A fast-hardening and early-strength material applied to emulsified asphalt thin slurry seal and a preparation method thereof

Abstract

The application relates to a fast-hardening early-strength material applied to emulsified asphalt slurry seal and a preparation method, and belongs to the field of pavement maintenance composite materials. In view of the defects of the prior art, the slurry seal material capable of quickly opening traffic is prepared from a magnesium phosphate cement matrix powder, emulsified asphalt, mixed water, machine-made sand, coarse aggregate and an anti-dispersion agent, has the fast-hardening early-strength characteristics of MPC and the flexibility of the emulsified asphalt material. The material can be used only by simple mixing, has the characteristics of high early strength, short setting time and excellent high-temperature resistance, is favorable for shortening the maintenance time, and simultaneously improves the high-temperature resistance of the maintenance site.

Description

Technical Field

[0001] This invention belongs to the field of road maintenance composite materials technology, specifically relating to a fast-hardening early-strength material for use in emulsified asphalt slurry seal and its preparation method. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Asphalt pavement is increasingly used on higher-grade highways. Its unique viscoelasticity makes it sensitive to temperature changes: in high summer temperatures, it exhibits a fluid state, low strength, and low elastic modulus, making it prone to rutting and other defects; in low winter temperatures, the elastic modulus of asphalt pavement increases, turning it into a rigid material, making it susceptible to brittle shrinkage cracks and other defects; during rainy seasons, asphalt pavement is also susceptible to water damage, resulting in aggregate loosening and spalling, leading to potholes. Worse still, asphalt pavement is subjected to repeated vehicle loads over long periods, coupled with the effects of water and temperature, making various defects more frequent and severe. Slurry seal technology is a preventative maintenance method for surface-treated pavements. Old asphalt pavements often have cracks and potholes. When the surface is worn, a thin layer of emulsified asphalt slurry seal mixture is spread on the pavement and allowed to cure quickly, thus protecting the asphalt concrete pavement. The thickness of the slurry seal is generally less than 3 cm. It is a maintenance and repair service aimed at restoring the function of the road surface and preventing further damage, so as to effectively extend the service life of highway road surfaces and reduce repair costs.

[0004] When laying slurry seal coats on highways or urban expressways, high-quality emulsified asphalt or polymer-modified emulsified asphalt should be used to increase the bond strength between the asphalt and aggregate. The emulsified asphalt should not segregate after mixing with the aggregate and during the mixing process, should have good adhesion to the aggregate, be in a good flowable state, and be able to set quickly after paving to allow traffic to resume. However, commonly used emulsified asphalt slurry takes more than 4-5 hours to set after paving, which seriously hinders the time required to open to traffic, causing traffic congestion and threatening driving safety.

[0005] Chemically bonded magnesium phosphate cementitious material (MPC) is a novel inorganic cementitious material with phosphate as the binder, produced by reacting magnesium oxide, soluble phosphate, admixtures, and mineral admixtures in a certain proportion under acidic conditions through acid-base chemical reactions and physical processes. It features high early strength, rapid setting time, and excellent bonding performance. In the inventors' prior research, emulsified asphalt was combined with MPC, resulting in a composite material that combines the rigidity of inorganic materials with the flexibility of organic materials. This provides an environmentally friendly and easy-to-use crack sealing material that can effectively shorten road damage repair time. However, the application methods of slurry seal and crack sealing materials differ significantly, and the performance requirements for composite materials also differ considerably. Direct conversion cannot meet construction requirements; therefore, providing a composite material suitable for slurry seal is of significant research importance. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a slurry seal composite material suitable for asphalt pavement maintenance. This material features rapid hardening and early strength, high early strength after paving, and short setting time, which helps to shorten the construction time of pavement maintenance work.

[0007] The technical concept of this invention is as follows:

[0008] In a first aspect, the present invention provides a fast-hardening and early-strength material for use in emulsified asphalt slurry seal, comprising the following raw materials in parts by weight: magnesium phosphate cement matrix powder, emulsified asphalt, mixing water, manufactured sand, coarse aggregate and anti-dispersant agent;

[0009] The magnesium phosphate cement matrix powder is composed of calcined magnesium oxide, borax, ammonium dihydrogen phosphate, mineral powder, silica fume, and fly ash.

[0010] The anti-dispersant includes cellulose ether, nano-SiO2, and ultrafine fly ash.

[0011] Traditional slurry seal materials suffer from poor strength, long strength development time, and insufficient adhesion in practical applications, making it difficult to truly achieve the purpose of road maintenance. This invention incorporates magnesium phosphate cementitious matrix (MPC) into emulsified asphalt to form an organic-inorganic composite system. The hydration of magnesium phosphate cement consumes the water in the emulsified asphalt, and the heat of hydration released by cement hydration accelerates the demulsification rate of the emulsified asphalt. After demulsification, the emulsified asphalt recovers its original adhesion properties and interacts with the MPC material to form a semi-rigid cementitious material between MPC and emulsified asphalt. The mechanical interlocking of the MPC-emulsified asphalt system and the interlocking between the mixtures work together to build strength, enabling rapid application.

[0012] Furthermore, emulsified asphalt is added at 40%–70% of the total mass of MPC, with the total water-cement ratio (W / C) adjusted to 0.15–0.45. Insufficient emulsified asphalt content will result in incomplete encapsulation of the MPC material, leading to segregation and affecting the material's uniformity. Excessive emulsified asphalt content significantly reduces the material's mechanical properties and setting time, causing it to lose its performance advantages. Literature review and experimental testing indicate that a content of 40%–70% emulsified asphalt results in a significant performance advantage.

[0013] The cellulose ether in the aforementioned anti-dispersant is hydroxypropyl methylcellulose, which plays multiple roles in cement-based material systems, including water retention and dispersion, thickening and viscosity enhancement, air entrainment and lubrication, and retarding. Previous research results indicate that cellulose ether at concentrations greater than 0.15% significantly increases the consistency of the material system and reduces its mechanical properties. Conversely, low concentrations of cellulose ether effectively disperse particles in suspensions, improving the stability of the material. Previous studies have shown that a cellulose ether content of 0.05%-0.5% by mass in the matrix material is reasonable in anti-dispersants. Nano-SiO2 has been shown to improve the suspension stability, bond strength, and weather resistance of cement-based materials. However, previous studies have indicated that excessive dosage can negatively impact mechanical properties. The recommended dosage of nanomaterials in anti-dispersants is 1%-3%. As an ultrafine powder, adding a small amount of ultrafine fly ash can improve the stability of the material and prevent magnesium oxide from precipitating due to gravity when the magnesium-phosphorus ratio is low, thus avoiding uneven material distribution. At the same time, a certain amount of fly ash can also improve the structural density of the material and enhance its flowability and mechanical properties. It is recommended that the dosage not exceed 20% of the magnesium phosphate cement matrix powder.

[0014] This invention also provides a method for preparing the above-mentioned fast-hardening and early-strength material, in which MPC dry material and anti-dispersant are added to a liquid and mixed evenly, and then coarse aggregates are added. After mixing, the material is spread on the road surface to form an asphalt seal. After processes such as coating, demulsification, water separation, evaporation and curing, it is firmly bonded to the original road surface to form a dense, strong, wear-resistant road surface seal, which greatly improves the performance of the road surface.

[0015] The beneficial effects of one or more of the above technical solutions are:

[0016] 1. The slurry seal provided by this invention has a significantly shorter setting time compared to existing asphalt pavement repair materials, with the hardening time controlled within 2 hours, effectively shortening the road maintenance construction time, allowing for faster traffic opening, and rapid early strength development.

[0017] 2. The slurry seal material provided by this invention is made from green and environmentally friendly raw materials, which avoids pollution to the environment and groundwater and achieves green repair. Detailed Implementation

[0018] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] As described in the background section, existing materials for asphalt pavement maintenance suffer from long construction times. To address these issues, this invention proposes a fast-setting, early-strength material for emulsified asphalt slurry seal coatings. The specific solution is as follows:

[0021] In a first aspect, the present invention provides a fast-hardening and early-strength material for use in emulsified asphalt slurry seal, the raw materials of which are the following components in parts by weight: 21-50 parts magnesium phosphate cement matrix powder, 10-25 parts emulsified asphalt, 5-15 parts mixing water, 5-20 parts manufactured sand, 40-60 parts coarse aggregate, and 0.5-1 part anti-dispersant.

[0022] The magnesium phosphate cement powder is prepared from 10-20 parts of reburned magnesium oxide, 1-4 parts of borax, 5-10 parts of ammonium dihydrogen phosphate, 0-3 parts of mineral powder, 0-3 parts of silica fume, and 5-10 parts of fly ash.

[0023] Regarding the first aspect, the present invention also provides the following preferred technical solutions:

[0024] Emulsified asphalt: The emulsified asphalt in this invention is a cationic polymer-modified emulsified asphalt with a solid content of 55% to 60%, which conforms to the BCR type requirements in the "Technical Guidelines for Microsurfacing and Slurry Seal" (JTG / T F40-02-2005).

[0025] Mixing water: Mixing water is the water used to mix the above components. According to the water source, it can be divided into drinking water, surface water, groundwater, seawater, and industrial wastewater after appropriate treatment or disposal. Under normal circumstances, the source of mixing water has almost no impact on the strength of concrete materials. Technicians can make conventional selections according to the requirements of building codes. In the embodiments provided by this invention, tap water can be used as the mixing water.

[0026] Manufactured sand: Manufactured sand is sand produced through sand making machines and other auxiliary equipment. Compared with river sand, manufactured sand has little impact on the performance of MPC material mixtures. Furthermore, manufactured sand offers advantages such as energy saving, emission reduction, low pollution, and low manufacturing costs, making it a better choice as aggregate in this system. The particle size of manufactured sand is 40-80 mesh.

[0027] Coarse aggregate: This invention preferably uses basalt, which has better compatibility with cationic emulsified asphalt, and selects SMA-13 ​​with a dense skeleton structure for gradation. The aggregate is screened according to JTG E42-2005 "Specifications for Testing Aggregates in Highway Engineering".

[0028] Anti-dispersant: The anti-dispersant comprises the following components in parts by weight: 0.05-0.15 parts cellulose ether, 1-3 parts nano-SiO2, and 0-5 parts ultrafine fly ash. Ultrafine fly ash plays a role in maintaining slurry stability and has minimal impact on flowability. It acts as an auxiliary agent after the addition of cellulose ether and nano-SiO2. If specific flowability requirements exist at the construction site, the amount of ultrafine fly ash can be increased while the amounts of cellulose ether and nano-SiO2 can be reduced.

[0029] Regarding magnesium phosphate cement powder, the present invention also provides the following preferred embodiments:

[0030] Calcinated magnesium oxide: The calcined magnesium oxide used in this invention is obtained by calcining magnesite at high temperature and then crushing and grinding it. It has a light yellow appearance, a purity of 90% or higher, and a fineness of no more than 200 mesh. In a specific example, the purity of magnesium oxide is approximately 91%.

[0031] Borax: In this invention, borax acts as a retarder in the material. Borax decahydrate is often selected; it is a crystalline white powder with a density of 1.72 g / cm³. 3 The purity is greater than 95%.

[0032] Ammonium dihydrogen phosphate: Industrial grade, white powder granules, NH4H2PO4 content is 99%.

[0033] Mineral powder: More than 80% of the particles are less than 1 μm in size, with an average particle size of 0.1-0.3 μm.

[0034] Silica fume: The average particle size of silica fume is 0.1-0.15 μm.

[0035] Fly ash: Its average particle size distribution is approximately 8–20 μm, and its specific surface area is 300–600 m². 2 / kg; furthermore, coarse aggregate is added at 1.25 to 4 times the total mass of magnesium phosphate cement matrix powder. The coarse aggregate should be crushed stone with small particle size and small difference (refer to the crushed stone particle size requirements in the road maintenance standard). If the amount of coarse aggregate added is too small, it will lead to a large difference in uniformity between the original asphalt pavement and the repair area, and the pavement anti-skid performance will be poor. If the proportion of coarse aggregate is too large, the material will not be able to coat the coarse aggregate, and the bonding performance between the aggregates will be affected. The test results show that the performance is better when the coarse aggregate is between 1.25 and 4 times the mass of MPC.

[0036] In a second aspect, the present invention provides a method for preparing the rapid-hardening, early-strength material described in the first aspect, comprising the following steps:

[0037] Ammonium dihydrogen phosphate, borax, calcined magnesium oxide, mineral powder, silica fume, and fly ash are mixed in a certain proportion to prepare MPC dry material; emulsified asphalt and mixing water are mixed and stirred at low speed, and MPC dry material and anti-dispersant are slowly added and thoroughly mixed to form MPC-EA binder;

[0038] Then, manufactured sand is added and mixed at high speed to form MPC-EA mortar; finally, coarse aggregate is added and mixed at high speed to prepare MPC-EA mixture, which is then spread on the road surface to form the slurry seal layer.

[0039] Preferably, the low-speed stirring speed is 140±5 r / min, and the stirring time is 0.1 to 1 min.

[0040] Preferably, the above-mentioned MPC dry material and anti-dispersant should be added at a slow and uniform rate. In the preferred embodiment, the addition is completed within 0.8 to 1.2 minutes, and the mixture is stirred continuously for 2 to 4 minutes after the addition is completed to obtain MPC-EA binder.

[0041] Preferably, the high-speed stirring speed is 285±3 r / min, and the stirring time is 3 to 5 min.

[0042] When the above-mentioned MPC-EA mixture is laid on the road surface, if necessary, local construction defects can be repaired manually and allowed to cure naturally for 1.5 to 2 hours before traffic can be opened.

[0043] Preferably, the paving and compaction speed of the MPC-EA mixture should be consistent with the mixing volume, and the thickness should not exceed 3cm.

[0044] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0045] Example 1

[0046] A rapid-hardening, early-strength material for emulsified asphalt slurry seal is prepared by uniformly mixing recalcined magnesium oxide, ammonium dihydrogen phosphate, and borax to obtain a cementitious material, which is then mixed with emulsified asphalt and water to obtain an MPC-emulsified asphalt composite system. The mass fraction of the magnesium phosphate cementitious material is: 15 parts recalcined magnesium oxide, 5 parts ammonium dihydrogen phosphate, 1 part borax, 5 parts fly ash, 1 part mineral powder, and 1 part silica fume.

[0047] In the aforementioned anti-dispersant, the ratio of cellulose ether: nano-SiO2: ultrafine fly ash is 0.05:1:3.

[0048] The emulsified asphalt content is 12 parts; manufactured sand, 13 parts; SMA-13 ​​coarse aggregate, 50 parts; and mixing water, 8 parts.

[0049] Ammonium dihydrogen phosphate, borax, calcined magnesium oxide, mineral powder, silica fume, and fly ash are mixed in proportion to prepare MPC dry material; emulsified asphalt and mixing water are mixed and stirred at low speed for 1 minute, and MPC dry material and anti-dispersant are slowly added over 0.8 to 1.2 minutes. After the addition is complete, stirring is continued for 2 to 4 minutes to fully mix and form MPC-EA binder.

[0050] Then, manufactured sand is added and mixed at high speed to form MPC-EA mortar; finally, coarse aggregate is added and mixed at high speed for 4 minutes to prepare MPC-EA mixture, which is then spread on the road surface to form the slurry seal layer; the above mixing process is carried out in a planetary mortar mixer, using the instrument's rotation mode, with a high-speed mixing speed of 285±3 r / min and a low-speed mixing speed of 140±5 r / min.

[0051] After mixing thoroughly according to the above method, test its working time to be approximately 40 minutes. Spread it evenly on the road section to be maintained and compact it. Place warning signs and allow it to cure naturally for 2 hours before reopening to traffic.

[0052] Example 2

[0053] The specific implementation method differs from Example 1 only in the proportions of the following materials; the operating steps and material composition are basically the same. It uses a mixture of recalcined magnesium oxide, ammonium dihydrogen phosphate, and borax to prepare a cementitious material, which is then mixed with emulsified asphalt and water to obtain the MPC-emulsified asphalt composite system. The mass fractions of the magnesium phosphate cementitious material are: 20 parts recalcined magnesium oxide, 7 parts ammonium dihydrogen phosphate, 1.2 parts borax, 10 parts fly ash, 0 parts mineral powder, and 2 parts silica fume.

[0054] In the aforementioned anti-dispersant, the ratio of cellulose ether: nano-SiO2: ultrafine fly ash is 0.1:1:5.

[0055] The emulsified asphalt content is 20 parts; manufactured sand, 10 parts; SMA-13 ​​aggregate, 60 parts; and mixing water, 8 parts.

[0056] After mixing evenly according to the mixing method in Example 1, the working time is tested to be about 23 minutes. Spread evenly on the road section to be maintained and compact it. Place warning signs and allow it to cure naturally for 1.5 hours before opening to traffic.

[0057] Example 3

[0058] The specific implementation method differs from Example 1 only in the following material ratios. The operation steps and material composition are basically the same. The cementitious material is prepared by uniformly mixing calcined magnesium oxide, ammonium dihydrogen phosphate, and borax, and then mixing it with emulsified asphalt and water to obtain the MPC-emulsified asphalt composite system. The mass fraction of magnesium phosphate cementitious material is: 20 parts calcined magnesium oxide and 5 parts ammonium dihydrogen phosphate, 1.6 parts borax, 15 parts fly ash, 2 parts mineral powder, and 2 parts silica fume.

[0059] In the aforementioned anti-dispersant, the ratio of cellulose ether: nano-SiO2: ultrafine fly ash is 0.1:2:0.

[0060] The emulsified asphalt content is 25 parts; manufactured sand, 15 parts; SMA-13 ​​aggregate, 40 parts; and mixing water, 10 parts.

[0061] After mixing evenly according to the mixing method in Example 1, the working time is tested to be about 20 minutes. Spread evenly on the road section to be maintained and compact it. Place warning signs and allow it to cure naturally for 1.5 hours before opening to traffic.

[0062] Example 4

[0063] The specific implementation method differs from Example 1 only in the following material ratios. The operation steps and material composition are basically the same. The cementitious material is prepared by uniformly mixing calcined magnesium oxide, ammonium dihydrogen phosphate, and borax. Then, it is mixed with emulsified asphalt with a solid content of 60% and water to obtain the MPC-emulsified asphalt composite system. The mass fraction of the magnesium phosphate cement-based material is as follows: 15 parts calcined magnesium oxide, 5 parts ammonium dihydrogen phosphate, 2 parts borax, 20 parts fly ash, 5 parts mineral powder, and 5 parts silica fume.

[0064] In the aforementioned anti-dispersant, the ratio of cellulose ether: nano-SiO2: ultrafine fly ash is 0.15:3:10.

[0065] The emulsified asphalt content is 30 parts; manufactured sand, 15 parts; SMA-13 ​​aggregate, 45 parts; and mixing water, 10 parts.

[0066] After mixing evenly according to the mixing method in Example 1, its working time is tested to be about 50 minutes. Spread it evenly on the road section to be maintained and compact it. Place warning signs and allow it to cure naturally for 2 hours before opening it to traffic.

[0067] Example 5

[0068] The specific implementation method differs from Example 1 only in the following material ratios. The operation steps and material composition are basically the same. The method involves uniformly mixing calcined magnesium oxide, ammonium dihydrogen phosphate, and borax to prepare the following mass fraction of the cementitious magnesium phosphate cementitious material: 10 parts calcined magnesium oxide, 5 parts ammonium dihydrogen phosphate, 1 part borax, 20 parts fly ash, 7 parts mineral powder, and 5 parts silica fume.

[0069] In the aforementioned anti-dispersant, the ratio of cellulose ether: nano-SiO2: ultrafine fly ash is 0.15:2:5.

[0070] The emulsified asphalt content is 25 parts; manufactured sand, 15 parts; SMA-13 ​​aggregate, 50 parts; and mixing water, 15 parts.

[0071] After mixing evenly according to the mixing method in Example 1, the working time is tested to be about 60 minutes. Spread evenly on the road section to be maintained and compact it. Place warning signs and allow it to cure naturally for 2 hours before opening to traffic.

[0072] There are no clear and standardized testing methods for the relevant properties of the MPC-emulsified asphalt composite system. Due to the rapid hardening characteristics of the material, this invention mainly focuses on preliminary performance tests of its working time (i.e., the time when the slurry loses its fluidity), hardening time, unconfined compressive strength, flexural strength, and bond strength with the old matrix.

[0073] The specific performance parameter test values ​​for Examples 1 to 5 are shown in Table 1:

[0074] Table 1. Material performance test results

[0075]

[0076] As can be seen from the above test data, the setting time of the material of the present invention can be adjusted by adjusting the mix ratio. The setting time can be adjusted within 30 to 70 minutes. The strength of the mixture is significantly higher than that of mortar under the same ratio. The composite material can adapt to different construction requirements under different environments and roads. The maintenance conditions are simple and the impact on traffic is small, which greatly reduces economic losses and safety hazards. In addition, the fast hardening and early strength performance of MPC material makes its strength develop rapidly within 1 hour, which can provide a new option in the field of emulsified asphalt slurry seal materials.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fast-hardening, early-strength material for use in emulsified asphalt slurry seal coatings, characterized in that, Its raw materials are the following components by weight: 21-50 parts magnesium phosphate cement matrix powder, 10-25 parts emulsified asphalt, 5-15 parts mixing water, 5-20 parts manufactured sand, 40-60 parts coarse aggregate, and 0.5-1 part anti-dispersant agent. The magnesium phosphate cement matrix powder is prepared from 10-20 parts of reburned magnesium oxide, 1-4 parts of borax, 5-10 parts of ammonium dihydrogen phosphate, 0-3 parts of mineral powder, 0-3 parts of silica fume, and 5-10 parts of fly ash. The anti-dispersant comprises the following components in parts by weight: 0.05-0.15 parts cellulose ether, 1-3 parts nano-SiO2, and 0-5 parts ultrafine fly ash.

2. The fast-hardening, early-strength material for emulsified asphalt slurry seal as described in claim 1, characterized in that, The emulsified asphalt is a cationic polymer-modified emulsified asphalt with a solid content of 55%~60%, which conforms to the BCR type requirements in the "Technical Guidelines for Microsurfacing and Slurry Seal" (JTG / T F40-02-2005); The mixing water is tap water; The particle size of the manufactured sand is 40-80 mesh; The coarse aggregate is made of basalt, with an SMA-13 ​​gradation. The aggregate is screened according to JTG E42-2005 "Specifications for Testing Aggregates in Highway Engineering".

3. The fast-hardening, early-strength material for use in emulsified asphalt slurry seal as described in claim 1, characterized in that, The recalcined magnesia is obtained by calcining magnesite at high temperature, followed by crushing and grinding. It has a light yellow appearance, a purity of 90% or higher, a fineness of no more than 200 mesh, and a magnesia purity of 91%. The borax used is decahydrate borax, a crystalline white powder with a density of 1.72 g / cm³. 3 The purity is greater than 95%.

4. The fast-hardening, early-strength material for use in emulsified asphalt slurry seal as described in claim 1, characterized in that, The ammonium dihydrogen phosphate is industrial grade, a white powder / granule, with an NH4H2PO4 content of 99%. More than 80% of the mineral powder has a fineness of less than 1 μm, and the average particle size is between 0.1 and 0.3 μm.

5. The fast-hardening, early-strength material for use in emulsified asphalt slurry seal as described in claim 1, characterized in that, The average particle size of the silica fume is 0.1-0.15 μm; The fly ash has an average particle size distribution of 8–20 μm and a specific surface area of ​​300–600 m². 2 / kg.

6. The fast-hardening, early-strength material for use in emulsified asphalt slurry seal as described in claim 1, characterized in that, The coarse aggregate is added at 1.25 to 4 times the total mass of magnesium phosphate cement matrix powder. The coarse aggregate is selected as crushed stone with small particle size and small difference, referring to the crushed stone particle size requirements in the road maintenance standard.

7. The method for preparing the fast-hardening, early-strength material according to any one of claims 1-6, characterized in that, The process includes the following steps: mixing ammonium dihydrogen phosphate, borax, calcined magnesium oxide, mineral powder, silica fume, and fly ash in a certain proportion to prepare MPC dry material; mixing emulsified asphalt and mixing water at low speed, slowly adding MPC dry material and anti-dispersant agent, and mixing thoroughly to form MPC-EA binder; Then, manufactured sand is added and mixed at high speed to form MPC-EA mortar; finally, coarse aggregate is added and mixed at high speed to prepare MPC-EA mixture, which is then spread on the road surface to form the slurry seal layer.

8. The method for preparing the rapid-hardening, early-strength material as described in claim 7, characterized in that, The low-speed stirring speed is 140±5 r / min and the stirring time is 0.1~1 min; the high-speed stirring speed is 285±3 r / min and the stirring time is 3~5 min. Alternatively, the MPC dry material and anti-dispersant are added within 0.8 to 1.2 minutes, and then stirred continuously for 2 to 4 minutes to obtain MPC-EA binder.

9. The method for preparing the rapid-hardening, early-strength material as described in claim 7, characterized in that, The MPC-EA mixture is laid on the road surface and allowed to cure naturally for 1.5 to 2 hours before it can be opened to traffic. Alternatively, the paving and compaction speed of the MPC-EA mixture should be consistent with the mixing volume, and the thickness should not exceed 3cm.

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