Reinforced cast-in-place semi-flexible pavement and construction method thereof

Abstract

The present invention provides a reinforced grouting type semi-flexible pavement and a construction method thereof. The present invention adds modified magnetic particle micron Fe3O4@SiO2 mesoporous microspheres to a cement-based grouting material and an anti-dispersant to prepare a cement-based magnetic grouting material. At the same time, NdFeB waste is added to the porous asphalt mixture as a magnetic material to provide a magnetic field. When the cement-based magnetizable grouting material is injected into the porous asphalt mixture, the magnetic grouting liquid can be directed and adsorbed at a fixed point under the action of the magnetic field by means of the magnetic adsorption effect. The use of the semi-flexible pavement grouting material significantly improves the grouting material filling rate, significantly improves the bonding performance of the interface between asphalt and cement materials, effectively reduces the generation of interface cracks, and extends the service life of the semi-flexible pavement. The semi-flexible pavement cement of the present invention has good compressive strength, flexural strength, tensile strength, bonding strength, fluidity, shrinkage rate, etc., and is an ideal base liquid for cement-based magnetic grouting liquid.

Description

Technical Field

[0001] The invention belongs to the technical field of cast-in-place semi-flexible pavement design, and in particular relates to a reinforced cast-in-place semi-flexible pavement and a construction method thereof. Background Art

[0002] Cast-in-place semi-flexible pavement (SFP) material is a composite material with extremely complex composition, structure and interface formed by pouring special performance cement-based grouting materials into porous asphalt mixture (PAM). SFP has a high load-bearing capacity and outstanding anti-rutting properties. In engineering, it has been widely used as a means of repairing rutting on asphalt pavements at heavy traffic sections such as road intersections and bus stops. However, in actual engineering applications, semi-flexible pavements are prone to cracking under the action of vehicle loads due to their high stiffness, and the cracking is mostly in the form of interface cracks between asphalt and cement materials, which affects the service life of the road and restricts its large-scale promotion and use. Therefore, how to enhance the interface performance between asphalt and cement materials and reduce interface cracks is an engineering problem that urgently needs to be solved for cast-in-place semi-flexible pavement materials. Summary of the Invention

[0003] In view of the deficiencies in the prior art, the present invention aims to provide a reinforced cast-in-place semi-flexible pavement and a construction method thereof.

[0004] This invention draws on the concept of magnetic fluids by adding suitably modified magnetizable particles (Fe₃O₄) to cement-based grouting materials and incorporating an anti-dispersant to create a cement-based magnetic grouting material. Furthermore, NdFeB waste (replacing some aggregate with the same gradation) is added to the porous asphalt mixture as a magnetic material to provide a magnetic field. When the cement-based magnetizable grouting material is injected into the porous asphalt mixture, the magnetic attraction effect significantly improves the bonding strength at the asphalt-cement interface, effectively reducing the occurrence of interfacial cracks.

[0005] To achieve the above object, the solution of the present invention is:

[0006] A reinforced grouting type semi-flexible pavement comprising a magnetizable grouting fluid and a porous asphalt mixture;

[0007] The porous asphalt mixture provides a magnetic field effect. During grouting, the magnetizable grouting liquid moves in a direction and is adsorbed at a fixed point under the action of the magnetic field of the porous asphalt mixture. The use of the magnetizable grouting liquid in the semi-flexible pavement grouting material significantly improves the grouting material filling rate, greatly enhances the asphalt-cement interface performance, reduces the generation of interface cracks, and realizes crack-free grouting of the semi-flexible pavement material, thereby extending the service life of the semi-flexible pavement.

[0008] Wherein, the magnetizable grouting fluid comprises the following components in parts by mass:

[0009] 80-100 parts of Fe3O4@SiO2 mesoporous microspheres, 380-400 parts of cement, 90-100 parts of water, 0.6-2 parts of anti-dispersant;

[0010] The porous asphalt mixture comprises the following components in parts by mass:

[0011] 2-2.50 parts of high viscosity modified asphalt, 55.38-59.35 parts of coarse aggregate, 10.65-14.62 parts of fine aggregate, 23.74-25.44 parts of coarse magnetic aggregate, 4.56-6.26 parts of fine magnetic aggregate, and 2.40-3 parts of filler.

[0012] Furthermore, the total porosity of the porous asphalt mixture is 25%, and the mix design parameters are shown in Table 3.

[0013] Furthermore, the Fe3O4@SiO2 mesoporous microspheres have a core-shell structure, the particle size of the mesoporous microspheres is 6-12μm, the core is micron-sized Fe3O4 magnetic particles, the average core particle size is 5-10μm; the shell is SiO2, and the average shell thickness is 0.5-1μm.

[0014] Furthermore, Fe3O4@SiO2 mesoporous microspheres use micron-sized Fe3O4 magnetic particles as the core and tetraethoxysilane (TEOS) as the silicon source. The sol-gel method is combined with the template method and the calcination method to coat the surface of mesoporous SiO2 to synthesize micron Fe3O4@SiO2 mesoporous microspheres with a core-shell structure.

[0015] The specific preparation method is:

[0016] (1) SiO2 shell coating:

[0017] 1) Dispersing the magnetic core: Disperse micron-sized Fe3O4 particles in ethanol and deionized water and ultrasonicate to obtain a uniformly dispersed suspension;

[0018] 2) Introducing a silicon source: adding TEOS and 25% molar concentration of ammonia water, stirring and reacting at room temperature;

[0019] 3) Collection and washing: The product was collected by magnetic separation, washed three times with ethanol and deionized water alternately, and dried for later use;

[0020] (2) Formation of mesoporous structure:

[0021] 1) Adding a template: dissolving hexadecyltrimethylammonium bromide or polyethylene oxide as a template in a mixture of deionized water and ethanol, adding Fe3O4 particles coated with SiO2, and ultrasonically dispersing the mixture;

[0022] 2) Mesoporous shell formation: TEOS was added dropwise under stirring and the reaction was continued with stirring;

[0023] 3) Cleaning and drying: Collect the sample by magnetic separation and wash with ethanol and deionized water in sequence;

[0024] (3) Removal of template:

[0025] 1) Place the sample in a ceramic crucible and heat it to 500-600°C at a rate of 5°C / min;

[0026] 2) Maintaining constant temperature for calcination to remove hexadecyltrimethylammonium bromide or polyethylene oxide.

[0027] Furthermore, the cement used is high-performance semi-flexible pavement cement, model is Youlike G30B, the color is black-brown, produced by Zhejiang Weihua New Building Materials Co., Ltd., and its main components are silica fume, water reducer and basalt fine powder.

[0028] Furthermore, the anti-dispersant used is a cement mortar suspension anti-dispersant, manufactured by Guangdong Zhongke Hongtai New Materials Co., Ltd. This anti-dispersant exhibits excellent anti-dispersibility and fluidity, reducing cement loss while preventing water seepage, providing a controllable setting time, and achieving an anti-seepage rating exceeding S20 and an anti-corrosion coefficient of no less than 0.85. The anti-dispersant of the present invention disperses the core-shell Fe3O4@SiO2 mesoporous microspheres, ensuring their uniform distribution within the grouting solution and reducing precipitation.

[0029] Furthermore, high-viscosity modified asphalt is prepared by adding a high-viscosity modifier to 70# base asphalt. The high-viscosity modifier uses RST-P type high-viscosity particles produced by Shanghai Pudong Road and Bridge Construction Co., Ltd., and the 70# base asphalt is produced by Sinopec Refining and Sales Co., Ltd.

[0030] Furthermore, the coarse aggregate and the fine aggregate are discontinuously graded. The coarse aggregate is basalt produced by Jiangsu Yabang Mining Co., Ltd., and has a size greater than 2.36 mm. The fine aggregate is limestone produced by Chibi Yuanda Mining Co., Ltd., and has a size less than 2.36 mm.

[0031] Specifically, compared with continuous grading, discontinuous grading can reduce interference between particles, have fewer isolated voids, a larger and more uniform 3D pore structure, a larger throat size, better pore connectivity and permeability coefficient, and is more conducive to the penetration of grouting materials in the voids of porous asphalt mixtures.

[0032] Furthermore, both the coarse magnetic aggregate and the fine magnetic aggregate are made of NdFeB scrap, which is produced by Hengshui Beirui Metal Trading Co., Ltd.

[0033] This invention uses NdFeB waste as magnetic aggregate to provide magnetic field conditions. While the magnetic aggregate possesses a certain degree of magnetism, its magnetic force is insufficient to cause particles to aggregate, but it can attract magnetic grouting fluid. This magnetic aggregate creates a simple and ingenious magnetic field for porous asphalt mixtures, facilitating subsequent magnetic grouting. This achieves solid waste utilization while reducing material costs, laying the foundation for practical engineering applications.

[0034] Specifically, the magnetic aggregate is graded consistently with the aggregate, using NdFeB scrap material selected to meet the requirements of coarse aggregate (greater than 2.36mm) and fine aggregate (less than 2.36mm). The mass ratio of magnetic aggregate to aggregate is 3:7, equivalent to replacing 30% of the original aggregate. The magnetic aggregate is a porous asphalt mixture with a simple and ingenious magnetic field designed to facilitate subsequent magnetic grouting. The adsorption between the magnetic grouting liquid and the magnetic aggregate optimizes interfacial properties, providing a new approach to crack resistance in poured semi-flexible pavements.

[0035] Furthermore, the filler is limestone powder produced by Shanghai Huchang Building Materials Co., Ltd.

[0036] A construction method of the aforementioned reinforced cast-in-place semi-flexible pavement comprises the following steps:

[0037] Step 1: Prepare high-viscosity modified asphalt. The production process is as follows:

[0038] (1) First, the 70# matrix asphalt was heated to liquid at 150°C, and the RST-P high-viscosity particles were preheated at 100°C.

[0039] (2) Secondly, a specified mass of high-viscosity particles was added to 70# matrix asphalt and stirred at 180°C and 250 r / min for 30 min to allow the particles to fully swell;

[0040] (3) Then, high-speed shearing was performed at a speed of 4000 r / min for 60 minutes to ensure that the high-viscosity particles were evenly mixed with the 70# matrix asphalt;

[0041] (4) Finally, stir at a speed of 300 r / min for 30 minutes to fully develop the high-viscosity modified asphalt;

[0042] Step 2: Prepare porous asphalt mixture:

[0043] High-viscosity modified asphalt, coarse aggregate, fine aggregate, coarse magnetic aggregate, fine magnetic aggregate, and filler are prepared in the mass ratio of (2-2.50):(55.38-59.35):(10.65-14.62):(23.74-25.44):(4.56-6.26):(2.40-3). The mixing and transportation process refers to the Technical Specification for Road Pouring Semi-flexible Pavement (T / CECS G:D51-01-2019) to mix the porous asphalt mixture;

[0044] Step 3: Pave porous asphalt mixture:

[0045] The main paving process refers to the Technical Specifications for Road Pouring Semi-flexible Pavement (T / CECS G:D51-01-2019);

[0046] (1) Spreading of the mixture: Before paving, use an asphalt spreader to evenly spray the tack coat oil. Use an automatic paver to spread the mixture according to the hot mix and hot paving method. The paving temperature should be 155-165℃. The mixture should be spread evenly without segregation.

[0047] (2) Rolling of the mixture: First, use a 12t double steel wheel roller to vibrate and roll the new and old pavement joints or the junction with the curb for 3 times; then use a 12t steel wheel roller to statically roll the new pavement except the joints for 5 times;

[0048] (3) Pavement edge wrapping: After the asphalt is paved and compacted, the pavement edge is wrapped with polyurethane foam glue and wood strips;

[0049] Step 4: Preparation of Fe3O4@SiO2 mesoporous microspheres:

[0050] The following steps are involved:

[0051] (1) SiO2 shell coating (sol-gel method):

[0052] 1) Dispersing the magnetic core: Disperse micron-sized Fe3O4 particles in ethanol and deionized water and ultrasonicate to obtain a uniformly dispersed suspension;

[0053] 2) Introducing a silicon source: adding tetraethoxysilane and 25% molar concentration of ammonia water, stirring and reacting at room temperature;

[0054] 3) Collection and cleaning: The product was collected by magnetic separation, washed three times with ethanol and deionized water alternately, and dried for later use;

[0055] (2) Formation of mesoporous structure (template method):

[0056] 1) Adding a template: dissolving hexadecyltrimethylammonium bromide or polyethylene oxide as a template in a mixture of deionized water and ethanol, adding Fe3O4 particles coated with SiO2, and ultrasonically dispersing the mixture;

[0057] 2) Mesoporous shell formation: Tetraethoxysilane was added dropwise under stirring and the reaction was continued with stirring;

[0058] 3) Cleaning and drying: Collect the sample by magnetic separation and wash with ethanol and deionized water in sequence;

[0059] (3) Removal of template (calcination method):

[0060] 1) Place the sample in a ceramic crucible and program the temperature to 500-600°C at a heating rate of 5°C / min;

[0061] 2) maintaining a constant temperature for calcination to remove hexadecyltrimethylammonium bromide or polyethylene oxide;

[0062] Step 5: Prepare magnetizable grouting fluid:

[0063] Add Fe3O4@SiO2 mesoporous microspheres, cement, water, and anti-dispersant in a mass ratio of (80-100):(380-400):(90-100):(0.6-2) into the mixing tank of a vehicle-mounted mixing and pouring machine for preparation. The preparation process is as follows:

[0064] (1) Add cement first, then add Fe3O4@SiO2 mesoporous microspheres, and mix them evenly for 60 seconds;

[0065] (2) Add water, stir evenly, and stir for 30 seconds;

[0066] (3) Add anti-dispersant, stir evenly, and stir for 30 seconds;

[0067] Step 6: Grouting: When the porous asphalt mixture is confirmed to have cooled to below 50°C, a vehicle-mounted mixing and pouring machine (produced by Zhejiang Weihua New Building Materials Co., Ltd.) is used to pour cement-based magnetizable grouting liquid. Under the action of the magnetic field of the porous asphalt mixture, the grouting liquid moves in a targeted manner into the pores and is adsorbed at a fixed point. The grouting liquid has a high filling rate, enhances the asphalt-cement interface performance, avoids the generation of interface cracks, and extends the service life of the semi-flexible pavement.

[0068] Step 7: Scraping: Scraping should be done within 5-10 minutes after pouring when no more bubbles come out of the pores of the asphalt mixture. The scraping must be done before the mortar surface crusts. Use a rubber scraper to scrape off excess mortar on the surface to expose the aggregate of the asphalt mixture. In addition, the scraping must be done in the same direction to avoid scratches. At this point, the construction is completed.

[0069] Due to the adoption of the above solution, the beneficial effects of the present invention are:

[0070] First, the present invention adds modified magnetic particles (Fe3O4)—micronized Fe3O4@SiO2 mesoporous microspheres—to a cement-based grouting material, along with an anti-dispersant, to prepare a cement-based magnetic grouting material. Simultaneously, NdFeB waste (replacing some aggregate with the same gradation) is added to the porous asphalt mixture as a magnetic material to provide a magnetic field. When the magnetizable cement-based grouting material is injected into the porous asphalt mixture, the magnetic grouting fluid, through the magnetic adsorption effect, can be directed and adsorbed to a specific point under the action of the magnetic field. This significantly increases the grouting material filling rate (approximately 100%) when used in semi-flexible pavement grouting, significantly improves the bonding performance at the interface between asphalt and cement, effectively reduces the occurrence of interfacial cracks, and extends the service life of the semi-flexible pavement.

[0071] Second, the Fe3O4@SiO2 mesoporous microspheres of the present invention have many advantages such as large specific surface area, uniform size, large pore volume, strong adsorption capacity, protection of the core, excellent magnetic properties, and dispersibility. They improve the "carrying and transmission" ability and corrosion resistance of ordinary micron Fe3O4 particles, thereby reducing the segregation of magnetic grouting fluid; the SiO2 coated on the surface can hinder the contact of Fe3O4 particles with water and air, improve the corrosion resistance, and thus enhance its durability; solve the segregation and corrosion problems of existing cement-based magnetic grouting fluid (based on ordinary Fe3O4 particles), and further promote the application of cement-based magnetic grouting fluid in actual engineering.

[0072] Third, the high-performance semi-flexible pavement cement of the present invention has extremely good compressive strength, flexural strength, tensile strength, bonding strength, fluidity, shrinkage rate, etc., and all indicators exceed the requirements of the specifications. It is an ideal base liquid for cement-based magnetic grouting fluid, and its performance is significantly better than the ordinary Portland cement of the existing cement-based magnetic grouting fluid.

[0073] Fourth, the present invention uses NdFeB waste as magnetic aggregate to provide magnetic field conditions, thereby realizing solid waste utilization, reducing material costs, and laying the foundation for practical engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 This is a schematic diagram of the composition structure of micronized Fe3O4@SiO2 mesoporous microspheres according to Example 1 of the present invention.

[0075] Figure 2 This is a schematic diagram of the reinforced cast-in-place semi-flexible pavement structure of Example 1 of the present invention. DETAILED DESCRIPTION

[0076] The invention provides a construction method for a reinforced cast-in-place semi-flexible pavement.

[0077] The present invention will be further described below with reference to specific examples. This example is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following examples.

[0078] Embodiment 1 (optimum embodiment):

[0079] The construction method of the grouting type semi-flexible pavement based on the magnetic grouting fluid of this embodiment includes the following steps:

[0080] Step 1: Prepare high-viscosity modified asphalt. The production process is as follows:

[0081] (1) First, the 70# matrix asphalt was heated to liquid at 150°C, and the RST-P high-viscosity particles were preheated at 100°C.

[0082] (2) Secondly, a specified mass of high-viscosity particles was added to 70# matrix asphalt and stirred at 180°C and 250 r / min for 30 min to allow the particles to fully swell;

[0083] (3) Then, high-speed shearing was performed at a speed of 4000 r / min for 60 minutes to ensure that the high-viscosity particles were evenly mixed with the 70# matrix asphalt;

[0084] (4) Finally, the mixture was stirred at a speed of 300 r / min for 30 minutes to allow the high-viscosity modified asphalt to fully develop. Detailed parameters of the high-viscosity modified asphalt are shown in Table 4.

[0085] Step 2: Prepare porous asphalt mixture:

[0086] High-viscosity modified asphalt, basalt (coarse aggregate), limestone (fine aggregate), NdFeB waste (coarse magnetic aggregate), NdFeB waste (fine magnetic aggregate), and limestone slag (filler) were prepared in a mass ratio of 2.50:59.35:14.62:25.44:6.26:3 (see Table 3). The mixing and transportation process was carried out in accordance with the Technical Specifications for Pouring Semi-flexible Pavements for Roads (T / CECS G:D51-01-2019) to mix the porous asphalt mixture.

[0087] Step 3: Pave porous asphalt mixture. The main paving process refers to the "Technical Specifications for Road Pouring Semi-flexible Pavement" (T / CECS G:D51-01-2019).

[0088] (1) Spreading of mixture: Before spreading, use an asphalt spreader to evenly spray tack coat oil. Use an automatic paver to spread the mixture according to the hot mix and hot paving method. The paving temperature should be 165°C. The mixture should be spread evenly without segregation.

[0089] (2) Rolling of the mixture: First, use a 12t double steel wheel roller to vibrate and roll the joint of the new and old pavement (or the junction with the curb) for 3 times; then use a 12t steel wheel roller to statically roll the new pavement except the joint for 5 times.

[0090] (3) Pavement edge wrapping: After the asphalt is paved and compacted, polyurethane foam glue and wooden strips are used to wrap the pavement edges.

[0091] Step 4: Preparation of Fe3O4@SiO2 mesoporous microspheres:

[0092] The process includes the following steps (taking the modification of 2g micron Fe3O4 particles as an example):

[0093] (1) SiO2 shell coating (sol-gel method)

[0094] 1) Dispersion of magnetic cores: 2 g of micronized Fe3O4 particles (average particle size 5-10 μm) were dispersed in 50 mL of ethanol and 5 mL of deionized water and sonicated for 30 min to obtain a uniformly dispersed suspension;

[0095] 2) Introducing a silicon source: Add 1 mL of TEOS and 0.5 mL of 25% ammonia water, and stir the reaction at room temperature for 12 hours;

[0096] 3) Collection and cleaning: The product was collected by magnetic separation, washed three times with ethanol and deionized water alternately, and dried for later use.

[0097] (2) Formation of mesoporous structure (template method)

[0098] 1) Adding a template: Dissolve 0.5 g of CTAB (or P123) as a template in a 50 mL mixture of deionized water and ethanol. Add Fe3O4 particles coated with SiO2 (average thickness 0.5-1 μm) and ultrasonically disperse for 30 minutes.

[0099] 2) Mesoporous shell formation: 1 mL of TEOS was added dropwise under stirring, and the stirring reaction was continued for 24 hours.

[0100] 3) Cleaning and drying: The samples were collected by magnetic separation and washed with ethanol and deionized water in sequence.

[0101] (3) Removal of template (calcination method)

[0102] 1) Place the sample in a ceramic crucible and program the temperature to 600°C (heating rate of 5°C / min);

[0103] 2) Maintain constant temperature and calcination for 6 hours to remove CTAB or P123.

[0104] like Figure 1 As shown, the core of Fe3O4@SiO2 mesoporous microspheres (particle size 6-12μm) is composed of micron-sized Fe3O4 magnetic particles, providing magnetic drive performance. The shell is composed of SiO2, which protects the Fe3O4. The mesopores in the Fe3O4@SiO2 mesoporous microspheres carry and transport the base fluid. Therefore, nano-Fe3O4@SiO2 mesoporous microspheres are prepared by modifying nano-Fe3O4 particles. Due to their unique core-shell structure and mesoporous properties, they are mainly used in technical fields such as biomedicine, catalysis, and environmental remediation.

[0105] Step 5: Prepare magnetic grouting fluid:

[0106] Fe3O4@SiO2 mesoporous microspheres, high-performance semi-flexible pavement cement, water, and cement mortar suspension anti-dispersant are added into the mixing tank of a vehicle-mounted mixing and grouting machine at a mass ratio of 100:400:100:2 for preparation. The preparation process is as follows (the stirring time is based on the preparation of 602g of magnetic grouting liquid, and the actual stirring time depends on the amount of slurry required for the project):

[0107] (1) Add cement first, then add Fe3O4@SiO2 mesoporous microspheres, and mix them evenly for 60 seconds;

[0108] (2) Add water, stir evenly, and stir for 30 seconds;

[0109] (3) Add anti-dispersant and stir evenly for 30 seconds.

[0110] Step 6: Magnetic Grouting: Once the porous asphalt mixture has cooled to below 50°C, cement-based magnetic grouting fluid is injected using a vehicle-mounted mixing and pouring machine. Under the influence of the magnetic field of the magnetic aggregate incorporated into the porous asphalt mixture, the magnetic grouting fluid migrates and adheres to specific points within the pores, significantly increasing the grouting fill rate, significantly strengthening the asphalt-cement interface, reducing interfacial cracks, and extending the service life of the semi-flexible pavement.

[0111] Step 7: Scraping: Within 10 minutes after pouring, when no more bubbles are released from the pores of the asphalt mixture, begin scraping. Scraping must be done before a crust forms on the mortar surface. Use a rubber scraper (not a sponge scraper) to forcefully remove excess mortar from the surface, exposing the asphalt aggregate. Scraping must be done in the same direction (back and forth is acceptable) to avoid scratches. This completes the process.

[0112] Compared with the prior art, the magnetic particles of the cement-based magnetizable grouting material used are ordinary Fe3O4 particles, and the cement is ordinary Portland cement, whose compressive strength, flexural strength, fluidity and shrinkage rate are all worse than those of the high-performance semi-flexible pavement cement of this embodiment (see Table 2).

[0113] Among them, the cement used is high-performance semi-flexible pavement cement, model is Youlike G30B, the color is black-brown, and it is produced by Zhejiang Weihua New Building Materials Co., Ltd.

[0114] The anti-dispersant used is cement mortar suspended anti-dispersant, produced by Guangdong Zhongke Hongtai New Materials Co., Ltd.

[0115] The high-viscosity modifier uses RST-P high-viscosity particles produced by Shanghai Pudong Road and Bridge Construction Co., Ltd., and the 70# base asphalt is produced by Sinopec Refining and Sales Co., Ltd.

[0116] Coarse and fine aggregates were graded discontinuously. The coarse aggregate was basalt produced by Jiangsu Yabang Mining Co., Ltd., with a size larger than 2.36 mm. The fine aggregate was limestone produced by Chibi Yuanda Mining Co., Ltd., with a size smaller than 2.36 mm. Detailed basic performance indicators of the coarse and fine aggregates are shown in Table 1.

[0117] Both coarse magnetic aggregate and fine magnetic aggregate are made of NdFeB scrap and are produced by Hengshui Beirui Metal Trading Co., Ltd.

[0118] The filler is limestone powder, produced by Shanghai Huchang Building Materials Co., Ltd. The detailed basic performance indicators are shown in Table 5

[0119] like Figure 2 As shown, in the cast-in-place semi-flexible pavement of this embodiment, from a microscopic perspective, NdFeB waste is added to the porous asphalt mixture as a magnetic material to provide a magnetic field. When the micronized Fe3O4@SiO2 mesoporous microspheres in the cement-based magnetic grouting material are injected into the porous asphalt mixture, the magnetic grouting material can move in a directional manner and be adsorbed at a fixed point under the action of the magnetic field by means of the magnetic adsorption effect, which significantly improves the bonding performance of the interface between asphalt and cement materials, increases the filling rate of the grouting material, effectively reduces the generation of interface cracks, and extends the service life of the semi-flexible pavement.

[0120] Example 2:

[0121] The construction method of the cast-in-place semi-flexible pavement of this embodiment includes the following steps:

[0122] Step 1: Prepare high-viscosity modified asphalt. The production process is as follows:

[0123] (1) First, the 70# matrix asphalt was heated to liquid at 150°C, and the RST-P high-viscosity particles were preheated at 100°C.

[0124] (2) Secondly, a specified mass of high-viscosity particles was added to 70# matrix asphalt and stirred at 180°C and 250 r / min for 30 min to allow the particles to fully swell;

[0125] (3) Then, high-speed shearing was performed at a speed of 4000 r / min for 60 minutes to ensure that the high-viscosity particles were evenly mixed with the 70# matrix asphalt;

[0126] (4) Finally, stir at a speed of 300 r / min for 30 minutes to allow the high-viscosity modified asphalt to fully develop.

[0127] Step 2: Prepare porous asphalt mixture:

[0128] High-viscosity modified asphalt, basalt (coarse aggregate), limestone (fine aggregate), NdFeB waste (coarse magnetic aggregate), NdFeB waste (fine magnetic aggregate), and limestone slag (filler) were prepared in a mass ratio of 2:55.38:10.65:23.74:4.56:2.40 (see Table 3). The mixing and transportation process was carried out in accordance with the Technical Specifications for Cast-in-Place Semi-flexible Pavements for Roads (T / CECS G:D51-01-2019) to mix the porous asphalt mixture.

[0129] Step 3: Pave porous asphalt mixture. The main paving process refers to the "Technical Specifications for Road Pouring Semi-flexible Pavement" (T / CECS G:D51-01-2019).

[0130] (1) Spreading of mixture: Before spreading, use an asphalt spreader to evenly spray tack coat oil. Use an automatic paver to spread the mixture according to the hot mix and hot paving method. The paving temperature should be 155°C. The mixture should be spread evenly without segregation.

[0131] (2) Rolling of the mixture: First, use a 12t double steel wheel roller to vibrate and roll the joint of the new and old pavement (or the junction with the curb) for 3 times; then use a 12t steel wheel roller to statically roll the new pavement except the joint for 5 times.

[0132] (3) Pavement edge wrapping: After the asphalt is paved and compacted, polyurethane foam glue and wooden strips are used to wrap the pavement edges.

[0133] Step 4: Preparation of Fe3O4@SiO2 mesoporous microspheres:

[0134] The process includes the following steps (taking the modification of 2g micron Fe3O4 particles as an example):

[0135] (1) SiO2 shell coating (sol-gel method)

[0136] 1) Dispersion of magnetic cores: 2 g of micronized Fe3O4 particles (average particle size 5-10 μm) were dispersed in 50 mL of ethanol and 5 mL of deionized water and sonicated for 30 min to obtain a uniformly dispersed suspension;

[0137] 2) Introducing a silicon source: Add 1 mL of TEOS and 0.5 mL of 25% ammonia water, and stir the reaction at room temperature for 12 hours;

[0138] 3) Collection and cleaning: The product was collected by magnetic separation, washed three times with ethanol and deionized water alternately, and dried for later use.

[0139] (2) Formation of mesoporous structure (template method)

[0140] 1) Adding a template: Dissolve 0.5 g of CTAB (or P123) as a template in a 50 mL mixture of deionized water and ethanol. Add Fe3O4 particles coated with SiO2 (average thickness 0.5-1 μm) and ultrasonically disperse for 30 minutes.

[0141] 2) Mesoporous shell formation: 1 mL of TEOS was added dropwise under stirring, and the stirring reaction was continued for 24 hours.

[0142] 3) Cleaning and drying: The samples were collected by magnetic separation and washed with ethanol and deionized water in sequence.

[0143] (3) Removal of template (calcination method)

[0144] 1) Place the sample in a ceramic crucible and program the temperature to 500°C (heating rate of 5°C / min);

[0145] 2) Maintain constant temperature and calcination for 6 hours to remove CTAB or P123.

[0146] Step 5: Prepare magnetic grouting fluid:

[0147] Fe3O4@SiO2 mesoporous microspheres (particle size of 6-12μm), high-performance semi-flexible pavement cement, water, and cement mortar suspension anti-dispersant are added into the mixing tank of a vehicle-mounted mixing and grouting machine at a mass ratio of 80:380:90:0.6 for preparation. The preparation process is as follows (the stirring time is based on the preparation of 602g of magnetic grouting liquid, and the actual stirring time depends on the amount of slurry required for the project):

[0148] (1) Add cement first, then add Fe3O4@SiO2 mesoporous microspheres, mix the two evenly, and stir for 60s;

[0149] (2) Add water, stir evenly, and stir for 30 seconds;

[0150] (3) Add anti-dispersant and stir evenly for 30 seconds.

[0151] Step 6: Magnetic Grouting: Once the porous asphalt mixture has cooled to below 50°C, cement-based magnetic grouting fluid is injected using a vehicle-mounted mixing and pouring machine. Under the influence of the magnetic field generated by the magnetic aggregate incorporated into the porous asphalt mixture, the magnetic grouting fluid migrates and adheres to specific points within the pores, significantly increasing the grouting fill rate, significantly strengthening the asphalt-cement interface, reducing interfacial cracks, and extending the service life of the semi-flexible pavement.

[0152] Step 7: Scraping. Scraping should begin within 5 minutes of pouring, when no more bubbles are released from the pores of the asphalt mixture. Scraping must be performed before a crust forms on the mortar surface. Use a rubber scraper (not a sponge scraper) to forcefully remove excess mortar from the surface, exposing the asphalt aggregate. Scraping must be done in the same direction (back and forth is acceptable) to avoid scratches. At this point, the construction is complete.

[0153] Table 1 Basic performance indicators of aggregate

[0154]

[0155]

[0156] Table 2 Comparison of performance parameters of ordinary Portland cement (42.5R) and high-performance semi-flexible pavement cement

[0157]

[0158] Table 3 Mix proportion design of porous asphalt mixture

[0159]

[0160] Table 4 Basic performance indicators of high viscosity modified asphalt

[0161]

[0162] Table 5 Basic performance indicators of mineral powder

[0163]

[0164] The above description of the embodiments is intended to facilitate understanding and use of the present invention by those skilled in the art. Those skilled in the art will readily be able to make various modifications to these embodiments and apply the general principles described herein to other embodiments without resorting to creative effort. Therefore, the present invention is not limited to the above-described embodiments. Any improvements or modifications made by those skilled in the art based on the principles of the present invention that do not depart from the scope of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A reinforced perfusion type semi-flexible pavement, characterized in that: It includes a magnetizable grout and a porous asphalt mixture; The porous asphalt mixture provides a magnetic field effect. During grouting, the magnetizable grouting liquid moves in a directional manner and is adsorbed at a fixed point under the magnetic field of the porous asphalt mixture, thereby achieving a crack-free grouting semi-flexible pavement material. Wherein, the magnetizable grouting fluid comprises the following components in parts by mass: 80-100 parts of Fe3O4@SiO2 mesoporous microspheres, 380-400 parts of cement, 90-100 parts of water, 0.6-2 parts of anti-dispersant; The porous asphalt mixture comprises the following components in parts by mass: 2-2.50 parts of high viscosity modified asphalt, 55.38-59.35 parts of coarse aggregate, 10.65-14.62 parts of fine aggregate, 23.74-25.44 parts of coarse magnetic aggregate, 4.56-6.26 parts of fine magnetic aggregate, and 2.40-3 parts of filler.

2. The reinforced cast-in-place semi-flexible pavement according to claim 1, characterized in that: The Fe3O4@SiO2 mesoporous microspheres are of a core-shell structure with a particle size of 6-12 μm; the core is micron-sized Fe3O4 magnetic particles with an average particle size of 5-10 μm; the shell is SiO2 with an average shell thickness of 0.5-1 μm.

3. The reinforced cast-in-place semi-flexible pavement according to claim 1, characterized in that: The preparation method of the Fe3O4@SiO2 mesoporous microspheres is as follows: (1) Coating of SiO2 shell: 1) Dispersion of magnetic cores: Micron-sized Fe3O4 particles were dispersed in ethanol and deionized water and ultrasonicated to obtain a uniformly dispersed suspension; 2) Introducing silicon source: Add tetraethoxysilane and ammonia water, and stir the reaction at room temperature; 3) Collection and washing: The product was collected by magnetic separation, washed three times with ethanol and deionized water alternately, and dried for later use; (2) Formation of mesoporous structure: 1) Adding a template: Dissolve hexadecyltrimethylammonium bromide or polyethylene oxide as a template in a mixture of deionized water and ethanol, add Fe3O4 particles coated with SiO2, and disperse them by ultrasonication. 2) Mesoporous shell formation: Tetraethoxysilane was added dropwise under stirring and the reaction was continued with stirring; 3) Cleaning and drying: Collect the sample by magnetic separation and wash it with ethanol and deionized water in sequence; (3) Removal of template: 1) Place the sample in a ceramic crucible and program the temperature. 2) Maintaining constant temperature for calcination to remove hexadecyltrimethylammonium bromide or polyethylene oxide.

4. A construction method for a reinforced cast-in-place semi-flexible pavement according to any one of claims 1 to 3, characterized in that: It includes the following steps: Step 1: Prepare high-viscosity modified asphalt. The production process is as follows: (1) First, the matrix asphalt is heated to liquid state, and the RST-P type high viscosity particles are preheated at the same time; (2) Secondly, add the high-viscosity particles into the matrix asphalt and stir to allow the particles to fully swell; (3) Then shear to ensure that the high-viscosity particles are evenly mixed with the matrix asphalt; (4) Finally, stir to fully develop the high-viscosity modified asphalt; Step 2: Prepare porous asphalt mixture: High-viscosity modified asphalt, coarse aggregate, fine aggregate, coarse magnetic aggregate, fine magnetic aggregate, and filler are prepared in the mass ratio of (2-2.50): (55.38-59.35): (10.65-14.62): (23.74-25.44): (4.56-6.26): (2.40-3). The mixing and transportation process refers to the Technical Specifications for Pouring Semi-Flexible Pavement to mix porous asphalt mixture. Step 3: Pave porous asphalt mixture: The main paving process refers to the "Technical Specifications for Road Pouring Semi-flexible Pavement"; (1) Spreading of the mixture: Before paving, use an asphalt spreader to evenly spray the tack coat oil. Use an automatic paver to spread the mixture according to the hot mix and hot paving method. The mixture should be spread evenly without segregation. (2) Rolling of the mixture: First, use a double steel wheel roller to vibrate and roll the joints of the new and old pavement or the junction with the curb; then use a steel wheel roller to roll the new pavement except the joints using the static pressure method; (3) Pavement edge wrapping: After the asphalt is paved and compacted, the pavement edge is wrapped with polyurethane foam glue and wooden strips; Step 4: Preparation of Fe3O4@SiO2 mesoporous microspheres: The following steps are involved: (1) Coating of SiO2 shell: 1) Dispersion of magnetic cores: Micron-sized Fe3O4 particles were dispersed in ethanol and deionized water and ultrasonicated to obtain a uniformly dispersed suspension; 2) Introducing silicon source: Add tetraethoxysilane and ammonia water, and stir the reaction at room temperature; 3) Collection and washing: The product was collected by magnetic separation, washed three times with ethanol and deionized water alternately, and dried for later use; (2) Formation of mesoporous structure: 1) Adding a template: Dissolve hexadecyltrimethylammonium bromide or polyethylene oxide as a template in a mixture of deionized water and ethanol, add Fe3O4 particles coated with SiO2, and disperse them by ultrasonication. 2) Mesoporous shell formation: Tetraethoxysilane was added dropwise under stirring and the reaction was continued with stirring; 3) Cleaning and drying: Collect the sample by magnetic separation and wash it with ethanol and deionized water in sequence; (3) Removal of template: 1) Place the sample in a ceramic crucible and program the temperature. 2) Maintaining constant temperature for calcination to remove hexadecyltrimethylammonium bromide or polyethylene oxide; Step 5: Prepare magnetizable grouting fluid: Fe3O4@SiO2 mesoporous microspheres, cement, water, and anti-dispersant are added into the mixing tank of a vehicle-mounted mixing and pouring machine at a mass ratio of 100:400:100:2 for preparation. The preparation process is as follows: (1) Add cement first, then add Fe3O4@SiO2 mesoporous microspheres, and mix them evenly; (2) Add water and stir evenly; (3) Add anti-dispersant and stir evenly; Step 6: Grouting: When the porous asphalt mixture is confirmed to have cooled, pour the cement-based magnetizable grouting liquid through the vehicle-mounted mixing and pouring machine; Step 7: Scraping: After pouring, scrape the slurry when there are no more bubbles coming out of the pores of the asphalt mixture. The scraping must be done before the mortar surface crusts. Use a rubber scraper to scrape off the excess mortar on the surface to expose the aggregate of the asphalt mixture. In addition, the scraping must be done in the same direction to avoid scratches. At this point, the construction is completed.

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