Cementation methods

Patent metadata

Field	Value
Publication number	US-10563233-B2
Application number	US-201715803700-A
Country	US
Kind code	B2
Filing date	Nov 3, 2017
Priority date	Jul 17, 2012
Publication date	Feb 18, 2020
Grant date	Feb 18, 2020

Abstract

The present invention provides methods for mineral precipitation and/or cementation of permeable or fractured non-porous materials using isolated urease.

First claim

We claim:

1. A cementation method, comprising combining a column of a permeable starting material or a column of a non-porous but fractured starting material with a mixture comprising:
(a) isolated urease;
(b) urea;
(c) a source of divalent cations; and
(d) an organic additive,
wherein (a), (b), (c) and (d) are provided in amounts effective and the combining is carried out under conditions suitable to cause carbonate precipitation and/or cementation of the starting material within the column, and
wherein the combining comprises:
(i) mixing the urease with the starting material; and
(ii) injecting into the column of starting material, under pressure and via an injection tube, a solution comprising the urea and the source of divalent cations.

2. The method of claim 1 , wherein the method is used for one or more of improving bearing capacity of foundations; reducing settlement potential of foundations or embankments; increasing lateral resistance of foundations; enhancing stability of slopes or embankments; or reducing lateral earth pressures on retaining walls.

3. The method of claim 1 wherein the starting material comprises at least one of sand, silt, soil, clay, sediments, sawdust, fractured crystalline rocks, cracked concrete or sedimentary rocks.

4. The method of claim 1 , wherein the isolated urease comprises jack bean urease.

5. The method of claim 1 , wherein the source of divalent cations comprises a source of divalent calcium ions.

6. The method of claim 1 , wherein the combining step is carried out more than once.

7. The method of claim 1 , wherein the combining step is carried out once.

8. The method of claim 1 , wherein the permeable starting material comprises sand.

9. The method of claim 1 wherein the injecting is carried out two or more times.

10. The method of claim 1 wherein the urease is mixed with starting material in only a portion of the column prior to the injecting step.

11. The method of claim 1 , wherein the organic additive is water soluble.

12. The method of claim 1 , wherein the organic additive is powdered milk.

13. The method of claim 1 , wherein the organic additive is present in the mixture at a concentration of 1-10 g/L.

14. The method of claim 13 , wherein the organic additive is present in the mixture at a concentration of 3-5 g/L.

15. The method of claim 13 , wherein the organic additive is present in the mixture at a concentration of about 4 g/L.

Assignees

• Univ Arizona State

Inventors

• Kavazanjian Edward
• Hamdan Nasser

Classifications

• C12N9/80

  acting on amide bonds in linear amides {(3.5.1)} · CPC title

• C04B2111/72

  Repairing or restoring existing buildings or building materials · CPC title

• C12Y305/01005 Primary

  Urease (3.5.1.5) · CPC title

• C01F11/00

  Compounds of calcium, strontium, or barium (C01F7/00 takes precedence) · CPC title

• C04B2103/0001

  Living organisms, e.g. microorganisms, or enzymes · CPC title