A kind of silt soil carbonized brick and preparation method thereof

Abstract

The present invention discloses a silt soil carbonized brick, the components and their weight percentages including: 40-50 parts of enzymatically hydrolyzed silt soil, 30-50 parts of aggregate, 15-25 parts of carbonized raw materials, and 0.1-1 parts of fermentation liquid. The present invention uses silt soil with a high organic matter content as the main raw material, pre-treating it, hydrolyzing it with glucose enzyme, and enzymolyzing it with glucose oxidase to produce the enzymatically hydrolyzed silt soil. The carbonized raw materials and the fermentation liquid are then combined to create an oxygen-rich environment in the green brick, combined with yeast fermentation to generate carbon dioxide, effectively promoting uniform carbonization within the brick. The resulting carbonized brick has a compressive strength that meets the MU15 grade and excellent water-soaking performance, providing a new approach for the high-value-added resource utilization of silt soil. The preparation method involved is relatively simple, environmentally friendly, and suitable for promotion and application.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to a silt soil carbonized brick and a preparation method thereof. Background Art

[0002] Carbonized bricks are unfired bricks, typically made with calcium-based materials such as cement and lime as binders, and industrial waste residues such as slag, fly ash, and stone powder as aggregate and filler materials. They are formed through batching, digestion, and pressing (or vibration) before being carbonized. Carbonized bricks are typically produced using an external curing process. During this curing process, carbon dioxide diffuses from the exterior of the brick to the interior, resulting in significant differences in carbonization levels inside and outside the brick, making uniform carbonization impossible.

[0003] Due to its high water content, large porosity, and high organic matter content, silt soil is a common undesirable soil in engineering construction and cannot be used without treatment. Silt soil with a low organic matter content is generally solidified with high-cost curing agents such as cement and gypsum before reuse. As the organic matter content in silt soil increases, it will affect the curing effect of curing agents such as cement and the strength of the solidified soil. Silt soil with a high organic matter content often contains a large amount of easily corruptible substances and pathogens. If not properly disposed of, it can easily pose a threat to the ecological environment and human health. In addition, as a resource, silt soil with a high organic matter content will also lead to resource waste if it is randomly piled up. Therefore, how to achieve the rational utilization of silt soil with a high organic matter content has become an urgent problem to be solved. Summary of the Invention

[0004] The main purpose of the present invention is to address the problems and shortcomings of the existing technology and provide a carbonized brick prepared using silty soil. The brick has uniform internal carbonization, compressive strength that meets the MU15 grade, and excellent water-soaking performance, which can provide a new idea for the high-value-added resource utilization of silty soil; and the preparation method involved is relatively simple, environmentally friendly, and suitable for promotion and application.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A silt soil carbonized brick comprises the following components and their weight proportions: 40-50 parts of enzymatically hydrolyzed silt soil, 30-50 parts of aggregate, 15-25 parts of carbonized raw materials, and 0.1-1 part of fermentation liquid; wherein the enzymatically hydrolyzed silt soil is prepared by pre-treating the original silt soil, hydrolyzing it with glucose enzyme, and enzymolyzing it with glucose oxidase.

[0007] In the above scheme, the moisture content of the enzymatically hydrolyzed muddy soil is 15-20%.

[0008] In the above scheme, among the carbonized raw materials, C3S, C2S, C3S2, CS, C7MS4 (Ca 14The sum of the Mg2(SiO4)8) mineral content is 60-80%.

[0009] Furthermore, in the carbonized raw material, the main mineral components and their mass percentages include: C3S 0-20%, C2S 25-40%, C3S2 0-10%, CS 0-10%, and C7MS4 30-40%.

[0010] Furthermore, the carbonized raw material can be selected from one or more of ordinary Portland cement, low-calcium cement, steel slag, and magnesium slag.

[0011] In the above solution, the aggregate crushing value is ≤20%, and the mud content is <3%.

[0012] Furthermore, the aggregate can be selected from one or more of crushed stone, pebbles, recycled aggregates, etc., and the particle size thereof is 5 to 10 mm.

[0013] In the above scheme, the components and their weight proportions in the fermentation broth include: 0.1-0.5 parts of yeast powder and 50-70 parts of water (sterile purified water).

[0014] In the above solution, the cellulose content in the original muddy soil is 40-60 wt%; and the clay minerals account for 25-50 wt% of the total mineral composition.

[0015] Furthermore, the natural water content and liquid limit ratio of the original silty soil is 1.0 to 1.2; the natural porosity ratio is 1.0 to 1.5.

[0016] In the above solution, the pretreatment step reduces the degree of polymerization of cellulose, so that the degree of polymerization of cellulose is reduced by more than 30%.

[0017] In the above scheme, the pretreatment can be carried out by liquid hot water method, steam explosion method or a combination of the two methods.

[0018] Furthermore, the pretreatment preferably adopts liquid hot water method, and the inherent microbial flora is inactivated at the end of the pretreatment; the degree of polymerization of cellulose is reduced by 50-70%; and the efficiency of cellulose hydrolysis and enzymolysis in subsequent processes can be promoted.

[0019] In the above scheme, the glucose enzyme includes three types: exo-β-glucurase, endo-β-glucurase, and β-glucosidase.

[0020] Furthermore, in the glucose enzyme, the mass ratio of exo-β-glucosidase, endo-β-glucosidase and β-glucosidase is 1-4:1-2:0.5-1

[0021] Furthermore, in the glucose enzymatic hydrolysis step, the dosage of the three glucose enzymes accounts for 1 to 5% of the mass of the silty soil obtained after pretreatment.

[0022] Furthermore, in the glucose enzymatic hydrolysis step, the temperature used is 40-50° C. and the time is 48-72 hours; after the hydrolysis is completed, the obtained glucose yield is 50-80%.

[0023] In the above scheme, in the glucose oxidase enzymatic hydrolysis step, the amount of glucose oxidase used accounts for 0.01 to 0.1% of the mass of the silty soil obtained after glucose enzymatic hydrolysis.

[0024] Furthermore, in the glucose oxidase enzymatic hydrolysis step, the temperature used is 30-40° C., the time is 12-60 hours, and the enzymatic hydrolysis is completed with a glucose conversion rate of 10-30%.

[0025] The method for preparing the above-mentioned silt soil carbonized brick comprises the following steps:

[0026] 1) Preparation of enzymatically hydrolyzed muddy soil;

[0027] pre-treating the original muddy soil to obtain pre-treated muddy soil; hydrolyzing the obtained pre-treated muddy soil with glucose enzyme, and then enzymatically hydrolyzing the obtained hydrolyzed muddy soil with glucose oxidase to obtain enzymatically hydrolyzed muddy soil;

[0028] 2) Evenly mixing the enzymatically hydrolyzed muddy soil and fermentation liquid weighed according to the proportion, and then evenly mixing with the carbonized raw material and aggregate to prepare a mixture;

[0029] 3) forming the obtained mixture by static pressing to obtain green bricks;

[0030] 4) The obtained green brick is placed in a static state for curing to obtain the carbonized brick.

[0031] In the above scheme, in step 3), the moisture content of the mixture is controlled to be 5-8%; and static pressure molding is adopted with a molding pressure of 8-12 MPa.

[0032] In the above scheme, the temperature used in the static curing step of step 4) is 20-35° C., and the curing time is 1-5 days.

[0033] The silt soil carbonized bricks prepared according to the above scheme can realize high value-added utilization of solid waste resources; the compressive strength of the obtained carbonized bricks meets the MU15 grade, the softening coefficient is greater than 0.8, and the carbonization rate can reach 30-70kg / m 3 .

[0034] Principle of the patent of this invention:

[0035] The inherent structure of cellulose in silty soil has a natural anti-degradation effect on enzymes and microorganisms, and the natural degradation rate is low. The present invention first adopts a pretreatment process to promote the breaking of multiple connecting bonds in the cellulose structure, which can improve the conversion rate and efficiency of the hydrolysis process. Three types of glucose enzymes, namely exo-β-glucurase, endo-β-glucurase and β-glucosidase, are used to hydrolyze the cellulose into glucose. In the enzymatic hydrolysis process, glucose oxidase is used to enzymatically hydrolyze part of the glucose obtained by hydrolyzing the fiber to generate hydrogen peroxide.

[0036] During the mixture preparation process, the clay minerals in the silty soil provide plasticity for brick molding; the fermentation liquid and the enzymatically hydrolyzed silty soil are first mixed evenly, which is conducive to full contact between yeast and glucose; then the mixture is mixed evenly with the carbonized raw materials and aggregates and statically pressed to produce green bricks; during the static pressure curing process, hydrogen peroxide decomposes into water and oxygen, providing an oxygen-rich environment for yeast fermentation; yeast reproduces and ferments in an oxygen-rich, nitrogen-source, and carbon-source environment, and decomposes the glucose in the silty soil into CO2 and water inside the brick; the CO2 in the brick dissolves in water and reacts with the carbonized raw materials to form calcium carbonate. After the calcium carbonate crystals are precipitated, they provide strength to the brick and are conducive to promoting the degree and uniformity of carbonization during carbonization.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1) The pretreatment process of the silt soil inactivates the original bacterial flora, providing a sterile fermentation environment for the subsequent yeast fermentation. At the same time, it can effectively reduce the polymerization degree of fiber molecules, improve the subsequent cellulose hydrolysis and glucose enzymatic hydrolysis efficiency, and improve the preparation efficiency of silt soil carbonized bricks;

[0039] 2) Engineering construction often adopts the method of solidifying silty soil by adding raw materials such as cement and gypsum. When the organic matter content in the silt soil is high, a relatively high-cost solidifying agent is required. At the same time, the organic matter in the solidified silt soil releases CO2 into the external environment due to the degradation of microorganisms during the subsequent service process. The present invention proposes for the first time to transform the difficult-to-use organic matter in the silt soil into calcium carbonate minerals, which is beneficial to carbon emission reduction and can provide a new way for the resource utilization of silt soil.

[0040] 3) The oxygen-rich environment created by the green bricks of the present invention, combined with the principle of yeast fermentation to generate carbon dioxide, can effectively get rid of the current situation of traditional carbonization curing relying on curing equipment (traditional solid carbonized product curing methods mostly rely on the external environment to provide CO2), can significantly simplify the carbonization process, and is suitable for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The figure is a schematic diagram of the production process of silt soil carbonized bricks of the present invention. DETAILED DESCRIPTION

[0042] The principles and features of the present invention are described below with reference to the accompanying drawings and specific embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0043] It should be noted that, in the description of the embodiments of this application, the term "some specific embodiments" means that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same implementation or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples.

[0044] Based on the above embodiments, the present invention is further described in the following specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. Experimental methods in the following examples, where specific conditions are not specified, generally follow the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are calculated by mass.

[0045] In the following examples and comparative examples, the original silt soil used was peat soil sampled from Huaxin Cement Diqing Co., Ltd., with a natural water-to-liquid limit ratio of 1.1, a natural porosity ratio of 1.3, and a cellulose content of 53wt% measured by titration. Illite, kaolinite, montmorillonite, and chlorite clay minerals accounted for approximately 40wt% of its total mineral composition; the aggregate used was crushed stone with a particle size of 5 to 10 mm produced by Huaxin Aggregate Yangxin Co., Ltd., with a crushing value of 15% and a mud content of 1%; the carbonization raw material was low-calcium cement provided by Huaxin Jinlong Cement (Yunxian) Co., Ltd., and its mineral composition contained a C3S content of 15.8%, a C2S content of 27.6%, a C7MS4 content of 30.5%, a CS content of 5.4%, and a SiO2 content of 2.5%; the fermentation broth was prepared by 0.4 parts of commercially available yeast powder and 55 parts of sterile purified water.

[0046] In the examples and comparative examples, the pretreatment method of the silt soil mentioned above adopts the liquid hot water method, the equipment adopts the autoclave produced by Zhucheng Luguantong Company, the pretreatment constant temperature is 200 ° C, the constant pressure in the autoclave is controlled by the pressure control system to be 1.6 MPa, the constant temperature and constant pressure time are 30 min, the pretreatment is completed, and the cellulose polymerization degree is reduced by 53%. The silt soil is pretreated by hydrolysis using three glucose enzymes: commercially available exo-β-glucosidase (provided by Suzhou Geruisi Biotechnology Co., Ltd.), endo-β-glucosidase (provided by Shanghai Enzyme-Linked Biotechnology Co., Ltd.), and β-glucosidase (provided by Jiangsu Duoyang Bioengineering Technology Co., Ltd.). The dosage of the three glucose enzymes accounts for 0.3-0.7%, 0.5-1.0%, and 0.5-1.0% of the weight of the silt soil after pretreatment, respectively. The hydrolysis temperature is 50 ° C, the time is 48-72 h, and the glucose conversion rate is 55-76%.

[0047] The glucose oxidase used is commercially available, and its dosage after hydrolysis accounts for 0.02-0.05% of the weight of the hydrolyzed silt soil. The enzymatic hydrolysis temperature is 35°C, the time is 24-72h, the glucose enzymatic hydrolysis rate is 12%, and the moisture content of the silt soil is controlled to be 16% after enzymatic hydrolysis.

[0048] Carbonized bricks are statically pressed and pressed using a customized static pressure brick machine produced by Quanzhou Liushi Machinery Company, with a static pressure molding pressure of 8 to 12 MPa for brick blanks; carbonized bricks are vibrated and formed using a vibrating brick machine provided by Gongyi Zhanjie Yucheng Machinery Factory.

[0049] Example 1

[0050] A silt soil carbonized brick, the preparation method of which comprises the following steps:

[0051] 1) Place peat soil in a container filled with water in an autoclave, heat to 160° C., 0.6 MPa saturated water vapor pressure, and autoclave for 12 minutes to obtain pretreated peat soil;

[0052] 2) Pre-treating peat soil by adding 0.6% exo-β-glucurase, 0.8% endo-β-glucurase, and 0.6% β-glucosidase, based on its weight, and hydrolyzing at 50°C for 50 hours to obtain hydrolyzed peat soil with a glucose conversion rate of 58%;

[0053] 3) adding 0.02% by weight of glucose oxidase to the hydrolyzed peat soil, performing enzymatic hydrolysis at 35° C. for 48 hours, controlling the moisture content of the peat soil to 16%, and obtaining an enzymatically hydrolyzed peat soil with a glucose enzymatic hydrolysis rate of 12%;

[0054] 4) According to parts by weight, 45 parts of enzymatically hydrolyzed argillaceous soil and 0.3 parts of fermentation liquid were mixed evenly, and then mixed evenly with 37 parts of crushed stone and 18 parts of low-calcium cement to prepare a mixture;

[0055] 5) The obtained mixture (moisture content is controlled to be 7.5%) is formed by static pressing at a pressure of 8 MPa to obtain green bricks;

[0056] 6) Place the obtained green brick at 30°C and let it stand for 3 days to obtain a carbonized brick.

[0057] The carbonized bricks obtained in this example were tested for performance, and the specific test results are shown in Table 1

[0058] Table 1 Properties of carbonized bricks obtained in Example 1

[0059] <![CDATA[Unit weight (kg / m 3 )]]> Compressive strength (MPa) Softening coefficient <![CDATA[Carbon absorption amount (kg / m 3 )]]> 2012 16.5 0.85 47.5

[0060] Example 2

[0061] A silty soil carbonized brick, the preparation method of which is different from that of Example 1 in that:

[0062] In step 2), 0.6% of exo-β-glucurase, 0.8% of endo-β-glucurase, and 0.6% of β-glucosidase were added to the pretreated peat soil, and the mixture was hydrolyzed at 50° C. for 70 h to obtain hydrolyzed peat soil with a glucose conversion rate of 75%;

[0063] In step 3), 0.02% by weight of glucose oxidase was added to the hydrolyzed peat soil, and the enzymatic hydrolysis was carried out at 35° C. for 48 hours, and the moisture content of the peat soil was controlled to 16%, thereby obtaining an enzymatic hydrolysis rate of glucose in the hydrolyzed peat soil of 9%;

[0064] In step 4), 40 parts of enzymatically hydrolyzed argillaceous soil and 0.5 parts of fermentation liquid were mixed uniformly by weight, and then mixed uniformly with 35 parts of crushed stone and 25 parts of low-calcium cement to prepare a mixture;

[0065] In step 5), the obtained mixture (moisture content is controlled to be 6.9%) is formed by static pressing at a molding pressure of 12 MPa to obtain green bricks;

[0066] In step 6), the obtained green brick is placed at 30° C. and allowed to stand for 5 days to obtain a carbonized brick.

[0067] The carbonized bricks obtained in this example were tested for performance. The specific test results are shown in Table 2.

[0068] Table 2 Performance of carbonized bricks obtained in Example 2

[0069] <![CDATA[Unit weight (kg / m 3 )]]> Compressive strength (MPa) Softening coefficient <![CDATA[Carbon absorption amount (kg / m 3 )]]> 2055 18.3 0.81 68.4

[0070] Comparative Example 1

[0071] A silty soil carbonized brick, the preparation method of which is different from that of Example 1 in that: step 1) is omitted.

[0072] The carbonized bricks obtained in this comparative example were subjected to performance testing, and the specific test results are shown in Table 3.

[0073] Table 3 Performance of carbonized bricks obtained in Comparative Example 1

[0074] <![CDATA[Unit weight (kg / m 3 )]]> Compressive strength (MPa) Softening coefficient <![CDATA[Carbon absorption amount (kg / m 3 )]]> 2008 10.3 0.78 34.2

[0075] Comparative Example 2

[0076] A silty soil carbonized brick, the preparation method of which is different from that of Example 1 in that:

[0077] In step 2), 0.6% of the weight of exo-β-glucurase and 0.8% of the weight of endo-β-glucurase were added to the pretreated peat soil, and the mixture was hydrolyzed at 50° C. for 50 h to obtain hydrolyzed peat soil without glucose production;

[0078] In step 3), 0.02% by weight of glucose oxidase is added to the hydrolyzed peat soil, and the enzymatic hydrolysis is carried out at 35° C. for 48 hours, and the moisture content of the peat soil is controlled to be 16%, thereby obtaining enzymatically hydrolyzed peat soil.

[0079] The carbonized bricks obtained in this comparative example were subjected to performance testing, and the specific test results are shown in Table 4.

[0080] Table 4 Performance of carbonized bricks obtained in Comparative Example 2

[0081] <![CDATA[Unit weight (kg / m 3 )]]> Compressive strength (MPa) Softening coefficient <![CDATA[Carbon absorption amount (Kg / m 3 )]]> 2016 2.5 0.67 /

[0082] Comparative Example 3

[0083] A silty soil carbonized brick, the preparation method of which is different from that of Example 2 in that: in step 4), 45 parts of enzymatically hydrolyzed silty soil, 37 parts of crushed stone, and 18 parts of low-calcium cement are mixed uniformly by weight to prepare a mixture.

[0084] The carbonized bricks obtained in this comparative example were subjected to performance testing, and the specific test results are shown in Table 5.

[0085] Table 5 Performance of carbonized bricks obtained in comparative example 3

[0086] <![CDATA[Unit weight (kg / m 3 )]]> Compressive strength (MPa) Softening coefficient <![CDATA[Carbon absorption amount (kg / m 3 )]]> 2028 2.3 0.65 /

[0087] Comparative Example 4

[0088] A silty soil carbonized brick, the preparation method of which is different from that of Example 2 in that: in step 5), the obtained mixture (moisture content is controlled to be 6.9%) is formed by vibration molding with a vibration frequency of 30 Hz, an amplitude of 15 mm, and a vibration duration of 5 s to obtain a green brick.

[0089] The carbonized bricks obtained in this comparative example were subjected to performance testing, and the specific test results are shown in Table 6.

[0090] Table 6 Performance of carbonized bricks obtained in Comparative Example 4

[0091] <![CDATA[Unit weight (kg / m 3 )]]> Compressive strength (MPa) Softening coefficient <![CDATA[Carbon absorption amount (kg / m 3 )]]> 1965 12.1 0.55 26.7

[0092] The present invention is not limited to the above-described embodiments. Persons skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are deemed to be within the scope of protection of the present invention. Any matters not described in detail in this specification constitute prior art known to those skilled in the art.

Claims

1. A silt soil carbonized brick, characterized in that: The components and their weight proportions include: 40-50 parts of enzymatically hydrolyzed muddy soil, 30-50 parts of aggregate, 15-25 parts of carbonized raw materials, and 0.1-1 part of fermentation liquid; wherein the enzymatically hydrolyzed muddy soil is prepared by pre-treating the original muddy soil, hydrolyzing it with glucose enzyme, and then hydrolyzing it with glucose oxidase; The fermentation liquid comprises the following components and their weight proportions: 0.1-0.5 parts of yeast powder and 50-70 parts of water; The cellulose content in the original muddy soil is 40-60 wt%; clay minerals account for 25-50 wt% of the total mineral composition; The glucose enzyme includes exo-β-glucase, endo-β-glucase, and β-glucosidase; The pretreatment adopts one of a liquid hot water method and a steam explosion method or a combination of the two.

2. The silt soil carbonized brick according to claim 1, characterized in that: In the carbonized raw material, the sum of the contents of C3S, C2S, C3S2, CS, and C7MS4 minerals is 60-80%.

3. The silt soil carbonized brick according to claim 1, characterized in that: The carbonized raw material is one or more of ordinary Portland cement, low-calcium cement, steel slag, and magnesium slag.

4. The silt soil carbonized brick according to claim 1, characterized in that: The aggregate crushing value is ≤20%, and the mud content is <3%.

5. The silt soil carbonized brick according to claim 1, characterized in that: In the glucose enzymatic hydrolysis step, the temperature used is 40-50° C. and the time is 48-72 hours.

6. The silt soil carbonized brick according to claim 1, characterized in that: In the glucose oxidase enzymolysis step, the temperature used is 30-40° C. and the time is 12-60 hours.

7. The method for preparing the silt soil carbonized brick according to any one of claims 1 to 6, characterized in that: The following steps are involved: 1) Preparation of enzymatically hydrolyzed muddy soil; pre-treating the original muddy soil to obtain pre-treated muddy soil; hydrolyzing the obtained pre-treated muddy soil with glucose enzyme, and then enzymatically hydrolyzing the obtained hydrolyzed muddy soil with glucose oxidase to obtain enzymatically hydrolyzed muddy soil; 2) Evenly mixing the enzymatically hydrolyzed muddy soil and fermentation liquid weighed according to the proportion, and then evenly mixing with the carbonized raw material and aggregate to prepare a mixture; 3) The obtained mixture is formed by static pressing to produce green bricks; 4) The obtained green bricks are left to stand for curing to obtain the silt soil carbonized bricks.

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