Unsaturated microbial cemented bio-brick making method, device and bio-brick

Abstract

The invention relates to a method, a device and a bio-brick for making bio-bricks by using an unsaturated microbial cementation method. Firstly, a pre-configured powder slag raw material and a Bacillus pasteurian bacterial liquid are mixed and added into a molding cavity, and the powder slag raw material is compacted; then, a pre-configured cementing liquid is added into the molding cavity for a curing reaction, wherein the volume of the cementing liquid introduced is equal to the volume of the Bacillus pasteurian bacterial liquid and the sum of the volumes of the cementing liquid and the Bacillus pasteurian bacterial liquid is less than the pore volume of the compacted powder slag raw material; finally, after waiting for a set curing reaction time, demoulding and drying are performed to obtain the bio-brick. The bio-brick obtained by the method of the invention has high strength.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering, and in particular to a method and device for making bio-bricks bonded with unsaturated microbial glue, and bio-bricks. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Microbial Induced Carbonate Precipitation (MICP) is a biomineralization process that is widely present in nature. The principle of microbial induced calcium carbonate precipitation is based on the secretion of urease by microorganisms through metabolism to catalyze urea in the environment to produce ammonium ions and carbonate ions. In an alkaline environment, carbonate ions and calcium ions form calcium carbonate precipitates. Due to the characteristics of MICP, such as fast reaction speed, low environmental conditions, wide application range, and significant greenhouse gas emission reduction effect, it is widely promoted and applied in many fields such as geology, civil engineering, water conservancy, and environment. This method can also be applied to building composite materials. The calcium carbonate induced by microorganisms is precipitated in the pores of the material to cement the material particles. After being cemented with loose sand, the strength of the material can reach more than 4MPa.

[0004] Patent application CN113603407A discloses a method for preparing bio-bricks by microbially induced calcium carbonate precipitation and solidification of rare earth tailings sand. First, the rare earth tailings sand is treated, and then a solidifying liquid including a bacterial solution and a binder is prepared. The solidifying liquid is then poured into the treated rare earth tailings and stirred to obtain a bio-brick raw material. The bio-brick raw material is then compacted and transferred to a mold. After solidification for 2-3 days, the bio-brick is demolded and dried to obtain a bio-brick. However, the bacterial solution and the binder are pre-mixed to form a solidifying liquid by the above method. After the bacterial solution and the binder are mixed, a precipitate will be directly generated, and the reaction is very fast. After the generated precipitate is mixed with the raw material, i.e., the rare earth tailings sand, it is easy to form a blockage, resulting in uneven distribution of calcium carbonate. Calcium carbonate is not easily adsorbed between the raw material particles, which affects the strength of the bio-brick. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method and device for making bricks by unsaturated microbial cementation, so that the strength of the prepared bio-bricks is higher.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] In the first aspect, an embodiment of the present invention provides a method for making bio-bricks by an unsaturated microbial cementation method. First, a pre-configured powder slag raw material and a Bacillus pasteurian bacterial solution are mixed and added to a molding cavity and the powder slag raw material is compacted; then, a pre-configured bonding liquid is added to the molding cavity for a curing reaction, wherein the volume of the bonding liquid fed is equal to the volume of the Bacillus pasteurian bacterial solution and the sum of the volumes of the bonding liquid and the Bacillus pasteurian bacterial solution is less than the pore volume of the compacted powder slag raw material; finally, after waiting for a set time for the curing reaction, demolding and drying are performed to obtain the bio-brick.

[0008] Optionally, the method for determining the pore volume of the powder slag raw material after compaction is: first determine the porosity of the powder slag raw material after compaction, then determine the volume occupied by the powder slag raw material in the molding cavity after compaction, and finally obtain the pore volume of the powder slag raw material after compaction according to the volume occupied by the powder slag raw material in the molding cavity and the porosity.

[0009] Optionally, the ratio of the sum of the volumes of the binder liquid and the bacterial liquid to the pore volume of the compacted powder-slag raw material is 60%-80%.

[0010] Optionally, the preparation method of the binder is: put the same mole number of calcium chloride and urea into a container, then add deionized water into the container and stir, and the calcium chloride and urea are dissolved to form a binder.

[0011] Furthermore, the concentration of calcium chloride in the binder is not greater than 1 mol / L.

[0012] Optionally, the particle size of the powder-slag raw material is less than 1 mm.

[0013] Furthermore, the preparation method of the powder slag raw material is: crushing gravel and / or slag and / or construction waste and sieving out powder slag of different diameters through a sieve, and using powder slag with a particle size of less than 1 mm as the powder slag raw material.

[0014] Optionally, in the powder residue raw materials, the powder residue with a particle size of 0.5-1mm accounts for 3%-7% of the total weight; the powder residue with a particle size between 0.4-0.5mm accounts for 60%-70% of the total weight; the powder residue with a particle size between 0.2-0.4mm accounts for 20%-30% of the total weight; the powder residue with a particle size between 0.1-0.2mm accounts for 3%-7% of the total weight.

[0015] Optionally, the compaction degree of the powder-slag raw material is not less than 95%.

[0016] In the second aspect, an embodiment of the present invention provides a device for making unsaturated microbial cemented bio-bricks based on the first aspect, including a box body, in which a plurality of cross-arranged longitudinal baffles and transverse baffles are detachably provided to form a plurality of molding cavities, the molding cavities being used to place a mixture of powder slag raw materials and Bacillus pasteurianus liquid, a cover plate being provided on the top of the box body, a liquid inlet communicating with the molding cavity being provided on the cover plate, the liquid inlet being connected to a peristaltic pump through a pipeline, the peristaltic pump being connected to a liquid storage tank for containing a binder liquid through a pipeline, a liquid outlet being provided on the bottom surface of each molding cavity, and the liquid outlet being communicated with a waste liquid pool fixed at the bottom of the box body.

[0017] Optionally, a sealing ring is provided between the top of the box body and the cover plate.

[0018] In a third aspect, an embodiment of the present invention provides a bio-brick prepared by the unsaturated microbial cementation bio-brick making method described in the first aspect.

[0019] The beneficial effects of the present invention are as follows:

[0020] 1. The brick-making method of the present invention comprises the following steps: firstly, the Bacillus pasteurian bacterial liquid and the powder-slag raw material are mixed and added into a molding cavity for compaction; then a binder is added into the molding cavity; and the Bacillus pasteurian bacterial liquid is mixed with the powder-slag raw material and then drives the added binder to undergo a curing reaction. Since the Bacillus pasteurian bacterial liquid has been evenly distributed in the powder-slag raw material, the binder reacts evenly in the powder-slag raw material, and the calcium carbonate is more evenly distributed and easily adsorbed between the powder-slag raw material particles, thereby improving the strength of the bio-brick.

[0021] 2. In the brick-making method of the present invention, the volume of the binder is equal to the volume of the Bacillus pasteurianus liquid, and the sum of the volumes of the binder and the Bacillus pasteurianus liquid is less than the pore volume of the powder residue raw material after compaction, thereby maintaining an unsaturated state. The calcium carbonate produced in the unsaturated state is distributed at the liquid bridge to form a meniscus shape, which helps to improve the strength of the bio-brick. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0023] Figure 1 is a flow chart of the method of embodiment 1 of the present invention;

[0024] Figure 2 This is a front view of the overall structure of Example 2 of the present invention;

[0025] Figure 3 is a top view of the overall structure of embodiment 2 of the present invention;

[0026] Among them, 1. liquid storage tank, 2. peristaltic pump, 3. box body, 4. molding cavity, 5. liquid inlet, 6. longitudinal baffle, 7. transverse baffle, 8. cover plate. DETAILED DESCRIPTION

[0027] Example 1

[0028] This embodiment provides a method for making unsaturated microbial cemented bio-bricks, such as Figure 1 As shown, the following steps are included:

[0029] Step 1: Mix the pre-configured powder residue raw material and the Bacillus pasteurianus liquid, pour them into the molding cavity, and compact the powder residue raw material. The compaction degree of the powder residue raw material is a set compaction degree, and the set compaction degree is not less than 95%.

[0030] Specific:

[0031] Bacillus pasteurianus (Sporosarcina pasteurii) is used as the microorganism providing urease. Bacillus pasteurianus is a facultative anaerobic bacterium and is usually cultured under aerobic conditions, but it still has a large urease activity under anaerobic conditions. It is a highly adaptable strain that can adapt to different growth conditions to a certain extent, including temperature, pH value and nutritional conditions.

[0032] The preparation method of Bacillus pasteurianus liquid is as follows:

[0033] Take part of the culture medium and pour it into a conical flask. Use an inoculation loop to take the pasteurian bacteria from the test tube and inoculate it into the culture medium. Put the inoculated culture medium into a 30°C constant temperature incubator for activation culture. The culture time is 24-48 hours. After the culture is completed, measure the concentration and enzyme activity of the bacteria, and then store the cultured bacteria in a 4°C freezer and take them out when they are used.

[0034] In this embodiment, the Bacillus pasteurianus is a strain with the American Type Culture Collection number of ATCC11859.

[0035] In the examples of this institute, the culture medium is the recommended formula CASOAGAR + urea, which specifically consists of: Pepton from casein, Pepton from soymeal, NaCl, Agar, deionized water, and the pH is adjusted to 7-7.5 with 1 mol of NaOH. After sterilization at 121° C. for 15-30 min, a 20% urea solution that has been sterilized by filtration is added.

[0036] The preparation method of powder residue raw material is:

[0037] Gravel and / or slag and / or solid construction waste are selected as raw materials, crushed by a stone crusher, and sieved out powder slag of different diameters through a sieve, and powder slag of less than 1 mm is used as powder slag raw material, and the powder slag raw material is obtained by particle ratio. In this embodiment:

[0038] The uniform density of the powder residue used is 1.5-1.7g / cm 3 , the particle ratio is:

[0039] Among the powder residue raw materials, the powder residue with a particle size of 0.5-1mm accounts for 3%-7% of the total weight; the powder residue with a particle size between 0.4-0.5mm accounts for 60-70% of the total weight; the powder residue with a particle size between 0.2-0.4mm accounts for 20-30% of the total weight; the powder residue with a particle size of 0.1-0.2mm accounts for 3%-7% of the total weight.

[0040] The porosity of the powder-slag raw material at a set compaction degree is obtained. In this embodiment, the set compaction degree is not less than 95%. The porosity of the powder-slag raw material at the set compaction degree is obtained by an infiltration method, that is, a liquid of known density is slowly injected into the powder-slag raw material at the set compaction degree, and the porosity is calculated by measuring the weight change of the powder-slag raw material and the liquid.

[0041] Step 2: Add the pre-configured binder liquid into the molding cavity for curing reaction, wherein the volume of the binder liquid fed is equal to the volume of the Bacillus pasteurianus bacterial solution and the sum of the volumes of the binder liquid and the Bacillus pasteurianus bacterial solution is less than the pore volume of the powder residue raw material after compaction.

[0042] The cementing liquid is a mixture of urea and calcium chloride, containing reactants of MICP reaction, nitrogen and calcium. The specific preparation method is: take the same mole of calcium chloride and urea, put them into a container, add deionized water and stir, and dissolve to form the cementing liquid.

[0043] Because 1 unit of urea and 1 unit of calcium chloride are consumed to produce 1 unit of calcium carbonate, the number of moles of calcium chloride and urea is the same.

[0044] Preferably, the container is a beaker.

[0045] A higher concentration of calcium chloride has an inhibitory effect on the activity of bacterial urease in the cementing fluid. Therefore, in this embodiment, the concentration of calcium chloride in the cementing fluid does not exceed 1 mol / L.

[0046] In this embodiment, the volume ratio of the binder to the Bacillus pasteurianus liquid is 1:1, and the sum of the volumes of the binder and the Bacillus pasteurianus liquid is 60%-80% of the pore volume in the powder residue raw material after compaction.

[0047] The void volume of the powder-slag raw material after compaction is obtained according to the total volume of the compacted pore powder-slag raw material and the porosity under a set compaction degree, and the total volume of the powder-slag raw material is obtained according to the volume of the molding cavity.

[0048] In this embodiment, the pore volume of the powder-slag raw material at a set compaction degree is first obtained, and then the volume of the binder and the Bacillus pasteurianus liquid can be obtained, so that the binder and the Bacillus pasteurianus liquid can be prepared.

[0049] A peristaltic pump is used to pump the pre-prepared binder liquid into the molding cavity for a curing reaction. During the curing reaction, the ambient temperature is set to 30° C. and the humidity is 20%.

[0050] Step 3: After waiting for the set time for the curing reaction, demould and dry to obtain the bio-brick.

[0051] Further, the setting time is 1-2 days.

[0052] Since the MICP reaction occurs rapidly and is prone to blockage, resulting in uneven distribution of calcium carbonate, in this embodiment, the Bacillus pasteurian liquid and the powder-slag raw material are first mixed and added to the molding cavity for compaction, and then a binder is added to the molding cavity. After the Bacillus pasteurian liquid is mixed with the powder-slag raw material, the added binder drives the added binder to undergo a curing reaction. Since the Bacillus pasteurian liquid has been evenly distributed in the powder-slag raw material, the binder reacts evenly in the powder-slag raw material, and the calcium carbonate is more evenly distributed and easily adsorbed between the powder-slag raw material particles, thereby improving the strength of the biobrick. Moreover, the volume of the binder is equal to the volume of the Bacillus pasteurian liquid, and the sum of the volumes of the binder and the Bacillus pasteurian liquid is less than the pore volume of the powder-slag raw material after compaction, thereby maintaining an unsaturated state. The calcium carbonate produced in the unsaturated state is distributed at the liquid bridge to form a meniscus shape, which helps to improve the strength of the biobrick.

[0053] Example 2

[0054] This embodiment provides a device used in the method for making bio-bricks by unsaturated microbial cementation as described in Example 1, such as Figure 2-Figure 3 As shown, it includes a box body 3, in which a plurality of cross-arranged longitudinal baffles 6 and transverse baffles 7 are detachably provided to form a plurality of molding cavities 4, and the molding cavities 4 are used to place a mixture of powder residue raw materials and Bacillus pasteurianus liquid. A cover plate 8 is buckled on the top of the box body 3, and a plurality of liquid inlets 5 are arranged on the cover plate 8, each molding cavity corresponds to a liquid inlet 5, and the liquid inlet 5 is connected with the molding cavity, and the liquid inlet 5 is connected with the peristaltic pump 2 through a pipeline, and the peristaltic pump 2 is connected with a liquid storage tank 1 for containing a binder liquid through a pipeline, and a liquid outlet 9 is arranged on the bottom surface of each molding cavity, and the liquid outlet 9 is connected with a waste liquid pool 10 fixed at the bottom of the box body 3.

[0055] Furthermore, a sealing ring is provided between the top of the box body 3 and the cover plate.

[0056] Furthermore, the longitudinal baffle 6 and the transverse baffle 7 are detachably connected to the box body 3 by bolts, so as to facilitate demoulding of the bio-bricks.

[0057] The method of using the brick making device of this embodiment is as follows:

[0058] The brick-making device is placed in an environment with a temperature of 30°C and a humidity of 20%. A layer of latex film is laid on the cavity surface of the molding cavity 4 to facilitate better pumping of the binder and demolding. A mixture of powder residue raw materials and Bacillus pasteurianus liquid is placed in the molding cavity 4. Then the cover plate 8 is replaced, the liquid inlet 5 is connected to the peristaltic pump 2 through a pipeline, and the binder is added to the liquid storage tank.

[0059] The preparation of the powder residue raw material, Bacillus pasteurianus liquid and the cementing liquid is carried out by the method described in Example 1, which will not be repeated here.

[0060] Start the peristaltic pump to pump the binder into the molding cavity 4 for a curing reaction. After 1-2 days of curing reaction, remove the cover plate, dry the prepared bio-brick, and then remove the longitudinal baffle 6 and the transverse baffle 7 for demoulding to obtain the desired bio-brick.

[0061] By adopting the device and method of this embodiment, the mass production of unsaturated microbial bricks can be achieved. In the production process, bacterial liquid and binder liquid are saved, which saves costs and improves the strength of microbial bricks, thereby better meeting masonry specifications and requirements.

[0062] Example 3

[0063] This embodiment provides a bio-brick, which is manufactured using the brick making method described in Example 1.

[0064] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. The method for making unsaturated microbial cemented bio-bricks is characterized by: First, the pre-configured powder residue raw material and Bacillus pasteurianus liquid are mixed and added into the molding cavity and the powder residue raw material is compacted; then, the pre-configured cementing liquid is added into the molding cavity for curing reaction, wherein the volume of the cementing liquid fed is equal to the volume of the Bacillus pasteurianus liquid and the sum of the volume of the cementing liquid and the volume of the Bacillus pasteurianus liquid is less than the pore volume of the compacted powder residue raw material, thereby maintaining an unsaturated state, and the calcium carbonate produced in the unsaturated state is distributed at the liquid bridge to form a meniscus shape, and finally, after waiting for the curing reaction to set time, demoulding and drying are performed to obtain the bio-brick; The ratio of the sum of the volumes of the cementing liquid and the bacterial liquid to the pore volume of the compacted powder slag raw material is 60%-80%.

2. The method for making unsaturated microbial cemented bio-bricks according to claim 1, characterized in that: The method for determining the pore volume of the powder-slag raw material after compaction is as follows: firstly, the porosity of the powder-slag raw material after compaction is determined; then, the volume occupied by the powder-slag raw material in the molding cavity after compaction is determined; and finally, the pore volume of the powder-slag raw material after compaction is obtained according to the volume occupied by the powder-slag raw material in the molding cavity and the porosity after compaction.

3. The method for making unsaturated microbial cemented bio-bricks according to claim 1, characterized in that: The preparation method of the cementing liquid is as follows: putting calcium chloride and urea in the same mole number into a container, then adding deionized water into the container and stirring, and the calcium chloride and urea are dissolved to form a cementing liquid; Furthermore, the concentration of calcium chloride in the binder is not greater than 1 mol / L.

4. The method for making unsaturated microbial cemented bio-bricks according to claim 1, characterized in that: The particle size of the powder residue raw material is less than 1 mm; Furthermore, the preparation method of the powder slag raw material is: crushing gravel and / or slag and / or construction waste and sieving out powder slag of different diameters through a sieve, and using powder slag with a particle size of less than 1 mm as the powder slag raw material.

5. The method for making unsaturated microbial cemented bio-bricks according to claim 4, characterized in that: Among the powder residue raw materials, the powder residue with a particle size of 0.5-1mm accounts for 3%-7% of the total weight; the powder residue with a particle size between 0.4-0.5mm accounts for 60-70% of the total weight; the powder residue with a particle size between 0.2-0.4mm accounts for 20-30% of the total weight; the powder residue with a particle size of 0.1-0.2mm accounts for 3%-7% of the total weight.

6. The method for making unsaturated microbial cemented bio-bricks according to claim 1, characterized in that: The compaction degree of the powder slag raw materials shall not be less than 95%.

7. A device used in the method for making unsaturated microbial cemented bio-bricks according to any one of claims 1 to 6, characterized in that: It includes a box body, which is detachably provided with a plurality of cross-arranged longitudinal baffles and transverse baffles to form a plurality of molding cavities, the molding cavities are used to place a mixture of powder residue raw materials and Bacillus pasteurianus liquid, a cover plate is provided on the top of the box body, a liquid inlet connected to the molding cavity is provided on the cover plate, the liquid inlet is connected to a peristaltic pump through a pipeline, the peristaltic pump is connected to a liquid storage tank for holding a binder liquid through a pipeline, and a liquid outlet is provided on the bottom surface of each molding cavity, which is connected to a waste liquid pool fixed at the bottom of the box body.

8. The device used in the method for making unsaturated microbial cemented bio-bricks as claimed in claim 7 is characterized in that: A sealing ring is arranged between the top of the box body and the cover plate.

9. A bio-brick, characterized in that: The brick is prepared by the unsaturated microbial cemented bio-brick making method described in any one of claims 1 to 6.

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