CN114131733A - Preparation method and production line of green concrete composite material - Google Patents
Preparation method and production line of green concrete composite material Download PDFInfo
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- CN114131733A CN114131733A CN202111630641.1A CN202111630641A CN114131733A CN 114131733 A CN114131733 A CN 114131733A CN 202111630641 A CN202111630641 A CN 202111630641A CN 114131733 A CN114131733 A CN 114131733A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B15/00—General arrangement or layout of plant ; Industrial outlines or plant installations
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B1/00—Producing shaped prefabricated articles from the material
- B28B1/52—Producing shaped prefabricated articles from the material specially adapted for producing articles from mixtures containing fibres, e.g. asbestos cement
- B28B1/525—Producing shaped prefabricated articles from the material specially adapted for producing articles from mixtures containing fibres, e.g. asbestos cement containing organic fibres, e.g. wood fibres
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B11/00—Apparatus or processes for treating or working the shaped or preshaped articles
- B28B11/24—Apparatus or processes for treating or working the shaped or preshaped articles for curing, setting or hardening
- B28B11/245—Curing concrete articles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B17/00—Details of, or accessories for, apparatus for shaping the material; Auxiliary measures taken in connection with such shaping
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B3/00—Producing shaped articles from the material by using presses; Presses specially adapted therefor
- B28B3/006—Pressing by atmospheric pressure, as a result of vacuum generation or by gas or liquid pressure acting directly upon the material, e.g. jets of compressed air
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
- D21B1/00—Fibrous raw materials or their mechanical treatment
- D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
- D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
- D21B1/30—Defibrating by other means
- D21B1/34—Kneading or mixing; Pulpers
- D21B1/345—Pulpers
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- Manufacturing & Machinery (AREA)
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- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
本发明公开了一种青砼复合材料的制备方法和生产线，本发明以可再生的植物纤维和大规模工业生产的磨细水泥为主要原料，用添加剂、高效减水剂、超细粉进行调整，在制备过程中，首先在植物纤维离解时加入添加剂制得机械浆，接着将机械浆与磨细水泥在磨机中混合并加入高效减水剂制得纤维水泥浆，再加入超细粉调整后成型，制得标准板材、管材和型材以及非标零部件，然后在碳化釜中用超临界二氧化碳浸渍处理使青砼预制件快速碳化，最后对其表面进行修整和防腐耐磨处理制得青砼复合材料产品。本发明可实现工业规模制备的青砼复合材料，具有高强耐久可加工的特点，还能每吨固碳0.35吨以上，并可以规模化替代金属和塑料，每吨减排超过2吨。
The invention discloses a preparation method and production line of a green concrete composite material. The invention uses renewable plant fibers and large-scale industrially produced ground cement as main raw materials, and is adjusted with additives, superplasticizers and ultrafine powders. , in the preparation process, firstly add additives to make mechanical pulp when plant fibers dissociate, then mix mechanical pulp and ground cement in a mill and add superplasticizer to make fiber cement slurry, and then add ultrafine powder to adjust After forming, standard plates, pipes, profiles and non-standard parts are prepared, and then the green concrete prefabricated parts are rapidly carbonized by impregnation treatment with supercritical carbon dioxide in a carbonization kettle, and finally the surface is trimmed and treated with anti-corrosion and wear-resistance to obtain green concrete. Concrete composite products. The invention can realize the green concrete composite material prepared on an industrial scale, has the characteristics of high strength, durability and can be processed, can also fix more than 0.35 tons of carbon per ton, can replace metals and plastics on a large scale, and reduce emissions by more than 2 tons per ton.
Description
Technical Field
The present invention relates to the field of composite materials. More specifically, the invention relates to a preparation method and a production line of a green concrete composite material.
Background
The plant fiber produced by photosynthesis on the earth every year is more than 1500 hundred million tons, and a large amount of agricultural and forestry waste is also produced by agriculture and industrial activities of human beings every year, wherein the main component of wheat straw, rice straw and bamboo wood waste is the plant fiber, the global annual output is more than 30 hundred million tons, most of the agricultural and forestry waste is piled outside farmlands for burning or rotting, and a part of the agricultural and forestry waste is directly returned to the field, so that the pollution is caused by burning, the farmland operation and the soil ecology are influenced by returning to the field, the main treatment mode is natural degradation after piling, and the main treatment mode is also an important component of carbon dioxide circulation in the atmospheric environment. In wheat straws, rice straws and bamboo and wood wastes in agricultural and forestry wastes, the plant fiber content is very high, the content of cellulose, hemicellulose and lignin exceeds 90 percent, the plant fiber is an excellent renewable polymer material, the utilization rate is low at present, and the current industrialized application mainly comprises straw pulp papermaking, fiber density boards, fiber cement boards and the like, and accounts for less than 1 percent of the total amount.
With the development of human socioeconomic and the progress of industrial technology, the demand and the daily increase of industrial materials, the production capacity of artificial boards, pipes and profiles mainly made of metal and plastic is getting larger, the metal and plastic are high carbon materials, the accumulation of carbon emission is close to the critical value of atmospheric warming, wherein the productivity of Chinese crude steel, electrolytic aluminum, cement and plastic materials accounts for more than 50% of the whole world, meanwhile, the carbon emission accounts for more than 30% of the world, which causes the contradiction that the Chinese economic development and emission reduction are difficult to reconcile, the development of negative carbon materials is the inevitable way of reducing the productivity of industrial materials and promoting the development of socioeconomic, the renewable natural plant fiber materials become the first choice at present, the plant fibers are not only made of straw pulp paper, but also the fiber density boards and the fiber cement boards which take the plant fibers as main raw materials are common in the market, although the two materials are produced on an industrial scale, the applied products are only limited to plates, but the overall application is also limited to decoration and ornament engineering, mainly because the properties of the materials do not meet higher requirements, such as strength, water resistance, fire resistance, ultraviolet resistance, wear resistance, impact resistance and the like are low, the service life is generally not more than 15 years, and the materials cannot replace steel, aluminum alloy and plastic materials in the form of plates, pipes and profiles.
How to develop the composite material capable of replacing steel, aluminum alloy and plastic products is the key for solving the current social and economic development and emission reduction, particularly, the composite material capable of replacing metal and plastic is produced by using plant fibers in large-scale industry, the carbon dioxide discharged by natural degradation can be reduced, a large amount of carbon dioxide discharged by metal and plastic production can be reduced in large scale, and the composite material is an important way for solving the contradiction between emission reduction and development.
Disclosure of Invention
An object of the present invention is to solve at least the above problems and to provide at least the advantages described later.
The invention uses regenerative plant fiber and finely ground cement which is being produced in large scale industry as main raw materials, and uses additive, high efficiency water reducing agent, and ultra-fine powder to adjust, firstly, wood pulp machine is used to heat and crush and semi-dissociate the plant fiber, calcium magnesium sodium salt of sulfuric acid or sulfurous acid is added in dissociation process as additive to make mechanical pulp, then the mechanical pulp and finely ground cement are mixed in mill and high efficiency water reducing agent is added to make the plant fiber be ground and fully dispersed and mixed with finely ground cement base material to realize high proportion molecular level compounding, the ultra-fine powder and graded fine sand are added in the prepared fiber cement paste in mixer to adjust water content to make green concrete paste, the green concrete paste is vacuum-formed in extruder or press-vibration integrated machine to make green concrete, including standard plate, pipe and section bar and non-standard section bar and parts, then supercritical carbon dioxide dipping treatment is used to make the green concrete prefabricated member quickly carbonize, and finally, performing surface finishing and wear-resistant and anti-corrosion treatment on the carbonized green concrete prefabricated member to obtain a green concrete composite material product. The invention can realize the industrial scale preparation of the green concrete composite material, and the material not only has the characteristics of high strength, durability and processability, but also has the carbon-negative characteristic, or effectively solves the contradiction between the economic development and the carbon emission of the important material industry.
The invention aims to compound plant fiber and cement material in molecular level by physical dispersion and chemical compound technology, improve the compactness of the material by supercritical carbonization dipping technology and finish hardening quickly, so that the plant fiber is enclosed in the cement-based material permanently, the outer layer deepening treatment technology is adopted to make the surface of the composite material more compact and functional, the finally finished standard product and non-standard parts of the green concrete composite material have the appearances of metal and ceramic materials, exceed the specific strength of aluminum alloy, match the durability of ceramic and exceed the toughness of plastic, the green concrete composite material combining the toughness of the plant fiber and the rigidity of the cement material has high strength, good durability, higher compactness and good processability, has the comprehensive performance of replacing steel, aluminum alloy and plastic products, the supercritical carbonization technology shortens the production period of the material from one month to 1 day, and an enough foundation is laid for large-scale industrial production.
The green concrete composite material is different from the traditional material in that the green concrete composite material can fix and seal a large amount of carbon dioxide by utilizing plant fiber and supercritical carbonization energy, and each ton of green concrete composite material can cure and seal more than 0.35 ton of carbon dioxide, so that the green concrete composite material is a true negative carbon material, and can replace metal and plastic products on a large scale in the fields of building material engineering, mechanical manufacturing, basic construction and the like, so that a large amount of carbon dioxide discharged during metal and plastic production is greatly reduced.
To achieve these objects and other advantages in accordance with the present invention, there is provided a green concrete composite and a method for preparing the same, comprising the steps of:
step one, adding 15-45 parts by weight of plant fiber raw material and 0.3-7.5 parts by weight of additive into a wood pulp machine, heating, crushing and grinding to semi-dissociate plant fibers to prepare mechanical pulp;
step two, adding the mechanical pulp prepared in the step one, 25-57 parts by weight of ground cement and 0.3-9.5 parts by weight of high-efficiency water reducing agent into a wet mill, mixing, heating, grinding and decomposing to separate plant fibers, and dispersing in the ground cement slurry to prepare fiber cement slurry;
step three, integrally forming the fiber cement slurry prepared in the step two into a green concrete prefabricated part by extrusion or pressing vibration, wherein the green concrete prefabricated part comprises standard plates, pipes and sections, non-standard special-shaped parts and parts, and then carrying out steam pressure curing on the green concrete prefabricated part;
step four, placing the green concrete prefabricated member prepared in the step three in a carbonization kettle for vacuum degassing and dehydration, then soaking and carbonizing by using supercritical carbon dioxide, circularly carbonizing by using the carbon dioxide, reducing air discharge and improving efficiency;
and fifthly, taking out the carbonized green concrete prefabricated member from the carbonization kettle, polishing and finishing, and spraying an anticorrosive wear-resistant material on the surface of the green concrete prefabricated member.
Preferably, in the processing process of the second step, 15-35 parts by weight of ultrafine powder is added into a wet mill to adjust the water content, so that the molding is facilitated.
The preparation method closer to the invention also needs to adopt the following steps:
step one, adding 15-45 parts by weight of plant fiber raw material and 0.3-7.5 parts by weight of additive into a wood pulp machine, heating, crushing and grinding to semi-dissociate plant fibers to prepare mechanical pulp;
step two, adding the mechanical pulp prepared in the step one, 25-57 parts by weight of ground cement and 0.3-9.5 parts by weight of high-efficiency water reducing agent into a wet mill, mixing, heating, grinding and decomposing to separate plant fibers, and dispersing in the ground cement slurry to prepare fiber cement slurry;
step three, adding the fiber cement paste prepared in the step two, 15-35 parts by weight of ultrafine powder and 5-25 parts by weight of graded fine sand into a powerful stirrer, and heating and stirring to prepare green concrete paste;
step four, forming the green concrete slurry obtained in the step three to obtain a green concrete prefabricated part which comprises a plate, a pipe, a section bar and non-standard parts of standard models, and then carrying out autoclaved curing on the green concrete prefabricated part;
placing the green concrete prefabricated part prepared in the step four in a carbonization kettle for vacuum degassing and dehydration, and then soaking and carbonizing by using supercritical carbon dioxide;
and step six, taking out the carbonized green concrete prefabricated member from the carbonization kettle, polishing and finishing, and spraying an anticorrosive wear-resistant material on the surface of the prefabricated member.
In the above processing steps, the invention selects raw materials with high plant fiber content, including at least one of wheat straw, rice straw and bamboo and wood waste, the additive is sulfite solution containing at least one of calcium, magnesium, sodium and ammonia, a modifier and an activator are added during grinding, the mixing ratio of the modifier and the activator is 1: 0.3-3.4, the specific surface area of the ground cement is not less than 350m2/Kg；
Preferably, in the processing process of the first step, the heating temperature is 75-165 ℃, the crushing and grinding time is not more than 2 hours, quicklime is added into the wood pulp machine during heating, crushing and grinding, and the pH value in the wood pulp machine is adjusted to 7.5-11;
preferably, in the processing process of the second step, the heating temperature is 75-165 ℃, and the milling time is not more than 2.5 h.
It is preferable that the present invention specifies the specific surface area of the ultra-fine powder to be more than 450m for the purpose of adjusting moisture and utilizing environmentally friendly materials and improving performance2and/Kg, the superfine powder is at least one of silica fume, slag superfine powder and steel slag superfine powder, and when the superfine powder simultaneously contains the slag superfine powder and the steel slag superfine powder, the mass ratio of the slag superfine powder to the steel slag superfine powder is 1: 0.5 to 2.
The invention can also reduce the proportion of cement in the formula, wherein partial ground cement is replaced by metakaolin with equal quantity, and the fineness of the metakaolin is more than 400 meshes.
In the processing process, in order to enable the plant fiber to exert better tensile property, a circulating or multi-stage treatment process is adopted in the first definite step, so that the cell wall where the plant fiber is located is opened, cellulose, hemicellulose and lignin are not completely separated, wherein the maximum diameter of the cellulose is not more than 0.3mm, and the dissolution rate of the lignin is not more than 30%.
Preferably, after the stirring equipment is added, the heating temperature for heating and stirring is more than 95 ℃ in the processing process of the third step, the heating temperature for performing and molding the green concrete paste is more than 75 ℃ in the processing process of the fourth step, and the heating temperature for performing autoclaved curing is more than 85 ℃.
The preparation method of the green concrete composite material comprises but is not limited to a production line of the following equipment, a wood pulp machine for preparing mechanical pulp, a centrifugal mill or a vibration mill for preparing fiber cement slurry, equipment for preparing green concrete prefabricated parts, an autoclave for autoclaved curing of the prefabricated parts, a carbonization kettle for supercritical carbon dioxide impregnation treatment of the prefabricated parts and a grinding and spraying equipment for surface treatment;
the equipment for preparing the green concrete prefabricated member is a pipe extruder or a section extruder or a plate pressing and vibrating all-in-one machine of a standard prefabricated member and a mould extrusion or pressing and vibrating all-in-one machine of a non-standard prefabricated member.
Preferred is a method for preparing the green concrete composite material of the present invention, including but not limited to a production line of a wood pulp machine for preparing mechanical pulp, a centrifugal mill or a vibration mill for preparing fiber cement slurry, a powerful mixer for preparing green concrete slurry, a device for preparing green concrete preform, an autoclave for autoclave curing of the preform, a carbonization kettle for supercritical carbon dioxide impregnation treatment of the preform, and a sanding spraying device for surface treatment;
the equipment for preparing the green concrete prefabricated member is provided with a vacuum system which is communicated with a material forming cavity of the equipment for preparing the green concrete prefabricated member so as to perform vacuum prefabrication and forming, and the equipment for preparing the green concrete prefabricated member is a pipe extruder or a profile extruder or a plate pressing and vibrating all-in-one machine of a standard prefabricated member and a die extruding or pressing and vibrating all-in-one machine of a non-standard prefabricated member.
The green concrete composite material and the preparation method and production line thereof at least have the following beneficial effects:
the first step is to use wood pulp machine to dissociate plant fiber but not to completely separate cellulose, hemicellulose and lignin in the plant fiber, which is called semi-dissociation, by adding sulfate or sulfite of calcium, magnesium, sodium and ammonia as additive and controlling temperature, time and PH value in dissociation process, in crushing, heating and dissociation process, not only opening cell wall to make plant fiber diameter reach certain fineness, but also making the cellulose, hemicellulose and lignin of plant fiber open partial chemical link and not completely separate, by parameter control, the method of only cutting off a part of chemical bond is to control solubility of each component not more than 30%, and keeping temperature not less than 75 ℃ to make cellulose straighten, at the same time, the hemicellulose and lignin connected with cellulose open, active end is connected with sulfonic group and modifying group, the method has hydrophilicity, is beneficial to connecting with the active end of inorganic materials, and in the processing steps, the plant fiber raw material is determined to be at least one of wheat straw, rice straw and bamboo and wood waste.
And step two, the plant fibers are ground in a grinding machine to be continuously separated and dispersed in the cement-based material, a high-efficiency water reducing agent is added in the mixing and stirring process of the plant fibers and the cement-based material to improve the dispersion degree of the cellulose in the plant fibers and compound the cellulose with the active group of the cement-based material, wherein the active end of hemicellulose and lignin linked with the cellulose is continuously compounded with the active end of the cement-based material, the temperature and the time are controlled to ensure that the compounding rate of the active end of the lignin and the active end of the cement material is higher, the cellulose is straightened and is in a three-dimensional accumulation state in the cement-based material, the plant fibers are uniformly dispersed in the ground cement to prepare fiber cement slurry by mixing, heating and grinding, in order to increase the dispersion of the plant fibers in the cement-based material, a modifier and an active agent are added during grinding, and the mixing ratio of the modifier to the active agent is 1: 0.3-3.4, the specific surface area of the ground cement is not less than 350m2/Kg。
The third step has the effects that the water content of the fiber cement paste is effectively adjusted through the ultrafine powder and the graded fine sand added into the stirring machine, the molding is convenient, the specific surface area of the ultrafine powder is definitely larger than 450m in order to increase the using amount of the environment-friendly material and not influence the performance of the green concrete composite material2and/Kg, the superfine powder is at least one of silica fume, slag superfine powder and steel slag superfine powder, and when the superfine powder simultaneously contains the slag superfine powder and the steel slag superfine powder, the mass ratio of the slag superfine powder to the steel slag superfine powder is 1: 0.5-2, and meanwhile, the rigidity of the material is improved and the cost is reduced through grading fine sand, the prepared green concrete slurry has better plasticity and is convenient to form, and the step can be combined with the step two when the grading fine sand is not required to be added and some materials which do not need too high performance are produced, so that the investment cost can be saved, and the production efficiency is improved.
And step four, preparing the green concrete prefabricated member, wherein the green concrete prefabricated member comprises plates, pipes and sections with standard models and parts with non-standard models, and then placing the green concrete prefabricated member into an autoclave for autoclaved curing, so that the prefabricated member is quickly hardened, the manufacturing period is shortened, and in the forming process, a material forming cavity is connected with a vacuum system, so that air in the prefabricated member can be effectively removed, the porosity is reduced, and the compactness is improved, thereby effectively improving the strength of the green concrete composite material. The invention can effectively solve the problem of uncertainty of production of cement-based materials, particularly common concrete engineering, and change engineering materials into standard materials through the large-scale production of standard parts and non-standard parts, so that the production of the green concrete composite material can be changed into industrialization and large-scale production, which is the premise of large-scale industrial application.
The fifth step is used for quickly carbonizing the green concrete prefabricated part by using the supercritical carbon dioxide, because the permeability of the supercritical carbon dioxide is improved by more than 100 times than that of common gas and liquid, the carbonization efficiency can be effectively improved by adopting vacuum degassing dehydration before carbonization, the influence of water vapor and air on the supercritical carbon dioxide is reduced, and the carbonized green concrete composite material has the compactness comparable to that of metal and plastic and has three important functions: one is that the strength can be improved by more than 50 percent, the other is that the plant fiber can be completely sealed in the material, the oxidation and degradation loss of the biological material is basically solved, the service life of the material can reach more than 100 years, and the more important function is that the hardening time of the cement-based material can be shortened from 75 percent of 28 days to more than 3 hours and 85 percent of 85 percent by the rapid carbonization of the supercritical carbon dioxide, namely the manufacturing period is shortened from one month to 1 day, which is a revolutionary progress for the large-scale production of industrial materials and is also the key for the large-scale industrial production of the green concrete material.
And sixthly, the outer layer of the green concrete material is more compact and functional, the green concrete material can have the appearance of a metal or ceramic material, and simultaneously, the green concrete can have better compactness, better closure to biological materials, stronger functionality, more attractiveness and higher durability by polishing and finishing the carbonized material and deepening the outer layer, such as PVD (physical vapor deposition), electrostatic spraying, ion spraying of an anti-corrosion and wear-resistant material and the like.
Through the above description, it can be seen that the preparation method and the production line of the green concrete composite material have the advantages that the main devices in the steps and the production line are all absent, the production line composed of the devices provided by the invention is an important device for preparing the green concrete composite material, and the performance of the green concrete composite material and the performance of the plant fiber material and the cement-based material in the current market are revolutionarily changed through the organic combination of the devices, so that the green concrete composite material not only realizes large-scale carbon fixation and is a true negative carbon material, but also has excellent performance of replacing metal and plastic on a large scale, can realize large-scale emission reduction, and can effectively solve the contradiction between economic development and emission reduction.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Drawings
FIG. 1 is a schematic view of the manufacturing steps and production line of the present invention;
FIG. 2 is a schematic view of the addition of stirring steps and equipment in the preparation of the present invention.
Detailed Description
The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.
It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials, if not otherwise specified, are commercially available; in the description of the present invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
Example 1, according to the green concrete composite material and the preparation method and the production line thereof provided by the present invention, the green concrete composite material is prepared according to the following steps, and the production line of the green concrete composite material used in this example comprises a wood pulp machine for preparing mechanical pulp, a centrifugal mill or a vibration mill for preparing fiber cement slurry, equipment for preparing a green concrete prefabricated member (a pipe extruder or a profile extruder or a plate pressing and vibrating all-in-one machine of a standard product prefabricated member), an autoclave for performing autoclave curing of the prefabricated member and a carbonization kettle for performing supercritical carbon dioxide impregnation treatment on the prefabricated member. The green concrete composite material and the preparation method thereof comprise the following steps as shown in figure 1:
step one, adding 35 parts by weight of plant fiber raw materials and 3.5 parts by weight of additives into a wood pulp machine, heating, crushing and grinding to enable the plant fibers to be semi-dissociated to prepare mechanical pulp, wherein the plant fibers are cut into wheat straws for use, and the additives are calcium sulfite and sodium sulfite according to the weight ratio of 1: 1, mixing to reduce the use amount of sodium, heating at 150 ℃ during dissociation, crushing and dissociating for 1h, adding a container to be connected with a wood pulp machine in parallel, adopting a circulation treatment process, and controlling time, temperature and pH value to open cell walls where plant fibers are located, wherein cellulose, hemicellulose and lignin are not completely separated, the maximum diameter of the cellulose is not more than 0.3mm, and the dissolution rate of the lignin is not more than 30%;
step two, adding the mechanical pulp prepared in the step one, 47 parts by weight of ground cement and 2.5 parts by weight of high-efficiency water reducing agent into a wet centrifugal mill or a vibration mill, mixing, heating, grinding and hydrolyzing to modify plant fibers and the ground cement to prepare fiber cement paste, wherein the high-efficiency water reducing agent is a polycarboxylic acid water reducing agent, the concentration of the polycarboxylic acid water reducing agent is 25%, the heating temperature is 145 ℃, the grinding time is 1.5h, and ultrafine powder with the specific surface area of 550m is added in the later stage2The superfine powder is prepared by mixing silica fume, slag superfine powder and steel slag superfine powder according to the proportion of 1: 1: 1, the moisture content is lower than 18 percent;
step three, molding the fiber cement slurry prepared in the step two to prepare a green concrete prefabricated part, wherein the green concrete prefabricated part comprises plates, pipes and sections of standard models and parts of non-standard models, and then performing autoclaved curing on the green concrete prefabricated part;
step four, placing the prefabricated part prepared in the step three in a carbonization kettle for vacuum degassing and dehydration, and then soaking and carbonizing by using supercritical carbon dioxide, wherein the vacuum degree and the pressure are controlled to be 0.05MPa, and the supercritical carbon dioxide adopts circulating equipment, so that the reuse rate of the carbon dioxide is improved;
and fifthly, taking out the carbonized green concrete prefabricated member from the carbonization kettle, polishing and finishing, and then electrostatically spraying an anticorrosive wear-resistant material on the surface of the prefabricated member.
The green concrete composite material sample prepared in the embodiment 1 is calculated to reach 0.38 ton of carbon fixation per ton and exceed the standard of a negative carbon material, the compressive strength of the prepared section bar exceeds 350MPa, the tensile strength is not lower than 50 percent of the compressive strength, the strength reaches the aluminum alloy standard, the durability passes through multiple tests of impermeability, freezing and thawing resistance and sulfate corrosion resistance such as freezing and thawing, ultraviolet, rain, salt mist and the like, the impermeability grade reaches P15, 300 times of freezing and thawing cycles, the mass loss rate is less than 0.02 percent, the salt mist test cycles 80 times, the mass loss is less than 0.1 percent, the indexes far exceed the high-performance concrete, and the pressure resistance of the prepared sealed container reaches the common PVC standard. (in this example, the following examples and comparative examples, the strength test Standard "concrete Strength test evaluation Standard" B/T50107-2010, the durability test Standard "concrete durability test evaluation Standard" JGJ @ T193-2009, the salt fog test Standard "national salt fog test Standard" GB6458-86 "were used)
Embodiment 2, on the basis of embodiment 1, during crushing dissociation in the step one, quicklime is also added during crushing dissociation for 40min, and the pH value in a wood pulp machine is adjusted to 7.5-11; and during grinding in the second step, adding a modifier and an activator, wherein the mixing ratio of the modifier to the activator is 1: 1, the total weight of the modifier and the activator is 4.5 parts;
the green concrete composite material sample prepared in the embodiment 2 is calculated to reach 0.4 ton of carbon fixation per ton and exceed the standard of a negative carbon material, the compressive strength of the prepared section bar exceeds 360MPa, the tensile strength is not lower than 60 percent of the compressive strength, the strength reaches the aluminum alloy standard, the durability passes through multiple tests of impermeability, freezing and thawing resistance and sulfate corrosion resistance such as freezing and thawing, ultraviolet, rain, salt mist and the like, the impermeability grade reaches P15, 300 times of freezing and thawing cycles, the mass loss rate is less than 0.02 percent, the salt mist test cycles 80 times, the mass loss is less than 0.1 percent, the indexes far exceed the high-performance concrete, and the pressure resistance of the prepared sealed container reaches the common PVC standard.
Example 3, according to the green concrete composite material and the preparation method and the production line thereof provided by the present invention, the green concrete composite material with higher rigidity is prepared according to the following steps, and the production line of the green concrete composite material used in this example includes a wood pulp machine for preparing mechanical pulp, a centrifugal mill or a vibration mill for preparing fiber cement slurry, a powerful mixer for preparing green concrete slurry, equipment for preparing a green concrete preform (a pipe extruder or a profile extruder or a plate pressing and vibrating all-in-one machine of a standard product preform), an autoclave for autoclave curing the green concrete preform, and a carbonization kettle for supercritical carbon dioxide impregnation treatment of the green concrete preform. The green concrete composite material and the preparation method thereof comprise the following steps as shown in figure 2:
step one, adding 35 parts by weight of plant fiber raw materials and 3.5 parts by weight of additives into a wood pulp machine, heating, crushing and grinding to enable the plant fibers to be semi-dissociated to prepare mechanical pulp, wherein the plant fibers are cut into wheat straws for use, and the additives are calcium sulfite and sodium sulfite according to the weight ratio of 1: 1 mixing to reduce the amount of sodium used, the other parameters being performed as in example 1;
step two, adding the mechanical pulp prepared in the step one, 47 parts by weight of ground cement and 2.5 parts by weight of high-efficiency water reducing agent into a wet centrifugal mill or a vibration mill, mixing, heating, grinding and hydrolyzing to modify plant fibers and the ground cement to prepare fiber cement paste, wherein the modifier adopts a silane coupling agent, and other parameters are carried out according to the embodiment 1;
and step three, adding the fiber cement paste prepared in the step two, 17 parts by weight of ultrafine powder and 15 parts by weight of graded fine sand into a strong mixer, and adjusting the water content to be lower than 20%. Heating and stirring to prepare green concrete slurry, wherein in the stirring process, the heating temperature is more than 98 ℃, and other parameters are executed according to the embodiment 1;
step four, forming the green concrete slurry obtained in the step three to obtain a green concrete prefabricated part, wherein the green concrete prefabricated part comprises standard plates, pipes, profiles, non-standard special-shaped parts and parts, the heating temperature of the green concrete slurry during the prefabricated forming is 85 ℃, and then the green concrete prefabricated part is subjected to autoclaved curing, and the heating temperature of the prefabricated part during the autoclaved curing is 85 ℃;
placing the green concrete prefabricated part prepared in the step four in a carbonization kettle for vacuum degassing and dehydration, and then soaking and carbonizing by using supercritical carbon dioxide;
taking out the carbonized green concrete prefabricated member from the carbonization kettle, polishing and finishing, and spraying an anticorrosive wear-resistant material on the surface of the prefabricated member;
the above procedure was modified with reference to example 1, and the same procedures and data were referenced to example 1.
Example 3 for comparison, the plant fiber is still selected from wheat straw, the ultrafine powder is selected from the same materials and proportions as in example 1, each ton of carbon fixation of the prepared green concrete composite material sample reaches 0.42 ton, and exceeds the standard of a negative carbon material, the compressive strength of the prepared section bar is 360MPa, the tensile strength exceeds the compressive strength of 40%, the strength is close to the aluminum alloy standard, the durability is tested by multiple tests of impermeability, frost resistance and erosion resistance such as freeze thawing, ultraviolet, rain, salt fog and the like, the result is close to that in example 1, the high-performance concrete standard is reached, and the pressure-resistant sealing performance of the prepared sealed container reaches the common PVC standard.
Embodiment 4, on the basis of embodiment 3, during the crushing dissociation in the step one, quicklime is also added during the crushing dissociation for 40min, and the pH value in the wood pulp machine is adjusted to 7.5-11; and during grinding in the second step, adding a modifier and an activator, wherein the mixing ratio of the modifier to the activator is 1: 1, the total weight of the modifier and the activator is 4.5 parts;
the carbon fixation of each ton of the green concrete composite material sample prepared in the embodiment 4 reaches 0.43 ton and exceeds the standard of a negative carbon material, the compressive strength of the prepared section bar is 370MPa, the tensile strength exceeds 40 percent, the strength is close to the standard of aluminum alloy, the durability is subjected to multiple tests of impermeability, frost resistance and erosion resistance such as freeze thawing, ultraviolet, rain, salt spray and the like, the result is close to that of the embodiment 1, the high-performance concrete standard is reached, and the pressure-resistant sealing performance of the prepared sealing container reaches the common PVC standard.
Example 5, the test ground cement is replaced by metakaolin in equal amount, on the basis of example 2, the cement is replaced by metakaolin in equal amount, the replacement amount is 50%, the fineness of metakaolin is more than 800 meshes, and all other steps and parameters are finished according to the steps of example 2 by referring to example 2;
the carbon fixation of each ton of the green concrete composite material sample prepared in the embodiment 5 reaches 0.36 ton and exceeds the standard of a negative carbon material, the compressive strength of the prepared section is 320MPa, the tensile strength is 55 percent of the compressive strength, the strength ratio is higher than that of the embodiment 1 and the embodiment 2, the strength also reaches the standard of aluminum alloy, the durability passes through multiple tests of impermeability, frost resistance and erosion resistance such as freeze thawing, ultraviolet rays, rain, salt mist and the like, the comprehensive performance exceeds the embodiment 1 and the embodiment 3, the high-performance concrete standard is reached, and the pressure-resistant sealing performance of the prepared sealed container reaches the standard of common PVC.
Example 6, on the basis of example 3, the sequence of the production line disclosed in the present invention is followed, and the production line of the green concrete composite material used in the above examples comprises a wood pulp machine for preparing mechanical pulp, a centrifugal mill or a vibration mill for preparing fiber cement slurry, a powerful mixer for preparing green concrete slurry, a device for preparing a green concrete preform, an autoclave for autoclave curing the preform and a carbonization kettle for supercritical carbon dioxide impregnation treatment of the preform, in this example, the device for preparing the green concrete preform is communicated with a material forming cavity by a vacuum system to perform the material in a vacuum state, the device for preparing the green concrete preform is a pipe extruder or a profile extruder or a plate pressing and vibrating all-in-one machine of a standard product preform and a mold extruding or pressing and vibrating molding machine of a non-standard preform, the density of the finally finished sample is improved by 15 percent, and the strength is improved by 20 percent compared with the original strength.
Comparative example 1, a fiber density board product with a larger production capacity and plant fiber as a main raw material, in the instruction, the conventional specification is (length x width): 2440mm 1220mm thick (high): 6mm 8mm 12mm,15mm16mm 18mm, the strength index is as follows: indexes such as bending strength, tensile strength, water content, nail holding force, water absorption expansion rate, formaldehyde content and the like are all superior to national standards of GB _ T31765-.
Comparative example 2, the vegetable fibre cement material selected to be on the market was a building material developed in the early eighties of the twentieth century to replace asbestos. Due to the many advantages and good quality of this material, it has spread to date throughout australia, america, europe. In the United states, the sales are in the first place of the market, more than three million users exist, and the market share reaches more than eighty-five percent. The most common plant fiber cement hanging plate in the market at present is made of natural fiber cement (also called strong plant fiber cement), and the components of the plant fiber cement hanging plate comprise special plant fiber, cement, natural river sand, water and a small amount of chemical additives, and the plant fiber cement hanging plate does not contain asbestos, glass fiber and formaldehyde. The product provides physical and chemical properties superior to similar products, has the appearance and excellent properties of wood materials, is fireproof, does not decay and is almost free from maintenance, is mainly used for outer facade decoration and transformation of villas, factory buildings and houses, building roof decoration, indoor wall decoration, suspended ceilings, partition walls and retaining walls, indoor and outdoor ground decoration, grille fences and various garden building shapes and accessories at present, is mainly used for replacing the original materials such as wood boards, PVC hanging boards and the like so as to avoid the defects of easy aging, mildew, corrosion, flammability and the like, has wide application, is environment-friendly, has the standard requirement of the bending strength of the plant fiber board of more than 14MPa, has the bending strength of 18MPa after a detected sample, is superior to high-density board materials, but has at least one order of magnitude difference compared with metal materials. Compared with the green concrete composite material, the green concrete composite material has more complex manufacturing procedures, adopts the processes of vacuum forming, supercritical carbonization and the like, greatly improves the strength and the density, greatly improves the durability through surface treatment, has the strength and the processability for manufacturing pipes and profiles, has the foundation and the condition for replacing metal and plastic materials, and does not have the basic performance for replacing metal and plastic in the current plant fiber cement board on the market.
Comparative example 3, in the manufacturing process, step 1 of example 1 is not subjected to acid-base control, the heating temperature is less than 75 ℃, the temperature is less than the temperature requirement specified in the claims, the strength of the obtained material is slightly higher than that of comparative example 2, the strength is far lower than that of the green concrete material of example 1, the density is about 15 percent lower, the durability test is obviously reduced, the permeation resistance grade P8 is 300 times of freeze-thaw cycles, the mass loss rate is less than 0.2 percent, the salt spray test is repeated 80 times, and the mass loss is less than 1 percent.
Comparative example 4, the carbonization process in the fifth step of example 2 was omitted, supercritical impregnation was replaced with carbon dioxide gas pressurization, and the strength of the obtained material was reduced by about 50% in both compressive and tensile strengths, the durability test was also significantly reduced, the permeation resistance rating P13, 300 freeze-thaw cycles, the mass loss rate was less than 0.5%, the salt spray test was 80 cycles, and the mass loss was less than 2% as compared with example 2.
Comparative example 5, comparing with example 2, the proportion of the plant fiber raw material is reduced to 13 parts by weight, the proportion of the cement is increased to 62 parts by weight, and compared with example 2, the strength of the obtained material is basically unchanged, the tensile strength is reduced by about 30%, the durability test is also obviously reduced, the impermeability grade is P13, 300 times of freeze-thaw cycles, the mass loss rate is less than 0.4%, the salt spray test is cycled for 80 times, and the mass loss is less than 1.5%.
Comparative example 6, comparing with example 2, in the processing procedure of the third step, the heating temperature of heating and stirring is above 65 ℃, in the processing procedure of the fourth step, the heating temperature of the green concrete slurry during prefabrication and molding is above 55 ℃, the heating temperature of the prefabricated part during autoclave curing is 75 ℃, compared with the material strength of the example 2, the compression resistance is basically unchanged, the tensile strength is averagely reduced by about 20%, the durability test is not changed greatly, the impermeability grade P14 is subjected to 300 times of freeze-thaw cycles, the mass loss rate is less than 0.02%, and the salt spray test is subjected to 80 times of freeze-thaw cycles, and the mass loss is less than 0.5%.
The comparative examples can conclude that the green concrete composite material has obvious difference and improvement in the preparation and performance compared with the traditional plant fiber composite material after a large amount of tests and optimization in the aspects of process steps, proportion and parameter control.
While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020069791A1 (en) * | 2000-10-17 | 2002-06-13 | Merkley Donald J. | Fiber cement composite material using biocide treated durable cellulose fibers |
| CN104497609A (en) * | 2014-12-18 | 2015-04-08 | 广西大学 | Preparation method of all-fiber degradable composite material |
| CN113715143A (en) * | 2021-09-09 | 2021-11-30 | 席玉林 | Preparation method of super-strong durable material |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020069791A1 (en) * | 2000-10-17 | 2002-06-13 | Merkley Donald J. | Fiber cement composite material using biocide treated durable cellulose fibers |
| CN104497609A (en) * | 2014-12-18 | 2015-04-08 | 广西大学 | Preparation method of all-fiber degradable composite material |
| CN113715143A (en) * | 2021-09-09 | 2021-11-30 | 席玉林 | Preparation method of super-strong durable material |
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