Freeze-thaw-resistant and anti-freezing road concrete and preparation method thereof

Abstract

The invention discloses freeze-thaw-resistant and anti-freezing road concrete and a preparation method thereof, belongs to the technical field of concrete processing, and aims to solve the technical problem that the anti-freezing and anti-freezing performance of the road concrete in the prior art needs to be further improved. The preparation method specifically comprises the following preparation steps: putting the ardealite-based core-shell aggregate into a vacuum drying oven, adding a calcium magnesium acetate aqueous solution, vacuumizing to-0.09 to-0.08 MPa, reacting for 20-30 minutes, restoring to normal pressure, soaking for 20-24 hours, and performing post-treatment to obtain the salt-storage core-shell aggregate. The ardealite spherical aggregate is used as a core, the steel slag powder-ethylene-vinyl acetate copolymer powder is granulated into a shell and subjected to high-pressure carbonization to enhance the stability, calcium magnesium acetate is stored in vacuum to realize slow release, and a dopamine polymerization emulsion interface is matched to form a film, so that the freeze-thaw resistance and the anti-freezing performance of the road concrete are improved.

Description

Technical Field

[0001] This invention relates to the field of concrete processing technology, specifically to a freeze-thaw resistant and anti-icing road concrete and its preparation method. Background Technology

[0002] Road concrete in cold and humid regions faces multiple challenges, including freeze-thaw cycles, de-icing agent erosion, and ice adhesion. Durability requirements have evolved from simply resisting freezing to resisting both freeze-thaw cycles and ice formation. On one hand, this involves mitigating frost heave damage by reducing pore connectivity and increasing density in the interface transition zone. On the other hand, it focuses on the formation and adhesion process of ice on the road surface, reducing ice formation intensity and shortening ice formation duration by controlling surface energy, saline film, and ice crystal growth conditions. Meanwhile, solid waste resource utilization and low-carbonization have also become important directions, striving to balance material costs, construction adaptability, and environmental benefits while meeting mechanical and durability requirements.

[0003] Currently, methods often involve constructing an air-entraining system to form uniform microbubbles to release frost heave pressure, adding mineral admixtures to refine the pore structure, using fibers to inhibit the propagation of microcracks, and using surface hydrophobic / permeable crystalline protective materials, silane / siloxane impregnation or coatings to reduce water absorption. For anti-icing, methods such as surface texture optimization, hydrophobic coatings, phase change materials, or lightweight porous carriers for salt storage are often used to delay freezing or reduce ice adhesion.

[0004] In existing technologies, the reaction rate of mineral admixture pozzolanic material is significantly reduced under low-temperature conditions, resulting in insufficient early structural densification. It is still prone to water absorption and microcrack propagation in the early stages of freeze-thaw cycles. At the same time, its improvement effect is mainly concentrated on the slurry level, with limited control over the water absorption and frost heave behavior of the aggregate itself. Under freezing conditions, salt storage anti-icing schemes rely on the dissolution of salt to lower the freezing point and weaken ice layer formation. However, salt is prone to disordered release and loss under the drive of water migration, resulting in a decrease in the anti-icing effect. Moreover, most salt storage carriers have limited structural strength and stability, and are prone to structural damage under the combined action of freeze-thaw cycles and traffic loads, making it difficult to achieve long-term synergy between freeze-thaw resistance and anti-icing performance.

[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a freeze-thaw resistant and anti-icing road concrete and its preparation method, in order to solve the technical problem that the anti-icing and freeze-thaw resistance of road concrete in the prior art needs to be further improved.

[0007] The objective of this invention can be achieved through the following technical solution: a method for preparing freeze-thaw resistant and anti-icing road concrete, comprising the following preparation steps:

[0008] S1. Place the phosphogypsum-based core-shell aggregate in a vacuum drying oven, add calcium magnesium acetate aqueous solution, evacuate to -0.09 to -0.08 MPa, react for 20-30 min, restore to normal pressure, soak for 20-24 h, and then process to obtain salt-accumulating core-shell aggregate.

[0009] The reaction principle for preparing salt-storage core-shell aggregates is as follows:

[0010] During the reaction, under vacuum conditions, the gas in the interconnected pores inside the phosphogypsum-based core-shell aggregate is extracted, forming a negative pressure environment. After the pressure returns to normal, under the combined drive of pressure difference and capillary action, the calcium magnesium acetate aqueous solution penetrates and fills the pore structure of the aggregate. The dissolved calcium magnesium salt is distributed inside the core-shell aggregate in the form of physical adsorption and solution retention. The subsequent leaching and medium-temperature drying process promotes the evaporation of free water, and the calcium magnesium acetate is solidified and stably stored in the pores, resulting in salt-storage core-shell aggregate.

[0011] S2. Place crushed stone and medium sand in a mixer and mix for 30-60 seconds. Add cement, slag powder and salt-retaining core aggregate and mix for 15-30 seconds. Add mixing water, water-reducing agent and dopamine polymer emulsion and mix for 2-3 minutes to obtain road concrete.

[0012] The reaction principle for preparing road concrete is as follows:

[0013] During the reaction, crushed stone and medium sand are dry-mixed to form a graded skeleton. Cement, slag powder, and salt-retaining core-shell aggregate are then added to uniformly coat and fill the skeleton pores. The salt-retaining aggregate, acting as a porous carrier, releases calcium, magnesium, and acetate ions through pore solution exchange during the subsequent hydration process. After adding mixing water, cement clinker minerals hydrate to generate CSH gel and calcium hydroxide, forming an initial settling structure. Under the stimulation of high alkali and calcium hydroxide, slag powder undergoes a hydration / volcanic ash reaction, generating secondary hydration products. Dopamine polymer emulsion is stably dispersed in alkaline pore solution and forms a film at the interface of aggregate, paste, and hydration products, resulting in road concrete.

[0014] Further, in step S1, the ratio of the phosphogypsum-based core-shell aggregate to the calcium magnesium acetate aqueous solution is 80-100g:100-140mL, and the concentration of the calcium magnesium acetate aqueous solution is 15-25wt%. The post-treatment steps include: after soaking, removing the aggregate, draining for 10-15min, transferring it to an oven at a temperature of 40-55℃, and drying for 8-14h to obtain the salt-accumulating core-shell aggregate.

[0015] Furthermore, in step S2, the ratio of the amount of crushed stone, medium sand, cement, slag powder, salt-retaining core-shell aggregate, mixing water, water-reducing agent and dopamine polymer emulsion is 340-380g:200-260g:80-100g:30-40g:100-120g:30-45mL:1-1.5g:6-8g.

[0016] Furthermore, the dopamine polymeric emulsion is prepared by the following steps:

[0017] A1. Place dopamine hydrochloride and N,N-dimethylformamide in a light-protected reaction vessel and stir. Add triethylamine to adjust the pH to 7-8. Cool the reaction vessel to 0-5℃ and slowly add methacrylamide. Keep the reaction at this temperature for 2-4 hours. After post-treatment, olefin-modified dopamine is obtained.

[0018] A2. Place deionized water and sodium dodecyl sulfate in a reaction vessel under nitrogen atmosphere and stir. Add butyl acrylate, methyl methacrylate, olefin-modified dopamine and potassium persulfate aqueous solution. Heat the reaction vessel to 70-80℃ and keep it at this temperature for 15-20 min to obtain dopamine seed emulsion.

[0019] A3. Place the dopamine seed emulsion in a reaction vessel under nitrogen atmosphere and stir. Add butyl acrylate, methyl methacrylate, olefin-modified dopamine and potassium persulfate aqueous solution. Heat the reaction vessel to 70-80℃ and keep it at this temperature for 2-4 hours. After post-treatment, dopamine polymer emulsion is obtained.

[0020] The reaction principle for preparing dopamine polymer emulsion is as follows:

[0021] During the reaction, under the action of triethylamine, the amino group of dopamine hydrochloride undergoes acylation reaction with methacryloyl chloride under low temperature and light-protected conditions, introducing a methacryloyl group onto the dopamine molecule, resulting in olefin-modified dopamine. Under the emulsification of sodium dodecyl sulfate and the initiation of potassium persulfate, butyl acrylate, methyl methacrylate and olefin-modified dopamine undergo free radical emulsion polymerization in the aqueous phase to form a polymer core containing dopamine structural units, obtaining a dopamine seed emulsion. Using the seed emulsion as the nucleation center, monomers and initiators are added to achieve directional growth of monomers onto the surface of seed particles under the same emulsion polymerization conditions, resulting in a dopamine polymer emulsion.

[0022] Further, in step A1, the ratio of dopamine hydrochloride, N,N-dimethylformamide, and methacryloyl chloride is 2-4g:25-35mL:3-5g. The post-processing steps include: after the reaction is completed, the reaction solution is poured into ice water to precipitate the product, filtered, the filter cake is washed 2-4 times with deionized water, transferred to an oven at 50-60℃, and dried to constant weight to obtain olefin-modified dopamine.

[0023] Furthermore, in step A2, the ratio of deionized water, sodium dodecyl sulfate, butyl acrylate, methyl methacrylate, olefin-modified dopamine, and potassium persulfate aqueous solution is 160-180 mL: 0.5-0.8 g: 16-18 g: 10-15 g: 2-4 g: 8-10 mL, and the concentration of potassium persulfate aqueous solution is 1-3 wt%.

[0024] Further, in step A3, the ratio of the dopamine seed emulsion, butyl acrylate, methyl methacrylate, olefin-modified dopamine, and potassium persulfate aqueous solution is 200-220g:50-70g:50-55g:2-4g:20-60mL, and the concentration of the potassium persulfate aqueous solution is 1-3wt%. The post-treatment step includes: after the reaction is completed, after the reaction system cools to room temperature, adding ammonia water to the reaction solution to adjust the pH to 7-8, filtering to remove impurities, and obtaining dopamine polymer emulsion.

[0025] Furthermore, the anti-icing core shell aggregate is prepared by the following steps:

[0026] B1. Place phosphogypsum, slag powder, cement and metakaolin in a mixer, mix for 2-3 minutes, granulate to obtain phosphogypsum-based aggregate;

[0027] B2. Soak the phosphogypsum-based aggregate in deionized water for 0.5-1h, drain for 15-30min, transfer to a disc granulator, add refined steel slag powder and ethylene-vinyl acetate copolymer powder, spray with deionized water, form a shell, and then process to obtain crude phosphogypsum-based core-shell aggregate.

[0028] B3. Place the crude phosphogypsum-based core-shell aggregate in a carbonization kettle, introduce carbon dioxide, heat the kettle to 55-65℃, and carbonize for 20-24 hours to obtain phosphogypsum-based core-shell aggregate.

[0029] The reaction principle for preparing phosphogypsum-based core-shell aggregates is as follows:

[0030] During the reaction, phosphogypsum, slag powder, cement, and metakaolin are mixed and granulated to form initial particles, resulting in phosphogypsum-based aggregates with a skeletal structure. After being soaked in water, the surface of the phosphogypsum-based aggregates is moistened. During the disc granulation process, refined steel slag powder adheres to the surface of the aggregates under the action of water and mechanical rolling, and forms a continuous shell layer under the binding action of ethylene-vinyl acetate copolymer powder, resulting in a core-shell structured coarse aggregate. Further, under heated and pressurized carbon dioxide conditions, the active calcium phase in the shell and core undergoes a carbonization reaction with carbon dioxide to generate calcium carbonate, resulting in phosphogypsum-based core-shell aggregates.

[0031] Furthermore, in step B1, the weight ratio of the phosphogypsum, slag powder, cement, and metakaolin is 50-60:20-30:8-12:5-10.

[0032] Further, in step B1, the preparation method of the phosphogypsum-based aggregate is as follows: phosphogypsum, slag powder, cement, and metakaolin are placed in a mixer and stirred for 2-3 minutes. The mixture is then added in batches to a disc granulator, and deionized water is sprayed on. After the product forms spheres, sieving yields spherical aggregates of 10-20 mm. The spherical aggregates are placed in a sealed reactor for curing for 3 days. During curing, deionized water is sprayed daily at a rate equivalent to 0.01-0.02 times the mass of the spherical aggregates. After sealed curing, the spherical aggregates are placed in tap water at 20±2℃ for curing for 14-28 days. After curing, fine particles with a diameter less than 2.5 mm are sieved out, and the spherical aggregates are placed in a constant temperature drying oven at 40-50℃ and dried to constant weight to obtain the phosphogypsum-based aggregate.

[0033] Further, in step B2, the solid-liquid ratio of the phosphogypsum-based aggregate and deionized water is 1g:3-5mL. After leaching, the phosphogypsum-based aggregate is surface-wet with no obvious free water. The disc granulator has a disc diameter of 0.6-1.2m, a disc inclination angle of 40-55°, and a rotation speed of 18-35rpm. The weight ratio of the phosphogypsum-based aggregate, refined steel slag powder, and ethylene-vinyl acetate copolymer powder is 80-100:25-35:1-3. The amount of deionized water sprayed is 0.08-0.12 times the total dry mass of the phosphogypsum-based aggregate, refined steel slag powder, and ethylene-vinyl acetate copolymer powder. The post-processing steps include: after shell formation, sieving, transferring the product to a closed reactor for curing for 2-3 days at a temperature of 20-35℃ and a relative humidity of ≥90% in a closed environment to obtain crude phosphogypsum-based core-shell aggregate.

[0034] Among them, the present invention proposes a road concrete that is resistant to freeze-thaw cycles and anti-icing, which is prepared by the above-mentioned preparation method of a road concrete that is resistant to freeze-thaw cycles and anti-icing.

[0035] The present invention has the following beneficial effects:

[0036] 1. The phosphogypsum-based core-shell aggregate of the present invention uses phosphogypsum-based spherical aggregate as the core, and forms a dense outer shell with steel slag powder and ethylene-vinyl acetate copolymer powder. After high-pressure carbon dioxide carbonization treatment, the active minerals in the shell layer generate a stable carbonate phase, which significantly improves the surface density and mechanical stability of the aggregate. It effectively inhibits the structural damage of the phosphogypsum-based core-shell aggregate caused by water absorption and frost heave during freeze-thaw cycles. In addition, the steel slag powder particles are coated on the surface of the phosphogypsum-based aggregate during the disc granulation process. The irregular particle size and high hardness of the steel slag powder particles make the shell layer form a multi-scale rough surface with micro-protrusions and micro-concavities. At the same time, the free calcium oxide and strong calcium oxide in the steel slag shell layer are converted into a dense and stable carbonate phase, which reduces the content of high alkalinity and excessive active substances in the shell layer, avoids the deterioration caused by excessive interfacial chemical reaction, and retains active sites that can react with hydration products. This makes the chemical activity of the aggregate surface milder, enhances the bonding performance of the transition zone between the aggregate and the slurry, reduces the generation and expansion of interfacial micro-cracks, and improves the freeze-thaw durability of road concrete.

[0037] 2. This invention involves vacuum impregnating calcium magnesium acetate into the porous structure of phosphogypsum-based core-shell aggregates to obtain salt-retaining core-shell aggregates. Calcium magnesium acetate can be slowly released under low-temperature conditions, effectively reducing the freezing point of the concrete surface and weakening the adhesion strength between ice and concrete, thereby improving the concrete's anti-icing performance. Furthermore, dopamine polymer emulsion acts on the interface between the aggregates and cement paste, forming a highly adhesive and extensible interfacial film through enhanced interfacial adhesion and flexible control. This film can fix the slow-release salt in the effective action area, reducing its loss due to rainwater erosion. Simultaneously, a flexible network absorbs frost heave and salt-induced stress, preventing micro-cracks from penetrating along the interface, further improving the freeze-thaw resistance and anti-icing performance of road concrete.

[0038] 3. The salt-retaining core-shell aggregate of the present invention forms a stable carbonate and gel product by forming a shell from steel slag powder and undergoing carbonation treatment. This makes the outer shell denser and stronger. The presence of the shell layer can also effectively release salt, preventing free salt from directly interfering with the hydration process of cement paste or changing the environment of the pore solution, thereby improving the flexural and compressive strength of concrete. At the same time, the catechol groups retained in the structure of the dopamine polymer emulsion have multi-point hydrogen bond adsorption, which can form a fixed layer on the surface of cement hydration products and core-shell aggregate. This allows the emulsion to preferentially accumulate in the interfacial transition zone during mixing, forming a composite film that can fill capillary channels, delay the initiation of microcracks, make the transmission of compressive load more continuous and the stress concentration weaker. At the same time, it can bridge and passivate cracks on the tension side, providing support for compressive strength and providing an energy dissipation mechanism for flexural toughness. This reduces the generation of interfacial microcracks, ensures that the concrete distributes stress more evenly under compression, reduces stress concentration, and improves the compressive and flexural strength of concrete. Detailed Implementation

[0039] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The calcium magnesium acetate used in this invention was purchased from Shandong Haihe Chemical Co., Ltd., and its model is SDHH, with the product name being calcium magnesium acetate de-icing agent.

[0041] The crushed stone used in this invention was purchased from Chenming Yuhua Stone Processing Plant in Liuhe District, Nanjing City. It is 10mm in size, made of basalt, and has an apparent density of 2.915 kg / m³. 3 The bulk density is 2.642 kg / m³. 3 ;

[0042] The medium sand used in this invention was purchased from Yongshun Mineral Products Processing Plant in Lingshou County, with a density of 1.6 g / cm³. 3 The porosity is 45%, and the brand is Yongshun.

[0043] The cement used in this invention was purchased from Guangzhou Bijia Suo Building Materials Co., Ltd., model NBS-164, brand name Naiboshi;

[0044] The slag powder used in this invention was purchased from Yongshun Mineral Products Processing Plant in Lingshou County. It has a mesh size of 325 and a density of 2.65 g / cm³. 3 The purity is 98%.

[0045] The ethylene-vinyl acetate copolymer powder used in this invention was purchased from Dongguan Heshengyuan New Material Technology Co., Ltd., with a specification of 25mm and a brand name of Yangtze BASF.

[0046] The refined steel slag powder used in this invention was purchased from Chifeng Shenghong Renewable Resources Co., Ltd., with a specification of S105mm and a density of 2.91kg / m³. 3 ;

[0047] The phosphogypsum used in this invention was purchased from Shandong Longbang Gypsum Products Co., Ltd., and its density is 2.3 g / cm³. 3 The particle size is 100 mesh.

[0048] Example 1

[0049] This embodiment provides a method for preparing phosphogypsum-based core-shell aggregate, including the following steps:

[0050] Step I: Preparation of phosphogypsum-based aggregates

[0051] Weigh out 500g of phosphogypsum, 200g of slag powder, 80g of cement, and 50g of metakaolin and place them in a mixer. Mix for 2 minutes and add them in batches to a disc granulator. Spray with deionized water. After the product forms spheres, sieve to obtain spherical aggregates of 10-13mm. Place the spherical aggregates in a sealed reactor and cure for 3 days. During the curing period, spray with deionized water daily at a rate equivalent to 0.01 times the mass of the spherical aggregates. After sealed curing, place the spherical aggregates in tap water at 18℃ and cure for 14 years. After curing, remove fine particles with a diameter of less than 2.5mm and place the spherical aggregates in a constant temperature drying oven at 40℃ to dry to constant weight to obtain phosphogypsum-based aggregates.

[0052] Step II: Preparation of crude phosphogypsum-based core-shell aggregate

[0053] Weigh 800g of phosphogypsum-based aggregate and soak it in deionized water at a solid-liquid ratio of 1g:3mL for 0.5h. After draining for 15min, transfer it to a disc granulator, add 250g of refined steel slag powder and 10g of ethylene-vinyl acetate copolymer powder, and spray deionized water at 0.08 times the total dry mass of the phosphogypsum-based aggregate, refined steel slag powder and ethylene-vinyl acetate copolymer powder. After shell formation, sieve to obtain a product with a particle size of 20-22mm, transfer it to a closed reactor for curing for 2d at a curing temperature of 20℃ and a relative humidity of ≥90% in a closed environment to obtain crude phosphogypsum-based core-shell aggregate.

[0054] Step III: Preparation of phosphogypsum-based core-shell aggregate

[0055] The crude phosphogypsum-based core-shell aggregate was placed in a carbonization kettle, and carbon dioxide was introduced until the kettle pressure reached 0.4 MPa. The temperature of the carbonization kettle was raised to 55°C, and carbonization was carried out for 20 hours to obtain the phosphogypsum-based core-shell aggregate.

[0056] Example 2

[0057] This embodiment provides a method for preparing phosphogypsum-based core-shell aggregate, including the following steps:

[0058] Step I: Preparation of phosphogypsum-based aggregates

[0059] Weigh out 550g of phosphogypsum, 250g of slag powder, 100g of cement, and 75g of metakaolin and place them in a mixer. Mix for 3 minutes and add them in batches to a disc granulator. Spray with deionized water. After the product forms spheres, sieve to obtain spherical aggregates of 14-17mm. Place the spherical aggregates in a sealed reactor and cure for 3 days. During the curing period, spray with deionized water daily at a rate of 0.015 times the mass of the spherical aggregates. After sealed curing, place the spherical aggregates in tap water at 20℃ and cure for 21 days. After curing, remove fine particles with a diameter of less than 2.5mm and place the spherical aggregates in a constant temperature drying oven at 45℃ to dry to constant weight to obtain phosphogypsum-based aggregates.

[0060] Step II: Preparation of crude phosphogypsum-based core-shell aggregate

[0061] Weigh 900g of phosphogypsum-based aggregate and soak it in deionized water at a solid-liquid ratio of 1g:4mL for 1 hour. After draining for 23 minutes, transfer it to a disc granulator. Add 300g of refined steel slag powder and 20g of ethylene-vinyl acetate copolymer powder. Spray deionized water at 0.10 times the total dry mass of the phosphogypsum-based aggregate, refined steel slag powder, and ethylene-vinyl acetate copolymer powder. After shell formation, sieve to obtain a product with a particle size of 23-24mm. Transfer the product to a closed reactor and cure it for 2.5 days at a temperature of 30℃ and a relative humidity of ≥90% in a closed environment to obtain crude phosphogypsum-based core-shell aggregate.

[0062] Step III: Preparation of phosphogypsum-based core-shell aggregate

[0063] The crude phosphogypsum-based core-shell aggregate was placed in a carbonization kettle, and carbon dioxide was introduced until the kettle pressure reached 0.5 MPa. The temperature of the carbonization kettle was raised to 60°C, and carbonization was carried out for 22 hours to obtain the phosphogypsum-based core-shell aggregate.

[0064] Example 3

[0065] This embodiment provides a method for preparing phosphogypsum-based core-shell aggregate, including the following steps:

[0066] Step I: Preparation of phosphogypsum-based aggregates

[0067] Weigh out 600g of phosphogypsum, 300g of slag powder, 120g of cement, and 100g of metakaolin and place them in a mixer. Mix for 3 minutes and add them in batches to a disc granulator. Spray with deionized water. After the product forms spheres, sieve to obtain spherical aggregates of 18-20mm. Place the spherical aggregates in a sealed reactor and cure for 3 days. During the curing period, spray with deionized water daily, with the amount of water being 0.02 times the mass of the spherical aggregates. After sealed curing, place the spherical aggregates in tap water at 22℃ and cure for 28 days. After curing, remove fine particles with a particle size of less than 2.5mm and place the spherical aggregates in a constant temperature drying oven at 45℃ to dry to constant weight to obtain phosphogypsum-based aggregates.

[0068] Step II: Preparation of crude phosphogypsum-based core-shell aggregate

[0069] Weigh 1000g of phosphogypsum-based aggregate and soak it in deionized water at a solid-liquid ratio of 1g:5mL for 1 hour. Drain the liquid for 30 minutes and transfer it to a disc granulator. Add 350g of refined steel slag powder and 30g of ethylene-vinyl acetate copolymer powder. Spray deionized water at 0.12 times the total dry mass of the phosphogypsum-based aggregate, refined steel slag powder, and ethylene-vinyl acetate copolymer powder. After shell formation, sieve to obtain a product with a particle size of 24-25mm. Transfer the product to a closed reactor and cure it for 3 days at a temperature of 35℃ and a relative humidity of ≥90% in a closed environment to obtain crude phosphogypsum-based core-shell aggregate.

[0070] Step III: Preparation of phosphogypsum-based core-shell aggregate

[0071] The crude phosphogypsum-based core-shell aggregate was placed in a carbonization kettle, and carbon dioxide was introduced until the kettle pressure reached 0.6 MPa. The temperature of the carbonization kettle was raised to 65°C, and carbonization was carried out for 24 hours to obtain the phosphogypsum-based core-shell aggregate.

[0072] Example 4

[0073] This embodiment provides a method for preparing a dopamine polymer emulsion, including the following steps:

[0074] Step ①: Preparation of olefin-modified dopamine

[0075] Weigh 20g of dopamine hydrochloride and 250mL of N,N-dimethylformamide and place them in a light-protected reaction vessel and stir. Add triethylamine to adjust the pH to 7. Cool the reaction vessel to 0℃ and slowly add 30g of methacryloyl chloride. Keep the reaction vessel warm for 2 hours. After the reaction is complete, pour the reaction solution into ice water to precipitate the product. Filter the product and wash the filter cake twice with deionized water. Transfer the product to an oven at 50℃ and dry it to constant weight to obtain olefin-modified dopamine.

[0076] Step 2: Preparation of dopamine seed emulsion

[0077] Weigh out 1600 mL of deionized water and 5 g of sodium dodecyl sulfate and place them in a reaction vessel under nitrogen atmosphere and stir. Add 160 g of butyl acrylate, 100 g of methyl methacrylate, 20 g of olefin-modified dopamine and 80 mL of 1 wt% potassium persulfate aqueous solution. Heat the reaction vessel to 70 °C and keep it at that temperature for 15 min to obtain dopamine seed emulsion.

[0078] Step ③: Preparation of dopamine polymer emulsion

[0079] Weigh 2000g of dopamine seed emulsion and place it in a reaction vessel under nitrogen atmosphere protection and stir. Add 500g of butyl acrylate, 500g of methyl methacrylate, 20g of olefin-modified dopamine and 200mL of 1wt% potassium persulfate aqueous solution. Heat the reaction vessel to 70℃ and keep it at that temperature for 2h. After the reaction is completed, wait for the reaction system to cool to room temperature, add ammonia water to the reaction solution to adjust the pH to 7, filter to remove impurities, and obtain dopamine polymer emulsion.

[0080] Example 5

[0081] This embodiment provides a method for preparing a dopamine polymer emulsion, including the following steps:

[0082] Step ①: Preparation of olefin-modified dopamine

[0083] Weigh out 30g of dopamine hydrochloride and 300mL of N,N-dimethylformamide and place them in a light-protected reaction vessel and stir. Add triethylamine to adjust the pH to 7.5. Cool the reaction vessel to 3℃ and slowly add 40g of methacryloyl chloride. Keep the reaction vessel warm for 3h. After the reaction is complete, pour the reaction solution into ice water to precipitate the product. Filter the product and wash the filter cake three times with deionized water. Transfer the product to an oven at 55℃ and dry it to constant weight to obtain olefin-modified dopamine.

[0084] Step 2: Preparation of dopamine seed emulsion

[0085] Weigh out 1700 mL of deionized water and 6.5 g of sodium dodecyl sulfate and place them in a reaction vessel under nitrogen atmosphere and stir. Add 170 g of butyl acrylate, 125 g of methyl methacrylate, 30 g of olefin-modified dopamine and 90 mL of 2 wt% potassium persulfate aqueous solution. Heat the reaction vessel to 75 °C and keep it at that temperature for 18 min to obtain dopamine seed emulsion.

[0086] Step ③: Preparation of dopamine polymer emulsion

[0087] Weigh 2100g of dopamine seed emulsion and place it in a reaction vessel under nitrogen atmosphere protection and stir. Add 600g of butyl acrylate, 525g of methyl methacrylate, 30g of olefin-modified dopamine and 400mL of 2wt% potassium persulfate aqueous solution. Heat the reaction vessel to 75℃ and keep it at that temperature for 3h. After the reaction is completed, wait for the reaction system to cool to room temperature, add ammonia water to the reaction solution to adjust the pH to 7.5, filter to remove impurities, and obtain dopamine polymer emulsion.

[0088] Example 6

[0089] This embodiment provides a method for preparing a dopamine polymer emulsion, including the following steps:

[0090] Step ①: Preparation of olefin-modified dopamine

[0091] Weigh out 40g of dopamine hydrochloride and 350mL of N,N-dimethylformamide and place them in a light-protected reaction vessel and stir. Add triethylamine to adjust the pH to 8. Cool the reaction vessel to 5℃ and slowly add 50g of methacryloyl chloride. Keep the reaction vessel warm for 4h. After the reaction is complete, pour the reaction solution into ice water to precipitate the product. Filter the product and wash the filter cake 4 times with deionized water. Transfer the product to an oven at 60℃ and dry it to constant weight to obtain olefin-modified dopamine.

[0092] Step 2: Preparation of dopamine seed emulsion

[0093] Weigh 1800 mL of deionized water and 8 g of sodium dodecyl sulfate and place them in a reaction vessel under nitrogen atmosphere and stir. Add 180 g of butyl acrylate, 150 g of methyl methacrylate, 40 g of olefin-modified dopamine and 100 mL of 3 wt% potassium persulfate aqueous solution. Heat the reaction vessel to 80 °C and keep it at that temperature for 20 min to obtain dopamine seed emulsion.

[0094] Step ③: Preparation of dopamine polymer emulsion

[0095] Weigh 2200g of dopamine seed emulsion and place it in a reaction vessel under nitrogen atmosphere protection and stir. Add 700g of butyl acrylate, 550g of methyl methacrylate, 40g of olefin-modified dopamine and 600mL of 3wt% potassium persulfate aqueous solution. Heat the reaction vessel to 80℃ and keep it at that temperature for 4h. After the reaction is completed, wait for the reaction system to cool to room temperature, add ammonia water to the reaction solution to adjust the pH to 8, filter to remove impurities, and obtain dopamine polymer emulsion.

[0096] Example 7

[0097] This embodiment provides a method for preparing freeze-thaw resistant and anti-icing road concrete, including the following steps:

[0098] Step (1) Preparation of salt-storing core-shell aggregate

[0099] Weigh 800g of the phosphogypsum-based core-shell aggregate prepared in Example 1 and place it in a vacuum drying oven. Add 1000mL of 15wt% calcium magnesium acetate aqueous solution, evacuate to -0.09MPa, react for 20min, restore normal pressure, soak for 20h, remove after soaking, drain for 10min, transfer to an oven at 40℃ and dry for 8h to obtain salt-accumulating core-shell aggregate.

[0100] Step 2: Preparing road concrete

[0101] Weigh out 3400g of crushed stone and 2000g of medium sand and place them in a mixer. Mix for 30 seconds. Add 800g of cement, 300g of slag powder and 1000g of salt-retaining core-shell aggregate. Mix for 15 seconds. Add 300mL of mixing water, 10g of water-reducing agent and 60g of dopamine polymer emulsion prepared in Example 4. Mix for 2 minutes to obtain road concrete.

[0102] Example 8

[0103] This embodiment provides a method for preparing freeze-thaw resistant and anti-icing road concrete, including the following steps:

[0104] Step (1) Preparation of salt-storing core-shell aggregate

[0105] Weigh 900g of the phosphogypsum-based core-shell aggregate prepared in Example 2 and place it in a vacuum drying oven. Add 1200mL of 20wt% calcium magnesium acetate aqueous solution, evacuate to -0.085MPa, react for 25min, restore normal pressure, soak for 22h, remove after soaking, drain for 13min, transfer to an oven at 47℃ and dry for 11h to obtain salt-accumulating core-shell aggregate.

[0106] Step 2: Preparing road concrete

[0107] Weigh out 3600g of crushed stone and 2300g of medium sand and place them in a mixer. Mix for 45s. Add 900g of cement, 350g of slag powder and 1100g of salt-retaining core-shell aggregate. Mix for 22s. Add 375mL of mixing water, 12.5g of water-reducing agent and 70g of dopamine polymer emulsion prepared in Example 5. Mix for 2.5min to obtain road concrete.

[0108] Example 9

[0109] This embodiment provides a method for preparing freeze-thaw resistant and anti-icing road concrete, including the following steps:

[0110] Step (1) Preparation of salt-storing core-shell aggregate

[0111] Weigh 100g of the phosphogypsum-based core-shell aggregate prepared in Example 3 and place it in a vacuum drying oven. Add 1400mL of 25wt% calcium magnesium acetate aqueous solution, evacuate to -0.08MPa, react for 30min, restore normal pressure, soak for 24h, remove after soaking, drain for 15min, transfer to an oven at 55℃ and dry for 14h to obtain salt-accumulating core-shell aggregate.

[0112] Step 2: Preparing road concrete

[0113] Weigh out 3800g of crushed stone and 2600g of medium sand and place them in a mixer. Mix for 60s. Add 1000g of cement, 400g of slag powder and 1200g of salt-retaining core-shell aggregate. Mix for 30s. Add 450mL of mixing water, 15g of water-reducing agent and 80g of dopamine polymer emulsion prepared in Example 6. Mix for 3min to obtain road concrete.

[0114] Comparative Example 1

[0115] The difference between this comparative example and Example 9 is that, in step (1) when preparing the salt storage core-shell aggregate, phosphogypsum-based aggregate is used in an equal amount to replace the phosphogypsum-based core-shell aggregate.

[0116] Comparative Example 2

[0117] The difference between this comparative example and Example 9 is that the addition of salt-storage core-shell aggregate is omitted when preparing road concrete in step (2).

[0118] Comparative Example 3

[0119] The difference between this comparative example and Example 9 is that the addition of dopamine polymer emulsion was omitted in step (2) when preparing road concrete.

[0120] Performance testing:

[0121] The road concrete prepared in Examples 7-9 and Comparative Examples 1-3 was placed into molds and vibrated using an immersion vibrator. After the specimens were formed, they were left to stand at room temperature for 24 hours, demolded, and then cured to obtain road concrete specimens. The single-point vibration time of the immersion vibrator was 10-15 seconds / point, the spacing was 1.5 times the diameter of the vibrator rod, the diameter of the vibrator rod was φ30-φ50mm, the curing temperature was 20±2℃, the relative humidity of the curing environment was greater than or equal to 95%, and the curing time was 28 days.

[0122] The road concrete specimens prepared in Examples 7-9 and Comparative Examples 1-3 were tested for their freeze-thaw resistance in a rapid freezing test in accordance with the standard GB / T 50082-2024 "Standard for Test Methods of Long-Term Performance and Durability of Concrete". The freeze-thaw resistance was determined by the maximum number of freeze-thaw cycles when the relative dynamic modulus of elasticity dropped to not less than 60% or the mass loss rate did not exceed 5%, and was represented by the symbol F.

[0123] The flexural strength and compressive strength of the road concrete specimens prepared in Examples 7-9 and Comparative Examples 1-3 were tested in accordance with the standard GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete".

[0124] A 9 cm diameter ring was fixed on the road concrete specimens prepared in Examples 7-9 and Comparative Examples 1-3, and 0.5 cm high deionized water was injected. The anti-icing performance of the road concrete specimens was characterized by detecting the freezing time of the surface water at a temperature of -5 °C. Specific data are shown in Table 1.

[0125] Table 1 - Performance Test Data for Each Sample

[0126]

[0127] Data Analysis:

[0128] A comparative analysis of the data in Table 1 above shows that the road concrete prepared by this invention has a frost resistance grade greater than or equal to F400, a flexural strength of 6.3 MPa, and a compressive strength of 56.8 MPa. At the same time, the freezing time at -5℃ is 179 min, and all data are better than the comparative example.

[0129] This invention uses phosphogypsum-based spherical aggregate as the core, and employs disc granulation to coat its surface with steel slag powder and incorporate ethylene-vinyl acetate copolymer powder to form a dense outer shell. Subsequently, high-pressure carbon dioxide carbonization is carried out to transform the active minerals in the shell into a stable carbonate phase, thereby improving strength and resistance to water absorption and frost heave. On this basis, calcium magnesium acetate is stored in the core-shell structure through vacuum impregnation to achieve salt lock-in and slow release. When mixing concrete, dopamine polymer emulsion is added to form a film at the interface and enhance adhesion and energy dissipation, thereby simultaneously improving the freeze-thaw resistance and anti-icing performance of road concrete.

[0130] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing freeze-thaw resistant and anti-icing road concrete, characterized in that, The preparation steps include the following: S1. Place the phosphogypsum-based core-shell aggregate in a vacuum drying oven, add calcium magnesium acetate aqueous solution, evacuate to -0.09 to -0.08 MPa, react for 20-30 min, restore to normal pressure, soak for 20-24 h, and then process to obtain salt-accumulating core-shell aggregate. S2. Place crushed stone and medium sand in a mixer and mix for 30-60 seconds. Add cement, slag powder and salt-retaining core aggregate and mix for 15-30 seconds. Add mixing water, water-reducing agent and dopamine polymer emulsion and mix for 2-3 minutes to obtain road concrete.

2. The method for preparing freeze-thaw resistant and anti-icing road concrete according to claim 1, characterized in that, In step S1, the ratio of the phosphogypsum-based core-shell aggregate to the calcium magnesium acetate aqueous solution is 80-100g:100-140mL, and the concentration of the calcium magnesium acetate aqueous solution is 15-25wt%; in step S2, the ratio of the crushed stone, medium sand, cement, slag powder, salt-retaining core-shell aggregate, mixing water, water-reducing agent, and dopamine polymer emulsion is 340-380g:200-260g:30-40g:100-120g:30-45mL:1-1.5g:6-8g.

3. The method for preparing freeze-thaw resistant and anti-icing road concrete according to claim 1, characterized in that, The dopamine polymer emulsion was prepared by the following steps: A1. Place dopamine hydrochloride and N,N-dimethylformamide in a light-protected reaction vessel and stir. Add triethylamine to adjust the pH to 7-8. Cool the reaction vessel to 0-5℃ and slowly add methacrylamide. Keep the reaction at this temperature for 2-4 hours. After post-treatment, olefin-modified dopamine is obtained. A2. Place deionized water and sodium dodecyl sulfate in a reaction vessel under nitrogen atmosphere and stir. Add butyl acrylate, methyl methacrylate, olefin-modified dopamine and potassium persulfate aqueous solution. Heat the reaction vessel to 70-80℃ and keep it at this temperature for 15-20 min to obtain dopamine seed emulsion. A3. Place the dopamine seed emulsion in a reaction vessel under nitrogen atmosphere and stir. Add butyl acrylate, methyl methacrylate, olefin-modified dopamine and potassium persulfate aqueous solution. Heat the reaction vessel to 70-80℃ and keep it at this temperature for 2-4 hours. After post-treatment, dopamine polymer emulsion is obtained.

4. The method for preparing freeze-thaw resistant and anti-icing road concrete according to claim 3, characterized in that, In step A1, the ratio of dopamine hydrochloride, N,N-dimethylformamide, and methacryloyl chloride is 2-4g:25-35mL:3-5g; in step A2, the ratio of deionized water, sodium dodecyl sulfate, butyl acrylate, methyl methacrylate, olefin-modified dopamine, and potassium persulfate aqueous solution is 160-180mL:0.5-0.8g:16-18g:10-15g:2-4g:8-10mL, and the concentration of potassium persulfate aqueous solution is 1-3wt%; in step A3, the ratio of dopamine seed emulsion, butyl acrylate, methyl methacrylate, olefin-modified dopamine, and potassium persulfate aqueous solution is 200-220g:50-70g:50-55g:2-4g:20-60mL, and the concentration of potassium persulfate aqueous solution is 1-3wt%.

5. The method for preparing freeze-thaw resistant and anti-icing road concrete according to claim 1, characterized in that, The anti-freezing ice core shell aggregate is prepared by the following steps: B1. Place phosphogypsum, slag powder, cement and metakaolin in a mixer, mix for 2-3 minutes, granulate to obtain phosphogypsum-based aggregate; B2. Soak the phosphogypsum-based aggregate in deionized water for 0.5-1h, drain for 15-30min, transfer to a disc granulator, add refined steel slag powder and ethylene-vinyl acetate copolymer powder, spray with deionized water, form a shell, and then process to obtain the crude phosphogypsum-based core-shell aggregate. B3. Place the crude phosphogypsum-based core-shell aggregate in a carbonization kettle, introduce carbon dioxide, heat the kettle to 55-65℃, and carbonize for 20-24 hours to obtain phosphogypsum-based core-shell aggregate.

6. The method for preparing freeze-thaw resistant and anti-icing road concrete according to claim 5, characterized in that, In step B1, the weight ratio of phosphogypsum, slag powder, cement, and metakaolin is 50-60:20-30:8-12:5-10. In step B2, the weight ratio of phosphogypsum-based aggregate, refined steel slag powder, and ethylene-vinyl acetate copolymer powder is 80-100:25-35:1-3.

7. The method for preparing freeze-thaw resistant and anti-icing road concrete according to claim 5, characterized in that, In step B1, the preparation method of the phosphogypsum-based aggregate is as follows: phosphogypsum, slag powder, cement, and metakaolin are placed in a mixer and stirred for 2-3 minutes. The mixture is then added in batches to a disc granulator, and deionized water is sprayed on. After the product forms spheres, sieving yields spherical aggregates of 10-20 mm. The spherical aggregates are placed in a sealed reactor for curing for 3 days. During curing, deionized water is sprayed daily at a rate equivalent to 0.01-0.02 times the mass of the spherical aggregates. After sealed curing, the spherical aggregates are placed in tap water at 20±2℃ for curing for 14-28 days. After curing, fine particles smaller than 2.5 mm are sieved out, and the spherical aggregates are placed in a constant temperature drying oven at 40-50℃ and dried to constant weight to obtain the phosphogypsum-based aggregate.

8. A type of road concrete resistant to freeze-thaw cycles and ice formation, characterized in that, The freeze-thaw resistant and anti-icing road concrete is prepared using a method for preparing freeze-thaw resistant and anti-icing road concrete as described in any one of claims 1-7.

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