Mud soil carbonized brick and preparation method thereof

Abstract

The invention discloses a mucky soil carbonized brick, which is prepared from the following components in parts by weight: 40 to 50 parts of enzymolysis mucky soil, 30 to 50 parts of aggregate, 15 to 25 parts of carbonized raw materials and 0.1 to 1 part of fermentation liquor. According to the method, mucky soil with the high organic matter content serves as a main raw material and is subjected to pretreatment, glucolase hydrolysis and glucose oxidase enzymolysis to prepare enzymolysis mucky soil, then carbon dioxide is generated by combining an oxygen-enriched environment created in raw brick blanks with carbonization raw materials and fermentation liquor and combining yeast fermentation, and uniform carbonization in the bricks is effectively promoted; the compressive strength of the obtained carbonized brick meets the MU15 grade, the water soaking performance is excellent, and a new thought can be provided for high-value-added resource utilization of mucky soil; and the related preparation method is relatively simple, environment-friendly and suitable for popularization and application.

Description

Technical Field

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

[0002] Carbonized bricks are non-fired bricks, usually made of calcium materials such as cement and lime as binders, and industrial waste residues such as slag, fly ash and stone powder as aggregates and filling materials. They are made by batching, digestion and pressing (or vibration) to form, and then carbonizing the products. Carbonized bricks are generally produced using an external curing process. During the curing process, carbon dioxide diffuses from the outside of the brick to the inside, resulting in a large difference in the degree of carbonization inside and outside, making it impossible to achieve uniform carbonization.

[0003] Muddy soil is a common undesirable soil in engineering construction due to its high water content, large porosity, and high organic matter content. It cannot be used without treatment. Muddy soil with 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 muddy soil increases, it will affect the curing effect of curing agents such as cement and the strength of the solidified soil. Muddy soil with high organic matter content often contains a large amount of easily corruptible substances and pathogens. If it is not properly disposed of, it is easy to pose a threat to the ecological environment and human health. In addition, as a resource, silty soil with high organic matter content will also lead to resource waste if it is randomly piled up. Therefore, how to achieve the rational utilization of silty soil with 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 provide a carbonized brick prepared using silty soil in order to address the problems and shortcomings of the prior art. The carbonized brick has uniform internal structure, compressive strength that meets the MU15 grade, and excellent water-immersion performance, which can provide a new idea for the high-value-added resource utilization of silty soil. 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 silty soil carbonized brick, the components and their weight proportions include: 40-50 parts of enzymatically hydrolyzed silty 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 silty soil is prepared by pre-treating the original silty 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 Mg2(Si04)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 scheme, 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 scheme, the content of cellulose in the original muddy soil is 40-60wt%; and clay minerals account for 25-50wt% 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 scheme, 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 the liquid hot water method, and the inherent microbial flora is inactivated at the end of the pretreatment; the cellulose polymerization degree 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-glucase, endo-β-glucase 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 rate is 50-80%.

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

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

[0025] The above-mentioned method for preparing a silty 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 enzymolyzing the obtained hydrolyzed muddy soil with glucose oxidase to obtain enzymolyzed muddy soil;

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

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

[0030] 4) The obtained green brick is left to stand 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%; static pressure molding is adopted, and the molding pressure is 8-12MPa.

[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 silty soil carbonized bricks prepared according to the above scheme can realize high added value 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 carbon fixation rate can reach 30-70kg / m 3 .

[0034] Patent principle 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 glucose enzymes, namely, exo-β-glucosidase, endo-β-glucosidase, and β-glucosidase, are used to hydrolyze 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; first, the fermentation liquid and the enzymatically hydrolyzed silty soil are evenly mixed, which is conducive to the full contact between yeast and glucose; then, they are evenly mixed with carbonized raw materials and aggregates and statically pressed to obtain raw 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 glucose in the silty soil into CO2 and water inside the brick; CO2 in the brick dissolves in water and reacts with the carbonized raw materials to form calcium carbonate, which precipitates as calcium carbonate crystals to provide strength for the brick and is conducive to promoting the degree and uniformity of carbonization during carbonization conversion.

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

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

[0039] 2) Engineering construction often adopts the method of solidifying silty soil by adding cement, gypsum and other raw materials. When the organic matter content in the silty soil is high, a relatively high-cost solidifying agent is required. At the same time, the organic matter in the solidified silty 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 silty soil into calcium carbonate minerals, which is beneficial to carbon emission reduction and can provide a new way for the resource utilization of silty 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 (the traditional curing method of solid carbonized products mostly relies on the external environment to provide CO2), which 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 in conjunction with 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 the present application, the description of the term "some specific embodiments" means that the specific features, structures, materials or characteristics described in conjunction with the 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 one or more embodiments or examples in a suitable manner.

[0044] On the basis of the above-mentioned embodiments, the present invention provides the following specific examples to further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. The experimental methods without specifying specific conditions in the following examples are usually based on the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are calculated by mass.

[0045] In the following embodiments and comparative examples, the original silty soil is the peat soil sampled by Huaxin Cement Diqing Co., Ltd., with a natural water content 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 account for about 40wt% of its total mineral composition; the aggregate used is crushed stone with a particle size of 5 to 10mm produced by Huaxin Aggregate Yangxin Co., Ltd., with a crushing value of 15% and a mud content of 1%; the carbonized raw material is low-calcium cement provided by Huaxin Jinlong Cement (Yunxian) Co., Ltd., and its mineral composition includes C3S content of 15.8%, C2S content of 27.6%, C7MS4 content of 30.5%, CS content of 5.4%, and SiO2 content of 2.5%; the fermentation broth is prepared by 0.4 parts of commercially available yeast powder and 55 parts of sterile purified water.

[0046] In the embodiments and comparative examples, the pretreatment method of the silty 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 1.6MPa, the constant temperature and constant pressure time is 30min, the pretreatment is completed, and the cellulose polymerization degree is reduced by 53%. The commercially available exo-β-glucose enzyme (provided by Suzhou Geruisi Biotechnology Co., Ltd.), endo-β-glucose enzyme (provided by Shanghai Enzyme-Linked Biotechnology Co., Ltd.), and β-glucosidase (provided by Jiangsu Duoyang Bioengineering Technology Co., Ltd.) are used to hydrolyze the silty soil. 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 silty soil after pretreatment, respectively. The hydrolysis temperature is 50°C, the time is 48-72h, 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 silt soil after hydrolysis. The enzymolysis temperature is 35°C, the time is 24-72h, the glucose enzymolysis rate is 12%, and the moisture content of the silt soil is controlled to be 16% after enzymolysis.

[0048] The carbonized bricks are statically pressed and compacted using a customized static pressure brick machine produced by Quanzhou Liushi Machinery Company, with a static pressure molding pressure of 8 to 12 MPa. The carbonized bricks are vibration molded using a vibration brick machine provided by Gongyi Zhanjie Yucheng Machinery Factory.

[0049] Example 1

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

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

[0052] 2) adding 0.6% of exo-β-glucurase, 0.8% of endo-β-glucurase and 0.6% of β-glucosidase to the pretreated peat soil, and hydrolyzing at 50° C. for 50 h to obtain hydrolyzed peat soil, the glucose conversion rate of which was 58%;

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

[0054] 4) According to weight proportions, 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 (the moisture content is controlled to be 7.5%) is formed by static pressing at a pressure of 8 MPa to obtain a green brick;

[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. The specific test results are shown in Table 1.

[0058] Table 1 Performance 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 by weight are added to the pretreated peat soil, and the soil is 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% glucose oxidase is added to the hydrolyzed peat soil, and the 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 an enzymatically hydrolyzed peat soil with a glucose enzymatic hydrolysis rate of 9%;

[0064] In step 4), 40 parts of enzymatically hydrolyzed argillaceous soil and 0.5 parts of fermentation liquid are mixed evenly by weight, and then mixed evenly 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 a green brick;

[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: there is no step 1).

[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 exo-β-glucurase and 0.8% of endo-β-glucurase by weight are added to the pretreated peat soil, and the mixture is 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 carbon 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-mentioned embodiments. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A silty 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 enzymolyzing it with glucose oxidase.

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 fermentation liquid, the components and their weight proportions include: 0.1-0.5 parts of yeast powder and 50-70 parts of water.

6. The silt soil carbonized brick according to claim 1, characterized in that: The content of cellulose in the original muddy soil is 40-60wt%; and clay minerals account for 25-50wt% of the total mineral composition.

7. The silty soil carbonized brick according to claim 1, characterized in that: The glucose enzyme includes exo-β-glucase, endo-β-glucase and β-glucosidase.

8. 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.

9. The silty 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.

10. The method for preparing the muddy soil carbonized brick according to any one of claims 1 to 9, 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 enzymolyzing the obtained hydrolyzed muddy soil with glucose oxidase to obtain enzymolyzed 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 obtain a mixture; 3) forming the obtained mixture by static pressing to obtain green bricks; 4) The obtained green brick is left to stand for curing to obtain the silty soil carbonized brick.

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