A high-performance polyvinyl alcohol layered fiber cement board and its preparation method

Abstract

This invention discloses a high-performance polyvinyl alcohol (PVA) layered fiber cement board and its preparation method. The PVA layered fiber cement board comprises a lower layer, a middle layer, and an upper layer structure, wherein the lower layer is a PVA fiber concrete layer, the middle layer is a low-density thermal insulation concrete layer, and the upper layer is a thin waterproof concrete layer. Compared with traditional fiber cement boards, the PVA layered fiber cement board of this invention has a layering structure that conforms to mechanical principles. The lower layer is subjected to tensile stress and uses a PVA fiber concrete panel with excellent tensile and deformation properties, while the middle layer is subjected to compression and uses a lightweight low-density thermal insulation concrete panel. This achieves the goal of lightweight and high-strength mechanical properties and reduces the use of fibers and high-grade cement, thereby reducing the material cost of the product. The entire product combines thermal insulation, waterproofing, and sound insulation functions, thus improving the overall performance of the cement board.

Description

Technical Field

[0001] This invention belongs to the field of fiber cement board manufacturing technology, specifically relating to a high-performance polyvinyl alcohol (PVA) layered fiber cement board and its preparation method. Background Technology

[0002] Fiber cement board is a lightweight thin board made by mixing certain medium and short fibers as reinforcement materials with inorganic cementitious materials to form a pulp, which is then formed by sheet forming or flow forming and cured under high pressure with steam. Fiber cement board is generally used as interior wall panels, exterior wall panels, and ceiling panels in buildings, and has excellent properties such as non-combustibility, dimensional stability, corrosion resistance, and insect resistance.

[0003] Current fiber cement boards still have many shortcomings. For building exterior wall panels, which are constantly subjected to rain erosion, wind force, and the demands of hoisting and installation, they should possess excellent properties such as impermeability, lightweight, and high strength. However, even with a simple manufacturing process, fiber cement boards struggle to simultaneously achieve both high strength and lightweight characteristics. Generally, higher specimen strength corresponds to higher density. Currently, there is a lack of lightweight, high-strength fiber cement boards that, while being simple to manufacture, also possess tensile strength, deformation resistance, thermal insulation, waterproofing, fireproofing, and ease of processing.

[0004] For example, the fiber cement board disclosed in the utility model with authorization announcement number CN204738443U, although it also improves the toughness, stress resistance, thermal insulation and other properties of the fiber cement board by combining fiber cement board and wood board surface, has a weaker fire resistance due to the use of wood board surface, and its panel has many layers, including thermal insulation layer, filling layer, adhesive layer, wood layer and fiber cement board layer, making the manufacturing process relatively complicated.

[0005] Announcement No. CN208363412U discloses a multi-layer composite fiber cement board with fiber cement boards on the top and bottom layers and a hollow cavity filled with insulation material. It includes a fiber cement board body, consisting of an upper fiber cement board, an insulation layer, and a lower fiber cement board from top to bottom, connected by an adhesive layer. While this patent incorporates a reinforcing mesh to improve overall flexural and impact resistance, the connection between the insulation layer and the upper and lower fiber cement boards is complex, requiring an adhesive layer with protrusions on the connecting surface, resulting in a complex and costly manufacturing process. Furthermore, the insulation material filling the hollow cavity has a relatively low bonding strength with the upper and lower fiber boards, potentially affecting the overall integrity of the board. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a high-performance polyvinyl alcohol (PVA) layered fiber cement board and its preparation method, thereby solving the aforementioned problems in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] The present invention relates to a high-performance polyvinyl alcohol layered fiber cement board, comprising a lower layer, a middle layer, and an upper layer structure, wherein the lower layer is a PVA fiber concrete layer, the middle layer is a low-density heat-insulating concrete layer, and the upper layer is a waterproof concrete thin layer.

[0009] The components of the PVA fiber reinforced concrete layer are as follows by mass parts:

[0010] Water 25-30 parts, cement 50-70 parts, silica fume 10-15 parts, ultrafine fly ash 10-20 parts, mineral powder 10-15 parts, quartz sand 70-90 parts, polycarboxylate superplasticizer 1-2 parts, PVA fiber 1-2 parts, nano titanium dioxide 3-6 parts.

[0011] The components of the low-density thermal insulation concrete layer are as follows by mass parts:

[0012] Water 40-45 parts, cement 40-60 parts, silica fume 5-10 parts, fly ash and coal beads 20-30 parts, mineral powder 15-20 parts, ordinary water-reducing agent 4-6 parts, sand 130-150 parts.

[0013] The components of the waterproof concrete thin layer are as follows by mass parts:

[0014] Water 40-45 parts, cement 60-70 parts, silica fume 10-15 parts, mineral powder 20-25 parts, ordinary water-reducing agent 4-6 parts, sand 200-220 parts.

[0015] The present invention discloses a method for preparing high-performance polyvinyl alcohol layered fiber cement board, comprising the following steps:

[0016] Step 1: Preparation of the lower layer

[0017] Mix the specified amounts of water, cement, silica fume, ultrafine fly ash, mineral powder, and polycarboxylate superplasticizer and stir slowly (60-70 R / min) for 60 seconds. During the first 30 seconds of the slow stirring, add PVA fibers in batches. After adding PVA fibers, continue stirring slowly for another 30 seconds. Then, gradually add quartz sand and nano titanium dioxide. After adding quartz sand and nano titanium dioxide, stir slowly for 30 seconds, then stir quickly (120-130 R / min) for 30 seconds. Stop stirring for 120 seconds, then stir quickly for another 120 seconds. Once the mixing is complete, the lower layer of slurry is obtained.

[0018] Step 2: Preparation of the middle layer

[0019] Mix the specified amounts of water, cement, silica fume, fly ash, mineral powder, and water-reducing agent and stir slowly (60-70 R / min) for 60 seconds. Then, while continuing to stir slowly, gradually add sand, completing the addition within 60 seconds. Stop stirring for 120 seconds, then stir quickly (120-130 R / min) for 120 seconds. Once the mixing is complete, the intermediate layer slurry is obtained.

[0020] Step 3: Preparation of the upper layer

[0021] Mix the proportions of water, cement, mineral powder, silica fume, and water-reducing agent and stir slowly (60-70 R / min) for 60 seconds. Then, while continuing to stir slowly, gradually add sand, completing the addition within 60 seconds. Stop stirring for 120 seconds, then stir quickly (120-130 R / min) for 120 seconds. Once the mixing is complete, the upper layer slurry is obtained.

[0022] Step 4: Assembly

[0023] First, prepare a mold that has been brushed with oil. When installing the mold, install the lower layer first. Send the prepared lower layer slurry into the board making machine, filter the water, stack the obtained solid wet material layer by layer, cut it to make the wet blank board of the lower part of the fiber cement board, and put the blank board into the mold for later use. The thickness of the lower blank board is 10mm.

[0024] Then add the middle layer slurry until the mold is full. When pouring the middle layer slurry, the pouring speed needs to be controlled to avoid damaging the lower blank as much as possible. The thickness of the middle layer is 8mm.

[0025] After the lower and middle layers of slurry have initially set, the upper layer is then prepared, and the upper layer slurry is spread over the initially set lower and middle layers. The thickness of the upper layer is 2 mm.

[0026] After the mold is installed, let it stand for 24 hours, then remove the mold and place the resulting specimen in a standard curing room for 28 days. Then, apply a polyacrylate emulsion sealant to the upper surface to obtain the layered fiber cement board.

[0027] The length of the PVA fiber is 9-12 mm.

[0028] The quartz sand has a mesh size of 100-200.

[0029] The nano-titanium dioxide particles have a diameter of 15-25 nm.

[0030] This board has strong impact resistance. Nano-titanium dioxide fills the micropores in the cement base, improving the microstructure of the cement base and thus enhancing the flexural strength of the fiber cement board. In addition, this cement board is lightweight and has good waterproof performance, making it suitable for use in prefabricated sandwich exterior wall panels.

[0031] The beneficial effects of this invention are reflected in:

[0032] Compared to traditional fiber cement boards, this invention's polyvinyl alcohol (PVA) layered fiber cement board features a layered design that conforms to mechanical principles. The lower layer, subjected to tensile stress, utilizes a PVA fiber-reinforced concrete panel with excellent tensile and deformation properties. The middle layer, subjected to compression, employs a lightweight, low-density, heat-insulating concrete panel. This achieves the goal of lightweight yet high-strength mechanical properties while reducing the use of fibers and high-grade cement, thereby lowering the product's material costs. The entire product combines thermal insulation, waterproofing, and sound insulation functions, thus enhancing the overall performance of the cement board. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the polyvinyl alcohol layered fiber cement board of the present invention. In the figure: 1 lower layer - PVA fiber concrete layer; 2 middle layer - low-density thermal insulation concrete layer; 3 upper layer - waterproof concrete thin layer. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0035] Example 1:

[0036] (1) Weigh out the mass of each component in the lower layer according to the proportion. The mass ratio of each component is cementitious material: water: polycarboxylate superplasticizer: PVA fiber: quartz sand: nano titanium dioxide = 1: 0.27: 0.02: 0.02: 0.8: 0.04. The mass ratio of each component of cementitious material is cement: silica fume: ultrafine fly ash: mineral powder = 1: 0.2: 0.26: 0.2.

[0037] (2) Mix the proportions of water, cement, silica fume, ultrafine fly ash, mineral powder and polycarboxylate superplasticizer and stir slowly (60-70 R / MIN) for 60 seconds. During the first 30 seconds of the slow stirring, add PVA fiber in batches. After adding PVA fiber, continue stirring slowly for 30 seconds. Then gradually add quartz sand and nano titanium dioxide. After adding quartz sand and nano titanium dioxide, stir slowly for 30 seconds, then stir quickly (about 120-130 R / MIN) for 30 seconds. Then stop stirring for 120 seconds, then stir quickly for 120 seconds. After stirring is complete, the lower layer of slurry is obtained.

[0038] (3) The lower layer slurry obtained in step (2) is fed into the board making machine, the water is filtered, the obtained solid wet material is stacked layer by layer, and cut into a wet blank board of the lower layer of fiber cement board. The blank board is then put into a mold for later use.

[0039] (4) Weigh out the mass of each component in the middle layer according to the proportion. The mass ratio of each component is cementitious material: water: ordinary water-reducing agent: sand: fly ash and coal beads = 1: 0.45: 0.05: 1.1: 0.3. The mass ratio of each component of cementitious material is cement: silica fume: mineral powder = 1: 0.18: 0.35.

[0040] (5) Mix the proportions of water, cement, silica fume, fly ash, mineral powder and water-reducing agent and stir slowly for 60 seconds. Then, continue stirring slowly and gradually add sand, adding it all within 60 seconds. Then stop stirring for 120 seconds, and then stir quickly for 120 seconds. Once the stirring is complete, the intermediate layer slurry is obtained.

[0041] (6) Pour the middle layer slurry obtained in step (5) into the mold, let it flatten under its own gravity, cover the lower layer plate, and let it stand for 45 minutes to allow it to initially solidify.

[0042] (7) Weigh out the mass of each component in the upper layer according to the proportion. The mass ratio of each component is cementitious material: water: ordinary water-reducing agent: sand = 1: 0.45: 0.05: 2. The mass ratio of each component of cementitious material is cement: silica fume: mineral powder = 1: 0.18: 0.35.

[0043] (8) Mix the proportions of water, cement, silica fume, mineral powder and water-reducing agent and stir slowly for 60 seconds. Then, continue stirring slowly and gradually add sand, adding it all within 60 seconds. Then stop stirring for 120 seconds, and then stir quickly for 120 seconds. Once the stirring is complete, the intermediate layer slurry is obtained.

[0044] (9) Pour the upper layer slurry obtained in step (8) into the mold and cover the middle layer after initial setting.

[0045] (10) After the mold is installed, let it stand for 24 hours, then remove the mold and place the obtained specimen in a standard curing room for 28 days. Then apply polyacrylic emulsion sealant to the upper surface to obtain the layered fiber cement board.

[0046] Example 2:

[0047] (1) Weigh the components of the lower layer according to the proportion. The mass ratio of each component is cementitious material: water: polycarboxylate superplasticizer: PVA fiber: quartz sand: nano titanium dioxide = 1: 0.25: 0.02: 0.02: 0.8: 0.03. The mass ratio of each component of the cementitious material is cement: silica fume: ultrafine fly ash: mineral powder = 1: 0.2: 0.26: 0.2.

[0048] (2) Mix the proportions of water, cement, silica fume, ultrafine fly ash, mineral powder and polycarboxylate superplasticizer and stir slowly (60-70 R / MIN) for 80 seconds. During the first 30 seconds of the slow stirring, add PVA fiber in batches. After adding PVA fiber, continue stirring slowly for 30 seconds. Then gradually add quartz sand and nano titanium dioxide. After adding quartz sand and nano titanium dioxide, stir slowly for 30 seconds, then stir quickly (about 120-130 R / MIN) for 30 seconds. Then stop stirring for 120 seconds, then stir quickly for 180 seconds. After stirring is complete, the lower layer of slurry is obtained.

[0049] The remaining steps are the same as in Example 1.

[0050] Comparative Example 1:

[0051] (1) Weigh out the mass of each component in the lower layer according to the proportion. The mass ratio of each component is cementitious material: water: polycarboxylate superplasticizer: PVA fiber: quartz sand: nano silica = 1: 0.27: 0.02: 0.02: 0.8: 0.06. The mass ratio of each component of cementitious material is cement: silica fume: ultrafine fly ash: mineral powder = 1: 0.2: 0.26: 0.2.

[0052] (2) Mix the proportions of water, cement, silica fume, ultrafine fly ash, mineral powder and polycarboxylate superplasticizer and stir slowly (60-70 R / MIN) for 60 seconds. During the first 30 seconds of the slow stirring, add PVA fiber in batches. After adding PVA fiber, continue stirring slowly for 30 seconds. Then gradually add quartz sand and nano silica. After adding quartz sand and nano silica, stir slowly for 30 seconds, then stir quickly (about 120-130 R / MIN) for 30 seconds. Then stop stirring for 120 seconds, then stir quickly for 120 seconds. After stirring is complete, the lower layer of slurry is obtained.

[0053] The remaining steps are the same as in Example 1.

[0054] Comparative Example 2:

[0055] (1) Weigh out the mass of each component in the lower layer according to the proportion. The mass ratio of each component is cementitious material: water: polycarboxylate superplasticizer: PVA fiber: quartz sand = 1: 0.27: 0.02: 0.02: 0.8. The mass ratio of each component of cementitious material is cement: silica fume: ultrafine fly ash: mineral powder = 1: 0.2: 0.26: 0.2.

[0056] (2) Mix the proportions of water, cement, silica fume, ultrafine fly ash, mineral powder and polycarboxylate superplasticizer and stir slowly (60-70 R / MIN) for 60 seconds. During the first 30 seconds of the slow stirring, add PVA fiber in batches. After adding PVA fiber, continue stirring slowly for 30 seconds. Then gradually add quartz sand. After adding quartz sand, stir slowly for 30 seconds, then stir quickly (about 120-130 R / MIN) for 30 seconds. Then stop stirring for 120 seconds, then stir quickly for 120 seconds. After stirring is complete, the lower layer of slurry is obtained.

[0057] The remaining steps are the same as in Example 1.

[0058] Comparative Example 3:

[0059] (1) Weigh out the mass of each component in the lower layer according to the proportion. The mass ratio of each component is cementitious material: water: polycarboxylate superplasticizer: PVA fiber: sand = 1: 0.24: 0.02: 0.02: 1. The mass ratio of each component of cementitious material is cement: silica fume: ultrafine fly ash: mineral powder = 1: 0.2: 0.24: 0.2.

[0060] (2) Mix the proportions of water, cement, silica fume, ultrafine fly ash, mineral powder and polycarboxylate superplasticizer and stir slowly (60-70 R / MIN) for 80 seconds. During the first 30 seconds of the slow stirring, add PVA fiber in batches. After adding PVA fiber, continue stirring slowly for 30 seconds. Then gradually add quartz sand. After adding quartz sand, stir slowly for 30 seconds, then stir quickly (about 120-130 R / MIN) for 30 seconds. Then stop stirring for 120 seconds, then stir quickly for 180 seconds. After stirring is complete, cement slurry is obtained.

[0061] (3) The lower layer slurry obtained in step (2) is fed into the board making machine, the water is filtered, the obtained solid wet material is stacked layer by layer, and cut into the wet blank board of the lower part of the fiber cement board. The obtained blank board is placed in a standard curing room for 28 days, and then polyacrylic emulsion sealant is applied to the upper surface to obtain the fiber cement board.

[0062] Test example:

[0063] The layered fiber cement boards prepared in Examples 1-2 and Comparative Examples 1-3 of this invention were subjected to performance tests, and the results are shown in Table 1. Flexural strength was tested according to GB / T7019.

[0064] As shown in Table 1, the nano-titanium dioxide layered fiber cement boards prepared in Examples 1-2 of this invention have low density and excellent mechanical properties. The nano-silica layered fiber cement board prepared in Comparative Example 1 has low density but slightly poorer mechanical properties. The layered fiber cement board prepared in Comparative Example 2 has the worst mechanical properties among all layered cement boards because it lacks nanomaterials to improve the microstructure of the cement matrix. Comparative Example 3 is a fiber cement board without layering treatment; its mechanical properties are slightly improved compared to Comparative Example 2, but its higher density is detrimental to construction.

[0065] Table 1. Mechanical property test results of fiber cement boards prepared in Examples 1-2 and Comparative Examples 1-3

[0066] <![CDATA[Bulk density (g / cm 3 )]]> Non-flammable Flexural strength (MPa) Compressive strength (MPa) Example 1 1.5-1.6 Grade A 13.9 39.84 Example 2 1.6-1.7 Grade A 14.3 43.26 Comparative Example 1 1.5-1.6 Grade A 13.5 38.65 Comparative Example 2 1.5-1.6 Grade A 12.9 36.54 Comparative Example 3 1.8-1.9 Grade A 13.4 45.69

[0067] As shown in Table 1, the nano-titanium dioxide layered fiber cement boards prepared in Examples 1-2 of this invention have low density and excellent mechanical properties. The nano-silica layered fiber cement board prepared in Comparative Example 1 has low density but slightly poorer mechanical properties. The layered fiber cement board prepared in Comparative Example 2 has the worst mechanical properties among all layered cement boards because it lacks nanomaterials to improve the microstructure of the cement matrix. Comparative Example 3 is a fiber cement board without layering treatment; its mechanical properties are slightly improved compared to Comparative Example 2, but its higher density is detrimental to construction.

[0068] In summary, compared to traditional fiber cement boards, this invention features a layered design that conforms to mechanical principles. The lower layer 1, subjected to tensile stress, utilizes a PVA concrete panel with excellent tensile and deformation properties. The middle layer 2, subjected to compression, employs a lightweight, low-density, heat-insulating concrete panel, achieving the goal of lightweight and high-strength mechanical properties while reducing the use of fibers and high-grade cement, thus lowering the product's material costs. The inclusion of a thin waterproof layer 3 achieves a low-cost solution to the waterproofing problem of fiber cement boards. The lightweight, low-density, heat-insulating concrete used in the middle layer 2 provides certain thermal and sound insulation functions, expanding the application areas and scope of fiber cement boards. The upper layer 3, middle layer 2, and lower layer 1 are all cement-based panels with strong inter-layer bonding, eliminating the need for special adhesive layers and simplifying the manufacturing process, further expanding the application range of fiber cement boards.

[0069] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-performance polyvinyl alcohol layered fiber cement board, characterized in that: The polyvinyl alcohol layered fiber cement board includes a lower layer, a middle layer, and an upper layer structure, wherein the lower layer is a PVA fiber concrete layer, the middle layer is a low-density heat-insulating concrete layer, and the upper layer is a waterproof concrete thin layer. The components of the PVA fiber reinforced concrete layer are as follows by mass parts: Water 25-30 parts, cement 50-70 parts, silica fume 10-15 parts, ultrafine fly ash 10-20 parts, mineral powder 10-15 parts, quartz sand 70-90 parts, polycarboxylate superplasticizer 1-2 parts, PVA fiber 1-2 parts, nano titanium dioxide 3-6 parts. The components of the low-density thermal insulation concrete layer are as follows by mass parts: Water 40-45 parts, cement 40-60 parts, silica fume 5-10 parts, fly ash and coal beads 20-30 parts, mineral powder 15-20 parts, ordinary water-reducing agent 4-6 parts, sand 130-150 parts. The components of the waterproof concrete thin layer are as follows by mass parts: Water 40-45 parts, cement 60-70 parts, silica fume 10-15 parts, mineral powder 20-25 parts, ordinary water-reducing agent 4-6 parts, sand 200-220 parts; The polyvinyl alcohol layered fiber cement board is prepared by a method comprising the following steps: Step 1: Preparation of the lower layer Mix the specified amounts of water, cement, silica fume, ultrafine fly ash, mineral powder, and polycarboxylate superplasticizer and stir slowly for 60 seconds. During the first 30 seconds of the 60-second slow stirring, add PVA fibers in batches. After adding the PVA fibers, continue stirring slowly for another 30 seconds. Then, gradually add quartz sand and nano titanium dioxide. After adding the quartz sand and nano titanium dioxide, stir slowly for 30 seconds, then stir quickly for 30 seconds. Stop stirring for 120 seconds, then stir quickly for another 120 seconds. Once the stirring is complete, the lower layer of slurry is obtained. Step 2: Preparation of the middle layer Mix the proportioned amounts of water, cement, silica fume, fly ash, mineral powder, and water-reducing agent and stir slowly for 60 seconds. Then, while continuing to stir slowly, gradually add sand, completing the addition within 60 seconds. Stop stirring for 120 seconds, then stir quickly for 120 seconds. Once the mixing is complete, the intermediate layer slurry is obtained. Step 3: Preparation of the upper layer Mix the proportioned amounts of water, cement, mineral powder, silica fume, and water-reducing agent and stir slowly for 60 seconds. Then, while continuing to stir slowly, gradually add sand, completing the addition within 60 seconds. Stop stirring for 120 seconds, then stir quickly for 120 seconds. Once the mixing is complete, the upper layer of slurry is obtained. Step 4: Assembly First, prepare a mold that has been coated with oil. When installing the mold, install the lower layer first. Feed the prepared lower layer slurry into the board making machine, filter the water, and stack the resulting solid wet material layer by layer. Cut the solid wet material to make the wet blank board of the lower layer of fiber cement board. Put the lower blank board into the mold for later use. Then add the middle layer slurry until the mold is full. When pouring the middle layer slurry, the pouring speed needs to be controlled to avoid damaging the lower blank board as much as possible. After the lower and middle layers of slurry have initially set, make the upper layer and spread the upper layer slurry to cover the initially set lower and middle layers. After the mold is installed, let it stand for 24 hours, then remove the mold and place the obtained specimen in a standard curing room for 28 days. Finally, apply a polyacrylate emulsion sealant to the surface of the upper layer to obtain the layered fiber cement board. The length of the PVA fiber is 9-12 mm; The quartz sand has a mesh size of 100-200. The nano-titanium dioxide particles have a diameter of 15-25 nm; In step 4, the thickness of the lower blank is 10mm, the thickness of the middle slurry is controlled at 8mm, and the thickness of the upper slurry is controlled at 2mm.

2. The high-performance polyvinyl alcohol layered fiber cement board according to claim 1, characterized in that: The stirring speed for slow stirring is 60-70 R / min, and the stirring speed for fast stirring is 120-130 R / min.

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