cement composition is disclosed which utilizes as part of an expansive component novel coated particles of high alumina cement. The particles have a core of substantially unhydrated high alumina cement and an outer layer of hydration products of the core, which outer layer delays the reaction of the particles with other materials in the composition. By varying the nature and relative amounts of the coated particles the amount the cement composition may expand and the setting time of the cement may be varied. The coated particles may be formed by partial hydration, drying and grinding of a mixture of high alumina cement powder alone with water.
Claims27
A cement composition formed by mixing:
- (a) a Portland cement component;
- and
- (b) an expanding component, comprising:
- (i) a partially hydrated high alumina cement powder consisting of coated particles, said particles consisting of an inner core consisting of unhydrated high alumina cement and an outer coating consisting of hydration products of high alumina cement, said coating delaying reaction between the high alumina cement of the core of the particles and other materials in the cement composition;
- and
- (ii) a calcium sulfate substance selected from the group consisting of anhydrous calcium sulfate, hemihydrate calcium sulfate and dihydrate calcium sulfate;
- said partially hydrated high alumina cement powder being formed independently and prior to mixing with the remainder of the composition.
A cement composition formed by mixing:
- (a) a Portland cement component;
- (b) a partially hydrated high alumina cement powder;
- (c) a calcium sulfate substance selected from the group consisting of anhydrous, hemihydrate and dihydrate calcium sulphate, and
- (d) a calcium oxide substance selected from calcium oxide and calcium hydroxide;
- wherein said partially hydrated high alumina cement powder is formed independently and prior to mixing with the remainder of the composition by a process of:
- (i) forming a mixture consisting of water and unhydrated high alumina cement, the ratio of high alumina cement to water being from about 1:1 to about 4:1;
- (ii) allowing the mixture of high alumina cement and water to set;
- and
- (iii) mechanically reducing the product of step (ii) into a resultant powder.
Dependencies are inferred from the claim text.