Patent EA-000302-B1 (EA)
Title: Cement treated with high-pressure co2
Inventor: JONES ROGER H JR
IPC: C04B41/45
Filed: 1996-06-03
Abstract: 1. 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 CO2. 2. A method according to Claim 1 wherein the step of subjecting the mixture to supercritical CO2 is performed after the step of curing has been initiated. 3. A method according to Claim 2 wherein the step of subjecting is at least in part performed after the step of curing has been substantially completed. 4. A method according to Claim 1 including the step of generating supercritical CO2 by raising the pressure of the CO2 to at least 1071 psi and simultaneously bringing the temperature of the CO2 to at least 31 degree C. 5. A method according to Claim 1 including the step of further treating the mixture with CO2 at a pressure of more than 1071 psi and at a temperature below about 31 degree c after the step of subjecting the mixture to supercritical CO2. 6. A method according to Claim 5 wherein the temperature of the CO2 is in the range of between about 2 degree C and no more than 31 degree C. 7. A method according to Claim 1 including the step of entraining in the supercritical CO2 a third material, and conducting the step of subjecting the mixture to supercritical CO; thereafter to thereby infuse the supercritical CO2 bearing the third material into the mixture. 8. A method according to Claim 7 wherein the third material comprises a substance; which is soluble in CO2 and including the step of dissolving the third material in the supercritical CO2 prior to the subjecting step. 9. A method according to Claim 7 wherein the third material is insoluble in the CO2 and comprises a powder composed of powder particles of a size sufficiently small so that the particles can be transported with the supercritical CO2 through pores and capillaries forming passages in the mixture. 10. A method according to Claim 9 wherein the third material is a metal. 11. A method according to Claim 10 including the step of heating the cured mixture and the infused particles to at least about a melting temperature of the metal to thereby to provide the cured mixture with a modified electrical conductivity. 12. A method according to Claim 1 including the step of testing the cured mixture subsequent to the subjecting step to determine if the supercritical CO2 penetrated into an interior of the cured mixture to thereby determine if the cured mixture includes an additive preventing the supercritical CO2 from penetrating the cured mixture. 13. A method of protecting alkali-intolerant matter in a cured cement product and changing characteristics of the cement product, wherein the product is subjected to supercritical CO2 and comprising the admixture thereby lower the pH of the cement product, the material being in a form in which it can enter the cement product through pores and capillaries therein and withdrawing at least some of the supercritical CO2 from the cement product. 14. A method according to Claim 13 wherein the step of adding comprises the step of dissolving the material in the supercritical CO2. 15. A method according to Claim 13 wherein the step 6f adding comprises the step of suspending the material in the supercritical CO2. 16. A method according to Claim 15 including the step of pulverizing the material prior to the subjecting step. 17. A method according to Claim 13 wherein the step of subjecting the cement product to the admixture comprises reducing the pH of the cement product to about 7. 18. A method of changing a characteristic of a cured cement product wherein the product is subjected to supercritical CO2 and comprising the admixture the material being in a form in which it can enter the cement product through pores and capillaries therein, flowing the i admixture into the cement product, and depositing at least some of the material, whereby the deposited material changes a characteristic of the cement product. 19. A method according to Claim 18 wherein the material comprises pulverized metal particles entrained in the supercritical CO2. 20. A method according to Claim 19 including the step of heating the cement product to a sufficient temperature to fuse at least some of the metal particles to each other and thereby change electrical conductivity of the product.