Extrusion-molded carbon mineralized fiber cement board and preparation method thereof

Abstract

The invention discloses an extrusion-molded carbon mineralized fiber cement board and a preparation method thereof, and the preparation method comprises the following steps: dispersing fibers, a plasticizer, a lubricant and a dispersant in water to obtain a fiber suspension; adding powder containing the calcium silicate ore phase into the fiber suspension, and kneading into plastic pug; aging the plastic pug, performing vacuum pugging, and performing vacuum extrusion molding to obtain a fiber cement board blank; and drying and pre-curing the fiber cement board blank, and then carrying out CO2 curing to obtain the carbon mineralized fiber cement board, the raw material formula is simple, the powder with high carbonization activity and low hydration activity is adopted as a gelling component, so that the plasticity of the pug is stable, fibers are uniformly dispersed, and the production efficiency and the product performance of the fiber cement board prepared by an extrusion molding process are remarkably improved by combining normal-temperature and normal-pressure CO2 curing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, and in particular to an extrusion-molded carbon-mineralized fiber cement board and a preparation method thereof. BACKGROUND

[0002] As an important cement-based composite material, fiber cement board is widely used in the fields of building walls, floors, decorative panels, etc. The traditional production process is mainly based on the papermaking method and the flow slurry method, and the core process includes the steps of slurry preparation, layer molding, steam pressure curing, etc. However, such process has the following defects: uneven dispersion of fibers, easy agglomeration of short fibers, and difficulty in uniform distribution of long fibers, resulting in uneven strength of the board; low molding efficiency, long time consumption of multi-layer paving process; high curing energy consumption, high-temperature and high-pressure environment required for steam pressure curing, and high carbon emission.

[0003] To overcome the above-mentioned defects, the extrusion molding process is gradually applied to the production of fiber cement board due to its continuous and high-efficiency characteristics, but the extrusion molding process also has various problems: firstly, cement is prone to hydration reaction during the production of fiber cement board, which causes poor plasticity of the mud, not only causing molding difficulties, increasing internal defects, and wrapping fibers with hydration products to cause uneven dispersion of fibers, but also causing the mold to be blocked during the extrusion process, affecting the production efficiency, and the increase of internal defects and uneven dispersion of fibers easily lead to extrusion cracking, insufficient density of the board, poor bending strength and water resistance, and difficulty in meeting the needs of high load or high humidity scenarios; secondly, the main component of fiber cement board, quartz sand, is prone to wear the mold during mud preparation and extrusion, causing the service life of the equipment to be shortened.

[0004] Therefore, it is urgent to develop a material system and process suitable for extrusion molding to prepare fiber cement board, so as to improve the production efficiency and product performance of fiber cement board. SUMMARY

[0005] Therefore, the present application provides an extrusion-molded carbon-mineralized fiber cement board and a preparation method thereof, which are used to solve the problem of how to improve the production efficiency and product mechanical properties of fiber cement board prepared by the extrusion molding process.

[0006] To achieve the above technical purposes, the present application adopts the following technical solutions: In a first aspect, the present application provides a preparation method of an extrusion-molded carbon-mineralized fiber cement board, comprising the following steps: S1. dispersing fibers, plasticizers, lubricants, and dispersants in water to obtain a fiber suspension; S2. adding a powder containing a calcium silicate mineral phase to the fiber suspension and kneading into a plastic mud; S3. aging the plastic mud, then vacuuming the mud, and then vacuum extrusion molding to obtain a fiber cement board blank; S4. After the fiber cement board blank is dried and pre-cured, CO2 curing is performed, and a carbon-mineralized fiber cement board is obtained.

[0007] Preferably, the mass of the fiber is 1-6 parts, the mass of the plasticizer is 1-2 parts, the mass of the lubricant is 0.5-1 part, the mass of the dispersant is 1-3 parts, and the mass of the water is 18-25% of the total mass of the fiber, the plasticizer, the lubricant, the dispersant, and the powder containing the calcium silicate mineral phase, based on 100 parts of the mass of the powder containing the calcium silicate mineral phase.

[0008] Preferably, the powder containing the calcium silicate mineral phase is one or more of calcium silicate mineral powder and industrial solid waste (steel slag powder, magnesium slag powder) rich in the calcium silicate mineral phase; the calcium silicate mineral phase includes one or more of γ-C2S, C3S2, and CS; the mass fraction of the calcium silicate mineral phase in the calcium silicate mineral powder is ≥ 90%, and the average particle size is ≤ 50 μm; the mass fraction of the calcium silicate mineral phase in the industrial solid waste is ≥ 60%, and the average particle size is ≤ 50 μm.

[0009] Preferably, the fiber is one or more of pulp fiber, alkali-resistant glass fiber, PVA fiber, PP fiber, PE fiber, and PAN fiber; the plasticizer includes one or more of hydroxypropyl methyl cellulose ether, starch ether, and glycerol; the lubricant includes one or more of calcium stearate and magnesium stearate; and the dispersant includes one or more of sodium hexametaphosphate, an organic silicon coupling agent, polyvinyl alcohol, and polyacrylamide.

[0010] Preferably, the temperature of the aging is 20-30℃, the humidity of the aging is 40-60% RH, and the aging time is 24 h.

[0011] Preferably, the vacuum degree of the vacuum pugging is ≥ 0.09 MPa, and the pugging time of the vacuum pugging is ≥ 30 min.

[0012] Preferably, the pressure of the vacuum extrusion molding is 5-15 MPa.

[0013] Preferably, the temperature of the dry pre-curing is 40-50℃, and the humidity of the dry pre-curing is 30-40% RH.

[0014] Preferably, the pressure of the CO2 curing is 0.1-0.3 MPa, the time of the CO2 curing is 2-48 h, and the concentration of the CO2 is ≥ 20% VOL.

[0015] In a second aspect, the present application provides a carbon-mineralized fiber cement board.

[0016] The beneficial effects of the present application are as follows: The formula of the present application is simple, the gelling component only includes calcium silicate mineral powder or industrial solid waste rich in calcium silicate mineral phase, and quartz sand is not used, which reduces the requirement for lubricity of the fiber cement board in the extrusion process; the gelling component used does not have a hydration reaction with water to harden, and no additional retarder needs to be added during preparation, which ensures good dispersibility of the gelling material and the fiber; the raw material formula of the present application effectively maintains the plastic stability of the mud during the molding process, facilitates continuous and stable extrusion molding, and thus significantly improves the production efficiency. The present application cures under CO2 conditions, the gelling material has a carbonation reaction with CO2 to generate calcium carbonate mainly in the form of calcite, and the matrix is densified through carbon absorption mineralization, which significantly reduces the porosity and greatly improves the mechanical properties of the board; The present application uses CO2 curing at normal temperature and pressure, without the need for complex curing conditions such as high temperature and high pressure, which reduces energy consumption and equipment investment, and at the same time realizes effective sequestration of greenhouse gas CO2, with good environmental benefits. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0018] The present application provides a preparation method of an extrusion-molded carbon-mineralized fiber cement board, comprising the following steps: S1. dispersing fibers, plasticizers, lubricants and dispersants in water to obtain a fiber suspension; S2. adding a powder containing a calcium silicate mineral phase to the fiber suspension and kneading into a plastic mud; S3. aging the plastic mud, then vacuuming the mud, and then vacuum extrusion molding to obtain a fiber cement board blank; S4. drying and pre-curing the fiber cement board blank, and then performing CO2 curing to obtain a carbon-mineralized fiber cement board.

[0019] The application uses a powder containing a calcium silicate mineral phase as a cementitious material, utilizes its high carbonation activity and low hydration activity, and under CO2 curing conditions, uses a semi-dry / extrusion molding combined process to efficiently prepare a fiber cement board with excellent physical and mechanical properties. The reason is that the cementitious material of the application will not harden with hydration reaction with water, which is beneficial to ensure the plasticity of the mud, facilitate subsequent stable extrusion molding, and improve the production efficiency; at the same time, since the cementitious material of the application does not react with water, it does not need to add a retarder during preparation, which also ensures the good dispersibility of the cementitious material and the fiber to ensure the mechanical properties of the board; in addition, the reaction of the cementitious material of the application with CO2 is based on the carbon absorption mineralization and densification of the matrix, which belongs to the process of increasing quality, and the porosity of the matrix will be greatly reduced, and the mechanical properties of the board can be significantly improved.

[0020] In some embodiments, the mass of the fiber is 1-6 parts, the mass of the plasticizer is 1-2 parts, the mass of the lubricant is 0.5-1 part, the mass of the dispersant is 1-3 parts, and the mass of the water is 18-25% of the total mass of the fiber, the plasticizer, the lubricant, the dispersant and the powder containing the calcium silicate mineral phase.

[0021] In some embodiments, the powder containing the calcium silicate mineral phase is one or more of calcium silicate mineral powder and industrial solid waste (steel slag powder, magnesium slag powder) rich in calcium silicate mineral phase; the calcium silicate mineral phase includes one or more of γ-C2S, C3S2, and CS; the mass fraction of the calcium silicate mineral phase in the calcium silicate mineral powder is ≥90%, and the average particle size is ≤50 μm; the mass fraction of the calcium silicate mineral phase in the industrial solid waste is ≥60%, and the average particle size is ≤50 μm.

[0022] In this embodiment, the industrial solid waste containing the calcium silicate mineral phase includes one or more of steel slag powder containing the calcium silicate mineral phase and magnesium slag powder containing the calcium silicate mineral phase.

[0023] In some embodiments, the fiber is one or more of pulp fiber, alkali-resistant glass fiber, PVA fiber, PP fiber, PE fiber, and PAN fiber; the plasticizer includes one or more of hydroxypropyl methyl cellulose ether, starch ether, and glycerol; the lubricant includes one or more of calcium stearate and magnesium stearate; and the dispersant includes one or more of sodium hexametaphosphate, an organic silicon coupling agent, polyvinyl alcohol, and polyacrylamide.

[0024] In this embodiment, the pulp fiber is sulfate pretreated wood pulp / bamboo pulp, with a length of 0.5-3 mm and a single filament diameter of 30-40 μm; the alkali-resistant glass fiber, PVA fiber, PP fiber, PE fiber, and PAN fiber have a length of 3 mm and a single filament diameter of 30-40 μm.

[0025] In the present application, the fibers, dispersants and water are first stirred uniformly to form a mixed solution, and then the mixed solution is slowly added with plasticizers and lubricants under the condition of a water bath at 30-40℃ and stirred uniformly to form a fiber suspension, and the stirring rate is 200-400r / min.

[0026] In some embodiments, the aging temperature is 20-30℃, the aging humidity is 40-60% RH, and the aging time is 24h.

[0027] In this embodiment, the plastic clay is aged to obtain a clay ball, and the aging promotes the uniform distribution of water in the clay, reduces the molding shrinkage, and improves the plasticity.

[0028] In some embodiments, the vacuum degree of the vacuum pugging is ≥0.09MPa, and the pugging time is ≥30min.

[0029] In some embodiments, the die pressure of the vacuum extrusion molding is 5-15MPa.

[0030] In this embodiment, the clay ball is pugged in a vacuum environment, and then extruded by a spiral vacuum extruder to obtain a fiber cement board blank, and a flat plate-shaped extrusion die is used for extrusion molding.

[0031] In some embodiments, the drying pre-curing temperature is 40-50℃, and the drying pre-curing humidity is 30-40% RH.

[0032] In this embodiment, after the drying pre-curing under the above conditions, the water content of the fiber cement board blank is reduced to 12-15%.

[0033] In some embodiments, the CO2 curing pressure is 0.1-0.3MPa, the CO2 curing time is 2-48h, the CO2 curing temperature is 20-40℃, and the CO2 concentration is ≥20% VOL.

[0034] In this embodiment, the source of the CO2 gas used in the CO2 atmosphere is preferably CO2-rich industrial kiln exhaust gas, or preferably high-concentration CO2 gas enriched from various industrial waste gases; the volume concentration of the high-concentration CO2 gas is preferably 30-99% VOL; through CO2 curing, the cementitious material reacts with CO2, and the carbon mineralization is used to densify the matrix, and under this oxidation condition, calcite crystal type-based calcium carbonate is obtained, which is beneficial to the long-term durability of the carbon mineralized fiber cement board.

[0035] The present application provides a carbon mineralized fiber cement board, which is suitable for high humidity (50-80% RH) environment.

[0036] The present application is further described below through specific embodiments.

[0037] Example 1 A preparation method of an extrusion-molded carbon-mineralized fiber cement board, comprising the following steps: S1. 2 parts of pulp fibers (sulfate pretreated wood pulp, length range of 0.5-3 mm, monofilament diameter of 30-40 μm), 2 parts of polyacrylamide are dispersed in water, and then 1 part of glycerol and 0.5 part of calcium stearate are added and stirred, the stirring rate is 300 r / min, and the stirring time is 15 min, to obtain a fiber suspension, wherein the water accounts for 25% of the total mass of the dry materials (pulp fibers, polyacrylamide, glycerol, calcium stearate, powder); S2. 100 parts of calcium silicate mineral powder (γ-C2S accounts for 93.2%, and the average particle size is 21.32 μm) are added to the fiber suspension as a powder and stirred uniformly, the stirring rate is 300 r / min, the stirring time is 45 min, and kneading is performed to form a plastic mud; S3. The plastic mud is aged, the aging temperature is 25℃, the aging humidity is 50% RH, and the aging time is 24 h, to obtain a mud ball, the mud ball is subjected to mud conditioning in a vacuum environment, the vacuum degree of the vacuum mud conditioning is 0.09 MPa, the mud conditioning time is 30 min, and then the mud ball is extruded through a spiral vacuum extruder and a flat plate-shaped extrusion die, the die head pressure of the extrusion molding is 10 MPa, to obtain a fiber cement board blank; S4. The fiber cement board blank is placed in a blast drying box with a temperature of 40℃ and a humidity of 30% RH for drying and pre-curing, so that the water content of the fiber cement board blank is reduced to 15%, and the pre-cured board blank is placed in a CO2 atmosphere for curing, the CO2 curing pressure is 0.2 MPa, the CO2 concentration is 99% VOL, and the CO2 curing time is 24 h, to obtain a carbon-mineralized fiber cement board.

[0038] Example 2 A preparation method of an extrusion-molded carbon-mineralized fiber cement board, other contents are the same as those in Example 1, except that the calcium silicate mineral powder is replaced by steel slag containing a calcium silicate mineral phase (γ-C2S accounts for 64.7%, and the average particle size is 14.48 μm).

[0039] Example 3 A preparation method of an extrusion-molded carbon-mineralized fiber cement board, other contents are the same as those in Example 1, except that the calcium silicate mineral powder is replaced by magnesium slag containing a calcium silicate mineral phase (γ-C2S accounts for 83.6%, and the average particle size is 17.51 μm).

[0040] Example 4 A preparation method of an extrusion-molded carbon-mineralized fiber cement board, other contents are the same as those in Example 1, except that the fiber is PAN fiber 2 parts.

[0041] Example 5 A method for preparing an extruded carbon-mineralized fiber cement board, other contents being the same as those in Example 1, except that the CO2 curing time is 2 h.

[0042] Example 6 A method for preparing an extruded carbon-mineralized fiber cement board, other contents being the same as those in Example 1, except that the CO2 curing pressure is 0.1 MPa and the concentration is 20% VOL.

[0043] Comparative Example 1 A method for preparing a fiber cement board, other contents being the same as those in Example 1, except that the amount of pulp fiber is 10 parts.

[0044] Comparative Example 2 A method for preparing a fiber cement board, other contents being the same as those in Example 1, except that no glycerol is added.

[0045] Comparative Example 3 A method for preparing a fiber cement board, other contents being the same as those in Example 1, except that no calcium stearate is added.

[0046] Comparative Example 4 A method for preparing a fiber cement board, other contents being the same as those in Example 1, except that no polyacrylamide is added.

[0047] Comparative Example 5 A method for preparing a fiber cement board, other contents being the same as those in Example 1, except that γ-C2S is replaced by cement.

[0048] Testing and Evaluation The fiber cement boards obtained in different examples and comparative examples were saturated with water for 1 d, and then performance tests were performed. The porosity, water absorption rate, and saturated flexural strength were tested according to GB / T7019-2014, and the test results are shown in Table 1.

[0049] Table 1 Test Results

[0050] It can be known from Table 1 that the carbon mineralized fiber cement board prepared by the preparation method has excellent physical and mechanical properties, and can reach the R4 strength grade of A-class board (referring to the requirements of JC / T 412.1-2018). In addition, the preparation method has important significance for building material productization of industrial solid waste (steel slag, magnesium slag). Moreover, the curing method taking CO2 curing as the strength source of the matrix has lower requirements for curing conditions, and does not need harsh conditions similar to traditional autoclave curing, and can quickly react with the powder to form a matrix mainly composed of calcium carbonate and form strength at normal temperature and pressure. The calcite crystal type-based calcium carbonate can be more conducive to improving the long-term durability of the carbon mineralized fiber cement board. The CO2 curing also has the effect of storing CO2, and has significant environmental benefits.

[0051] The technical solutions outside the proportioning range provided by the application cannot achieve the performance of the embodiments. In the proportioning, the fiber component is difficult to disperse and is easy to block the mold during extrusion, resulting in failure to form. Similarly, without adding plasticizer / lubricant / dispersant, the mud is also easy to cause problems such as difficulty in forming, surface cracking of the extruded plate blank, and increased porosity, thereby reducing the performance of the plate. The preparation method provided by the application cannot form when using cement as the powder under the same conditions. The reason is that cement is prone to hydration and hardening during stirring and preparation without adding retarder and water reducing agent, so that the plasticity of the mud is poor, the hydration product of the cement is attached to the surface of the fiber, the dispersion of the fiber is poor during mud preparation, and the extrusion process is affected. It is worth mentioning that in order to overcome the hydration of cement, the conventional method is to add a retarder to delay the hydration process of the cement, but this method will cause the plasticity of the mud to be uncontrollable during extrusion. The mud of the application does not need to add a retarder, and has good and stable plasticity.

[0052] The above is only a preferred specific embodiment of the application, but the protection scope of the application is not limited thereto, and any changes or replacements within the technical range disclosed by the application can be easily thought of by those skilled in the art, and should be covered within the protection scope of the application.

Claims

1. A method for preparing an extruded carbon mineralized fiber cement board, characterized in that: The following steps are involved: Dispersing fibers, plasticizer, lubricant, and dispersant in water to obtain a fiber suspension; adding powder containing calcium silicate mineral phase into the fiber suspension and kneading the mixture into a plastic mud; The plastic mud material is aged, vacuum kneaded, and then vacuum extruded to obtain a fiber cement board blank; The fiber cement board slab is dried and pre-cured, and then CO2 cured to obtain the carbon mineralized fiber cement board.

2. The method for preparing the extruded carbon mineralized fiber cement board according to claim 1, characterized in that: Based on 100 parts by mass of the powder containing the calcium silicate mineral phase, the mass of the fiber is 1-6 parts, the mass of the plasticizer is 1-2 parts, the mass of the lubricant is 0.5-1 parts, and the mass of the dispersant is 1-3 parts; the mass of the water is 18-25% of the total mass of the fiber, plasticizer, lubricant, dispersant and the powder containing the calcium silicate mineral phase.

3. The method for preparing the extruded carbon mineralized fiber cement board according to claim 1, characterized in that: The powder containing calcium silicate mineral phase is one or more of calcium silicate mineral powder and industrial solid waste rich in calcium silicate mineral phase (steel slag powder, magnesium slag powder); the calcium silicate mineral phase includes one or more of γ-C2S, C3S2, and CS; the mass proportion of calcium silicate mineral phase in the calcium silicate mineral powder is ≥90%, and the average particle size is ≤50μm; the mass proportion of calcium silicate mineral phase in the industrial solid waste is ≥60%, and the average particle size is ≤50μm.

4. The method for preparing the extruded carbon mineralized fiber cement board according to claim 1, characterized in that: The fiber is one or more of pulp fiber, alkali-resistant glass fiber, PVA fiber, PP fiber, PE fiber, and PAN fiber; the plasticizer includes one or more of hydroxypropyl methylcellulose ether, starch ether, and glycerol; the lubricant includes one or more of calcium stearate and magnesium stearate; and the dispersant includes one or more of sodium hexametaphosphate, silicone coupling agent, polyvinyl alcohol, and polyacrylamide.

5. The method for preparing the extruded carbon mineralized fiber cement board according to claim 1, characterized in that: The aging temperature is 20-30° C., the aging humidity is 40-60% RH, and the aging time is 24 hours.

6. The method for preparing the extruded carbon mineralized fiber cement board according to claim 1, characterized in that: The vacuum degree of the vacuum mud training is ≥0.09MPa, and the mud training time of the vacuum mud training is ≥30min.

7. The method for preparing the extruded carbon mineralized fiber cement board according to claim 1, characterized in that: The die pressure for vacuum extrusion molding is 5-15MPa.

8. The method for preparing the extruded carbon mineralized fiber cement board according to claim 1, characterized in that: The temperature of the drying pre-curing is 40-50° C., and the humidity of the drying pre-curing is 30-40% RH.

9. The method for preparing the extruded carbon mineralized fiber cement board according to claim 1, characterized in that: The CO2 curing pressure is 0.1-0.3 MPa, the CO2 curing time is 2-48 hours, and the CO2 concentration is ≥20%VOL.

10. A carbon mineralized fiber cement board obtained by the preparation method according to any one of claims 1 to 9.

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