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US 4,205,994 AGranted
Expansive cement and agent therefor
AssigneeRaychem Corporation
InventorsWendell W. Moyer, Jr., Robert Smith-Johannsen
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AssigneeRaychem Corporation
InventorsWendell W. Moyer, Jr., Robert Smith-Johannsen
Estimating the term…
Expansive cement compositions and novel expansion agents containing free lime for use in such compositions. The expansion agents are prepared by heating lime of particle size less than 250 microns in an atmosphere comprising water vapor at 100.degree. to 400.degree. C. or carbon dioxide at 350.degree. to 850.degree. C., or by heating a partially hydrated lime at a temperature of at least 100.degree. C. The encapsulated limes produced in this way are useful as expansion agents in hydratable cement compositions, the amount thereof generally being less than 30%, preferably 3 to 10%, based on the weight of the cement and additive. Cement compositions containing the novel expansion agents are useful in a wide variety of uses where shrinkage of the composition on drying has to be prevented or reduced.
A pulverulent composition which is useful as an expansion additive for hydratable cement compositions;
A process for the production of a composition useful as an expansion additive for hydratable cement compositions, which process comprises heating particles (a) having a size less than 100 microns and (b) initially comprising at least 80% by weight of CaO at a temperature of 100 to 400.degree. C. in an atmosphere comprising water vapor for a time sufficient to increase the weight of the particles by at least 2%, said heating being carried out under conditions such that the product contains 36 to 95% by weight of CaO and exhibits an Expansion Factor of at least 0.06%.
A process for the production of a composition useful as an expansive additive for hydratable cement compositions, which process comprises heating particles (a) having a size less than 100 microns and (b) initially comprising at least 80% by weight of CaO at a temperature of 350.degree. to 850.degree. C. in an atmosphere comprising CO.sub.2 for a time sufficient to increase the weight of the particles by at least 2%, said heating being carried out under conditions such that the product contains 36 to 95% by weight of CaO and exhibits an Expansion Factor of at least 0.06%.
A process for the production of a composition useful as an expansion additive for hydratable cement compositions, which process comprises heating particles (a) having a size less than 100 microns and (b) initially comprising at least 80% by weight of CaO, the particles being maintained at a temperature of at least 100.degree. C. in an atmosphere which comrpises CO.sub.2 and water vapor for a time sufficient to increase the weight of the particles by 4 to 14%, said heating being carried out under conditions such that the product contains 36 to 95% by weight of CaO and exhibits an Expansion Factor of at least 0.06%.
A process for the production of a composition useful as an expansion additive for hydratable cement compositions, which process comprises heating hydrated lime particles at a temperature of 100.degree. to 400.degree. C., said particles (a) having a size less than 100 microns and (b) comprising at least 36% by weight of CaO and 8 to 64% by weight of Ca(OH).sub.2, said heating being carried out under conditions such that the product contains 36 to 95% by weight of CaO and exhibits an Expansion Factor of at least 0.06%.
A cement composition comprising a Portland cement, water and a pulverulent composition which consists essentially of particles having a size less than 100 microns and comprising a core of calcium oxide and a protective coating around said core of calcium carbonate;
A process for the production of a cement composition comprising a Portland cement, water and a pulverulent composition which consists essentially of particles having a size less than 100 microns and comprising a core of calcium oxide and a protective coating around said core of calcium carbonate;
A pulverulent composition which is useful as an expansion additive for hydratable cement compositions;
A pulverulent composition which is useful as an expansion additive for hydratable cement compositions;
A cement composition comprising a Portland cement, water and a pulverulent composition which consists essentially of particles having a size less than 100 microns and comprising a core of calcium oxide and a protective coating around said core of calcium hydroxide;
A cement composition comprising a Portland cement, water and a pulverulent composition which consists essentially of particles having a size less than 100 microns and comprising a core of calcium oxide and a protective coating around said core of calcium hydroxide and calcium carbonate;
A process for the production of a cement composition comprising a Portland cement, water and a pulverulent composition which consists essentially of particles having a size less than 100 microns and comprising a core of calcium oxide and a protective coating around said core of calcium hydroxide;
A process for the production of a cement composition comprising a Portland cement, water and a pulverulent composition which consists essentially of particles having a size less than 100 microns and comprising a core of calcium oxide and a protective coating around said core of calcium hydroxide and calcium carbonate;
Dependencies are inferred from the claim text.