Fabricated composite cement board for building and preparation process thereof

Abstract

The application discloses a composite cement board for fabricated buildings and a preparation process thereof, and relates to the technical field of composite cement boards. Gel material, aggregate, fiber, additive and water are mixed and stirred to form a slurry; the slurry is paved and formed, a mesh cloth is added in the paving process, and the slurry is pressed, shaped, and maintained to obtain the composite cement board. The maintenance includes heat maintenance and normal-temperature oxidation. Through the temperature-chemical coupling effect in the heat maintenance process, the cement hydration is accelerated, the strength skeleton is quickly established, the organic-inorganic interface chemical bonding is promoted, and the multiphase microstructure is optimized, so that the cement board has good early strength and durability and can meet the rapid construction requirement of fabricated buildings.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite cement board, and particularly relates to a composite cement board for fabricated building and a preparation process thereof. BACKGROUND

[0002] Under the tide of building industrialization, as a prefabricated board made of cement-based gel material, filler and functional additives through a specific process, the fabricated cement board has the characteristics of standardized production, rapid installation on site, controllable thickness, etc., and can be widely applied to building components such as walls and partitions. In order to adapt to the rapid construction requirements of prefabricated cement board fabricated buildings, the component needs to reach a certain strength to be safely lifted and transported. However, the ordinary portland cement commonly used has slow setting speed and low early strength. Therefore, the present application provides a composite cement board for fabricated building and a preparation process thereof. SUMMARY

[0003] The present application aims to provide a composite cement board for fabricated building and a preparation process thereof to solve the problems in the background art.

[0004] In order to solve the above technical problems, the present application provides the following technical scheme: a composite cement board for fabricated building, comprising the following components: gel material, aggregate, fiber, additive, mesh cloth and water.

[0005] Further, the gel material is a mixture of cement, fly ash and silica fume.

[0006] Further, the cement is a mixture of portland cement and sulphoaluminate cement.

[0007] Further, the gel material comprises the following components: 50-60 parts of portland cement, 12-20 parts of sulphoaluminate cement, 40-50 parts of fly ash and 5-10 parts of silica fume by mass.

[0008] Further, the aggregate is a mixture of one or more of perlite, glass beads, ceramsite, organic particles, kaolin and sand.

[0009] Further, the fiber is a mixture of one or more of plant fiber, inorganic fiber, metal fiber and high molecular organic fiber.

[0010] The fiber length is 6-12 mm.

[0011] Further, the additive is a mixture of two or more of water reducing agent, defoaming agent, waterproof agent, retarder and early strength agent.

[0012] Further, the mesh cloth is one of carbon fiber mesh cloth, basalt fiber cloth and glass fiber mesh cloth.

[0013] Further, the mass ratio of the gel material, aggregate, fiber, and additive is (50-60):(20-25):(0.5-2.0):(2-6).

[0014] The mesh cloth is provided with 1-2 layers.

[0015] Further, the water-cement ratio is 0.32-0.38.

[0016] Further, the aggregate comprises the following components: 20-30 parts by volume of expanded perlite, 15-25 parts by volume of closed-cell vitrified microbeads, and 10-20 parts by volume of recycled EPS particles.

[0017] Further, the thickness of the composite cement board is 9-18 mm.

[0018] In the above technical solution, the gel material is a mixture of Portland cement, sulphoaluminate cement, fly ash, and silica fume. The Portland cement provides the main compressive strength of the cement board, and an appropriate amount helps to give the cement board good strength performance while reducing the risk of cracking caused by drying shrinkage. The sulphoaluminate cement can improve the early strength of the cement board, has a slight expansion, can compensate for the shrinkage of the Portland cement, and reduce the cracking of the cement board. The fly ash can improve the fluidity of the slurry, reduce its water requirement, and help to improve the long-term strength of the cement board. The added fiber can not only bear the load transmission and improve the mechanical properties, but also inhibit the plastic shrinkage cracks of the cement board, bridge the macro cracks, and improve the fracture toughness of the cement board.

[0019] A preparation process of a composite cement board for fabricated buildings, comprising the following processes:

[0020] Mixing and stirring the gel material, aggregate, fiber, additive, and water to form a slurry, laying up and molding, adding mesh cloth during the laying up process, pressing and shaping, curing, and obtaining the composite cement board.

[0021] Further, the fiber and mesh cloth are sprayed with organic emulsion before use; and the spraying is left to air at room temperature for 10-15 min.

[0022] The spraying amount of the organic emulsion sprayed on the mesh cloth is 8-12 wt%;

[0023] The spraying amount of the organic emulsion sprayed on the fiber is 5-8 wt%;

[0024] The mass of water in the organic emulsion is included in the mass of the added water.

[0025] Further, the organic emulsion is water-based resin emulsified asphalt, which is prepared by the following process:

[0026] The humic acid is dissolved in water to form a humic acid solution, and the pH of the system is adjusted to 2-3; under the protection of a nitrogen atmosphere, acrylic acid, N-hydroxyethyl acrylamide, dimethylaminoethyl methacrylate, N,N'-methylene bisacrylamide, and 1 / 3 initiator are mixed, and the temperature is raised to 40-55 DEG C, and the reaction is carried out for 20-30 min; molten pitch and the remaining initiator are slowly added, and the temperature is raised to 135-150 DEG C at a rate of 2-5 DEG C / min, and the hydrothermal reaction is carried out for 5-8 h; after the reaction, the temperature is lowered to 55-65 DEG C, and shearing is carried out, to obtain an organic emulsion.

[0027] Further, the mass concentration of the humic acid solution is 12-15%;

[0028] When shearing, water is added to the system to adjust the solid content of the organic emulsion to 45-50%; the water in the organic emulsion is used as the added water.

[0029] Further, the organic emulsion comprises the following components: 1-2 parts of humic acid, 5-12 parts of acrylic acid, 9-36 parts of N-hydroxyethyl acrylamide, 10-25 parts of dimethylaminoethyl methacrylate, 0.01-0.02 parts of N,N'-methylene bisacrylamide, 0.003-0.020 parts of initiator, and 47-85 parts of molten pitch, in terms of mass parts.

[0030] Further, the molten pitch is obtained by mixing base pitch and octadecyl imidazoline, and is obtained by keeping the temperature at 150±5 DEG C for 30-60 min.

[0031] Further, the octadecyl imidazoline is obtained by the following process:

[0032] Octadecanoic acid, diethylenetriamine, and dimethylbenzene are mixed, and the temperature is raised to 140±5 DEG C, and stirring is carried out for 100-150 min; the temperature is raised to 180±5 DEG C, and the reaction is continued for 320-400 min; after the reaction, dimethylbenzene is removed by distillation under reduced pressure, and vacuum drying is carried out.

[0033] The mass ratio of octadecanoic acid, diethylenetriamine, and dimethylbenzene is 1:(0.35-0.45):(0.5-1.0).

[0034] Further, the initiator is one of ammonium persulfate and sodium persulfate, or a compound of one of sodium thiosulfate and sodium bisulfite.

[0035] Further, the shearing process is as follows: the rotation speed is 5000-10000 rpm, and the time length is 10-20 min.

[0036] In the above technical scheme, under acidic conditions, the phenolic hydroxyl and carboxyl groups in humic acid are paperized, pre-assembled with acrylic acid (AA), and free radicals are generated by decomposition of the initiator, co-extrusion of the alkenyl double bond, initiation of chain growth, and free radical polymerization with N-hydroxyethyl acrylamide (HEAA) and dimethylaminoethyl methacrylate (DMAEMA) to form a copolymer; the double acrylamide groups of the crosslinking agent N,N'-methylenebisacrylamide (MBA) are coupled to the copolymer chain to construct a three-dimensional network structure.

[0037] The base asphalt is modified with acrylic acid (ester) monomer, and a stable emulsion is formed by emulsification process to obtain an organic emulsion, in which the asphalt particles (core) are wrapped by humic acid-acrylic acid copolymer (shell), and the carboxyl groups in the asphalt form amide bonds with the -NH2 of the copolymer. The base asphalt is pre-reacted with octadecyl imidazoline before adding the water-based resin system, the amine group and the carbonyl group undergo nucleophilic addition to form a stable amine-ester bond, which can reduce the polarity of the asphalt and improve the compatibility with the water-based resin; and can effectively avoid the occurrence of side reactions, while promoting the subsequent free radical polymerization reaction between the acrylic acid (ester) monomer (copolymer), so that a stable cross-linked structure is formed between the asphalt and the copolymer, and finally a composite emulsion system with core-shell structure is constructed. The technical effects of the organic emulsion are: (1) In the aspect of interface enhancement, in the prepared organic emulsion, the carboxyl groups (-COOH) and amide groups (-CONH) form multiple chemical bonds with the hydration products of cement (such as C-S-H gel), including hydrogen bonds and coordination bonds; dimethylaminoethyl methacrylate forms a salt under acidic conditions, and its cationic properties can produce electrostatic adsorption with negatively charged cement particles, significantly reducing interface defects, thereby greatly improving the tensile strength and crack resistance of the prepared cement board. (2) In the aspect of material toughening, the emulsified asphalt forms a three-dimensional elastic network structure during the hardening of cement, this microstructure can effectively absorb and disperse impact energy, improving the low-temperature toughness of the cement board and significantly improving its impact resistance and crack resistance. And the modification of octadecyl imidazoline to asphalt improves the thermal stability of asphalt and improves its dispersibility in the system, so that the cement board has excellent high and low temperature stability. (3) In the aspect of durability, the copolymer of humic acid and acrylic acid can form a dense hydrophobic film layer inside the cement board, making the cement board have very low water absorption and excellent resistance to chloride ion penetration. At the same time, the addition of organic emulsion can also effectively reduce the viscosity of the slurry, significantly improve its pouring fluidity, and provide convenience for the processing process.

[0038] Through organic emulsion treatment of the fiber and the mesh cloth, the fiber / mesh cloth and the cement interface is strongly combined, the interface strength is improved, so that the fiber / mesh cloth and the matrix cooperatively bear; the formed flexible asphalt elastic network can effectively inhibit crack propagation, and effectively improve the impact resistance and crack resistance of the cement board; in cooperation with the hydrophobic barrier formed by the humic acid-acrylic acid copolymer, the cement board has excellent impermeability and long-term durability.

[0039] In terms of process parameter control, the solid content of the organic emulsion is selected to be 45-50%, which avoids uneven spraying caused by too high solid content and prevents film discontinuity caused by too low solid content. By controlling the spraying amount, sufficient wetting of the mesh cloth nodes is ensured, and the occurrence of fiber agglomeration is effectively prevented, which provides protection for stable performance of the cement board.

[0040] Further, before use, the aggregate is surface treated, and the specific process is as follows:

[0041] The aggregate and water are mixed, and then magnesium chloride, dihydrogen phosphate, and magnesium oxide are added in sequence and stirred and mixed for 10-30 min to form a magnesium silicate hydrate gel;

[0042] Para-aminosalicylic acid is added to the system, heated to 92-95℃, and stirred and reacted for 20-30 min to obtain a modified aggregate.

[0043] Further, the water contained in the modified aggregate exists as added water.

[0044] Further, the modified aggregate comprises the following components: 100 parts of aggregate, 24.2-32.2 parts of magnesium oxide, 9.3-9.7 parts of magnesium chloride, 1.1-1.4 parts of dihydrogen phosphate, 23.4-28.8 parts of water, and 4.8-20.7 parts of para-aminosalicylic acid.

[0045] The dihydrogen phosphate is one of potassium dihydrogen phosphate, sodium dihydrogen phosphate, and aluminum dihydrogen phosphate.

[0046] In the above technical solution, the functional modification of the aggregate surface is realized through the reaction among the aggregate, magnesium oxide, magnesium chloride, dihydrogen phosphate, and para-aminosalicylic acid. First, magnesium oxide hydrolyzes in the water medium to form magnesium hydroxide [Mg(OH)2]; SiO2 on the surface of the aggregate partially dissolves under acidic conditions to release silicate ions, which react with Mg(OH)2 to form amorphous magnesium silicate hydrate gel (M-S-H); and the dihydrogen phosphate buffers the pH to 5-6, which can inhibit the rapid precipitation of Mg(OH)2 and ensure the uniform formation of the M-S-H gel. Subsequently, para-aminosalicylic acid is introduced, which condenses with the hydroxyl groups on the surface of the aggregate through the carboxyl groups in its molecular structure, and the amino groups react with Mg 2+ 2+ ​The coordination bonds formed, through dual chemical interactions, significantly enhance the interfacial bonding strength. The MSH gel forms a surface coating on the aggregate surface, enabling it to form chemical bonds (Si-O-Ca bonds) with the calcium silicate hydration products (CSH) in the cement matrix; the additional hydrogen bonding sites provided by the synergistically introduced benzene rings and carboxyl groups further enhance the interfacial bonding strength between the aggregate and cement.

[0047] MSH gel effectively fills the aggregate-cement interface transition zone, significantly reducing the porosity of this area. Simultaneously, the hydrophobic benzene ring structure in the PABA molecule forms a hydrophobic barrier at the interface, not only reducing water penetration and significantly lowering the water absorption rate of the cement board, but also effectively inhibiting the diffusion of harmful substances such as chloride ions. This dual protection mechanism significantly improves the density and long-term durability of cement-based materials.

[0048] Furthermore, the maintenance includes heat maintenance and room temperature oxidation;

[0049] The heat curing process conditions are: temperature 50-100℃, duration 6-12h;

[0050] The process conditions for ambient temperature curing are: temperature 17~25℃, humidity 95~100%RH, duration 7~28d.

[0051] In the above technical solution, the hydration reaction of cement is accelerated in the heat curing environment. High temperature promotes the hydrolysis of tricalcium silicate (C3S) and dicalcium silicate (C2S), generating more CSH gel and Ca(OH)2. The MSH gel (MgO·SiO2·nH2O) on the aggregate surface crosslinks with the CSH of the cement matrix through Si-O-Ca bonds, forming a dense interfacial transition zone and rapidly establishing a strength skeleton. The organic emulsion undergoes crosslinking and curing, and at high temperature, the carboxyl groups (-COOH) in the copolymer react with the cement Ca... 2+ More coordination bonds are formed, and the crosslinking agent N,N'-methylenebisacrylamide (MBA) undergoes further condensation; the emulsified asphalt undergoes a phase transition above 50°C, and the asphalt particles fuse into a continuous elastic phase, filling the capillary pores. This results in a rapid improvement in the mechanical properties of the cement board and gives it excellent durability.

[0052] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0053] 1. The preparation process of a composite cement board for fabricated buildings described in the application realizes the strong combination of fiber / gauze and cement interface through organic emulsion treatment of fiber and gauze, improves the interface strength, and makes fiber / gauze and matrix bear load cooperatively; the flexible asphalt elastic network formed can effectively inhibit crack propagation and effectively improve the impact resistance and crack resistance of the cement board; the hydrophobic barrier formed by humic acid-acrylic acid copolymer makes the cement board have excellent impermeability and long-term durability.

[0054] 2. The preparation process of a composite cement board for fabricated buildings described in the application builds a M-S-H gel / PABA composite modified layer with a multi-level structure on the surface of aggregate through a surface treatment process of aggregate. The modified layer optimizes the microstructure of the interface transition zone on the one hand and introduces hydrophobic groups and multiple active sites on the other hand, so that the obtained cement-based composite material finally exhibits excellent high strength, low permeability and long life characteristics.

[0055] 3. The preparation process of a composite cement board for fabricated buildings described in the application accelerates cement hydration, quickly establishes a strength skeleton, promotes organic-inorganic interface chemical bonding, and optimizes the multiphase microstructure through the temperature-chemical coupling effect in the heat curing process, so that the cement board has good early strength and durability and can adapt to the rapid construction requirements of fabricated buildings. DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0057] In the following detailed description,

[0058] Portland cement: Shield 42.5R ordinary Portland cement; Sulfoaluminate cement: R.SAC42.5 ordinary sulfoaluminate cement;

[0059] Fly ash: secondary fly ash, oxide mass components as follows: 48.1% SiO2, 34.4% Al2O3, 4.5% Fe2O3, 0.9% CaO, 1.2% TiO2, 0.7% MgO, 0.7% K2O, loss on ignition 7.65;

[0060] Silica fume: 93.1% SiO2, loss on ignition 1.4; Magnesia: active magnesia T-LBM, specific surface area 300 m 2 / kg, α-MgO content 65.5%;

[0061] The admixture is a mixture of water reducing agent (SKY 8233), defoaming agent (BYK 024) and waterproofing agent (BASF 501) with a mass ratio of 1:0.1:1.5;

[0062] The fiber is polypropylene fiber with a length of 10 mm, a tensile strength of 500 MPa, an elastic modulus of 3.3 GPa, and a density of 0.91 g / cm 3 ;

[0063] The mesh cloth is basalt fiber cloth with a tensile strength of 2322 MPa, an elastic modulus of 129 GPa, and a density of 2.8 g / cm 3 ;

[0064] The average particle size of the expanded perlite is 2 μm; the average particle size of the closed-cell vitrified microsphere is 1 μm; the average particle size of the recycled EPS particle is 3.2 μm; the thickness of the composite cement board is 15 mm;

[0065] Matrix asphalt: Shell 60 / 80 asphalt;

[0066] The mass of water in the organic emulsion and modified aggregate is included in the added water;

[0067] Octadecyl imidazoline is prepared by the following process: mixing octadecanoic acid, diethylene triamine, and xylene, heating to 140°C, stirring for 2 h; heating to 180°C and continuing to react for 4 h; after reaction, vacuum distillation to remove xylene and vacuum drying; the mass ratio of octadecanoic acid, diethylene triamine, and xylene is 1:0.4:0.8;

[0068] The initiator is a mixture of sodium persulfate and sodium thiosulfate with a mass ratio of 1:0.4;

[0069] Pure acrylic emulsion: solid content 50%, pH 7.8, glass transition temperature 23°C.

[0070] Example 1: A preparation process of a composite cement board for fabricated buildings, comprising the following processes:

[0071] Step 1: Mix the matrix asphalt with 2 wt% octadecyl imidazoline, heat to 155°C and react for 30 min to obtain molten asphalt;

[0072] Humic acid is dissolved in water to form a 12wt% humic acid solution, and the pH of the system is adjusted to 3; under the protection of a nitrogen atmosphere, acrylic acid, N-hydroxyethyl acrylamide, dimethylaminoethyl methacrylate, N,N'-methylene bisacrylamide, and 1 / 3 initiator are mixed and heated to 40℃ for 20min; molten pitch and the remaining initiator are slowly added while heating at a rate of 2℃ / min to 135℃ for 8h; after the reaction, the temperature is lowered to 55℃, sheared at 10000rpm for 10min, and water is added to obtain an organic emulsion with a solid content of 45%; the organic emulsion comprises the following components: 1 part of humic acid, 5 parts of acrylic acid, 9 parts of N-hydroxyethyl acrylamide, 10 parts of dimethylaminoethyl methacrylate, 0.01 parts of N,N'-methylene bisacrylamide, 0.003 parts of initiator, and 47 parts of molten pitch;

[0073] The organic emulsion is sprayed on the fibers and the mesh cloth, respectively, and left to air dry at room temperature for 10min; the spraying amount of the organic emulsion on the mesh cloth is 8wt%; the spraying amount of the organic emulsion on the fibers is 5wt%;

[0074] Step 2: The aggregate and water are mixed, and then magnesium chloride, dihydrogen phosphate, and magnesium oxide are added in sequence and stirred for 10min to form a magnesium silicate hydrate gel; para-aminosalicylic acid is added to the system and heated to 92℃ for 20min to obtain a modified aggregate; the modified aggregate comprises the following components: 100 parts of aggregate, 24.2 parts of magnesium oxide, 9.3 parts of magnesium chloride, 1.1 parts of potassium dihydrogen phosphate, 23.4 parts of water, and 4.8-20.7 parts of para-aminosalicylic acid; the aggregate comprises the following components: 20 parts of expanded perlite, 15 parts of closed-cell vitrified microbeads, and 10 parts of recycled EPS particles;

[0075] Step 3: The gel material, modified aggregate, fibers, admixture, and water are mixed and stirred to form a slurry; the slurry is spread and molded, and mesh cloth is added during the spreading process; the slurry is pressed and shaped, and cured, including hot curing and normal temperature oxidation; the process conditions for hot curing are: temperature 50℃, time 12h; the process conditions for normal temperature curing are: temperature 20℃, humidity 95%RH, time 28d, to obtain a composite cement board; the mass ratio of the gel material, modified aggregate, fibers, and admixture is 55:22:1.2:4; the gel material comprises the following components: 60 parts of Portland cement, 12 parts of sulfoaluminate cement, 40 parts of fly ash, and 5 parts of silica fume; the mesh cloth is arranged in two layers and pressed in two times; the water-cement ratio is 0.38.

[0076] Example 2: A preparation process of a composite cement board for fabricated buildings, comprising the following processes:

[0077] Step 1: Base pitch is mixed with 3wt% octadecyl imidazoline, and heated at 150℃ for 40min to obtain molten pitch;

[0078] Humic acid is dissolved in water to form a 13wt% humic acid solution, and the pH of the system is adjusted to 2.5; under the protection of a nitrogen atmosphere, acrylic acid, N-hydroxyethyl acrylamide, dimethylaminoethyl methacrylate, N,N'-methylene bisacrylamide, and 1 / 3 initiator are mixed and heated to 48℃, and reacted for 25min; molten pitch and the remaining initiator are slowly added, and the temperature is increased to 142℃ at a rate of 3℃ / min, and hydrothermal reaction is performed for 6h; after the reaction, the temperature is reduced to 60℃, and shearing is performed at 8000rpm for 115min while water is added, to obtain an organic emulsion with a solid content of 48%; the organic emulsion comprises the following components: 1.5 parts by mass of humic acid, 8.5 parts by mass of acrylic acid, 22.5 parts by mass of N-hydroxyethyl acrylamide, 17.5 parts by mass of dimethylaminoethyl methacrylate, 0.015 parts by mass of N,N'-methylene bisacrylamide, 0.012 parts by mass of initiator, and 66 parts by mass of molten pitch;

[0079] The organic emulsion is sprayed on the fibers and the mesh cloth, respectively, and after spraying, the mixture is left to stand at room temperature for 12min; the spraying amount of the organic emulsion sprayed on the mesh cloth is 10wt%; the spraying amount of the organic emulsion sprayed on the fibers is 6wt%;

[0080] Step 2: The aggregate and water are mixed, and then magnesium chloride, sodium dihydrogen phosphate, and magnesium oxide are added in sequence and stirred for 20min to form a magnesium silicate hydrate gel; para-aminosalicylic acid is added to the system, heated to 94℃, and stirred for 25min to obtain a modified aggregate; the modified aggregate comprises the following components: 100 parts by mass of aggregate, 28.2 parts by mass of magnesium oxide, 9.5 parts by mass of magnesium chloride, 1.2 parts by mass of sodium dihydrogen phosphate, 26.1 parts by mass of water, and 12.7 parts by mass of para-aminosalicylic acid; the aggregate comprises the following components: 25 parts by volume of expanded perlite, 20 parts by volume of closed-cell vitrified microbeads, and 15 parts by volume of recycled EPS particles;

[0081] Step 3: The gel material, modified aggregate, fibers, admixture, and water are mixed and stirred to form a slurry; the slurry is laid up and formed, and mesh cloth is added during the laying-up process; the slurry is pressed and shaped, and cured, including hot curing and normal temperature oxidation; the process conditions for hot curing are: a temperature of 75℃ and a duration of 8h; the process conditions for normal temperature curing are: a temperature of 20℃, a humidity of 95%RH, and a duration of 28d, to obtain a composite cement board; the mass ratio of the gel material, modified aggregate, fibers, and admixture is 55:22:1.2:4; the gel material comprises the following components: 55 parts by mass of Portland cement, 16 parts by mass of sulphoaluminate cement, 45 parts by mass of fly ash, and 8 parts by mass of silica fume; the mesh cloth is arranged in two layers and pressed in two times; the water-cement ratio is 0.35.

[0082] Example 3: A preparation process of a composite cement board for fabricated buildings, comprising the following processes:

[0083] Step 1: mix the matrix asphalt with 4wt% octadecyl imidazoline, heat and react at 145℃ for 60min to obtain the molten asphalt;

[0084] Dissolve humic acid in water to form a 15wt% humic acid solution, adjust the pH of the system to 2; under the protection of nitrogen atmosphere, add acrylic acid, N-hydroxyethyl acrylamide, dimethylaminoethyl methacrylate, N,N'-methylene bisacrylamide, 1 / 3 initiator mixture, heat to 55℃, and react for 30min; slowly add the molten asphalt and the remaining initiator, and heat to 150℃ at a rate of 5℃ / min, and hydrothermally react for 5h; after the reaction, cool to 65℃, shear at 5000rpm for 20min, and supplement water to obtain an organic emulsion with a solid content of 50%; the organic emulsion comprises the following components: 2 parts of humic acid, 12 parts of acrylic acid, 36 parts of N-hydroxyethyl acrylamide, 25 parts of dimethylaminoethyl methacrylate, 0.02 parts of N,N'-methylene bisacrylamide, 0.020 parts of initiator, and 85 parts of molten asphalt;

[0085] Spray the organic emulsion on the fibers and the mesh respectively, and air dry at room temperature for 15min; the spraying amount of the organic emulsion on the mesh is 12wt%; the spraying amount of the organic emulsion on the fibers is 8wt%;

[0086] Step 2: mix the aggregate and water, and then add magnesium chloride, sodium dihydrogen phosphate, and magnesium oxide in sequence, stir and mix for 30min to form a magnesium silicate hydrate gel; add p-aminosalicylic acid to the system, heat to 95℃, and stir and react for 30min to obtain a modified aggregate; the modified aggregate comprises the following components: 100 parts of aggregate, 32.2 parts of magnesium oxide, 9.7 parts of magnesium chloride, 1.4 parts of sodium dihydrogen phosphate, 28.8 parts of water, and 20.7 parts of p-aminosalicylic acid; the aggregate comprises the following components: 30 parts of expanded perlite, 25 parts of closed cell vitrified microsphere, and 20 parts of recycled EPS particles;

[0087] Step 3: mix and stir the gel material, modified aggregate, fibers, admixture, and water to form a slurry; lay up and form, add the mesh during the laying up process, press and shape, and cure, which includes hot curing and normal temperature oxidation; the process conditions of the hot curing are: temperature 100℃, time length 6h; the process conditions of the normal temperature curing are: temperature 20℃, humidity 95%RH, and time length 28d, to obtain a composite cement board; the mass ratio of the gel material, modified aggregate, fibers, and admixture is 55:22:1.2:4; the gel material comprises the following components: 50 parts of portland cement, 20 parts of sulphoaluminate cement, 50 parts of fly ash, and 10 parts of silica fume; the mesh is arranged in two layers and pressed in two times; the water-cement ratio is 0.32.

[0088] Comparative Example 1: a preparation process of a composite cement board for fabricated buildings, comprising the following processes:

[0089] Step 1: heat the base pitch to 155℃, keep for 30min, get the molten pitch; other process steps are the same as example 1, get the cement board.

[0090] Comparative example 2: a preparation process of a composite cement board for prefabricated building, comprising the following processes:

[0091] Step 1: spray pure acrylic emulsion on the fiber and the mesh respectively, and air dry at room temperature for 10min; the spraying amount of the mesh is 8wt%; the spraying amount of the fiber is 5wt%; other process steps are the same as comparative example 1, get the cement board.

[0092] Comparative example 3: a preparation process of a composite cement board for prefabricated building, comprising the following processes:

[0093] Step 1: spray tap water on the fiber and the mesh respectively, and air dry at room temperature for 10min; the spraying amount of the mesh is 4wt%; the spraying amount of the fiber is 2.5wt%; other process steps are the same as comparative example 1, get the cement board.

[0094] Comparative example 4: a preparation process of a composite cement board for prefabricated building, comprising the following processes:

[0095] Step 2: mix the aggregate and water, and then add magnesium chloride, dihydrogen phosphate and magnesium oxide in sequence and stir for 10min to obtain modified aggregate; the modified aggregate comprises the following components: 100 parts of aggregate, 24.2 parts of magnesium oxide, 9.3 parts of magnesium chloride, 1.1 parts of potassium dihydrogen phosphate and 23.4 parts of water by mass fraction; other process steps are the same as comparative example 3, get the cement board.

[0096] Comparative example 5: a preparation process of a composite cement board for prefabricated building, comprising the following processes:

[0097] Mix the gel material, aggregate, fiber, additive and water to form a slurry; lay up and form, add mesh cloth during the laying process, press and shape, and cure, which includes hot curing and normal temperature oxidation; the process conditions of hot curing are: temperature 50℃, time length 12h; the process conditions of normal temperature curing are: temperature 20℃, humidity 95%RH, time length 28d, to obtain the composite cement board; the mass ratio of gel material, aggregate, fiber and additive is 55:22:1.2:4; the gel material comprises the following components: 60 parts of Portland cement, 12 parts of sulphoaluminate cement, 40 parts of fly ash and 5 parts of silica fume by mass; the mesh cloth is set in two layers and pressed in two times; the water-cement ratio is 0.38; the aggregate comprises the following components: 20 parts of expanded perlite, 15 parts of closed-cell vitrified microsphere and 10 parts of recycled EPS particles by volume fraction.

[0098] Experiment: take the cement boards obtained before and after normal temperature curing in examples 1-3 and comparative examples 1-5, prepare samples, and detect the performance of the samples respectively and record the detection results:

[0099] According to GB / T 17671 as a reference standard, the strength of the sample after 12h, 3d and 28d normal temperature curing is detected;

[0100] According to ASTM C1581 as a reference standard, the crack resistance (circular ring constraint cracking) of the sample is detected, and the crack width (μm) of the 28d sample within 24h is taken as the characterization data;

[0101] According to JGJ / T 70 as a reference standard, the water resistance of the sample is detected, and the strength ratio (softening coefficient) of the 28d sample in saturated water absorption state and dry state is taken as the characterization data;

[0102] According to GB / T 50082 as a reference standard, the chloride ion penetration resistance of the sample is detected, and the electric quantity (coulomb) passed by the 28d sample under 60V direct current for 6h is taken as the characterization data;

[0103] According to GB / T 50082 as a reference standard, the long-term durability (freeze-thaw cycle) of the sample is detected, and the strength loss rate (%) of the 28d sample after 50 times of freeze-thaw cycle is taken as the characterization data.

[0104]

[0105] According to the data in the above table, the following conclusions can be clearly obtained:

[0106] The cement boards obtained in examples 1-3 are compared with the cement boards obtained in comparative examples 1-5, and the detection results show that,

[0107] Compared with the comparative examples, the cement boards obtained in examples 1-3 have higher early strength, which can reach 70-80% of the long-term strength, and have higher long-term strength data and lower crack width, softening coefficient, electric quantity, strength loss rate data. This fully shows that the present application realizes the comprehensive improvement of the strength, crack resistance, water resistance, chloride ion resistance and high and low temperature stability of the cement board.

[0108] Compared with example 1, the preparation process of the molten asphalt in comparative example 1 is different; in comparative example 2, the pure acrylic emulsion is used to surface treat the fiber and the mesh cloth; in comparative example 3, the tap water is used to surface treat the fiber and the mesh cloth; compared with comparative example 3, the preparation components of the modified aggregate in comparative example 4 are different; in comparative example 5, the aggregate and the fiber are not surface treated. The early strength, long-term strength and the ratio between the two, the crack width, the softening coefficient, the electric quantity and the strength loss rate data of the cement board obtained in comparative examples 1-5 are all increased. It can be known that the setting of the preparation process of the cement board and the components used in the present application can promote the comprehensive improvement of the strength, crack resistance, water resistance, chloride ion resistance and high and low temperature stability of the cement board.

[0109] It will be obvious to a person skilled in the art that, without departing from the spirit or essential characteristics of the application, the present application can be implemented in other specific forms. The present examples are therefore to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the description given above, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A composite cementitious panel for use in fabricated construction, characterized in that, The gel material, aggregate, fiber, additive, mesh cloth and water are mixed and stirred to form a slurry, which is paved and molded, and the mesh cloth is added during paving, and then the composite cement board is obtained by pressing, shaping and curing. The fiber and mesh cloth are sprayed with an organic emulsion before use, and are left to air at room temperature for 10-15 minutes after spraying; the organic emulsion is prepared by the following process: Humic acid is dissolved in water to form a humic acid solution, and the pH of the system is adjusted to 2-3; under the protection of a nitrogen atmosphere, acrylic acid, N-hydroxyethyl acrylamide, dimethylaminoethyl methacrylate, N,N'-methylene bisacrylamide and 1 / 3 initiator are mixed, and the temperature is raised to 40-55℃, and the reaction is carried out for 20-30 minutes; molten asphalt and the remaining initiator are slowly added, and the temperature is raised to 135-150℃ at a rate of 2-5℃ / min, and the hydrothermal reaction is carried out for 5-8 hours; after the reaction, the temperature is lowered to 55-65℃, and shearing is carried out to obtain the organic emulsion; The molten asphalt is obtained by mixing base asphalt and octadecyl imidazoline at 150±5℃ for 30-60 minutes; The organic emulsion comprises the following components: 1-2 parts of humic acid, 5-12 parts of acrylic acid, 9-36 parts of N-hydroxyethyl acrylamide, 10-25 parts of dimethylaminoethyl methacrylate, 0.01-0.02 parts of N,N'-methylene bisacrylamide, 0.003-0.020 parts of initiator, and 47-85 parts of molten asphalt.

2. The composite cementitious panel for use in fabricated construction of claim 1, wherein, The gel material comprises the following components: 50-60 parts of silicate cement, 12-20 parts of sulfoaluminate cement, 40-50 parts of fly ash, and 5-10 parts of silica fume.

3. The composite cementitious panel for use in fabricated construction of claim 1, wherein, The mass ratio of the gel material, aggregate, fiber and additive is (50-60):(20-25):(0.5-2.0):(2-6); The mesh cloth is provided with 1-2 layers.

4. A process for the preparation of a composite cementitious panel for use in fabricated construction according to any one of claims 1 to 3, characterized in that, The process comprises the following steps: The gel material, aggregate, fiber, additive and water are mixed and stirred to form a slurry, which is paved and molded, and the mesh cloth is added during paving, and then the composite cement board is obtained by pressing, shaping and curing.

5. A process for the preparation of a composite cementitious panel for fabricated construction according to claim 4, characterized in that, The aggregate is surface treated before use, and the specific process is as follows: The aggregate and water are mixed, and then magnesium chloride, dihydrogen phosphate and magnesium oxide are added and stirred for 10-30 minutes to form a magnesium silicate hydrate gel; To the system, para-aminosalicylic acid is added, heated to 92-95℃, and stirred for 20-30 minutes to obtain a modified aggregate.

6. The process for preparing a composite cementitious panel for fabricated construction according to claim 5, wherein, The modified aggregate comprises the following components: 100 parts of aggregate, 24.2-32.2 parts of magnesium oxide, 9.3-9.7 parts of magnesium chloride, 1.1-1.4 parts of dihydrogen phosphate, 23.4-28.8 parts of water, and 4.8-20.7 parts of para-aminosalicylic acid.

7. The process for preparing a composite cementitious panel for fabricated construction according to claim 4, wherein The curing comprises hot curing and normal temperature curing; The process conditions of the hot curing are as follows: temperature 50-100℃, and time length 6-12 hours; The process conditions of the normal temperature curing are as follows: temperature 17-25℃, humidity 95-100%RH, and time length 7-28 days.

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