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US 5,518,540 AGranted
Cement treated with high-pressure CO.sub.2
AssigneeMaterials Technology Corporation
InventorRoger H. Jones, Jr.
Life of this patent
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AssigneeMaterials Technology Corporation
InventorRoger H. Jones, Jr.
Estimating the term…
Cured cement matrices are exposed to dense-phase or supercritical CO.sub.2 which enters the matrix through passages therein to neutralize the natural alkalinity of the cement so that alkali-intolerant materials can be incorporated in the cement. The CO.sub.2 converts calcium hydroxide in the cement to calcium carbonate and water, and the high pressure of the dense-phase or supercritical CO.sub.2 forms rounded, closely packed and aligned crystals with few or no visible pores or capillaries to enhance the homogeneity and strength of the cured cement and its bonding with, for example, uncoated reinforcing glass fibers. The supercritical CO.sub.2 can be used to transport other organic or inorganic materials, including pulverized metal, in solution or suspension into the interior of the cement matrix to alter its chemical and/or physical characteristics. The supercritical CO.sub.2 can further be used to quickly determine if a particular cement specimen comes from a wet cement mix to which a material has been added which prevents or hinders cement carbonation.
A method of improving a cured cement product comprising the steps of mixing at least cement and water to form a mixture, curing the mixture, and subjecting the mixture to supercritical CO.sub.2.
A method of protecting alkali-intolerant matter in a cured cement product and changing characteristics of the cement product after curing comprising the steps of mixing cement, water and the matter to form a mixture, curing the mixture, providing supercritical CO.sub.2, adding a material to the supercritical CO.sub.2 to form a supercritical admixture, the material being in a form in which it can enter the cement product through pores and capillaries therein, subjecting the cement product to the admixture to thereby lower the pH of the cement product and infuse into the cement product the material, withdrawing at least some of the supercritical CO.sub.2 from the cement product, and leaving at least some of the material in the cement product to thereby change at least one of a chemical and a physical characteristic of the product with the material.
A method of changing a characteristic of a cured cement product comprising the steps of forming the product from a wet cement mix including at least cement and water, providing supercritical CO.sub.2, adding a material to the supercritical CO.sub.2 to form a supercritical mixture, the material being in a form in which it can enter the cement product through pores and capillaries therein, flowing the admixture into the cement product, and depositing at least some of the material on an interior of the cement product, whereby the deposited material changes a characteristic of the cement product.
Dependencies are inferred from the claim text.