CN111205052A - Preparation method of asbestos-free plant fiber reinforced calcium silicate board and asbestos-free plant fiber reinforced calcium silicate board - Google Patents

Preparation method of asbestos-free plant fiber reinforced calcium silicate board and asbestos-free plant fiber reinforced calcium silicate board Download PDF

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CN111205052A
CN111205052A CN202010143665.3A CN202010143665A CN111205052A CN 111205052 A CN111205052 A CN 111205052A CN 202010143665 A CN202010143665 A CN 202010143665A CN 111205052 A CN111205052 A CN 111205052A
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calcium silicate
water
asbestos
ramie
silicate board
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吕春粉
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Zhengzhou Zhitao Information Technology Co ltd
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    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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    • C04B28/00Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • C04B28/10Lime cements or magnesium oxide cements
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    • C04B20/00Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
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    • C04B20/04Heat treatment
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    • C04B2111/00Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
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    • C04B2201/00Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/30Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values
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    • C04B2201/00Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/50Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength

Abstract

The invention relates to a preparation method of a non-asbestos plant fiber reinforced calcium silicate board and the non-asbestos plant fiber reinforced calcium silicate board, wherein the preparation method comprises the following steps: s1, soaking and softening raw ramie by water, and then performing steam explosion to obtain a ramie blasting material; s2, putting the ramie blasting material into an alkaline degumming solution, boiling, washing with water, and drying to obtain ramie fibers; s3, spraying a gamma-aminopropyl triethoxysilane modifier on the ramie fibers to prepare modified ramie fibers; s4, mixing the modified ramie fibers, water, silica fume, metakaolin, potassium sulfate, slaked lime, portland cement, diatomite and quartz sand to prepare mixed slurry; and S5, preparing the mixed slurry into a plate blank, and performing pre-curing, autoclaved curing and drying to obtain the composite material. The calcium silicate board adopts the modified ramie fibers as the reinforcing material, has good appearance quality, low water absorption and wet expansion rate, better water resistance and moisture resistance, high mechanical property, good freeze-thaw resistance, good dry-wet cycle resistance and stable property.

Description

Preparation method of asbestos-free plant fiber reinforced calcium silicate board and asbestos-free plant fiber reinforced calcium silicate board
Technical Field
The invention belongs to the technical field of asbestos-free calcium silicate boards, and particularly relates to a preparation method of an asbestos-free plant fiber reinforced calcium silicate board and the asbestos-free plant fiber reinforced calcium silicate board.
Background
The fiber reinforced calcium silicate board is a novel board-shaped building material which is prepared by taking a siliceous material-a calcareous material as a main cementing material, taking inorganic mineral fibers, organic synthetic fibers or cellulose fibers as a reinforcing material and adding a certain proportion of raw materials such as an auxiliary agent, water and the like through the working procedures of pulping, molding, high-pressure steam curing and the like; the fireproof heat-insulation sound-insulation wall has the characteristics of light weight, high strength, fire resistance, incombustibility, earthquake resistance, mould resistance, easiness in construction and processing, heat insulation, sound insulation, long service life and the like; the composite heat-insulating board can be used for fireproof coating of partition boards and ceiling boards of industrial and civil buildings, steel structures of buildings and bearing parts, and can also be used as an external wall board and a composite heat-insulating system of the buildings after surface waterproof treatment, in particular to a large-breadth external wall board of a high-rise building.
Since the introduction of calcium silicate boards into the market, the reinforcing fibers used for a long time were all asbestos fibers. The asbestos fiber has small specific density and volume weight, good dispersibility in water, low thermal conductivity, high mechanical strength and stable chemical properties (alkali resistance, high temperature and high pressure resistance), and is an ideal reinforced fiber material; however, asbestos has carcinogenicity, and the possibility that the human body is infected with cancer-type mesothelioma and lung cancer is easily caused by long-term work in the environment where asbestos dust or fine asbestos fibers are seriously suspended, so that the application of asbestos and asbestos fibers is limited, and the development and production of asbestos-free calcium silicate boards are emphasized and developed.
In the prior art, the performance of some fibers is close to that of asbestos fibers, but most fibers have serious defects, such as poor alkali resistance, high temperature and high pressure resistance, poor compatibility with a calcium silicate matrix, no reinforcing performance and the like, and are not suitable for being used as a reinforcing material of a calcium silicate board. At present, the widely applied asbestos fiber substitute material is chemically treated conifer pulp fiber, because the grinded conifer pulp fiber has the process performance similar to the loosened asbestos fiber, has certain tensile strength, has the length within a certain range (the fiber content of the length of 1-6mm is 60-70 percent), has good high temperature and high humidity resistance, is harmless to human health, and belongs to reproducible natural resources. In the prior art, hardwood (such as eucalyptus) pulp is also used as a raw material to prepare the fiber-reinforced calcium silicate board, but the hardwood pulp pulping process needs to be further optimized and improved, fiber damage is reduced, and the softwood pulp can be completely replaced.
However, wood resources in China are relatively deficient and scarce, because the coverage rate of forests is not high, in order to protect tree resources in forest areas and maintain good ecological environment, and commercial felling (especially coniferous forest resources) is gradually forbidden, the yield of the timbers in China is obviously reduced, and the competition among downstream industries taking the timbers as raw materials is fierce, so that fiber-reinforced calcium silicate board manufacturers taking wood pulp fibers as reinforcing materials mainly rely on imported wood pulp, the price and the transportation cost are high, and the industrial development and the application of green environment-friendly asbestos-free fiber-reinforced calcium silicate boards are limited.
Disclosure of Invention
The invention aims to provide a preparation method of a non-asbestos plant fiber reinforced calcium silicate board.
The second purpose of the invention is to provide the asbestos-free plant fiber reinforced calcium silicate board prepared by the preparation method.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a preparation method of a non-asbestos plant fiber reinforced calcium silicate board comprises the following steps:
s1, cutting raw ramie into small sections, soaking and softening the small sections by using water for 12-16h, taking out the small sections, draining, performing steam explosion at the steam temperature of 190-;
s2, putting the ramie blasting material obtained in the step S1 into an alkaline degumming solution, boiling for 15-30min, washing with water, and drying to obtain ramie fibers;
s3, dissolving gamma-aminopropyl triethoxysilane in an ethanol water solution to prepare a modifier; spraying the obtained modifier on degummed ramie refined dry fibrilia, uniformly mixing, and drying to remove ethanol to obtain modified ramie fiber; wherein the dosage of the gamma-aminopropyl triethoxysilane is 1.2-1.4% of the weight of the degummed ramie fiber;
s4, adding the modified ramie fibers obtained in the step S3 into water, and dispersing to obtain a fiber mixed solution; adding silica fume, metakaolin and potassium sulfate into the obtained fiber mixed solution, and continuously dispersing to obtain fiber slurry; mixing lime, portland cement, diatomite and quartz sand to obtain a dry material; uniformly mixing the obtained dry material and the obtained fiber slurry to obtain mixed slurry;
s5, injecting the mixed slurry obtained in the step S4 into a mold and pressing to form a plate blank; and pre-curing, steam-pressure curing and drying the obtained plate blank to obtain the composite material.
In step S1, the draining is performed until the material drops no longer flow in a stream.
In step S2, the alkaline degumming solution includes the following components by mass: 0.8 to 1.2 percent of sodium hydroxide, 0.2 to 0.3 percent of sodium silicate, 0.35 to 0.45 percent of sodium sulfite and 0.15 to 0.25 percent of sodium pyrophosphate; the bath ratio of the boiling-off is 1: 18-22. Further, the balance of the alkaline degumming solution is water.
In step S2, the water washing step includes soaking in water and rinsing to neutral. The drying is carried out at the temperature of 100 ℃ and 110 ℃ until the water content is not more than 10 percent.
In step S3, the mass ratio of ethanol to water in the ethanol aqueous solution is 82: 8. In the modifier, the mass fraction of the gamma-aminopropyl triethoxysilane is 4.0-6.0%.
In step S4, the mixed slurry is mainly prepared from water and the following raw materials in parts by weight: 19-21 parts of slaked lime, 24-26 parts of Portland cement, 21-23 parts of diatomite, 24-26 parts of quartz sand, 4.5-5.5 parts of silica fume, 3.5-4.5 parts of metakaolin, 7.0-8.0 parts of modified ramie fiber and 1.6-1.8 parts of potassium sulfate; the water-cement ratio is 0.3-0.35.
In step S4, the dispersion is mechanical stirring dispersion, the stirring speed is 150-200rpm, and the stirring dispersion time is 15-25 min.
In step S5, the pressure of the pressure molding is 20-40MPa, and the pressure maintaining time is 5-15 min.
In step S5, the pre-curing is performed at room temperature for 4-6 h.
In step S5, the autoclave curing temperature is 175-185 ℃, the pressure is 1.0-1.2MPa, and the time is 6-8 h.
In step S5, the drying refers to drying at 100-110 ℃ until the moisture content of the board is not more than 7.0%.
The asbestos-free plant fiber reinforced calcium silicate board prepared by the preparation method.
The preparation method of the asbestos-free plant fiber reinforced calcium silicate board comprises the steps of cutting ramie into small sections, soaking and softening the small sections with water for 12-16h, wherein the soaking and softening with water are to prevent the ramie from being excessively crushed into powder after being subjected to steam explosion in a dry state. Performing steam explosion on the softened ramie raw ramie, controlling the steam temperature to be 190-200 ℃, the explosion pressure to be 2.0-2.2MPa and the pressure maintaining time to be 3.0-4.0min, wherein in the process of heat and pressure maintaining, steam and water quickly penetrate into the raw ramie fibers and contact with hemicellulose and pectin in the primary wall and hemicellulose and lignin in the secondary wall, the colloid is hydrolyzed, and the fibers are swelled. Under the conditions of high temperature and high pressure, the lignin macromolecules are degraded and separated, the hemicellulose connected with the lignin macromolecules is accelerated to dissolve, the pectin is dissolved out, the colloid macromolecules are damaged, the gluing effect is weakened, and the colloid is separated from the fibers. Because the heat preservation and pressure maintaining time is short, the cellulose which is the main component of the raw ramie can not be excessively hydrolyzed, and the structure and the strength of the ramie single fiber can not be influenced. After the heat preservation and pressure maintenance are finished, instant pressure relief and discharging are carried out by the steam explosion device, the pressure is suddenly released, the temperature is rapidly reduced, the wet raw ramie is exploded by secondary steam generated in the process, the fiber structure is rapidly torn due to the loss of the gluing effect of colloid macromolecules, the ramie fibers are separated and refined, and single fibers are released. The blasting material discharged from the steam blasting device directly enters a boiling device filled with alkaline degumming liquid for boiling, wherein the boiling has the function of dissolving loose colloidal substances separated from fibers by steam blasting out, and preventing the loose colloidal substances from being precipitated and coagulated again due to low temperature. Further, in the alkaline degumming solution, sodium hydroxide reacts with colloid macromolecules to reduce the surface residual gum of the fibers; the sodium phosphite and the sodium silicate have strong dispersing capacity and peptization capacity, and promote the colloidal substances to be dispersed and suspended in the liquid; sodium sulfite is used as a stabilizer to protect the fiber, reduce the damage and improve the fiber quality. The steam explosion damages the glued structure of the colloid and the fiber, the alkaline degumming liquid mainly plays a role in dissolving out, and the colloid substance can be fully dissolved out by boiling off for a short time, so that the aim of separating the colloid substance is fulfilled. Because the degumming treatment is carried out by high temperature and high pressure, alkali treatment and other operations, the obtained ramie fiber has good alkali resistance and high temperature and high pressure resistance.
According to the invention, a small amount of gamma-aminopropyltriethoxysilane is used for surface modification of ramie fibers, and the gamma-aminopropyltriethoxysilane is combined with hydrophilic groups on the surfaces of the ramie fibers to form a layer of silane coupling agent molecular film on the surfaces of the ramie fibers, so that the surfaces of the ramie fibers are changed from hydrophilicity to hydrophobicity, the water repellency of the fiber surfaces and the water retention of the fiber interiors are improved, and the fibers are protected, on one hand, the alkali resistance of the fibers is improved, and the weakening or disappearance of the fiber reinforcing effect caused by the excessive damage of an alkaline environment to the fibers in the plate forming process is prevented; on the other hand, the high-temperature water resistance of the fiber is improved, the erosion and damage of high-temperature and high-pressure steam to the fiber during subsequent autoclaved curing are reduced and prevented, and the reinforcing capability of the fiber to the plate is prevented from being damaged; meanwhile, the moisture regain and the hygroscopicity of the fiber are reduced, the hygroscopicity and the moisture expansion rate of the plate are further reduced, the capability of the plate in freeze-thaw resistance cycle and soaking and drying resistance cycle is improved, and the strength and the dimensional stability of the plate are maintained.
In the preparation method, the matrix raw materials adopt slaked lime, portland cement, diatomite, quartz sand, silica fume, metakaolin and potassium sulfate. The calcium silicate board is made of calcium silicate, calcium silicate cement and silicate cement, wherein the calcium silicate is used as a main calcium material, and the calcium silicate board is formed and has improved strength due to the fact that the silicate cement is used for assisting the calcium hydrate; diatomite and quartz sand are main siliceous materials, and SiO in the quartz sand2The diatomite is light and porous, and is used for reducing the quality of the calcium silicate board, enhancing the thermal resistance effect of the board, reducing the thermal conductivity coefficient of the board and ensuring that the board has good heat insulation performance. The siliceous material and the calcareous material are mutually matched and act synergistically, and the tobermorite crystal is generated by a chemical reaction in the steam-pressing process, so that the plate has good strength, mechanical property and dimensional stability. The silica fume and the metakaolin are used as the admixture, and the filling effect of the ultrafine particles (especially the filling effect of the silica fume) of the silica fume and the metakaolin is utilized to fill the pores between the fiber and the matrix, block the pore structure, reduce the capillary effect and increase the contact area between the fiber and the substrate, thereby improving the performance of the fiberThe bond stress of the base material to the fiber is enhanced, the interface bonding force between the fiber and the base material is enhanced, the shrinkage and expansion are reduced, and the dimensional stability and the mechanical property are improved. Amorphous, highly active SiO in silica fume2The content is more than 95 percent, which is beneficial to promoting the adhesion between material layers in the plate forming process and promoting the generation of tobermorite crystals in the steam pressing process. The metakaolin contains Al element which is beneficial to the formation of calcium silicate hydrate and the stability of the flaky structure of tobermorite; metakaolin can also rapidly react with calcium hydroxide generated by cement hydration to generate viscous mixtures such as ettringite, calcium silicate gel and the like, so that crystal grains at different sites are rapidly connected to form a framework, and the framework is filled between the base material and the fibers to improve the interface bonding strength of the fibers and the base material. The admixture can also reduce the alkalinity of the cement base material, reduce the damage effect on the structure of the fiber and improve the reinforcing effect of the fiber. Potassium sulfate is used as an activating agent to improve the reaction activity of siliceous materials such as quartz sand and the like; in a short curing time, potassium sulfate can cause higher polymerization degree of silicon acid chains than sodium sulfate, and the adoption of potassium sulfate as an activating agent can shorten the autoclave curing time and reduce the damage to fibers caused by overlong autoclave curing time.
The modified ramie fibers are added into water to be dispersed to obtain a fiber mixed solution, and then the silica fume, the metakaolin and the potassium sulfate are added into the obtained fiber mixed solution to be continuously dispersed to obtain the fiber slurry, so that the ultrafine materials of the silica fume and the metakaolin are attached to the surfaces, gaps and intertwining nodes of the rock wool fibers and the modified ramie fibers due to the adsorption effect, and are filled between the fibers and a matrix during final molding, and the bonding force of the fibers and the matrix is enhanced.
The finished product surface of the asbestos-free plant fiber reinforced calcium silicate board (original board) obtained by the invention has no phenomena of cracks, delamination, peeling and bubbling, has no obvious corner drop and edge drop, and meets the requirement of appearance quality; the thickness and the apparent density are not lower than the design requirements, and the dimensional deviation is within the specified range. The detection shows that the water absorption rate of the obtained board is below 21.91%, and the wet expansion rate is below 0.18%, which indicates that the ramie fibers in the calcium silicate board are tightly combined with the matrix, the pores are small, the board is not easy to absorb water, and the board has good water resistance and moisture resistance; the incombustibility of the obtained plate meets the requirement of GB8624 incombustibility A, and after the water impermeability test lasts for 24 hours, no water drops appear on the bottom surface of the plate, so that the water impermeability requirement is met. In a mechanical property detection test, the water saturation breaking strength of the obtained plate is respectively 12.94MPa, 13.15MPa and 12.89MPa, which are not lower than 12MPa, and the R3-level strength requirements of A-type and B-type plates are met. In an anti-freezing test, after 100 times of freeze-thaw cycles, the water-saturated breaking strength of the obtained plate is still more than 10.11MPa, the breaking strength ratio is more than 78.13%, the strength loss is small, and the plate has good anti-freezing performance; in a soaking-drying test, the obtained board has the water saturation breaking strength of more than 9.60MPa, the breaking strength ratio of more than 74.48 percent, small strength loss, good dry-wet cycle resistance and stable property. The obtained asbestos-free plant fiber reinforced calcium silicate board has excellent comprehensive performance and can replace the existing wood pulp fiber or paper fiber reinforced calcium silicate board.
Detailed Description
The present invention will be further described with reference to the following embodiments.
In a specific embodiment, the slaked lime is commercial slaked lime, and the content of effective calcium oxide is not less than 90%. The portland cement used was a commercial 42.5 grade ordinary portland cement. The diatomaceous earth used is commercially available technical grade, SiO2The content is not less than 99%. The quartz sand is commercially available fine quartz sand with the particle size of 200-300 meshes and SiO2The content is not less than 99%. The particle size of the used silica fume is 0.1-0.3 mu m, SiO2The content is not less than 95%. The metakaolin is a commercial product and is prepared by calcining kaolin at 800 deg.C for 4 hr, and has an average particle diameter of not more than 1.0 μm and specific gravity of 2.58g/cm3The activity is 35-40%.
In a specific embodiment, the ramie raw ramie is a commercial product, the content of the gum (pectin rate) is 20.03%, and the content of the cellulose is 68.57%.
Example 1
The preparation method of the asbestos-free plant fiber reinforced calcium silicate board comprises the following steps:
s1, cutting raw ramie into small sections with the length of 30-60 mm, soaking and softening the small sections with water for 16h, taking out the small sections, draining the small sections until water drops of the materials do not flow down into strands, putting the materials into a steam explosion device for steam explosion, keeping the steam temperature at 190 ℃, the explosion pressure at 2.2MPa and the pressure for 3.0min, and discharging the materials after the pressure is kept to obtain ramie explosion materials;
s2, preparing an alkaline degumming solution according to the following components and mass concentrations thereof: 1.2% of sodium hydroxide, 0.2% of sodium silicate, 0.35% of sodium sulfite, 0.25% of sodium pyrophosphate and the balance of water;
putting the ramie blasting material obtained in the step S1 into an alkaline degumming solution according to the bath ratio of 1:18, boiling for 15min, taking out, soaking with water, repeatedly rinsing until the washing water is neutral, drying until the water content is not more than 10%, sorting and screening to obtain ramie fibers; the obtained ramie fiber has length of 3-8mm, diameter of 10-30 μm, and average gel content (pectin rate) of 4.5%;
s3, dissolving gamma-aminopropyltriethoxysilane in an ethanol water solution (the mass ratio of ethanol to water is 82:8) to prepare a modifier with the mass concentration of 5.0%; spraying the obtained modifier on degummed ramie refined dry fibrilia, uniformly mixing, and drying at 85 ℃ to remove ethanol to obtain modified ramie fibers; wherein the dosage of the gamma-aminopropyl triethoxysilane is 1.2 percent of the mass of the degummed ramie fibers;
s4, preparing raw materials and water according to the following parts by weight: 19 parts of slaked lime, 26 parts of Portland cement, 21 parts of diatomite, 26 parts of ground quartz sand, 4.5 parts of silica fume, 4.5 parts of metakaolin, 7.0 parts of modified ramie fiber obtained in step S3 and 1.8 parts of potassium sulfate; the water-cement ratio is 0.32;
according to the formula amount, adding the modified ramie fibers into water, and stirring and dispersing for 20min at the rotating speed of 200rpm to obtain a fiber mixed solution; adding silica fume, metakaolin and potassium sulfate into the obtained fiber mixed solution, and continuously dispersing for 20min at the rotating speed of 200rpm to obtain fiber slurry; mixing slaked lime, portland cement, diatomite and ground quartz sand to obtain a dry material; uniformly mixing the obtained dry material and the obtained fiber slurry to obtain mixed slurry;
s5, injecting the mixed slurry obtained in the step S4 into a mold, pressurizing at 20MPa, maintaining the pressure for 10min and forming to obtain a plate blank;
and (3) pre-curing the obtained plate blank at room temperature for 4 hours, then demoulding, performing autoclaved curing at the temperature of 175 ℃ and the pressure of 1.2MPa for 7 hours, and then drying at the temperature of 105 ℃ until the water content of the plate is lower than 7.0 percent to obtain the asbestos-free plant fiber reinforced calcium silicate plate.
Example 2
The preparation method of the asbestos-free plant fiber reinforced calcium silicate board comprises the following steps:
s1, cutting raw ramie into small sections with the length of 30-60 mm, soaking and softening the small sections with water for 14h, taking out the small sections, draining the small sections until water drops of the materials do not flow down into strands, putting the materials into a steam explosion device for steam explosion, wherein the steam temperature is 195 ℃, the explosion pressure is 2.1MPa, the pressure maintaining time is 3.5min, and discharging the materials after the pressure maintaining is finished to obtain ramie explosion materials;
s2, preparing an alkaline degumming solution according to the following components and mass concentrations thereof: 1.0% of sodium hydroxide, 0.25% of sodium silicate, 0.40% of sodium sulfite, 0.20% of sodium pyrophosphate and the balance of water;
putting the ramie blasting material obtained in the step S1 into an alkaline degumming solution according to the bath ratio of 1:20, boiling for 20min, taking out, soaking with water, repeatedly rinsing until the washing water is neutral, drying until the water content is not more than 10%, sorting and screening to obtain ramie fibers; the obtained ramie fiber has length of 3-8mm, diameter of 10-30 μm, and average gel content (pectin rate) of 4.7%;
s3, dissolving gamma-aminopropyltriethoxysilane in an ethanol water solution (the mass ratio of ethanol to water is 82:8) to prepare a modifier with the mass concentration of 5.0%; spraying the obtained modifier on degummed ramie refined dry fibrilia, uniformly mixing, and drying at 85 ℃ to remove ethanol to obtain modified ramie fibers; wherein the dosage of the gamma-aminopropyl triethoxysilane is 1.3 percent of the mass of the degummed ramie fibers;
s4, preparing raw materials and water according to the following parts by weight: 20 parts of slaked lime, 25 parts of Portland cement, 22 parts of diatomite, 25 parts of ground quartz sand, 5.0 parts of silica fume, 4.0 parts of metakaolin, 7.5 parts of modified ramie fiber obtained in step S3 and 1.7 parts of potassium sulfate; the water-cement ratio is 0.32;
according to the formula amount, adding the modified ramie fibers into water, and stirring and dispersing for 20min at the rotating speed of 200rpm to obtain a fiber mixed solution; adding silica fume, metakaolin and potassium sulfate into the obtained fiber mixed solution, and continuously dispersing for 20min at the rotating speed of 200rpm to obtain fiber slurry; mixing slaked lime, portland cement, diatomite and ground quartz sand to obtain a dry material; uniformly mixing the obtained dry material and the obtained fiber slurry to obtain mixed slurry;
s5, injecting the mixed slurry obtained in the step S4 into a mold, pressurizing at 20MPa, maintaining the pressure for 10min and forming to obtain a plate blank;
and (3) pre-curing the obtained plate blank at room temperature for 5 hours, then demoulding, performing autoclaved curing at the temperature of 180 ℃ and the pressure of 1.1MPa for 6 hours, and then drying at the temperature of 105 ℃ until the water content of the plate is lower than 7.0 percent to obtain the asbestos-free plant fiber reinforced calcium silicate plate.
Example 3
The preparation method of the asbestos-free plant fiber reinforced calcium silicate board comprises the following steps:
s1, cutting raw ramie into small sections with the length of 30-60 mm, soaking and softening the small sections with water for 12 hours, taking out the small sections, draining the small sections until water drops of the materials do not flow down into strands, putting the materials into a steam explosion device for steam explosion, keeping the steam temperature at 200 ℃, the explosion pressure at 2.0MPa and the pressure for 4.0min, and discharging the materials after the pressure is kept to obtain ramie explosion materials;
s2, preparing an alkaline degumming solution according to the following components and mass concentrations thereof: 0.8% of sodium hydroxide, 0.3% of sodium silicate, 0.45% of sodium sulfite and 0.15% of sodium pyrophosphate. The balance of water;
putting the ramie blasting material obtained in the step S1 into an alkaline degumming solution according to the bath ratio of 1:22, boiling for 25min, taking out, soaking with water, repeatedly rinsing until the washing water is neutral, drying until the water content is not more than 10%, sorting and screening to obtain ramie fibers; the obtained ramie fiber has length of 3-8mm, diameter of 10-30 μm, and average gel content (pectin rate) of 5.2%;
s3, dissolving gamma-aminopropyltriethoxysilane in an ethanol water solution (the mass ratio of ethanol to water is 82:8) to prepare a modifier with the mass concentration of 5.0%; spraying the obtained modifier on degummed ramie refined dry fibrilia, uniformly mixing, and drying at 85 ℃ to remove ethanol to obtain modified ramie fibers; wherein the dosage of the gamma-aminopropyl triethoxysilane is 1.4 percent of the mass of the degummed ramie fibers;
s4, preparing raw materials and water according to the following parts by weight: 21 parts of slaked lime, 24 parts of Portland cement, 23 parts of diatomite, 24 parts of ground quartz sand, 5.5 parts of silica fume, 3.5 parts of metakaolin, 8.0 parts of modified ramie fiber obtained in step S3 and 1.6 parts of potassium sulfate; the water-cement ratio is 0.32;
according to the formula amount, adding the modified ramie fibers into water, and stirring and dispersing for 20min at the rotating speed of 200rpm to obtain a fiber mixed solution; adding silica fume, metakaolin and potassium sulfate into the obtained fiber mixed solution, and continuously dispersing for 20min at the rotating speed of 200rpm to obtain fiber slurry; mixing slaked lime, portland cement, diatomite and ground quartz sand to obtain a dry material; uniformly mixing the obtained dry material and the obtained fiber slurry to obtain mixed slurry;
s5, injecting the mixed slurry obtained in the step S4 into a mold, pressurizing at 20MPa, maintaining the pressure for 10min and forming to obtain a plate blank;
and (3) pre-curing the obtained plate blank at room temperature for 6h, then demoulding, performing autoclaved curing at 185 ℃ and 1.0MPa for 6h, and drying at 105 ℃ until the water content of the plate is lower than 7.0%, thus obtaining the asbestos-free plant fiber reinforced calcium silicate plate.
According to part 1 of JC/T564.1-2018 fiber reinforced calcium silicate board: the results of performance tests on the asbestos-free plant fiber-reinforced calcium silicate sheet (raw sheet) obtained as described above are shown in table 1.
Results of measuring Properties of asbestos-free plant fiber-reinforced calcium silicate sheets obtained in examples 1 to 3
As can be seen from Table 1, the finished products of the asbestos-free plant fiber reinforced calcium silicate boards (raw boards) obtained in examples 1-3 have no cracks, delamination, peeling and bubbling on the surface, have no obvious corner drop and edge drop, and meet the requirements of appearance qualitySolving; the design requirements for the thickness of the sheets of examples 1 to 3 were 10mm, and the apparent density of the sheets was 1.25g/cm2In the actual measurement result, the thickness and the apparent density are not lower than the design requirements, and the dimensional deviation is within the specified range. The detection shows that the water absorption rate of the obtained board is below 21.91%, and the wet expansion rate is below 0.18%, which indicates that the ramie fiber reinforcing material in the calcium silicate board is tightly combined with a matrix, has small porosity, is not easy to absorb water, and has better water resistance and moisture resistance; the incombustibility of the obtained plate meets the requirement of GB8624 incombustibility A, and after the water impermeability test lasts for 24 hours, no water drops appear on the bottom surface of the plate, so that the water impermeability requirement is met. In a mechanical property detection test, the water saturation breaking strength of the plate obtained in the examples 1-3 is respectively 12.94MPa, 13.15MPa and 12.89MPa, which are not lower than 12MPa, and the R3-level strength requirements of the A-type plate and the B-type plate are met. In an anti-freezing test, after 100 times of freeze-thaw cycles, the water-saturated breaking strength of the obtained plate is still more than 10.11MPa, the breaking strength ratio is more than 78.13%, the strength loss is small, and the plate has good anti-freezing performance; in a soaking-drying test, the obtained board has the water saturation breaking strength of more than 9.60MPa, the breaking strength ratio of more than 74.48 percent, small strength loss, and good dry-wet cycle resistance and stability.

Claims (9)

1. A preparation method of asbestos-free plant fiber reinforced calcium silicate board is characterized by comprising the following steps: the method comprises the following steps:
s1, cutting raw ramie into small sections, soaking and softening the small sections by using water for 12-16h, taking out the small sections, draining, performing steam explosion at the steam temperature of 190-;
s2, putting the ramie blasting material obtained in the step S1 into an alkaline degumming solution, boiling for 15-30min, washing with water, and drying to obtain ramie fibers;
s3, dissolving gamma-aminopropyl triethoxysilane in an ethanol water solution to prepare a modifier; spraying the obtained modifier on degummed ramie refined dry fibrilia, uniformly mixing, and drying to remove ethanol to obtain modified ramie fiber; wherein the dosage of the gamma-aminopropyl triethoxysilane is 1.2-1.4% of the weight of the degummed ramie fiber;
s4, adding the modified ramie fibers obtained in the step S3 into water, and dispersing to obtain a fiber mixed solution; adding silica fume, metakaolin and potassium sulfate into the obtained fiber mixed solution, and continuously dispersing to obtain fiber slurry; mixing lime, portland cement, diatomite and quartz sand to obtain a dry material; uniformly mixing the obtained dry material and the obtained fiber slurry to obtain mixed slurry;
s5, injecting the mixed slurry obtained in the step S4 into a mold and pressing to form a plate blank; and pre-curing, steam-pressure curing and drying the obtained plate blank to obtain the composite material.
2. The method for preparing the asbestos-free plant fiber reinforced calcium silicate board according to claim 1, wherein the method comprises the following steps: in step S2, the alkaline degumming solution includes the following components by mass: 0.8 to 1.2 percent of sodium hydroxide, 0.2 to 0.3 percent of sodium silicate, 0.35 to 0.45 percent of sodium sulfite and 0.15 to 0.25 percent of sodium pyrophosphate; the bath ratio of the boiling-off is 1: 18-22.
3. The method for preparing the asbestos-free plant fiber reinforced calcium silicate board according to claim 1, wherein the method comprises the following steps: in step S2, the water washing step includes soaking in water and rinsing to neutral.
4. The method for preparing the asbestos-free plant fiber reinforced calcium silicate board according to claim 1, wherein the method comprises the following steps: in step S4, the mixed slurry is mainly prepared from water and the following raw materials in parts by weight: 19-21 parts of slaked lime, 24-26 parts of Portland cement, 21-23 parts of diatomite, 24-26 parts of quartz sand, 4.5-5.5 parts of silica fume, 3.5-4.5 parts of metakaolin, 7.0-8.0 parts of modified ramie fiber and 1.6-1.8 parts of potassium sulfate; the water-cement ratio is 0.3-0.35.
5. The method for preparing the asbestos-free plant fiber reinforced calcium silicate board according to claim 1, wherein the method comprises the following steps: in step S5, the pressure of the pressure molding is 20-40MPa, and the pressure maintaining time is 5-15 min.
6. The method for preparing the asbestos-free plant fiber reinforced calcium silicate board according to claim 1, wherein the method comprises the following steps: in step S5, the pre-curing is performed at room temperature for 4-6 h.
7. The method for preparing the asbestos-free plant fiber reinforced calcium silicate board according to claim 1, wherein the method comprises the following steps: in step S5, the autoclave curing temperature is 175-185 ℃, the pressure is 1.0-1.2MPa, and the time is 6-8 h.
8. The method for preparing the asbestos-free plant fiber reinforced calcium silicate board according to claim 1, wherein the method comprises the following steps: in step S5, the drying refers to drying at 100-110 ℃ until the moisture content of the board is not more than 7.0%.
9. An asbestos-free plant fiber-reinforced calcium silicate sheet prepared by the method according to any one of claims 1 to 8.
CN202010143665.3A 2020-03-04 2020-03-04 Preparation method of asbestos-free plant fiber reinforced calcium silicate board and asbestos-free plant fiber reinforced calcium silicate board Withdrawn CN111205052A (en)

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CN111646763A (en) * 2020-07-02 2020-09-11 肇庆三乐集成房屋制造有限公司 Plant fiber reinforced calcium silicate board and preparation method thereof
CN113121141A (en) * 2021-03-31 2021-07-16 江苏赛恩工程技术有限公司 Manufacturing process of light sound insulation wall brick

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CN103449773A (en) * 2013-08-14 2013-12-18 武汉建筑材料工业设计研究院有限公司 Light-weight calcium silicate plate and preparation method thereof
CN108439921A (en) * 2018-06-07 2018-08-24 魏浩峰 A kind of agricultural crop straw complex cement base insulating wall material and preparation method thereof
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