Bio-catalytic calcium carbonate cementation
AssigneeUniversitetet I Oslo
InventorsAnja Røyne, Alexander Wentzel, Pawel Sikorski
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Abstract
The present invention is directed to methods of preparing biocement. The methods disclosed herein employ microbial or enzymatic means first to generate acid which dissolves CaCO3, and then to degrade urea, producing CO3− ions which increase the pH and lead to the reprecipitation of CaCO3. The precipitation of CaCO3 acts as a cementation process which can bind together particulate materials to yield mortars, concretes and suchlike. The invention further provides construction materials formed by the methods of the invention, and bacterial strains which can be used in the methods of the invention to generate organic acids.
Claims36
A method of forming a construction material from CaCO3 and a particulate starting material, comprising:
- (i) providing a combined mixture that includes a combination of the CaCO3 and the particulate starting material;
- (ii) enzymatically generating an acid in a first portion of the combined mixture, wherein the acid generation causes a local pH decrease in the first portion of the combined mixture, thereby locally dissolving at least a first portion of the CaCO3 in the first portion of the combined mixture;
- and
- (iii) enzymatically generating a local pH increase in a second portion of the combined mixture while enzymatically generating the acid in the first portion of the combined mixture thereby causing at least a second portion of the CaCO3 to precipitate and to bind together at least part of the particulate starting material and the precipitated CaCO3;
- wherein one or more reagents for enzymatically generating the local pH increase are present in the combined mixture.
A method of forming a construction material, comprising:
- (i) providing a combined mixture that includes a combination of CaCO3 and a particulate starting material;
- (ii) enzymatically generating an acid in the combined mixture during a first time period, wherein the acid generation causes a pH decrease in the combined mixture, thereby dissolving at least a first portion of the CaCO3 in the combined mixture;
- and
- (iii) enzymatically generating a pH increase in the combined mixture during a second time period thereby causing at least some of the first portion of the CaCO3 to precipitate and to bind together at least part of the particulate starting material and the precipitated CaCO3, wherein one or more reagents for enzymatically generating the pH increase or for enzymatically generating the acid are present in the combined mixture prior to enzymatically generating the acid in the combined mixture.
A method of manufacturing a construction material, comprising:
- acquiring a combined mixture that includes a combination of CaCO3 and a particulate starting material;
- enzymatically generating an acid in a first portion of the combined mixture, wherein the acid generation causes a local pH decrease in the first portion of the combined mixture and causes at least a first portion of the CaCO3 to be locally dissolved in the first portion of the combined mixture;
- and
- enzymatically generating a local pH increase in a second portion of the combined mixture while enzymatically generating the acid in the first portion of the combined mixture thereby causing at least a second portion of the CaCO3 to precipitate and to bind together at least part of the particulate starting material and the precipitated CaCO3, wherein one or more reagents for enzymatically generating the local pH increase are present in the combined mixture prior to enzymatically generating the acid in the first portion of the combined mixture.
A method of forming a construction material, comprising:
- (i) providing a combined mixture that includes a combination of CaCO3 and a particulate starting material;
- (ii) enzymatically generating an acid in the combined mixture during a first time period, wherein the acid generation causes a local pH decrease in the combined mixture, thereby locally dissolving at least a first portion of the CaCO3 in the combined mixture;
- and
- iii) enzymatically generating a local pH increase in the combined mixture during a second time period thereby causing at least some of the first portion of the CaCO3 to precipitate and to bind together at least part of the particulate starting material and the precipitated CaCO3, wherein one or more reagents for enzymatically generating the local pH increase and for enzymatically generating the acid are present in the combined mixture prior to enzymatically generating the acid in the combined mixture.
Dependencies are inferred from the claim text.