Preparation method of cement-fly ash foamed thermal insulation material

Abstract

The present invention relates to a preparation method of a cement-fly ash foamed thermal insulation material, which belongs to the technical field of building materials. The method comprises the following steps: step S1, preparing the following raw materials in parts by weight: 90-162 parts of cement, 15-33 parts of adsorbent aggregate, 10-15 parts of glass fiber, 1-3 parts of air entraining agent, 15-20 parts of foaming agent, 0.5-1 parts of foam stabilizer, 8-12 parts of water reducer, and 55-105 parts of deionized water; step S2, mixing the cement, adsorbent aggregate, glass fiber and foaming agent, adding deionized water for primary stirring, then adding foam stabilizer, air entraining agent and water reducer for secondary stirring, injection molding, steam treatment, and room temperature curing for 7 days to obtain the material; the outer side of the adsorbent aggregate added in the present application is coated with an emulsion containing long-chain alkanes, rigid benzene rings, amide groups, ester groups and magnetic ferrosoferric oxide, and the prepared thermal insulation material is safe and environmentally friendly and has excellent compressive strength, water resistance and chloride ion resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and in particular relates to a method for preparing a cement-fly ash foamed thermal insulation material. Background Art

[0002] Fly ash is the residue collected from the flue gas recovery systems of municipal waste-to-energy plants. It differs from fly ash from thermal power plants. Due to its small particle size, easy water absorption, and the presence of carcinogens such as heavy metals and dioxins, fly ash cannot be directly landfilled. Currently, domestic fly ash treatment primarily relies on solidification followed by landfilling, with solidification methods primarily including cement curing and chemical stabilization. The low cost of cement makes treatment relatively low. Furthermore, fly ash's primary composition is the Ca0-SiO2-Al2O3-FeO system, closely resembling the components of commonly used auxiliary cementitious materials such as blast furnace slag and fly ash, making it widely used in foam insulation materials.

[0003] In the existing technology, fly ash contains a large amount of heavy metal ions and chloride ions. During use, heavy metal ions are easily precipitated and chloride ions enter the cement, which can easily lead to a decrease in flexural strength. At the same time, most cement-based foaming materials have the problems of low compressive strength and high water absorption. Summary of the Invention

[0004] The purpose of the present invention is to provide solutions to the following technical problems:

[0005] In the existing technology, fly ash contains heavy metal ions that are easy to precipitate, which can easily cause harm to health during use. At the same time, chloride ions are easy to precipitate, resulting in a decrease in the flexural properties of cement. At the same time, foamed cement itself has a technical problem of high water absorption.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing a cement-fly ash foamed thermal insulation material comprises the following steps:

[0008] Step S1, prepare the following raw materials in parts by weight: 90-162 parts of cement, 15-33 parts of adsorbent aggregate, 10-15 parts of glass fiber, 1-3 parts of air entraining agent, 15-20 parts of foaming agent, 0.5-1 part of foam stabilizer, 8-12 parts of water reducer, and 55-105 parts of deionized water;

[0009] Step S2: Mix cement, adsorbent aggregate, glass fiber, and foaming agent by weight, then add deionized water and stir once, then add foam stabilizer, air entraining agent, and water reducer and stir twice, inject it into a mold, form it, steam treat it, and then place it at a temperature of 25° C. and a relative humidity of 95% RH for 7 days to obtain a cement-fly ash foam insulation material.

[0010] Furthermore, the first stirring time is 1-2 minutes, the stirring speed is 1300-1600 rpm, the second stirring time is 6-8 seconds, and the stirring speed is 2100-2500 rpm.

[0011] Furthermore, the cement is P·O 52.5 grade cement produced by Huaxin Cement Co., Ltd.

[0012] Furthermore, the glass fiber is A-grade alkali-free glass fiber chopped strands with a length of 6 mm.

[0013] Furthermore, the foaming agent is any one of calcium carbonate, magnesium carbonate and sodium bicarbonate.

[0014] Furthermore, the foam stabilizer is calcium stearate produced by Liyang Fengyuan Chemical Co., Ltd.

[0015] Furthermore, the air entraining agent is one or both of sodium rosinate and triterpenoid saponin.

[0016] Furthermore, the water reducer is any one of propylene polyoxyethylene ether, methyl allyl polyoxyethylene ether and hydroxypropyl methylcellulose. The water reducer is an admixture that can significantly reduce the amount of mixing water while maintaining the workability of cement paste, mortar and concrete unchanged. It can significantly improve the strength of concrete, improve the frost resistance and impermeability of concrete or reduce the amount of cement used.

[0017] Furthermore, the steam treatment is carried out in a steam chamber with a relative humidity of 90±5%, raising the temperature from room temperature to 70°C at a rate of 5°C / h, keeping the temperature for 48 hours, and then lowering the temperature to room temperature at a rate of 5°C / h.

[0018] Furthermore, the preparation method of the adsorption aggregate comprises the following steps:

[0019] Step A1: Prepare the following raw materials in parts by weight: 172-310 parts shale ceramsite, 25-45 parts fly ash, 10-18 parts silica fume, 190-345 parts standard sand, and 25-45 parts fly ash; wherein the fly ash is fly ash after heavy metal capture, and the fly ash is generated by incineration in a waste-to-energy plant;

[0020] Step A2: uniformly stirring the raw materials prepared in step A1, 100-160 parts of functional monomers, and 500-600 parts of deionized water to obtain a mixed slurry;

[0021] Step A3: Add 10-55 parts of sodium lauryl sulfate and 5-12 parts of sodium bicarbonate, by weight, to 200-300 parts of deionized water, stir evenly, then add 20-32 parts of methyl methacrylate, stir evenly, add the mixed slurry prepared in step A2, control the addition to be complete within 30 minutes, and continue stirring for 2-4 hours to obtain an emulsified emulsion;

[0022] Sodium dodecyl sulfate is an anionic surfactant used as an emulsifier. Sodium bicarbonate is alkaline and can stimulate the activity of fly ash and compact the pore structure of concrete. The long-chain alkane structure contained in the emulsified emulsion can make the finer fly ash, silica fume and fly ash evenly dispersed in the concrete paste. At the same time, the heavy metal ions and chloride ions in the fly ash can be coated in the emulsified emulsion, reducing its contact with the cement base and blocking the penetration of harmful ions into the cement base.

[0023] Step A4: 1-2.2 parts of ammonium persulfate, 5-12 parts of sodium lauryl sulfate, and the emulsified emulsion obtained in step A3 are uniformly stirred, heated to 82-86°C, and maintained for 1-2 hours. After the reaction is complete, the emulsion is dried to obtain an adsorbent aggregate. The functional monomer undergoes an emulsion polymerization reaction with methyl methacrylate using ammonium persulfate as an initiator to obtain a hydrophobic emulsion.

[0024] Furthermore, shale ceramsite is provided by Yichang Guangda Ceramsite Products Co., Ltd. It is made from natural ore through crushing, screening and burning. The particle size is 5-10mm and the bulk density is 795kg / m 3 , ceramsite itself has a low bulk density, a hard exterior and micropores inside. These micropores give ceramsite the characteristics of light weight, so ceramsite can give the material better thermal insulation properties.

[0025] Furthermore, the fly ash is Grade I fly ash produced by Wuhan Yangluo Power Plant, with a specific surface area of ​​450m 2 / kg, density is 2200kg / m 3 Fly ash has a dense filling effect, and after being added to concrete, it blocks the diffusion channels of free chloride ions in the concrete; the micro-aggregate effect makes the pore structure of hardened cement complex, which is not conducive to the movement of particles in the pores.

[0026] Furthermore, the silica fume is produced by Elkem of Norway, with a specific surface area of ​​25,000 m 2 / kg, density is 2200kg / m 3 Silica fume has high pozzolanic activity and its particles are extremely small. When added, it fills the pores of concrete and increases its density. In addition, the dense amorphous CSH gel fills around the aggregate, which improves the interface transition zone between the aggregate and cement, thereby improving the concrete's resistance to chloride ion penetration.

[0027] Furthermore, the bulk density of standard sand is 1325 kg / m 3 , the apparent density is 2650kg / m 3 .

[0028] Furthermore, the preparation method of the functional monomer comprises the following steps:

[0029] Step B1, add dimethylvinylchlorosilane to anhydrous ethanol, mix well, add pyridine under normal pressure, mechanical stirring and nitrogen protection, maintain the temperature at 0-5 ° C in an ice bath, add laurylamine dipropylene diamine dropwise, control the dropwise addition speed to 1-2 drops / second, maintain the temperature at 0-5 ° C, after the addition is completed, heat to 75-85 ° C, stir and react for 4-6 hours, after the reaction is completed, add toluene, wash with water several times to remove pyridine hydrochloride, and then remove toluene by reduced pressure distillation to obtain a terminal amino compound, wherein dimethylvinylchlorosilane, anhydrous ethanol, pyridine, The amount ratio of laurylamine dipropylene diamine and toluene is 4.6-7.6 g: 55-65 mL: 1.5-3.2 mL: 25-35 mL: 5-10 mL. Anhydrous ethanol is used as a solvent, pyridine is used as an acid-binding agent, and toluene is used as a dehydrating agent. Dimethylvinylchlorosilane and the amino group on laurylamine dipropylene diamine undergo a nucleophilic substitution reaction to obtain an amino-terminated compound containing an unsaturated double bond. During the above reaction process, the amount of laurylamine dipropylene diamine is controlled to be slightly higher than that of dimethylvinylchlorosilane so that the dimethylvinylchlorosilane can fully react.

[0030]

[0031] Step B2, adding the terminal amino compound and modified ferroferric oxide to N, N-dimethylformamide, heating to reflux for 12 hours, cooling to room temperature after the reaction, and removing N, N-dimethylformamide by rotary evaporation to obtain a functional monomer, wherein the amount ratio of the terminal amino compound, modified ferroferric oxide and N, N-dimethylformamide is 3.3-4.5g:5-7g:55-65mL, and the primary amino group on the terminal amino compound undergoes a ring-opening reaction with the anhydride on the modified ferroferric oxide to obtain a functional monomer.

[0032] Furthermore, the preparation method of modified magnetic ferrosoferric oxide comprises the following steps:

[0033] Step C1, adding citric acid and magnetic ferroferric oxide to deionized water, stirring and reacting at 60-80°C for 1-2h, cooling to room temperature, centrifuging, filtering, collecting the precipitate to obtain carboxylated magnetic ferroferric oxide, dissolving the carboxylated magnetic ferroferric oxide in dichloromethane, adding thionyl chloride and pyridine, and refluxing at 70°C for 3-4h. After the reaction is completed, the impurities are removed by rotary evaporation to obtain acyl chloride magnetic ferroferric oxide, wherein the amount ratio of citric acid and magnetic ferroferric oxide to deionized water is: 3-6g:2-5g:55-65mL, the amount ratio of carboxylated magnetic ferroferric oxide, dichloromethane, thionyl chloride and pyridine is 3.5-6.5g:40-60mL:0.5-1mL:0.05mL, the carboxyl groups on the magnetic ferroferric oxide and citric acid form carboxylated magnetic ferroferric oxide with two molecules of carboxyl groups through Fe-O coordination bonds, and then, using pyridine as a catalyst and dichloromethane as a solvent, the carboxylated magnetic ferroferric oxide undergoes an acyl chloride reaction to obtain acyl chloride magnetic ferroferric oxide;

[0034] Step C2, adding chlorinated magnetic ferrosoferric oxide, p-toluenesulfonic acid and toluene to N, N-dimethylformamide, stirring evenly, then adding 4-hydroxyphthalic anhydride, heating to 50-70°C, continuing stirring for 6-7h, and after the reaction is completed, naturally cooling to room temperature, centrifuging, and washing with N, N-dimethylformamide and ethanol aqueous solution 3-4 times in sequence to obtain modified magnetic ferrosoferric oxide, wherein the amount ratio of chlorinated magnetic ferrosoferric oxide, p-toluenesulfonic acid, toluene, N, N-dimethylformamide and 4-hydroxyphthalic anhydride is 3-5g:0.04-0.06g:10-20mL:45-55mL:1.2-1.8g, using N, N-dimethylformamide as solvent, p-toluenesulfonic acid as catalyst, and toluene as dehydrating agent, the chlorinated magnetic ferrosoferric oxide undergoes an electrophilic substitution reaction with the hydroxyl group on the 4-hydroxyphthalic anhydride to obtain modified magnetic ferrosoferric oxide.

[0035] Beneficial effects of the present invention:

[0036] The present invention uses shale ceramsite, fly ash, silica fume, standard sand and fly ash as aggregates, and adds functional monomers and methyl methacrylate to prepare an emulsified emulsion, prepares adsorption aggregate through emulsification copolymerization, and then prepares cement-fly ash foam insulation material through foaming molding. The functional monomers contain hydrophobic long-chain alkanes, rigid benzene rings, amide groups and ester groups. The functional monomers can not only form a hydrophobic network film with methyl methacrylate and adhere to the surface of the aggregate to improve the hydrophobicity of the aggregate, but also can make auxiliary adhesives such as water reducers, foaming agents and foam stabilizers absorb water under the action of steric hindrance of the long-chain alkanes in the functional monomers. The particles of the coagulating material disperse themselves. At the same time, the functional monomer also has a rigid benzene ring. Through the synergistic effect of the above structures, the compressive strength of the cement-fly ash foamed insulation material is improved. At the same time, the hydrophilic silane group, carboxyl group and amino group as well as the magnetic nano-ferroferric oxide in the functional monomer can chelate with the heavy metal cations in the fly ash through electrostatic action and van der Waals force. At the same time, under the joint action of foaming, curing and coating with the carboxyl-containing emulsion, the Si-O and Al-O in the fly ash and silica fume are broken, which further improves the chloride ion penetration resistance of the cement-fly ash foamed insulation material. DETAILED DESCRIPTION

[0037] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0038] The chemical composition of the cementitious material involved in this application is shown in Table 1:

[0039] Table 1

[0040]

[0041] The basic properties of the cement involved in this application are shown in Table 2;

[0042] Table 2

[0043]

[0044] Example 1

[0045] Preferably, the present embodiment provides a method for preparing modified magnetic ferroferric oxide, comprising the following steps:

[0046] Step C1, 4.5g of citric acid, 3.5g of magnetic ferrosoferric oxide and 60mL of deionized water were added to a three-necked flask, stirred and reacted at 70°C for 1.5h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, filtered, and the precipitate was collected to obtain carboxylated magnetic ferrosoferric oxide. 5g of carboxylated magnetic ferrosoferric oxide and 50mL of dichloromethane were added to a three-necked flask, and then 0.75mL of dichlorothione and 0.05mL of pyridine were added. The mixture was refluxed at 70°C for 3.5h. After the reaction was completed, impurities were removed by rotary evaporation to obtain acyl chloride magnetic ferrosoferric oxide;

[0047] Step C2, 4g of acyl chloride magnetic ferrosoferric oxide, 0.05g of p-toluenesulfonic acid, 15mL of toluene and 50mL of N,N-dimethylformamide were added to a three-necked flask and stirred evenly, and then 1.5g of 4-hydroxyphthalic anhydride was added, the temperature was raised to 60°C, and stirring was continued for 6.5h. After the reaction was completed, it was naturally cooled to room temperature, centrifuged, and washed four times with N,N-dimethylformamide and ethanol aqueous solution to obtain modified magnetic ferrosoferric oxide.

[0048] Example 2

[0049] Preferably, this embodiment provides a method for preparing a functional monomer, comprising the following steps:

[0050] Step B1, 6.1g of dimethylvinylchlorosilane and 60mL of anhydrous ethanol were added to a three-necked flask and mixed evenly. Under normal pressure, mechanical stirring and nitrogen protection, 2.4mL of pyridine was added, the ice bath was maintained at a temperature of 3°C, 30mL of laurylamine dipropylene diamine was added dropwise, the dropwise addition rate was controlled to 2 drops / second, and the temperature was maintained at 3°C. After the addition was completed, the temperature was raised to 80°C and stirred for 5h. After the reaction was completed, 7.5mL of toluene was added, washed with water several times to remove pyridine hydrochloride, and then toluene was removed by reduced pressure distillation to obtain an amino-terminated compound;

[0051] Step B2: 3.9 g of the amino-terminated compound, 6 g of the modified ferrosoferric oxide prepared in Example 1, and 60 mL of N,N-dimethylformamide were added to a three-necked flask, and the temperature was raised to reflux for 12 h. After the reaction was completed, the temperature was lowered to room temperature, and N,N-dimethylformamide was removed by rotary evaporation to obtain a functional monomer.

[0052] Example 3

[0053] Preferably, this embodiment provides a method for preparing an adsorption aggregate, comprising the following steps:

[0054] Step A1: Prepare the following raw materials in parts by weight: 241 parts shale ceramsite, 35 parts fly ash, 14 parts silica fume, 267.5 parts standard sand, and 35 parts fly ash; wherein the fly ash is fly ash after heavy metal capture, and the fly ash is generated by incineration in a waste-to-energy plant;

[0055] Step A2: adding the raw materials prepared in Step A1, 130 parts of the functional monomer prepared in Example 2, and 550 parts of deionized water into a blender, and stirring uniformly to obtain a mixed slurry;

[0056] Step A3: Add 32.5 parts of sodium lauryl sulfate, 8.5 parts of sodium bicarbonate, and 250 parts of deionized water to a blender by weight and stir evenly. Then, add 26 parts of methyl methacrylate and stir evenly. Then, add the mixed slurry prepared in step A2 and add the mixture within 30 minutes. Continue stirring for 3 hours to obtain an emulsified emulsion.

[0057] Step A4: 1.6 parts of ammonium persulfate, 8.5 parts of sodium dodecyl sulfate and the emulsified emulsion obtained in step A3 were stirred evenly, heated to 84° C., and kept warm for 1.5 hours. After the reaction was completed, the adsorption aggregate was dried.

[0058] Example 4

[0059] This embodiment provides a method for preparing a cement-fly ash foam insulation material, comprising the following steps:

[0060] Step S1, preparing the following raw materials in parts by weight: 90 parts of P·O 52.5 grade cement, 15 parts of adsorption aggregate prepared in Example 3, 10 parts of Class A alkali-free glass fiber chopped strands, 1 part of sodium rosinate, 15 parts of calcium carbonate, 0.5 parts of calcium stearate, 8 parts of propylene polyoxyethylene ether, and 55 parts of deionized water;

[0061] Step S2: Cement, adsorbent aggregate, grade A alkali-free glass fiber chopped strands, and calcium carbonate were added to a blender by weight, mixed evenly, and deionized water was added. The mixture was stirred at a speed of 1300 rpm for 1 minute. Calcium stearate, sodium rosinate, and propylene polyoxyethylene ether were then added. The speed was increased to 2100 rpm, stirred for 6 seconds, and injected into a mold. After molding, the mixture was heated from room temperature to 70° C. at a rate of 5° C. / h in a steam chamber with a relative humidity of 90±5%, kept warm for 48 hours, then cooled to room temperature at a rate of 5° C. / h, and then cured at a temperature of 25° C. and a relative humidity of 95% RH for 7 days to obtain a cement-fly ash foam insulation material.

[0062] Example 5

[0063] This embodiment provides a method for preparing a cement-fly ash foam insulation material, comprising the following steps:

[0064] Step S1, preparing the following raw materials in parts by weight: 126 parts of P·O 52.5 grade cement, 24 parts of adsorption aggregate prepared in Example 3, 12.5 parts of Class A alkali-free glass fiber chopped strands, 2 parts of triterpenoid saponin, 17.5 parts of magnesium carbonate, 0.75 parts of calcium stearate, 10 parts of methyl allyl polyoxyethylene ether, and 80 parts of deionized water;

[0065] Step S2, according to weight, cement, adsorption aggregate, Class A alkali-free glass fiber chopped strands and magnesium carbonate are added to a mixer, mixed, deionized water is added, and the speed is 1450 rpm and stirred for 1.5 minutes. Calcium stearate, triterpenoid saponin and methyl allyl polyoxyethylene ether are added, the speed is increased to 2300 rpm, stirred for 7 seconds, and injected into a mold. After molding, the temperature is raised from room temperature to 70°C at a rate of 5°C / h in a steam chamber with a relative humidity of 90±5%, kept warm for 48 hours, then cooled to room temperature at a rate of 5°C / h, and then placed at a temperature of 25°C and a relative humidity of 95% RH for 7 days to obtain a cement-fly ash foam insulation material.

[0066] Example 6

[0067] This embodiment provides a method for preparing a cement-fly ash foam insulation material, comprising the following steps:

[0068] Step S1, preparing the following raw materials in parts by weight: 162 parts of P·O 52.5 grade cement, 33 parts of adsorption aggregate prepared in Example 3, 15 parts of Class A alkali-free glass fiber chopped strands, 3 parts of sodium rosinate, 20 parts of sodium bicarbonate, 1 part of calcium stearate, 12 parts of hydroxypropyl methylcellulose, and 105 parts of deionized water;

[0069] Step S2, according to weight, cement, adsorption aggregate, Class A alkali-free glass fiber chopped strands and sodium bicarbonate are added to a blender, mixed, deionized water is added, and the speed is 1600 rpm and stirred for 2 minutes, and then calcium stearate, sodium rosinate and hydroxypropyl methylcellulose are added, the speed is increased to 2500 rpm, and stirred for 8 seconds. It is injected into a mold, and after molding, the temperature is raised from room temperature to 70°C at a rate of 5°C / h in a steam chamber with a relative humidity of 90±5%, and kept warm for 48 hours, then cooled to room temperature at a rate of 5°C / h, and then placed at a temperature of 25°C and a relative humidity of 95%RH for 7 days to obtain a cement-fly ash foam insulation material.

[0070] Comparative Example 1

[0071] The citric acid in Example 1 was removed, and the other raw materials and preparation process remained unchanged. The prepared substance was then used to replace the modified ferrosoferric oxide in Example 2, and the other raw materials and preparation process remained unchanged. The prepared substance was then used to replace the functional monomer in Example 3, and the other raw materials and preparation process remained unchanged. The prepared substance was then used to replace the adsorption aggregate in Example 5, and the other raw materials and preparation process remained unchanged.

[0072] Comparative Example 2

[0073] The dichloride in Example 1 was removed, and the other raw materials and preparation process remained unchanged. The prepared substance was then used to replace the modified ferrosoferric oxide in Example 2, and the other raw materials and preparation process remained unchanged. The prepared substance was then used to replace the functional monomer in Example 3, and the other raw materials and preparation process remained unchanged. The prepared substance was then used to replace the adsorption aggregate in Example 5, and the other raw materials and preparation process remained unchanged.

[0074] Comparative Example 3

[0075] The dimethylvinylchlorosilane in Example 2 was removed, and the other raw materials and preparation process remained unchanged. The prepared substance was then used to replace the functional monomer in Example 3, and the other raw materials and preparation process remained unchanged. The prepared substance was then used to replace the adsorption aggregate in Example 5, and the other raw materials and preparation process remained unchanged.

[0076] Comparative Example 4

[0077] Remove the laurylamine dipropylene diamine in Example 2, and the other raw materials and preparation process remain unchanged. Then replace the functional monomer in Example 3 with the prepared substance, and the other raw materials and preparation process remain unchanged. Then replace the adsorption aggregate in Example 5 with the prepared substance, and the other raw materials and preparation process remain unchanged.

[0078] Comparative Example 5

[0079] The modified ferrosoferric oxide in Example 2 was removed, and the other raw materials and preparation process remained unchanged. The prepared substance was then used to replace the functional monomer in Example 3, and the other raw materials and preparation process remained unchanged. The prepared substance was then used to replace the adsorption aggregate in Example 5, and the other raw materials and preparation process remained unchanged.

[0080] Comparative Example 6

[0081] The temperature raising step in the curing treatment in Example 5 was removed, and the mixture was kept at room temperature for 48 h. The other raw materials and preparation process remained unchanged.

[0082] Performance testing

[0083] The 7d compressive strength and water absorption of the cement-fly ash foam insulation materials prepared in Examples 4-6 and Comparative Examples 1-6 were tested according to the JG / T 266-2011 standard; the thermal conductivity was tested according to the GB / T 10294-2008 standard, as shown in Table 3:

[0084] Table 3

[0085]

[0086]

[0087] According to the environmental protection industry standard "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007), the cement-fly ash foam insulation materials prepared in Examples 4-6 and Comparative Examples 1-6 were tested for leaching heavy metal elements, as shown in Table 4.

[0088] Table 4

[0089]

[0090] Cylindrical concrete specimens with a diameter of 100 mm and a height of 50 mm were prepared according to the preparation methods of Examples 4-6 and Comparative Examples 1-6. The specimens were placed outdoors for natural curing for 90 days to obtain test blocks. The test blocks were then immersed in a 10 wt % sodium chloride corrosive medium for immersion tests at immersion times of 30 days, 90 days, 180 days, and 300 days. At each corrosive age, the 6-h electrical flux at each corrosive age was measured according to the method of GB / T 50082-2009. The results are shown in Table 5.

[0091] Table 5

[0092]

[0093] As shown in Table 3-5, compared with Comparative Examples 1-6, the cement-fly ash foamed insulation material prepared in Example 3-5 has excellent compressive strength, water absorption resistance, thermal insulation and chloride ion resistance. At the same time, it can adsorb heavy metal ions in fly ash and can be used safely. The specific reason is that in Comparative Example 1, there is a lack of citric acid that can chemically bond with ferroferric oxide, and the prepared monomer lacks a carboxyl group that can chelate with heavy metal ions, resulting in reduced performance of the cement-fly ash foamed insulation material finally prepared. In Comparative Example 2, dichloroxy thionyl is removed, resulting in the inability of the carboxyl group to be converted into an acyl chloride group with reactive performance, and the magnetic ferroferric oxide cannot be chemically bonded with the terminal amino compound, resulting in reduced performance of the cement-fly ash foamed insulation material finally prepared. The lack of hydrophilic silane groups and unsaturated double bonds with chemical polymerization leads to reduced performance of the cement-fly ash foamed insulation material finally prepared. Comparative Example 4 lacks hydrophobic long-chain alkanes and reactive amino groups, and the performance of the cement-fly ash foamed insulation material finally prepared is reduced. Comparative Example 5 lacks magnetic ferroferric oxide and carboxyl groups with strong adsorption properties, resulting in reduced performance of the cement-fly ash foamed insulation material finally prepared. In Comparative Example 6, due to the lack of steam treatment process, Si-O and Al-O in Al2O3 and SiO2 in the fly ash and silica fume ash of the prepared insulation material cannot be effectively broken under the coating of the prepared carboxyl-containing emulsion, which ultimately leads to reduced performance of the cement-fly ash foamed insulation material finally prepared.

[0094] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0095] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a cement-fly ash foamed thermal insulation material, characterized in that: The following steps are involved: Step S1, prepare the following raw materials by weight: 90-162 parts of cement, 15-33 parts of adsorbent aggregate, 10-15 parts of glass fiber, 1-3 parts of air entraining agent, 15-20 parts of foaming agent, 0.5-1 part of foam stabilizer, 8-12 parts of water reducer, and 55-105 parts of deionized water; Step S2: Mix cement, adsorbent aggregate, glass fiber, and foaming agent by weight, add deionized water, and stir once, then add a foam stabilizer, an air entraining agent, and a water reducer, and stir twice, inject the mixture into a mold, steam-treat, and then cure at 25° C. and 95% relative humidity for 7 days to obtain a cement-fly ash foamed thermal insulation material; The preparation method of adsorption aggregate comprises the following steps: Step A1: Prepare the following raw materials by weight: 172-310 parts shale ceramsite, 25-45 parts fly ash, 10-18 parts silica fume, 190-345 parts standard sand, and 25-45 parts fly ash; wherein the fly ash is fly ash after heavy metal capture, and the fly ash is generated by incineration in a waste-to-energy plant; Step A2, the raw materials prepared in step A1, 100-160 parts of functional monomers and 500-600 parts of deionized water are stirred to obtain a mixed slurry; Step A3: Add 10-55 parts of sodium lauryl sulfate and 5-12 parts of sodium bicarbonate, by weight, to 200-300 parts of deionized water and stir evenly. Then, add 20-32 parts of methyl methacrylate and stir evenly. Then, add the mixed slurry prepared in step A2 within 30 minutes and continue stirring for 2-4 hours to obtain an emulsified emulsion. Step A4: Evenly stir 1-2.2 parts of ammonium persulfate, 5-12 parts of sodium lauryl sulfate, and the emulsified emulsion obtained in step A3, raise the temperature to 82-86° C., and keep the temperature for 1-2 hours. After the reaction is completed, dry the mixture to obtain an adsorption aggregate. The preparation method of the functional monomer comprises the following steps: Step B1, dimethylvinylchlorosilane is added to anhydrous ethanol and mixed evenly. Pyridine is added under normal pressure, mechanical stirring and nitrogen protection. The temperature is maintained at 0-5°C in an ice bath. Laurylamine dipropylene diamine is added dropwise at a rate of 1-2 drops per second and the temperature is maintained at 0-5°C. After the addition is completed, the temperature is raised to 75-85°C and stirred for reaction for 4-6 hours. After the reaction is completed, toluene is added, the mixture is washed with water several times to remove pyridine hydrochloride, and the toluene is removed by reduced pressure distillation to obtain an amino-terminated compound; Step B2, adding the amino-terminated compound and modified ferrosoferric oxide to N,N-dimethylformamide, heating to reflux for 12 hours, cooling to room temperature after the reaction, and removing N,N-dimethylformamide by rotary evaporation to obtain a functional monomer; The preparation method of modified magnetic ferrosoferric oxide comprises the following steps: Step C1, adding citric acid and magnetic ferroferric oxide to deionized water, stirring and reacting at 60-80° C. for 1-2 hours, cooling to room temperature, centrifuging, filtering, and collecting the precipitate to obtain carboxylated magnetic ferroferric oxide, dissolving the carboxylated magnetic ferroferric oxide in dichloromethane, adding thionyl chloride and pyridine, and reflux reacting at 70° C. for 3-4 hours. After the reaction is completed, removing impurities by rotary evaporation to obtain acyl chloride magnetic ferroferric oxide; Step C2, adding chlorinated magnetic ferrosoferric oxide, p-toluenesulfonic acid and toluene to N, N-dimethylformamide, stirring evenly, then adding 4-hydroxyphthalic anhydride, heating to 50-70 ° C, continuing stirring for 6-7 hours, after the reaction is completed, naturally cooling to room temperature, centrifuging, and washing with N, N-dimethylformamide and ethanol aqueous solution 3-4 times in sequence to obtain modified magnetic ferrosoferric oxide.

2. The method for preparing a cement-fly ash foamed thermal insulation material according to claim 1, characterized in that: In step B1, the usage ratio of dimethylvinylchlorosilane, anhydrous ethanol, pyridine, laurylamine dipropylene diamine and toluene is 4.6-7.6 g: 55-65 mL: 1.5-3.3 mL: 25-35 mL: 5-10 mL.

3. The method for preparing a cement-fly ash foamed thermal insulation material according to claim 1, characterized in that: In step B2, the ratio of the amino-terminated compound, the modified ferrosoferric oxide, and N,N-dimethylformamide is 3.3-4.5 g: 5-7 g: 55-65 mL.

4. The method for preparing a cement-fly ash foamed thermal insulation material according to claim 1, characterized in that: In step C1, the usage ratio of citric acid, magnetic ferroferric oxide and deionized water is 3-6 g: 2-5 g: 55-65 mL.

5. The method for preparing a cement-fly ash foamed thermal insulation material according to claim 1, characterized in that: In step C1, the ratio of carboxylated magnetic ferrosoferric oxide, dichloromethane, thionyl chloride and pyridine is 3.5-6.5 g:40-60 mL:0.5-1 mL:0.05 mL.

6. The method for preparing a cement-fly ash foamed thermal insulation material according to claim 1, characterized in that In step C2, the usage ratio of acylated magnetic ferrosoferric oxide, p-toluenesulfonic acid, toluene, N,N-dimethylformamide and 4-hydroxyphthalic anhydride is 3-5 g: 0.04-0.06 g: 10-20 mL: 45-55 mL: 1.2-1.8 g.

7. The method for preparing a cement-fly ash foamed thermal insulation material according to claim 1, characterized in that: The stirring time is 1-2 minutes, and the stirring speed is 1300-1600 rpm.

8. The method for preparing a cement-fly ash foamed thermal insulation material according to claim 1, characterized in that: The secondary stirring time is 6-8s, and the stirring speed is 2100-2500rpm.

9. The method for preparing a cement-fly ash foamed thermal insulation material according to claim 1, characterized in that: In step S2, the steam treatment is performed in a steam chamber with a relative humidity of 90±5%, raising the temperature from room temperature to 70°C at a rate of 5°C / h, keeping the temperature for 48 hours, and then lowering the temperature to room temperature at a rate of 5°C / h.

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