A red mud-based multi-solid waste water-stable material with improved weather resistance and a preparation method thereof

Abstract

This invention relates to a red mud-based multi-solid wastewater stabilized material with improved weather resistance and its preparation method. The stabilized material comprises the following raw materials in parts by weight: 15-30 parts Bayer process red mud, 15-30 parts fly ash, 2.5-4 parts desulfurization ash, 3-5 parts cement, 80-100 parts aggregate, 30-40 parts hyperbranched epoxy resin emulsion, 1-3 parts alkanolamine early strength agent, and 5-15 parts water. The hyperbranched epoxy resin emulsion is prepared by a Michael addition reaction of multi-arm polyethylene glycol thiols and monoalkenyl epoxy compounds at a mercapto-alkenyl molar ratio of 1:1-1.1. The hyperbranched epoxy resin has a high density of terminal epoxy functional groups, and the epoxy groups react chemically with the active groups on the surface of the aggregate and the cementitious material, enhancing the bonding force between the aggregate and the cementitious material, reducing the risk of cracking between the aggregate and the industrial solid waste cementitious material under water-salt / freeze-thaw cycles, and extending the service life of the stabilized material.

Description

Technical Field

[0001] This invention belongs to the field of solid waste recycling technology, specifically relating to a red mud-based multi-solid wastewater stabilized material with improved weather resistance and its preparation method. Background Technology

[0002] The water-stabilized layer is a crucial structural layer between the base and surface layers of a highway, playing a decisive role in its overall performance. It typically uses cement-stabilized or lime-stabilized aggregates as the main base material. The construction process involves mixing aggregates with stabilizers (such as cement or lime) according to a specified ratio, adding water for further mixing, and then spreading and compacting the mixture to form a structure with a certain strength and stability. The main purpose of designing a water-stabilized layer is to improve the load-bearing capacity of the pavement structure and its resistance to deformation, ensuring that the asphalt or concrete surface layer receives stable and reliable foundation support. However, with the rapid development of highway construction, the consumption of materials such as sand, gravel, and cement is high, and the recyclability of these materials is poor. Therefore, there is an urgent need to find inexpensive, readily available, and safe materials to replace sand, gravel, and cement, thereby solving the resource shortage problem.

[0003] Industrial solid wastes such as red mud, fly ash, and slag are discharged daily. Currently, the technology for resource utilization of such solid wastes is not mature enough, and large-scale reuse is not possible. The main disposal method is stockpiling and burying, resulting in a waste of land resources. Resource utilization is the best way to dispose of industrial solid waste, especially in roadbed water-stabilized materials, which can achieve large-scale disposal of industrial solid waste and significantly improve the comprehensive utilization level of industrial solid waste. For example, patent CN101671986B discloses a road material produced using Bayer process red mud, comprising a road base layer, a road water-stabilized layer, and a road surface layer. The road base layer is made of the following raw materials by weight percentage: 4-25% low-temperature ceramic curing agent, 45-96% red mud, and 0-30% aggregate. The road water-stabilized layer is made of the following raw materials by weight percentage: 8-20% low-temperature ceramic curing agent, 10-20% red mud, and 60-82% aggregate. The road surface layer is made of the following raw materials by weight percentage: 10-30% low-temperature ceramic curing agent, 2-10% red mud, and 60-88% aggregate. Patent CN113698164B discloses a crack-resistant and settlement-resistant road water-stabilized layer material and its preparation method. The raw materials include gypsum cementitious material, aggregate, and water. The gypsum cementitious material includes a main ingredient and building admixtures. The main ingredient includes building gypsum, slag powder, silica fume, cement, and fly ash. The building admixtures include water-reducing agents, retarders, hydroxypropyl methylcellulose, and air-entraining agents. Patent CN110423085B discloses a road crack-resistant water-stabilized layer material containing electrolytic manganese slag and its preparation method. The water-stabilized layer material includes the following raw materials in parts by weight: 100 parts electrolytic manganese slag, 40-60 parts red mud, and 5-10 parts composite phase change material. The phase change composite material is formed by combining the phase change material and expanded graphite, then coating it with organic resin.

[0004] The above describes technologies that utilize industrial solid waste to replace cement and aggregates, thereby minimizing the use of cement and aggregates and effectively improving the reuse rate of industrial solid waste. This not only reduces the overall project cost but also meets current construction standards. However, due to the irregular shape, impurities, low activity, and high proportion of aggregates in the water-stabilized layer of industrial solid waste, the bonding interface between industrial solid waste and aggregates is not as tightly and continuously contacted and uniformly bonded as that between cement and aggregates. This results in defects such as excessive porosity, incomplete hydration, and discontinuous bonding. Although this does not significantly affect the overall compressive strength of the water-stabilized material, cracking can occur between the aggregates and the industrial solid waste cementitious material under water-salt / freeze-thaw cycles, significantly reducing the durability of the water-stabilized layer.

[0005] Therefore, it is necessary to develop a water-stabilized material with excellent resistance to water, salt, and freeze-thaw cycles in order to expand its application in areas covered by permafrost and saline soil. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a red mud-based multi-solid wastewater stabilized layer material with improved weather resistance and its preparation method. The raw material for the stabilized material includes a hyperbranched epoxy resin emulsion prepared by a Michael addition reaction of multi-arm polyethylene glycol thiols and monoalkenyl epoxy compounds. The hyperbranched epoxy resin has a high density of terminal epoxy functional groups, and a large number of terminal epoxy groups can chemically react with the active groups on the surface of aggregates and cementitious materials to form stable chemical bonds, thereby enhancing the bonding force between aggregates and cementitious materials, reducing the risk of cracking between aggregates and industrial solid waste cementitious materials under water-salt / freeze-thaw cycles, and extending the service life of the stabilized material.

[0007] To achieve the above objectives, the following technical solution is adopted:

[0008] A red mud-based multi-solid wastewater stabilizer for improving weather resistance comprises the following raw materials in parts by weight: 15-30 parts Bayer process red mud, 15-30 parts fly ash, 2.5-4 parts desulfurization ash, 3-5 parts cement, 80-100 parts aggregate, 30-40 parts hyperbranched epoxy resin emulsion, 1-3 parts alkanolamine early strength agent, and 5-15 parts water; wherein the hyperbranched epoxy resin emulsion is prepared by a Michael addition reaction of multi-arm polyethylene glycol thiols and monoalkenyl epoxy compounds at a mercapto-alkenyl molar ratio of 1:1-1.1.

[0009] The multi-arm polyethylene glycol thiols have a weight-average molecular weight of 10,000-30,000 and are selected from one or a combination of two or more of four-arm polyethylene glycol thiols, six-arm polyethylene glycol thiols, and eight-arm polyethylene glycol thiols. Eight-arm polyethylene glycol thiols are preferred.

[0010] The monoalkenyl epoxy compounds are selected from one or a combination of two or more of 3,4-epoxycyclohexyl methyl methacrylate, (3,4-epoxycyclohexyl) methyl acrylate, glycidyl acrylate, glycidyl methacrylate, and 4-hydroxybutyl acrylate glycidyl ether.

[0011] The hyperbranched epoxy resin emulsion has a solid content of 18-25%.

[0012] Specifically, the hyperbranched epoxy resin emulsion is prepared by a method comprising the following steps:

[0013] Multi-arm polyethylene glycol sulfur, alkaline catalyst, and organic solvent are mixed evenly, and a monoalkenyl epoxy compound is added to carry out the reaction under controlled temperature. After the reaction is completed, the organic solvent is evaporated, water is added, and the mixture is sheared and stirred to obtain a hyperbranched epoxy resin emulsion.

[0014] Hyperbranched epoxy resin is a polyether-type hyperbranched epoxy resin with a hydrophilic polyether backbone structure, which is prepared by Michael addition reaction of multi-arm polyethylene glycol thiols and monoalkenyl epoxy compounds. The hydrophilic polyether backbone and hydrophobic terminal epoxy groups enable hyperbranched epoxy resin to have self-emulsifying function and can spontaneously disperse into a stable emulsion in the aqueous phase.

[0015] The temperature-controlled reaction is carried out at 20-40℃ for 3-5 hours. The organic solvent is selected from one or a combination of two or more of methanol, DMSO, DMF, chloroform, tetrahydrofuran, ethyl acetate, diethyl ether, and acetone. The amount of the alkaline catalyst is 0.3-0.5 wt% of the total mass of polyethylene glycol sulfide and the monoalkenyl epoxy compound, and the alkaline catalyst is selected from one or a combination of two or more of dimethylamine, monoethylamine, diethylamine, isopropylamine, triethylamine, potassium carbonate, sodium carbonate, sodium hydroxide, and potassium hydroxide.

[0016] The alkanolamine early strength agent is selected from one or a combination of two or more of ethanolamine, triethanolamine, diisopropanolamine, and triisopropanolamine.

[0017] The aggregate comprises 15-35% quartz sand with a particle size of 0.01-5mm, 20-40% crushed stone with a particle size of 5-10mm, and 15-35% crushed stone with a particle size of 10-20mm.

[0018] The Bayer process red mud has a moisture content of 5wt%-20wt%, a particle size of ≤3mm, an Fe2O3 content of ≥50wt%, and a Na2O content of ≤3wt%.

[0019] The fly ash is selected from one or a combination of two of Grade I fly ash and Grade II fly ash.

[0020] The desulfurization ash is power plant desulfurization ash, with a CaO content of 65-85 wt%, an SO3 content of 8-30 wt%, and a moisture content of ≤1 wt%.

[0021] The cement is silicate cement with a strength grade of 42.5-52.5.

[0022] This invention also provides a method for preparing the above-mentioned red mud-based multi-solid wastewater stabilizer, comprising the following steps:

[0023] Mixing an alkanolamine early strength agent and water yields mixture 1. Mixing mixture 1, Bayer red mud, fly ash, desulfurization ash, and cement yields mixture 2. Mixing hyperbranched epoxy resin emulsion and aggregate yields mixture 3. Mixing mixture 2 and mixture 3 thoroughly yields a red mud-based multi-solid wastewater stabilized material.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] The water-stabilized material of this invention contains a self-made hyperbranched epoxy resin emulsion. The hyperbranched epoxy resin has a high density of terminal epoxy functional groups. A large number of terminal epoxy groups can chemically react with the active groups on the surface of the aggregate and the cementitious material to form a stable chemical bond, which enhances the bonding force between the aggregate and the cementitious material, reduces the risk of cracking between the aggregate and the industrial solid waste cementitious material under water-salt / freeze-thaw cycles, and extends the service life of the water-stabilized material.

[0026] This invention enables the comprehensive reuse of industrial solid waste resources, reduces the cost of road engineering, and effectively extends the service life of roads. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments, but is not limited to the contents of the specification. Unless otherwise specified, all "parts" mentioned in the embodiments of the present invention are parts by weight. All reagents used are commercially available in the art.

[0028] Eight-arm polyethylene glycol thiols with weight-average molecular weights of 10,000 and 30,000 were purchased from Shanghai Pengsheng Biotechnology Co., Ltd.

[0029] The four-arm polyethylene glycol thiols with a weight-average molecular weight of 30,000 were purchased from Shanghai Pengsheng Biotechnology Co., Ltd.

[0030] The Class I fly ash and Bayer process red mud both come from Hebei Wenfeng New Materials Co., Ltd.

[0031] The desulfurization ash from the power plant comes from Hebei Wenfeng New Materials Co., Ltd., with a CaO content of 85wt%, an SO3 content of 8.8wt%, and a moisture content of 0.01wt%.

[0032] Example 1

[0033] 1) Mix 0.0125 mol of octagonal polyethylene glycol thiol with a weight average molecular weight of 30,000, 1.18 g of triethylamine, and 450 g of DMF evenly, add 0.1 mol of glycidyl acrylate and react at 25°C for 3 h. After the reaction is complete, evaporate the organic solvent, add an appropriate amount of water, and shear and stir to obtain a hyperbranched epoxy resin emulsion with a concentration of 25 wt%.

[0034] 2) Mix 3g of diisopropanolamine and 10g of water to obtain mixture 1. Mix mixture 1, 30g of Bayer red mud, 30g of Grade I fly ash, 4g of power plant desulfurization ash, and 3g of 42.5 silicate cement evenly to obtain mixture 2. Mix 40g of hyperbranched epoxy resin emulsion and 100g of aggregate consisting of 30% quartz sand with a particle size of 0.01-5mm, 35% crushed stone with a particle size of 5-10mm, and 35% crushed stone with a particle size of 10-20mm evenly to obtain mixture 3. Mix mixture 2 and mixture 3 evenly and let stand for 12 hours to obtain red mud-based multi-solid waste-based water-stabilized material.

[0035] Example 2

[0036] The rest is the same as in Example 1, except that in step 1), an equimolar amount of octagonal polyethylene glycol thiol with a weight-average molecular weight of 10,000 is used instead of octagonal polyethylene glycol thiol with a weight-average molecular weight of 30,000.

[0037] Example 3

[0038] The rest is the same as in Example 1, except that in step 1), 0.025 mol of four-arm polyethylene glycol thiols with a weight average molecular weight of 30,000 is used instead of eight-arm polyethylene glycol thiols with a weight average molecular weight of 30,000.

[0039] Example 4

[0040] The rest is the same as in Example 1, except that in step 2), the amount of hyperbranched epoxy resin emulsion used is 30g.

[0041] Example 5

[0042] The rest is the same as in Example 1, except that in step 2), the amount of diisopropanolamine used is 2g.

[0043] Example 6

[0044] The rest is the same as in Example 1, except that in step 2), the amount of diisopropanolamine used is 1g.

[0045] Example 7

[0046] The rest is the same as in Example 1, except that in step 2), triethanolamine is used instead of diisopropanolamine in equal mass.

[0047] Example 8

[0048] 1) Mix 0.0125 mol of octagonal polyethylene glycol thiol with a weight average molecular weight of 30,000, 1.18 g of triethylamine, and 450 g of DMF evenly, add 0.11 mol of glycidyl acrylate and react at 25°C for 3 h. After the reaction is complete, evaporate the organic solvent, add an appropriate amount of water, and shear and stir to obtain a hyperbranched epoxy resin emulsion with a concentration of 20 wt%.

[0049] 2) Mix 3g of diisopropanolamine and 10g of water to obtain mixture 1. Mix mixture 1, 30g of Bayer red mud, 15g of Grade I fly ash, 4g of power plant desulfurization ash, and 5g of 42.5 silicate cement evenly to obtain mixture 2. Mix 40g of hyperbranched epoxy resin emulsion and 100g of aggregate consisting of 25% quartz sand with a particle size of 0.01-5mm, 40% crushed stone with a particle size of 5-10mm, and 35% crushed stone with a particle size of 10-20mm evenly to obtain mixture 3. Mix mixture 2 and mixture 3 evenly and let stand for 12 hours to obtain red mud-based multi-solid wastewater stabilized material.

[0050] Comparative Example 1

[0051] The rest is the same as in Example 1, except that in step 2), triethanolamine is replaced with an equal mass of calcium formate, a carboxylate-based early-strength agent.

[0052] Comparative Example 2

[0053] The rest is the same as in Example 1, except that in step 2), no hyperbranched polyepoxy resin emulsion is added, and the amount of water used is 40g.

[0054] The water-stabilized materials prepared in the above embodiments and comparative examples were subjected to the following performance tests:

[0055] Unconfined compressive strength test: Ф150mm×150mm specimens were prepared and cured in a constant temperature and humidity curing chamber at 20±1℃ and 95±1% relative humidity until the appropriate age was reached. Referring to T0805-1994 of the "Test Procedure for Inorganic Binder Stabilized Materials in Highway Engineering", the unconfined compressive strength of the specimens at two different ages (7 days and 28 days) was determined using a press.

[0056] Water-salt / freeze-thaw cycle: After curing for 28 days, the specimens were soaked in an 8 wt% sodium sulfate solution and then placed in a freeze-thaw equipment for 50 freeze-thaw cycles. One cycle included: 4 hours of cooling from 10°C to -25°C, 4 hours of holding at -25°C, 2 hours of heating from -25°C to 10°C, and 2 hours of holding at 10°C. The unconfined compressive strength was then retested, and the strength loss rate was calculated.

[0057] Heavy metal toxicity leaching rate: The method and procedure of "Leaching Method for Toxicity of Solid Waste - Horizontal Oscillation Method" (HJ 557-2009) were followed, and the content of harmful ions in the leachate was determined by inductively coupled plasma mass spectrometry (ICP-MS).

[0058] Table 1 Performance Test Results

[0059]

[0060]

[0061] Table 2 Performance Test Results

[0062]

[0063] As can be seen from Table 1, the water-stable material prepared by the present invention has excellent resistance to water-salt / freeze-thaw cycles.

[0064] As can be seen from the heavy metal leaching rate test results of Examples 1, 5-7 and the comparative examples in Table 2, alkanolamine early strength agents have a significant synergistic effect with hyperbranched epoxy resin in reducing the leaching rate of heavy metal ions.

[0065] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A red mud-based multi-solid wastewater stabilizer with improved weather resistance, characterized in that, The raw materials include the following parts by weight: 15-30 parts Bayer red mud, 15-30 parts fly ash, 2.5-4 parts desulfurization ash, 3-5 parts cement, 80-100 parts aggregate, 30-40 parts hyperbranched epoxy resin emulsion, 1-3 parts alkanolamine early strength agent, and 5-15 parts water; wherein the hyperbranched epoxy resin emulsion is prepared by Michael addition reaction of multi-arm polyethylene glycol thiol and monoalkenyl epoxy compound at a mercapto to alkenyl molar ratio of 1:1-1.

1.

2. The red mud-based multi-solid wastewater stabilizer with improved weather resistance according to claim 1, characterized in that, The multi-arm polyethylene glycol thiols have a weight-average molecular weight of 10,000 to 30,000 and are selected from one or a combination of two or more of four-arm polyethylene glycol thiols, six-arm polyethylene glycol thiols, and eight-arm polyethylene glycol thiols.

3. The red mud-based multi-solid wastewater stabilizer with improved weather resistance according to claim 1, characterized in that, The monoalkenyl epoxy compounds are selected from one or a combination of two or more of 3,4-epoxycyclohexyl methyl methacrylate, (3,4-epoxycyclohexyl) methyl acrylate, glycidyl acrylate, glycidyl methacrylate, and 4-hydroxybutyl acrylate glycidyl ether.

4. The red mud-based multi-solid wastewater stabilizer with improved weather resistance according to claim 1, characterized in that, The hyperbranched epoxy resin emulsion has a solid content of 18-25%.

5. The red mud-based multi-solid wastewater stabilizer with improved weather resistance according to claim 1, characterized in that, The hyperbranched epoxy resin emulsion is prepared by a method comprising the following steps: Multi-arm polyethylene glycol thiols, an alkaline catalyst, and an organic solvent are mixed evenly. A monoalkenyl epoxy compound is then added and the reaction is carried out under controlled temperature. After the reaction is completed, the organic solvent is evaporated, water is added, and the mixture is sheared and stirred to obtain a hyperbranched epoxy resin emulsion.

6. The red mud-based multi-solid wastewater stabilizer with improved weather resistance according to claim 5, characterized in that, The temperature-controlled reaction is carried out at 20-40℃ for 3-5 hours; the organic solvent is selected from one or a combination of two or more of methanol, DMSO, DMF, chloroform, tetrahydrofuran, ethyl acetate, diethyl ether, and acetone; the amount of the alkaline catalyst is 0.3-0.5 wt% of the total mass of the multi-arm polyethylene glycol thiols and monoalkenyl epoxy compounds, and the alkaline catalyst is selected from one or a combination of two or more of dimethylamine, monoethylamine, diethylamine, isopropylamine, triethylamine, potassium carbonate, sodium carbonate, sodium hydroxide, and potassium hydroxide.

7. The red mud-based multi-solid wastewater stabilizer with improved weather resistance according to claim 1, characterized in that, The alkanolamine early strength agent is selected from one or a combination of two or more of ethanolamine, triethanolamine, diisopropanolamine, and triisopropanolamine.

8. The red mud-based multi-solid wastewater stabilizer with improved weather resistance according to claim 1, characterized in that, The aggregate comprises 15-35% quartz sand with a particle size of 0.01-5mm, 20-40% crushed stone with a particle size of 5-10mm, and 15-35% crushed stone with a particle size of 10-20mm.

9. The red mud-based multi-solid wastewater stabilizer with improved weather resistance according to claim 1, characterized in that, The fly ash is selected from one or a combination of two of Class I fly ash and Class II fly ash; the desulfurization ash is power plant desulfurization ash with a CaO content of 65-85wt%, an SO3 content of 8-30wt%, and a moisture content of ≤1wt%; the Bayer process red mud has a moisture content of 5wt%-20wt%, a particle size of ≤3mm, an Fe2O3 content of ≥50wt%, and a Na2O content of ≤3wt%.

10. The method for preparing the red mud-based multi-solid wastewater stabilized material with improved weather resistance as described in any one of claims 1-9, characterized in that, Includes the following steps: Mixing an alkanolamine early strength agent and water yields mixture 1. Mixing mixture 1, Bayer red mud, fly ash, desulfurization ash, and cement yields mixture 2. Mixing hyperbranched epoxy resin emulsion and aggregate yields mixture 3. Mixing mixture 2 and mixture 3 together yields a red mud-based multi-solid wastewater stabilized material with improved weather resistance.

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