Claims
- 1. A method for immobilizing an oily or non-polar substance in a concrete matrix comprising the following steps:
- (a) combining said oily or non-polar substance with sufficient metakaolin to absorb said oily or non-polar substance, said metakaolin being capable of undergoing a pozzolonic reaction with calcium hydroxide and having a particle size of 0.1 to 50 .mu.m;
- (b) forming a hardenable concrete mix comprising:
- (i) from 5 to 30% by weight, based on the weight of the solids in said mix, of the combined metakaolin and absorbed oily or non-polar substance formed in step (a);
- (ii) from 20 to 95% by weight, based on the weight of the solids in the mix, of a cement;
- (iii) from 0 to 80% by weight, based on the weight of the solids in said mix, of a fine aggregate comprising particles having a size of from 0.15 to 5 mm; and
- (iv) sufficient water to form the hardenable concrete mix; and
- (c) permitting the resultant concrete mix to harden to form a substantially impervious concrete matrix in which said oily or non-polar substance is permanently fixed, the calcium hydroxide formed during hydration of the cement reacting during the hardening process in a pozzolonic reaction with said metakaolin to provide cementitious phases which are incorporated in the bulk structure of the concrete and substantially fill the pores which normally make concrete permeable.
- 2. A method according to claim 1, wherein the amount of metakaolin employed is at least sufficient to absorb the oily or non-polar substance.
- 3. A method according to claim 1, wherein at least 0.5 kilogram of metakaolin is employed per kilogram of oily or non-polar substance.
- 4. A method according to claim 1, wherein the amount of metakaolin employed does not exceed 5.0 kilograms per kilogram of oily or non-polar substance.
- 5. A method according to claim 1, wherein the amount of the metakaolin used is from 1.0 to 2.0 kg. per kilogram of oily or non-polar substance.
- 6. A method according to claim 1, wherein the metakaolin is formed by calcining a kaolinitic clay mineral at about 750.degree. C. for about 4 hours.
- 7. A method according to claim 1, wherein the oily or non-polar substance is a toxic liquid component of a waste material.
- 8. A hardenable concrete mix incorporating a metakaolin onto which is absorbed an oily or non-polar substance, said metakaolin being formed by heating a calcined kandite clay mineral to a temperature in the range from 450.degree. C. to 950.degree. C. for a time such that the loss on ignition for two hours at 1000.degree. C. of a sample of the calcined mineral is less than 1% by weight.
- 9. A substantially liquid impervious concrete matrix having an oily or non-polar substance substantially permanently isolated within pores in the matrix, said pores being sealed off from each other by the mineral which crystallizes in situ in the pozzolonic reaction between a metakaolin and calcium hydroxide formed during hydration of the cement in the concrete matrix, said metakaolin being formed by heating a calcined kandite clay mineral to a temperature in the range from 450.degree. C. to 950.degree. C. for a time such that the loss on ignition for two hours at 1000.degree. C. of a sample of the calcined mineral is less than 1% by weight.
- 10. A hardened concrete matrix containing an oily or non-polar substance isolated in the concrete matrix prepared by a method comprising the following steps:
- (a) absorbing said oily or non-polar substance into a metakaolin, said metakaolin being formed by heating a calcined kandite clay mineral to a temperature in the range from 450.degree. C. to 950.degree. C. for a time such that the loss on ignition for two hours at 1000.degree. C. of a sample of the calcined mineral is less than 1% by weight;
- (b) incorporating the metakaolin and absorbed oily or non-polar substance formed in step (a) in a hardenable concrete mix; and
- (c) permitting the resultant concrete mix to harden.
Priority Claims (1)
Number |
Date |
Country |
Kind |
9220561 |
Sep 1992 |
GBX |
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Parent Case Info
This application is a continuation of application Ser. No. 08/550,064, filed Oct. 30, 1995, now abandoned, which is a continuation of Ser. No. 08/128,595 which is now abandoned, filed Sep. 28, 1993.
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Continuations (2)
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Parent |
550064 |
Oct 1995 |
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Parent |
128595 |
Sep 1993 |
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