An airport pavement salt-out modified polymer-based magnesium phosphate cement repair material and a preparation method thereof

Abstract

This invention belongs to the field of new materials technology, specifically relating to a polymer-based magnesium phosphate cement repair material for airport pavement salt precipitation modification and its preparation method. The cement repair material is prepared by mixing and stirring magnesium-based raw materials, phosphorus-based raw materials, solid waste aggregates, polymer materials, retarder, and modifier in specific mass proportions, followed by molding, salt precipitation soaking, and standard curing. This invention solves the problems of existing magnesium phosphate cement repair materials, such as high brittleness, limited long-term mechanical properties, poor high-temperature stability, and insufficient weather resistance. It combines the characteristics of rapid hardening and early strength, excellent mechanical properties, outstanding durability, and environmental friendliness. It is simple to operate and has low repair costs, meeting the requirements of rapid airport pavement repair for short downtime, high strength, and long service life. It can effectively cope with freeze-thaw cycles, wear, and salt corrosion of airport pavements under extreme weather conditions, and is of great significance for ensuring flight safety and extending the service life of pavements.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology, specifically relating to a polymer-based magnesium phosphate cement repair material modified by salt precipitation of airport pavement and its preparation method. Background Technology

[0002] Cement concrete, with its advantages of high cost-effectiveness, high strength, high stability, and long service life, has become the dominant material for airport pavement construction in my country. New, relocated, and expanded airport pavements mostly adopt this structure, and this trend is expected to continue for a long time. However, the extreme climates in most of my country's airports significantly exacerbate pavement damage, seriously threatening flight safety and shortening the service life of airports.

[0003] From a regional climatic perspective, the western and northwestern regions experience hot, dry summers and cold, dry winters, with large diurnal temperature variations and frequent wet-dry cycles. This leads to plastic cracking of concrete during construction and, during service, freeze-thaw erosion causes pavement spalling and sandblasting. In the northeast and north China, severe winters (minimum temperatures reaching -50°C) and heavy snowfall, coupled with frequent use of de-icing fluids and freeze-thaw cycles, exacerbate pavement erosion. Surveys show that most pavements develop defects such as pitting, peeling, cracking, edge chipping, and broken slabs within a short period. Concrete damage is a global challenge for airport maintenance.

[0004] Foreign object debris (FOD) caused by pavement defects can easily lead to accidents such as tire blowouts, landing gear and engine damage, directly threatening flight safety. Timely repair of pavement defects is a core requirement for safe airport operations.

[0005] Airport runway repairs have extremely high time requirements, necessitating the reduction of downtime and rapid reopening to air traffic, thus resolving the time conflict between construction and operation. However, existing repair materials have shortcomings such as insufficient early strength, susceptibility to cracking, weak interfacial adhesion, and poor durability. The repaired areas have short lifespans, require frequent rework, increase costs, and disrupt operations.

[0006] Magnesium phosphate cement repair materials, based on magnesium phosphate cement, possess advantages such as ultra-fast setting, early and high strength, volume stability, and strong interfacial adhesion, overcoming the technical bottlenecks of conventional cement-based materials. They also exhibit excellent wear resistance and freeze-thaw resistance, improving the durability of repaired structures. However, their high brittleness, large shrinkage fluctuations, and poor water resistance limit their application in airport pavements. Existing modification methods, such as admixture filling and fiber toughening, all suffer from an imbalance between reinforcement effect and economic benefits, making it difficult to simultaneously meet the dual requirements of practicality and economy.

[0007] Polymer modification balances effectiveness and cost, and has wide applications. For example, invention patents with patent numbers CN120622884B and CN118771845B improve the toughness and impact resistance of materials through polymer modification. However, the enhancement of mechanical properties by this technology is limited, and polymers are prone to softening at high temperatures, which cannot meet the requirements of the extreme temperature difference environment of airports.

[0008] Therefore, developing repair materials that combine rapid hardening and early strength, excellent mechanical properties, good weather resistance, simple construction, and controllable cost is crucial for ensuring flight safety and extending pavement life. Summary of the Invention

[0009] Based on the above technical background, the main objective of this invention is to provide a polymer-based magnesium phosphate cement repair material modified by salt precipitation of airport pavement and its preparation method, so as to overcome the shortcomings of the prior art.

[0010] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0011] The first aspect of this invention is to provide a polymer-based magnesium phosphate cement repair material modified by salting out of airport pavement, wherein the polymer-based magnesium phosphate cement repair material is obtained by modifying a cement repair mixture by soaking in a salting out solution; The cement repair mixture comprises the following raw materials in parts by weight: 40-80 parts by weight of magnesium-based raw materials; 12-30 parts by weight of phosphorus-based raw materials; 10-40 parts by weight of solid waste aggregate; 5 to 40 parts by weight of polymer material; 2-10 parts by weight of retarder; Modifier: 0.01–0.04 parts by weight; Initiator: 0.05–0.5 parts by weight; Crosslinking agent 0.05 to 0.5 parts by weight.

[0012] Preferably, the cement repair mixture comprises the following raw materials in parts by weight: 50 parts by weight of magnesium-based raw material; 12 parts by weight of phosphorus-based raw material; 20 parts by weight of solid waste aggregate; 20 parts by weight of polymer material; 5 parts by weight of retarder; Modifier 0.01 parts by weight; Initiator 0.1 parts by weight; 0.1 parts by weight of crosslinking agent.

[0013] Preferably, the cement repair mixture comprises the following raw materials in parts by weight: 65 parts by weight of magnesium-based raw material; 20 parts by weight of phosphorus-based raw material; 10 parts by weight of solid waste aggregate; 40 parts by weight of polymer material; 8 parts by weight of retarder; Modifier 0.03 parts by weight; Initiator 0.4 parts by weight; 0.4 parts by weight of crosslinking agent.

[0014] Preferably, the cement repair mixture comprises the following raw materials in parts by weight: 45 parts by weight of magnesium-based raw material; 12 parts by weight of phosphorus-based raw material; 40 parts by weight of solid waste aggregate; 20 parts by weight of polymer material; 3 parts by weight of retarder; Modifier 0.02 parts by weight; Initiator 0.3 parts by weight; 0.3 parts by weight of crosslinking agent.

[0015] The raw materials of the cement repair mixture also include 6 to 11 parts by weight of water.

[0016] Preferably, the amount of water added is 7 parts by weight, 10 parts by weight, or 6 parts by weight.

[0017] The magnesium-based raw material is selected from one or more of calcined magnesium oxide and magnesium slag.

[0018] Preferably, the magnesium-based raw material is calcined magnesium oxide.

[0019] The phosphorus-based raw material is selected from one or both of potassium dihydrogen phosphate or ammonium dihydrogen phosphate.

[0020] Preferably, the phosphorus-based raw material is potassium dihydrogen phosphate.

[0021] The solid waste aggregate is selected from one or more of fly ash, slag and metakaolin.

[0022] Preferably, the solid waste aggregate is a composite of fly ash and slag, or a composite of fly ash and metakaolin.

[0023] More preferably, the solid waste aggregate is a composite material obtained by mixing fly ash and slag in a mass ratio of 1:1, or the solid waste aggregate is a composite material obtained by mixing fly ash and metakaolin in a mass ratio of 1:1.

[0024] The polymer material is selected from one or more of polyacrylamide, polyacrylic acid, and polyvinyl alcohol.

[0025] Preferably, the polymer material is a composite obtained by mixing polyacrylamide and polyacrylic acid in a mass ratio of 1:1.

[0026] The retarder is selected from one or two of borax and boric acid.

[0027] Preferably, the retarder is borax.

[0028] The modifier is selected from one or more of ethylene glycol and active silane coupling agents.

[0029] Preferably, the modifier is a mixed modifier obtained by mixing ethylene glycol and an active silane coupling agent.

[0030] More preferably, the modifier is a mixed modifier obtained by mixing ethylene glycol and an active silane coupling agent in a mass ratio of (1-2):1.

[0031] For example, the modifier is a mixed modifier obtained by mixing ethylene glycol and an active silane coupling agent in a mass ratio of 1:1.

[0032] The initiator is selected from one or both of ammonium persulfate and potassium persulfate.

[0033] Preferably, the initiator is potassium persulfate.

[0034] The crosslinking agent is selected from one or both of N,N′-methylenebisacrylamide and methacrylate.

[0035] Preferably, the crosslinking agent is methacrylate.

[0036] The concentration of the salting-out solution is 1–3 M, preferably 2 M.

[0037] The salting-out solution is selected from one or both of sodium citrate solution and potassium citrate solution.

[0038] Preferably, the salting-out solution is sodium citrate.

[0039] This invention prepares cement repair materials by adding a salting-out solution and modifying them through salting-out. It has the advantages of simple operation, economy and efficiency, and is expected to break through the performance bottleneck of polymer-based magnesium phosphate cement.

[0040] The mechanism of salting-out modification by adding salting-out solution in this invention is as follows: During salting out, salt ions penetrate into the magnesium phosphate cement matrix, competing with polymer chains for water molecules. This forces the originally spread-out polymer segments, separated by the hydration layer, to move closer together. This significantly enhances secondary forces such as hydrophobic interactions, hydrogen bonds, and van der Waals forces between the segments, forming numerous dynamic "physical cross-linking points." Consequently, the three-dimensional polymer network becomes denser and more robust, macroscopically manifesting as a simultaneous increase in the modulus, strength, and toughness (tear resistance) of the cement repair material. Thanks to the enhanced polymer network performance, the performance of magnesium phosphate cement-based materials is further improved.

[0041] A second aspect of the present invention is to provide a method for preparing the polymer-based magnesium phosphate cement repair material described in the first aspect of the present invention, the preparation method comprising the following steps: The cement repair mixture is poured into a mold, demolded after molding, and then soaked in a salting-out solution for modification, followed by curing to obtain a polymer-based magnesium phosphate cement repair material. The preparation method of the cement repair mixture includes the following steps: Magnesium-based raw materials are mixed with solid waste aggregates, followed by the addition of polymer materials and stirring until homogeneous. Then, initiators and crosslinking agents are added and mixing continues. Finally, phosphorus-based raw materials, retarder, modifiers, and water are added and mixed until homogeneous to obtain a cement repair mixture.

[0042] The steps described above are described in detail below.

[0043] The molding conditions are: molding at 35-45℃ for 5-7 hours.

[0044] Preferably, the molding conditions are: molding at 40°C for 6 hours.

[0045] After demolding, the sample is modified by soaking in the salting-out solution at room temperature for 5-7 hours, preferably 6 hours.

[0046] The amount of salting-out solution added is 20 to 60 parts by weight, based on 40 to 80 parts by weight of magnesium-based raw material.

[0047] Preferably, the amount of salting-out solution added is 50 parts by weight or 30 parts by weight, based on 40 to 80 parts by weight of magnesium-based raw material.

[0048] The curing conditions are as follows: curing in a curing box with a temperature of 17-22℃ and a relative humidity of 90±5% for 1-7 days.

[0049] Preferably, the curing conditions are: curing in a curing box with a temperature of 20±1℃ and a relative humidity of 90±5% for 1 to 7 days.

[0050] The magnesium-based raw materials and solid waste aggregates are stirred at a stirring speed of 55-65 r / min for 1-3 min.

[0051] Preferably, the magnesium-based raw material and solid waste aggregate are stirred at a stirring speed of 60 r / min for 2 min.

[0052] Add the polymer material and stir for 1 to 3 minutes at a stirring speed of 55 to 65 r / min.

[0053] Preferably, the polymer material is added and stirred for 2 minutes at a stirring speed of 60 r / min.

[0054] Add the initiator and crosslinking agent, and stir for 1 to 3 minutes at a stirring speed of 55 to 65 r / min.

[0055] Preferably, an initiator and a crosslinking agent are added, and the mixture is stirred for 2 minutes at a stirring speed of 60 r / min.

[0056] Add phosphorus-based raw materials, retarder, modifier and water, stir at a stirring speed of 55-65 r / min for 1-3 min, and then mix evenly at a stirring speed of 120-140 r / min.

[0057] Preferably, phosphorus-based raw materials, retarder, modifier and water are added, and the mixture is stirred at a stirring speed of 60 r / min for 2 min, and then mixed evenly at a stirring speed of 130 r / min.

[0058] The temperature of the water is 0 to 4°C; preferably, the temperature of the water is 4°C.

[0059] The beneficial effects of this invention are as follows: (1) This invention employs salting-out modification treatment. Salt ions in the salting-out solution penetrate into the magnesium phosphate cement matrix and compete with the polymer chains for water molecules, which can strengthen the secondary forces between chain segments to form a physical cross-linking network, effectively improving the modulus, mechanical strength, and toughness of the cement repair material. Mechanical performance tests show that the compressive strength of this material can reach 58.0 MPa or above at 1 day, and 65.2 MPa or above at 7 days. The interfacial bonding strength at 7 days is greater than 8.5 MPa, far exceeding that of similar materials without salting-out treatment. At the same time, it can still maintain high mechanical properties at a high temperature of 60℃. Its mechanical strength at high temperature is only slightly lower than that at room temperature, solving the shortcoming of traditional polymer modified materials that are easy to soften at high temperatures. It can achieve synergistic optimization of toughness and mechanical properties at high temperatures, and can effectively resist the damage caused by extreme temperature differences and frequent loading of airport pavement.

[0060] (2) The cement repair material described in this invention has excellent antifreeze, anti-salt corrosion and wear resistance properties. The antifreeze grade can reach F350-F400. Its salt-freeze peeling and wear are low. The cement repair material can withstand the long cold, hot and humid conditions and de-icing liquid erosion in Northeast and Northwest China. It can significantly extend the service life of airport pavement after repair, reduce the frequency of repeated repairs and reduce airport operation and maintenance costs.

[0061] (3) The cement repair material of the present invention incorporates solid waste aggregates such as fly ash, slag, and metakaolin as raw materials, which can significantly increase the amount of solid waste disposal, realize the high added value utilization of solid waste, reduce the environmental pressure caused by solid waste stockpiling, and meet the needs of building a low-carbon economy and a resource-saving and environmentally friendly society. At the same time, the preparation process does not require complex equipment, is simple to operate and convenient, and the salt precipitation modification method is economical and efficient. Compared with traditional reinforcement methods, the cement repair material of the present invention reduces the cost of raw materials and production energy consumption while ensuring the reinforcement effect, thus achieving both environmental and economic benefits.

[0062] (4) This invention relies on the rapid hardening and early strength characteristics of magnesium phosphate cement, combined with the salt precipitation modification and strengthening properties, so that the cement repair material can reach high strength in a short time, meeting the core requirement of "less downtime and faster reopening" of airport pavements, and can effectively resolve the time conflict between pavement maintenance and construction and flight support. At the same time, the cement repair material has strong interfacial adhesion, which can effectively repair pavement defects such as pitting, peeling, cracking, and edge chipping, which can reduce aircraft safety accidents caused by foreign object damage and provide a solid guarantee for flight safety.

[0063] (5) This invention creatively modifies polymer-based magnesium phosphate cement through the salting-out effect, overcoming the contradiction between the strengthening effect and economic benefits of traditional admixture modification and fiber reinforcement strategies, and also making up for the limited mechanical improvement of simple polymer modification. This cement repair material is not only suitable for airport pavement repair, but can also be extended to infrastructure fields such as highways, bridges, and military engineering that require rapid repair, high strength, and high durability. It has a wide range of applications and huge market potential. Detailed Implementation

[0064] The present invention will now be described in detail, and its features and advantages will become clearer and more apparent from these descriptions.

[0065] Example The present invention is further illustrated below with specific examples. These embodiments are merely illustrative and not intended to limit the scope of the invention. All raw materials used in the following embodiments of the present invention were commercially available.

[0066] Example 1 Weigh each ingredient according to the following proportions by weight: The composition includes 50 parts by weight of calcined magnesium oxide (a magnesium-based raw material), 12 parts by weight of potassium dihydrogen phosphate (a phosphorus-based raw material), 20 parts by weight of solid waste aggregate, 20 parts by weight of polymer material, 5 parts by weight of borax (a retarder), 0.01 parts by weight of modifier, 7 parts by weight of ice water at 4°C, 50 parts by weight of salting-out solution, 0.1 parts by weight of initiator, and 0.1 parts by weight of crosslinking agent. The concentration of the salting-out solution is 2 M.

[0067] The solid waste aggregate is a composite of fly ash and slag, wherein the mass ratio of fly ash to slag is 1:2.

[0068] The polymer material is a composite of polyacrylamide and polyacrylic acid, wherein the mass ratio of polyacrylamide to polyacrylic acid is 1:1.

[0069] The modifier is a mixture of ethylene glycol and an active silane coupling agent, wherein the mass ratio of ethylene glycol to hydroxyl-type active silane coupling agent KH550 (γ-aminopropyltriethoxysilane) is 1:1.

[0070] The salting-out solution is a sodium citrate solution.

[0071] The initiator is potassium persulfate.

[0072] The crosslinking agent is methacrylate.

[0073] The preparation method of the polymer-based magnesium phosphate cement repair material includes the following steps: Step 1: Mix magnesium-based raw materials and solid waste aggregates in a specified ratio, pour into a mixing pot, and stir at 60 r / min for 2 min. Pour the polymer material into the mixing pot, stir at 60 r / min for 2 min, add the initiator and crosslinking agent, and continue stirring at 60 r / min for 2 min. Then, pour the phosphorus-based raw materials, retarder, modifier, and water into the mixing pot, stir at 60 r / min for 2 min, and then switch to 130 r / min to stir until uniformly mixed to obtain the cement repair mixture. Step 2: Pour the cement repair mixture into a molding mold and mold it for 6 hours. Then demold the test block. Immerse the demolded test block in the salting-out solution at room temperature for 6 hours. Place the test block after soaking in the salting-out solution in a curing chamber at a temperature of 20±1℃ and a relative humidity of 90±5% for 1 day and 7 days.

[0074] Example 2 Weigh each ingredient according to the following proportions by weight: The composition includes 65 parts by weight of magnesium-based raw material, 20 parts by weight of phosphorus-based raw material ammonium dihydrogen phosphate, 10 parts by weight of solid waste aggregate, 40 parts by weight of polymer material, 8 parts by weight of retarder, 0.03 parts by weight of modifier, 10 parts by weight of ice water at 4°C, 50 parts by weight of salting-out solution, 0.4 parts by weight of initiator, and 0.4 parts by weight of crosslinking agent. The concentration of the salting-out solution is 3 M.

[0075] The magnesium-based raw material is calcined magnesium oxide.

[0076] The solid waste aggregate is a composite of fly ash and metakaolin, with a mass ratio of fly ash to metakaolin of 1:1.

[0077] The polymer material is a composite of polyacrylamide and polyvinyl alcohol, wherein the mass ratio of polyacrylamide to polyvinyl alcohol is 2:1.

[0078] The retarder is borax.

[0079] The modifier is a mixture of ethylene glycol and an active silane coupling agent, wherein the mass ratio of ethylene glycol to hydroxyl-type active silane coupling agent KH550 is 2:1.

[0080] The salting-out solution is a sodium citrate solution.

[0081] The preparation method of the polymer-based magnesium phosphate cement repair material includes the following steps: Step 1: Mix magnesium-based raw materials and solid waste aggregates in a specified ratio, pour into a mixing pot, and stir at 55 r / min for 3 min. Pour polymer materials into the mixing pot and stir at 55 r / min for 3 min. Add initiator and crosslinking agent, and continue stirring at 55 r / min for 3 min. The initiator is ammonium persulfate, and the crosslinking agent is N,N′-methylenebisacrylamide. Then, pour phosphorus-based raw materials, retarder, modifier, and water into the mixing pot and stir at 55 r / min for 3 min. Then switch to 120 r / min and stir until uniformly mixed to obtain the cement repair mixture. Step 2: Pour the cement repair mixture into a molding mold and mold it for 5 hours. Then demold the test block. Immerse the demolded test block in the salting-out solution at room temperature for 5 hours. Place the test block after soaking in the salting-out solution in a curing chamber at a temperature of 20±1℃ and a relative humidity of 90±5% for 1 day and 7 days.

[0082] Example 3 Weigh each ingredient according to the following proportions by weight: The mixture comprises 45 parts by weight of magnesium-based raw material, 12 parts by weight of potassium dihydrogen phosphate (phosphorus-based raw material), 40 parts by weight of solid waste aggregate, 20 parts by weight of polymer material, 3 parts by weight of retarder, 0.02 parts by weight of modifier, 6 parts by weight of ice water at 4°C, 30 parts by weight of salting-out solution, 0.4 parts by weight of initiator, and 0.4 parts by weight of crosslinking agent. The concentration of the salting-out solution is 1 M.

[0083] The magnesium-based raw material is magnesium slag.

[0084] The solid waste aggregate is a composite of fly ash and slag, wherein the mass ratio of fly ash to slag is 3:1.

[0085] The polymer material is a composite of polyacrylamide and polyacrylic acid, wherein the mass ratio of polyacrylamide to polyacrylic acid is 1:1.

[0086] The retarder is boric acid.

[0087] The modifier is a mixture of ethylene glycol and an active silane coupling agent, wherein the mass ratio of ethylene glycol to hydroxyl-type active silane coupling agent KH550 is 1:1.

[0088] The salting-out solution is a sodium citrate solution.

[0089] The preparation method of the polymer-based magnesium phosphate cement repair material includes the following steps: Step 1: Mix magnesium-based raw materials and solid waste aggregates in a specified ratio, pour into a mixing pot, and stir at 65 r / min for 1 min. Pour polymer materials into the mixing pot, stir at 65 r / min for 1 min, and add initiator and crosslinking agent, continuing to stir at 65 r / min for 1 min. The initiator is potassium persulfate, and the crosslinking agent is N,N′-methylenebisacrylamide. Then, pour phosphorus-based raw materials, retarder, modifier, and water into the mixing pot, stir at 65 r / min for 1 min, and then switch to 140 r / min to stir until uniformly mixed, obtaining a cement repair mixture. Step 2: Pour the cement repair mixture into a molding mold and mold it for 7 hours. Then demold the test block. Immerse the demolded test block in the salting-out solution at room temperature for 7 hours. Place the test block after soaking in the salting-out solution in a curing chamber at a temperature of 20±1℃ and a relative humidity of 90±5% for 1 day and 7 days.

[0090] Example 4 The polymer-based magnesium phosphate cement remediation material was prepared in a manner similar to that in Example 1, except that the solid waste aggregate was fly ash.

[0091] Example 5 The polymer-based magnesium phosphate cement repair material was prepared in a manner similar to that in Example 1, except that the polymer material was polyacrylamide.

[0092] Example 6 The polymer-based magnesium phosphate cement repair material was prepared in a manner similar to that in Example 1, except that the modifier was ethylene glycol.

[0093] Comparative Example Comparative Example 1 The polymer-based magnesium phosphate cement repair material was prepared in a manner similar to that in Example 1, except that salting out was not performed.

[0094] Comparative Example 2 The polymer-based magnesium phosphate cement repair material was prepared in a manner similar to that in Example 1, except that ice water was replaced with room temperature water.

[0095] Comparative Example 3 The polymer-based magnesium phosphate cement repair material was prepared in a manner similar to that in Example 2, except that the demolded sample blocks were not immersed in the salting-out solution; instead, the salting-out solution was sprayed onto the surface of the blocks at a rate of 300 g / m². 2 The concentration of the salting-out solution is 1M.

[0096] Comparative Example 4 The polymer-based magnesium phosphate cement repair material was prepared in a manner similar to that in Example 3, except that the concentration of the salting-out solution was 6M.

[0097] Experimental Example Experiment Example 1: Mechanical and Durability Tests After the polymer-based magnesium phosphate cement prepared in each embodiment was cured to the specified age, it was taken out for mechanical property testing. The compressive strength and flexural strength of the cement-based materials were tested according to GB / T 17671-1999 "Test Method for Strength of Cement Mortar", and the samples were made of neat cement paste; the 7-day interfacial bond strength (flexural strength) was tested according to "Technical Specification for Maintenance of Cement Concrete Pavement of Civil Airport", and the frost resistance grade and abrasion amount were tested according to JTG 3420-2020 "Test Procedures for Cement and Cement Concrete in Highway Engineering"; the salt-frost spalling amount was tested according to MH / T 5006 "Technical Specification for Construction of Cement Concrete Surface Layer of Civil Airport". The mechanical property test results are shown in Table 1, and the durability test results are shown in Table 2.

[0098] Table 1 Mechanical properties of polymer-based magnesium phosphate cement repair materials

[0099] Table 2 Durability of Polymer-Based Magnesium Phosphate Cement Repair Materials

[0100] Tables 1 and 2 show the mechanical and durability data of a polymer-based magnesium phosphate cement repair material modified by salting-out treatment for airport pavement. Tables 1 and 2 show that Example 1 and Comparative Example 1 analyzed the effect of salting-out modification on the polymer-based magnesium phosphate cement repair material. Example 1 showed significant improvements in compressive strength, flexural strength, 7-day interfacial bond strength (flexural), frost resistance, salt-frost spalling, and abrasion after 1 day and 7 days of salting-out treatment. Example 1 and Comparative Example 2 analyzed the importance of the ice-water mixture for salting-out modification. The results indicate that the mechanical strength and durability of the sample without the ice-water mixture decreased significantly. This is mainly because the hydration of magnesium phosphate cement itself releases a large amount of heat, inducing polymerization. Excessive hydration leads to rapid polymerization and agglomeration of the polymer system, resulting in decreased mechanical and durability properties. Example 2 and Comparative Example 3 compared the effects of spraying and soaking methods on the performance of the repair material. The mechanical and durability properties of the repair material after spraying were significantly lower than those after salting-out soaking. The comparison results show that the reinforcing effect of spraying is far less than that of soaking treatment. Example 3 and Comparative Example 4 were compared and analyzed to investigate the effect of salting-out solution concentration on mechanical properties and durability. The results showed that when the salting-out solution concentration was increased to 6M, it would actually damage the strength and durability of the repair material. This is because excessively high concentrations would cause the polymer system to precipitate excessively, failing to achieve the encapsulation effect, thereby destroying the uniformity of the polymer network and affecting its strength and durability.

[0101] Examples 1 and 4 compared and analyzed the impact of solid waste aggregate on the performance of repair materials. In Example 4, the solid waste aggregate was replaced by a composite of fly ash and slag with fly ash. The comparison results showed that when the solid waste aggregate was a composite of fly ash and metakaolin, the strength and durability of the repair material were much higher than those of using fly ash alone. This indicates that using a composite of fly ash and metakaolin as the solid waste aggregate is more conducive to improving the strength and durability of the repair material.

[0102] Examples 1 and 5 compared and analyzed the effect of polymer materials on the performance of repair materials. In Example 5, the polymer material was replaced by a composite of polyacrylamide and polyacrylic acid with polyacrylamide. The comparison results showed that when the polymer material was a composite of polyacrylamide and polyacrylic acid, the mechanical strength and durability of the repair material were much higher than those of using polyacrylamide alone. This indicates that using a composite of polyacrylamide and polyacrylic acid as the polymer material is more beneficial to improving the mechanical strength and durability of the repair material.

[0103] Examples 1 and 6 compared and analyzed the effect of the modifier on the performance of the repair material. In Example 6, the modifier was replaced by ethylene glycol instead of a mixture of ethylene glycol and active silane coupling agent. The comparison results showed that when the modifier was a mixture of ethylene glycol and active silane coupling agent, the mechanical strength and durability of the repair material were much higher than those of using ethylene glycol alone. This indicates that using ethylene glycol and active silane coupling agent as the modifier is more beneficial to improving the mechanical strength and durability of the repair material.

[0104] Experimental Example 2: High-Temperature Mechanical Property Testing The mechanical properties of the different polymer-based magnesium phosphate cement repair materials prepared in Example 1 and Comparative Example 1 were tested at 60°C, and the test results are shown in Table 3.

[0105] Table 3 Mechanical properties of polymer-based magnesium phosphate cement repair materials at 60℃

[0106] As shown in Table 3, the mechanical strength of Example 1 after salting-out treatment decreased only slightly, while the mechanical strength of Comparative Example 1 decreased significantly. This indicates that salting-out treatment can effectively enhance the performance of polymer-based magnesium phosphate cement repair materials at high temperatures.

[0107] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A polymer-based magnesium phosphate cement repair material modified by salt precipitation of airport pavement, characterized in that, The polymer-based magnesium phosphate cement repair material is obtained by modifying a cement repair mixture through soaking in a salting-out solution; The cement repair mixture comprises the following raw materials in parts by weight: 40-80 parts by weight of magnesium-based raw materials; 12-30 parts by weight of phosphorus-based raw materials; 10-40 parts by weight of solid waste aggregate; 5 to 40 parts by weight of polymer material; 2-10 parts by weight of retarder; Modifier: 0.01–0.04 parts by weight; Initiator: 0.05–0.5 parts by weight; Crosslinking agent 0.05 to 0.5 parts by weight.

2. The polymer-based magnesium phosphate cement repair material according to claim 1, characterized in that, The cement repair mixture comprises the following raw materials in parts by weight: 50 parts by weight of magnesium-based raw material; 12 parts by weight of phosphorus-based raw material; 20 parts by weight of solid waste aggregate; 20 parts by weight of polymer material; 5 parts by weight of retarder; Modifier 0.01 parts by weight; Initiator 0.1 parts by weight; 0.1 parts by weight of crosslinking agent.

3. The polymer-based magnesium phosphate cement repair material according to claim 1, characterized in that, The cement repair mixture comprises the following raw materials in parts by weight: 65 parts by weight of magnesium-based raw material; 20 parts by weight of phosphorus-based raw material; 10 parts by weight of solid waste aggregate; 40 parts by weight of polymer material; 8 parts by weight of retarder; Modifier 0.03 parts by weight; Initiator 0.4 parts by weight; 0.4 parts by weight of crosslinking agent.

4. The polymer-based magnesium phosphate cement repair material according to claim 1, characterized in that, The cement repair mixture comprises the following raw materials in parts by weight: 45 parts by weight of magnesium-based raw material; 12 parts by weight of phosphorus-based raw material; 40 parts by weight of solid waste aggregate; 20 parts by weight of polymer material; 3 parts by weight of retarder; Modifier 0.02 parts by weight; Initiator 0.3 parts by weight; 0.3 parts by weight of crosslinking agent.

5. The polymer-based magnesium phosphate cement repair material according to claim 1, characterized in that, The raw materials of the cement repair mixture also include 6 to 11 parts by weight of water; and / or, The magnesium-based raw material is selected from one or two of calcined magnesium oxide and magnesium slag; and / or, The phosphorus-based raw material is selected from one or both of potassium dihydrogen phosphate or ammonium dihydrogen phosphate; and / or, The solid waste aggregate is selected from one or more of fly ash, slag, and metakaolin; and / or, The polymer material is selected from one or more of polyacrylamide, polyacrylic acid, and polyvinyl alcohol; and / or, The retarder is selected from one or two of borax and boric acid; and / or, The modifier is selected from one or two of ethylene glycol and active silane coupling agents; and / or, The initiator is selected from one or both of ammonium persulfate and potassium persulfate; and / or, The crosslinking agent is selected from one or both of N,N′-methylenebisacrylamide and methacrylate; and / or, The salting-out solution is selected from one or both of sodium citrate solution and potassium citrate solution.

6. A method for preparing the polymer-based magnesium phosphate cement repair material according to any one of claims 1 to 5, characterized in that, The preparation method includes the following steps: The cement repair mixture is poured into a mold, demolded after molding, and then soaked in a salting-out solution for modification, followed by curing to obtain a polymer-based magnesium phosphate cement repair material. The preparation method of the cement repair mixture includes the following steps: Magnesium-based raw materials are mixed with solid waste aggregates, followed by the addition of polymer materials and stirring until homogeneous. Then, initiators and crosslinking agents are added and mixing continues. Finally, phosphorus-based raw materials, retarder, modifiers, and water are added and mixed until homogeneous to obtain a cement repair mixture.

7. The preparation method according to claim 6, characterized in that, The molding conditions are: molding at 35-45℃ for 5-7 hours; After demolding, the sample is soaked in a salting-out solution for 5–7 h for modification. The concentration of the salting-out solution is 1–3 M.

8. The preparation method according to claim 6, characterized in that, The curing conditions are as follows: curing in a curing box with a temperature of 17-22℃ and a relative humidity of 90±5% for 1-7 days.

9. The preparation method according to claim 6, characterized in that, The magnesium-based raw materials and solid waste aggregates are stirred at a stirring speed of 55-65 r / min for 1-3 min. Then, the polymer material is added and stirred at a stirring speed of 55-65 r / min for 1-3 min. Finally, the initiator and crosslinking agent are added and stirred at a stirring speed of 55-65 r / min for 1-3 min.

10. The preparation method according to claim 6, characterized in that, Add phosphorus-based raw materials, retarder, modifier and water, stir at a stirring speed of 55-65 r / min for 1-3 min, and then mix evenly at a stirring speed of 120-140 r / min.

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