A composite material for road repair and a method for preparing the same

Abstract

The application discloses a composite material for road surface repair and a preparation method thereof. The composite material is prepared by mixing dry powder components and liquid components. The dry powder components include sulphoaluminate cement clinker, ordinary Portland cement, anhydrous calcium sulfate, zinc sulfate heptahydrate and sodium tetraborate decahydrate; and the liquid components include water, polyvinyl alcohol, sodium gluconate, gamma-glycidoxypropyltrimethoxysilane and glacial acetic acid. In the initial stage of mixing and adding water, the system generates a calcium-zinc salt film layer and a heat-responsive borate ester gel network wrapping the sodium gluconate, so as to block the initial hydration and maintain the construction fluidity; with the internal hydration heat release and temperature rise, the gel network depolymerizes and releases the gluconate, so as to promote the film layer to dissolve and further initiate the rapid secondary hydration to establish the early mechanical strength. Meanwhile, the silane molecules are hydrolyzed and crosslinked under the strong alkaline excitation of the old road surface, so as to improve the bonding performance of the new and old interfaces. The application effectively solves the contradiction between the construction time and the early strength of the repair material.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a composite material for road repair and its preparation method. Background Technology

[0002] With the continuous increase in highway traffic loads and the long-term effects of environmental factors, concrete pavements inevitably suffer from localized damage such as surface peeling, potholes, and broken slabs. In order to minimize the impact of road closures for maintenance on traffic operations, engineering practices generally require that pavement repair materials cure as quickly as possible after pouring, so as to reach the early load-bearing strength required to open traffic within a few hours.

[0003] Currently, commonly used rapid repair materials in engineering projects are mostly based on sulfoaluminate cement or special rapid-hardening cement. These inorganic cementitious materials undergo a very vigorous hydration reaction upon contact with water, resulting in rapid curing and high early strength. However, in actual on-site construction, this extremely rapid hydration characteristic leads to an excessively short setting time. After the slurry is mixed, the time window left for on-site construction workers to spread, vibrate, and smooth the surface is often less than ten minutes. If there is any slight delay in on-site work or the temperature is too high, the slurry will quickly lose its fluidity and dry out and harden, making it impossible to compact and form a solid shape, directly affecting the construction quality of the repair project. To extend the workable time, the conventional approach is to add a large dose of retarder to the system. However, the inhibitory effect of retarder on the hydration process is usually global. While delaying the slurry setting time, it also severely hinders the formation of early hydration products, resulting in slow development of the material's early mechanical strength. This contradicts the original intention of rapid repair projects and makes it difficult to achieve an effective balance between construction operation time and early strength.

[0004] Furthermore, localized road repairs inevitably involve the bonding of newly poured repair materials with the existing old concrete substrate. Existing inorganic repair materials, after hardening, rely primarily on macroscopic physical friction from the rough surface and mechanical interlocking between microscopic pores to bond with the old pavement. This physical interface bonding is relatively limited, lacking microscopic chemical bonding. After the road is put into use, the repeated impacts and shearing from heavy vehicles, as well as the thermal expansion and contraction stress caused by seasonal changes, easily lead to stress concentration and microcracks at the interface between the new and old pavements. This can result in the overall peeling and detachment of the repair layer, making it difficult to maintain the long-term repair effect. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a composite material for road repair and its preparation method, which solves the contradiction between the early workability time of repair materials and the rapid curing to obtain early mechanical strength in road repair projects. At the same time, conventional repair materials have insufficient interfacial bonding performance with the old road substrate and are susceptible to peeling failure due to environmental stress.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a composite material for road repair, comprising a dry powder component and a liquid component; the dry powder component comprises the following raw materials in parts by weight: 60-70 parts of sulfoaluminate cement clinker, 20-30 parts of ordinary silicate cement, 5-10 parts of anhydrous calcium sulfate, 1.5-2.5 parts of zinc sulfate heptahydrate, and 0.5-1.0 parts of sodium tetraborate decahydrate; the liquid component comprises the following raw materials in parts by weight: 40-50 parts of deionized water, 2-4 parts of polyvinyl alcohol, 0.5-1.0 parts of sodium gluconate, 1-2 parts of γ-glycidoxypropyltrimethoxysilane, and glacial acetic acid in an amount such that the pH of the liquid component system is 4.5-5.0.

[0007] By adopting the above technical solution, and through the combination of inorganic and organic materials, a unified engineering effect of extending construction time and accelerating hydration and curing is achieved, while simultaneously improving the chemical anchoring strength of the interface between new and old concrete. Its reaction mechanism and innovative principle specifically include the following processes:

[0008] After the composite material is mixed with water, a series of synergistic reactions occur between the inorganic and organic components. Specifically, in the initial stage of water addition, sulfoaluminate cement clinker and ordinary silicate cement begin to undergo trace hydration, at which point calcium ions and hydroxide ions are released into the liquid phase of the system. The subsequently dissolved zinc sulfate heptahydrate provides zinc ions, which co-precipitate on the surface of the incompletely hydrated cement clinker, forming a calcium zincate film, which to some extent hinders the further penetration of water into the interior.

[0009] During the film formation process, sodium tetraborate decahydrate in the dry powder dissociates into tetrahydroxyborate ions, which can crosslink with the hydroxyl groups on the polyvinyl alcohol molecular chains in the liquid component. This crosslinking constructs a three-dimensional network of borate ester gel with thermally responsive characteristics. Sodium gluconate in the liquid component, being within this network space, is temporarily physically bound and cannot freely diffuse to the surface of the clinker particles. It is precisely based on the combined effect of the calcium zincate film layer and the borate ester gel network that the initial hydration kinetics of the material are suppressed, allowing the slurry to maintain high fluidity for a set time, thereby meeting the construction requirements for on-site paving and vibration compaction.

[0010] The recovery and hardening of the slurry primarily depends on the accumulation of slow, exothermic hydration within the system. The cross-linking bonds of the borate ester gel network are highly sensitive to temperature changes. Once the accumulated heat causes the local temperature to reach its depolymerization threshold, the gel structure begins to disintegrate, releasing the previously bound gluconate ions into the liquid phase. Due to their complexing properties, gluconate ions actively compete with calcium ions in the calcium zincate film for complexation, causing the film coating the cement particles to dissolve. Without this barrier, the clinker particles come into direct contact with water, rapidly accelerating the hydration reaction and producing products such as ettringite and hydrated calcium silicate gel. At this point, the slurry quickly loses its fluidity and establishes an early mechanical structure.

[0011] To improve the bonding mechanism between the old and new interfaces, this solution introduces glacial acetic acid into the liquid phase to maintain a slightly acidic environment. This is primarily to reduce the spontaneous hydrolysis and condensation activity of silane molecules (γ-glycidoxypropyltrimethoxysilane), thus maintaining the stability of the material during storage. When the slurry is poured onto the old substrate, some of the monomeric silane molecules seep into the capillaries of the old substrate along with the water. The strong alkaline environment of the old concrete itself, combined with the temperature rise caused by the secondary hydration of the material, jointly stimulates the hydrolysis of the silane. The generated silanol groups can undergo dehydration condensation with the hydrates and aggregates on the surface of the old substrate to form siloxane-silicon bonds, while the epoxy groups at the other end of the silane molecules participate in the cross-linking within the repair material. Through this cross-interface chemical cross-linking network, the shear bond strength of the repair interface is improved.

[0012] Preferably, the preferred proportions of the raw materials are as follows: Dry powder components: 65 parts sulfoaluminate cement clinker, 25 parts ordinary silicate cement, 8 parts anhydrous calcium sulfate, 2 parts zinc sulfate heptahydrate, and 0.8 parts sodium tetraborate decahydrate; Liquid components: 45 parts deionized water, 3 parts polyvinyl alcohol, 0.8 parts sodium gluconate, and 1.5 parts γ-glycidoxypropyltrimethoxysilane. By adopting the above technical solution, the ratio between the film-forming ion concentration and the gel network structure is better balanced, the thermodynamic unlocking temperature of the hydration process of the system remains stable, and the interference of sudden changes in external environmental temperature on the material depolymerization time is reduced.

[0013] Preferably, the raw material has the following parameters: the specific surface area of ​​the sulfoaluminate cement clinker is controlled at 350-450 m². 2 / kg; the ordinary Portland cement has a strength grade of P·O42.5 and a specific surface area of ​​330-380m². 2 / kg; the degree of alcoholysis of the polyvinyl alcohol is 87%-89%, and the average degree of polymerization is 1700-2000.

[0014] By adopting the above technical solution, the particle size distribution of inorganic clinker can be limited to match the temperature rise rate of hydration exothermic reaction; and by selecting polyvinyl alcohol with a specific degree of alcoholysis and polymerization, the number of reaction sites is controlled, so that the generated borate ester gel network has the corresponding structural disintegration sensitivity when heated.

[0015] Preferably, the anhydrous calcium sulfate particles have a fineness such that the residue on a 200-mesh standard sieve is less than 1.0%; and the sodium tetraborate decahydrate powder has a particle size of no more than 150 μm.

[0016] By adopting the above technical solution, local uneven concentration caused by individual large powder particles is avoided, ensuring that the solid additive can be quickly dissolved and play its role when mixed with water on site.

[0017] Preferably, the liquid-solid mass ratio of the dry powder component to the liquid component when mixed on-site is 0.28-0.32.

[0018] By adopting the above technical solution, a reasonable internal water-cement ratio is maintained, which provides sufficient water to generate stable crystalline minerals while avoiding excessive free water forming ineffective capillary pores inside the hardened body.

[0019] A method for preparing a composite material for road repair includes the following steps:

[0020] S1. Preparation of dry powder components: Fully dried sulfoaluminate cement clinker, ordinary silicate cement, anhydrous calcium sulfate, zinc sulfate heptahydrate and sodium tetraborate decahydrate are added into a dry powder mixer according to the proportion and mixed. The dry powder components are then discharged.

[0021] S2. Preparation of liquid component: Deionized water is injected into a reaction vessel equipped with a heating and stirring device and the temperature is raised. Polyvinyl alcohol is added and stirred continuously until a transparent homogeneous solution is formed. After the solution is cooled, sodium gluconate is added and stirred until dissolved. Then, glacial acetic acid is added dropwise to adjust the pH value of the system. Finally, γ-glycidoxypropyltrimethoxysilane is added dropwise and stirred continuously. The liquid component is then discharged.

[0022] S3. On-site compounding process: The dry powder component prepared in step S1 and the liquid component prepared in step S2 are put into a forced mixer according to the set liquid-solid mass ratio for mixing. The resulting slurry after mixing is the composite material used for road repair.

[0023] By adopting the above technical solution, the process of preparing and storing the dry powder component and the liquid component separately isolates the inorganic active hydrated substance from the physical contact between the liquid phase and the liquid phase during storage. In preparing the liquid component, a specific order of addition is set: first, heating promotes the dissolution of polyvinyl alcohol, followed by cooling to reduce the thermal motion of the system molecules, and then adding sodium gluconate and glacial acetic acid. After the system is adjusted to a slightly acidic state by glacial acetic acid, silane molecules are added last. This preparation sequence prevents the spontaneous polymerization of silanes under high temperature or neutral conditions, allowing the liquid mixture containing multiple active molecules to remain stable over a longer storage period.

[0024] Preferably, in step S1, a plow-type dry powder mixer is used to mix the powder at room temperature for 15-20 minutes. By adopting the above technical solution, trace amounts of additive salts are uniformly dispersed in the main material particles, eliminating the potential for inconsistent film-forming rates caused by component segregation.

[0025] Preferably, the specific process parameters for step S2 are as follows: inject deionized water into the reactor, start stirring, set the speed to 150-200 rpm, and heat to 80-85℃; add polyvinyl alcohol particles at a uniform rate, and stir continuously at a constant temperature for 1.5-2 hours until the liquid is a transparent homogeneous solution; cool the solution to 20-30℃; add sodium gluconate, and stir at room temperature for 15-20 minutes until completely dissolved; slowly add glacial acetic acid, and stop adding when the pH of the system stabilizes at 4.5-5.0; add γ-glycidoxypropyltrimethoxysilane at a uniform rate, and stir continuously at room temperature in a closed state for 2-2.5 hours.

[0026] By adopting the above technical solution, the required temperature and stirring conditions for dissolution are limited, preventing the precipitation of organic materials and ensuring that the final liquid system has stable physicochemical properties.

[0027] Preferably, in step S3, the dry powder component and the liquid component are added into a forced mixer at a liquid-to-solid mass ratio of 0.28-0.32 and continuously stirred at room temperature for 2.0-3.0 minutes.

[0028] By adopting the above technical solution, mechanical shearing force is used to quickly complete the encapsulation and wetting of the powder and liquid phases within a specified time, creating contact conditions for the formation of the internal film layer.

[0029] Preferably, after step S3, the obtained slurry is directly poured onto the road surface to be repaired, vibrated to remove air bubbles and smoothed. Before pouring, the road surface is roughened and moistened until the surface is dry and the interior is saturated.

[0030] By adopting the above technical solution, on the one hand, the surface laitance lacking strength of the old road surface is removed by chiseling, exposing the internal dense structure; on the other hand, the wetting treatment can prevent the old concrete from absorbing moisture from the composite material and causing cracking. Combined with the silane hydrolysis and condensation at the interface, the structural integrity of the junction between the old and new materials is ensured.

[0031] This invention provides a composite material for road surface repair and its preparation method. It has the following beneficial effects:

[0032] 1. This invention resolves the contradiction between the workability time and early strength development of repair materials by incorporating zinc sulfate heptahydrate and sodium tetraborate decahydrate into the dry powder component, combined with polyvinyl alcohol and sodium gluconate in the liquid component. After mixing with water on-site, a calcium zincate film layer adhering to the clinker surface and a borate ester gel network encapsulating sodium gluconate are simultaneously generated within the system. The formation of these two structures inhibits the initial hydration of the material, allowing sufficient time for flow state during on-site paving. When the internal micro-hydration releases heat and the temperature reaches the depolymerization threshold, the gel network disintegrates and releases gluconate ions with strong complexing properties, promoting the dissolution of the surface film layer. Cement particles then undergo large-scale secondary hydration with water, thereby enabling the material to rapidly establish the early structural strength required for open traffic.

[0033] 2. This invention significantly improves the chemical anchoring strength of the interface between new and old concrete. The method introduces γ-glycidoxypropyltrimethoxysilane into the liquid component and uses glacial acetic acid to maintain the system in a slightly acidic environment, avoiding spontaneous hydrolysis of silane molecules during storage and initial mixing. When the repair grout contacts and penetrates the treated old pavement substrate, the inherent strong alkalinity of the old concrete, combined with the hydration heating effect, triggers the hydrolysis of the silane. The resulting silanol groups directly undergo dehydration condensation with the old substrate surface to form siloxane-silicon covalent bonds, while the epoxy groups at the other end participate in the hydration crosslinking of the repair material itself. This transformation from physical friction to cross-interfacial chemical bonding effectively reduces the risk of delamination at the repair interface under complex stress.

[0034] 3. The dry powder and liquid two-component separation mode and the corresponding preparation sequence design adopted in this invention ensure the long-term storage stability of the composite material. The physical isolation between the inorganic powder and the liquid phase eliminates the possibility of premature hydration of the clinker during storage. When preparing the liquid component, the process of first heating and dissolving polyvinyl alcohol, then cooling and adding glacial acetic acid for acidification, and finally adding silane dropwise is strictly followed. This specific process temperature and pH control route cuts off the reaction conditions for disordered condensation polymerization of silane molecules under high temperature or neutral conditions, ensuring that the liquid component can maintain its original interfacial modification activity and uniformity even after long-term static storage. Attached Figure Description

[0035] Figure 1 The diagram shows the thermal storage stability and temperature response rheological properties of the liquid phase according to the present invention.

[0036] Figure 2 This is a macroscopic test diagram showing the hydration exothermic properties of the composite material mixture of the present invention;

[0037] Figure 3 This is a macroscopic comparison diagram of the fluidity loss over time and the setting time characteristics of the composite material mixture of the present invention;

[0038] Figure 4 This is an evolution curve of the early and late mechanical strength development of the composite material of the present invention;

[0039] Figure 5 This is a diagram showing the evolution of macroscopic shear bond strength at the old and new interfaces of this invention. Detailed Implementation

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] This invention provides a composite material for road repair and its preparation method. The main raw materials and reagents used in the following examples and comparative examples are sourced and specified as follows. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0042] The main characteristic mineral component of sulfoaluminate cement clinker is anhydrous calcium sulfoaluminate, with a specific surface area controlled at 350-450 m². 2 / kg.

[0043] Ordinary Portland cement with a strength grade of P·O42.5 and a specific surface area of ​​330-380 m² is used. 2 / kg.

[0044] The chemical formula of anhydrous calcium sulfate is CaSO4, the CAS number is 7778-18-9, the purity is ≥99.0%, and the particle size is less than 1.0% after passing through a 200-mesh standard sieve.

[0045] The molecular formula of zinc sulfate heptahydrate is ZnSO4·7H2O, the CAS number is 7446-20-0, and the purity is ≥99.5%.

[0046] Sodium tetraborate decahydrate has the molecular formula Na2B4O7·10H2O, CAS number 1303-96-4, purity ≥99.5%, and powder particle size not greater than 150μm.

[0047] Polyvinyl alcohol has the CAS number 9002-89-5, its degree of alcoholysis is 87%-89%, and its average degree of polymerization is 1700-2000.

[0048] The molecular formula of γ-glycidoxypropyltrimethoxysilane is C9H. 20 O5Si, CAS number 2530-83-8, purity ≥98.0%.

[0049] Sodium gluconate has the chemical name sodium pentahydroxyhexanoate and the molecular formula C6H. 11 NaO7, CAS number 527-07-1, purity ≥99.0%.

[0050] The CAS number for glacial acetic acid is 64-19-7, and its purity is ≥99.5%.

[0051] Deionized water is either commercially available or prepared using conventional methods, with a conductivity ≤1.0 μS / cm.

[0052] Preparation Example 1:

[0053] This preparation example provides a method for preparing the liquid component of a composite material for road repair, including the following steps:

[0054] 45 kg of deionized water was injected into the reactor equipped with a jacketed heating and mechanical stirring device. The stirring was started, the speed was set to 180 rpm, and the temperature was raised to 85°C.

[0055] Add 3 kg of polyvinyl alcohol granules at a uniform rate, and stir continuously at a constant temperature for 1.5 hours until the liquid is a transparent homogeneous solution.

[0056] Turn on the cooling water in the reactor jacket to cool the solution to 25°C;

[0057] Add 0.8 kg of sodium gluconate and stir at room temperature for 15 minutes until completely dissolved;

[0058] Add glacial acetic acid slowly using a metering pump, monitor the pH of the system in real time, and stop adding when the pH stabilizes at 4.8.

[0059] 1.5 kg of γ-glycidoxypropyltrimethoxysilane was added dropwise at a uniform rate. The mixture was stirred continuously for 2 hours under a sealed environment at room temperature. The mixture was then discharged into a container for later use and designated as liquid component A1.

[0060] Preparation Example 2:

[0061] This preparation example provides a method for preparing the liquid component of a composite material for road repair, including the following steps:

[0062] Inject 40 kg of deionized water into the reactor equipped with a jacketed heating and mechanical stirring device, turn on the stirring, set the speed to 150 rpm, and raise the temperature to 80°C.

[0063] Add 2 kg of polyvinyl alcohol granules at a uniform rate, and stir continuously at a constant temperature for 2 hours until the liquid is a transparent homogeneous solution.

[0064] Turn on the cooling water in the reactor jacket to cool the solution to 20°C;

[0065] Add 0.5 kg of sodium gluconate and stir at room temperature for 20 minutes until completely dissolved;

[0066] Add glacial acetic acid slowly using a metering pump, monitoring the pH of the system in real time. Stop adding the acid when the pH stabilizes at 4.5.

[0067] 1 kg of γ-glycidoxypropyltrimethoxysilane was added dropwise at a uniform rate, and the mixture was stirred continuously for 2.5 hours under a sealed environment at room temperature. The mixture was then discharged into a container for later use and designated as liquid component A2.

[0068] Preparation Example 3:

[0069] This preparation example provides a method for preparing the liquid component of a composite material for road repair, including the following steps:

[0070] Inject 50 kg of deionized water into the reactor equipped with a jacketed heating and mechanical stirring device, turn on the stirring, set the speed to 200 rpm, and raise the temperature to 85°C.

[0071] Add 4 kg of polyvinyl alcohol granules at a uniform rate, and stir continuously at a constant temperature for 1.5 hours until the liquid becomes a transparent homogeneous solution.

[0072] Turn on the cooling water in the reactor jacket to cool the solution to 30°C;

[0073] Add 1 kg of sodium gluconate and stir at room temperature for 15 minutes until completely dissolved;

[0074] Add glacial acetic acid slowly using a metering pump, monitoring the pH of the system in real time. Stop adding the acid when the pH stabilizes at 5.0.

[0075] Add 2 kg of γ-glycidyl etheroxypropyltrimethoxysilane dropwise at a uniform rate, and stir continuously for 2 hours under a sealed condition at room temperature. Discharge the material into a container for later use and label it as liquid component A3.

[0076] Example 1:

[0077] This embodiment provides a composite material for road surface repair and its preparation method, including the following steps:

[0078] Preparation of dry powder components:

[0079] 65 kg of fully dried sulfoaluminate cement clinker, 25 kg of ordinary silicate cement, 8 kg of anhydrous calcium sulfate, 2 kg of zinc sulfate heptahydrate and 0.8 kg of sodium tetraborate decahydrate are put into a plow-type dry powder mixer and mixed at room temperature for 15 minutes to make the inorganic powder uniformly distributed. The mixture is then discharged, sealed and packaged to obtain the dry powder components.

[0080] On-site compounding process:

[0081] The dry powder component prepared above and the liquid component A1 obtained in Preparation Example 1 are added into a forced mixer at a liquid-solid mass ratio of 0.30 and continuously stirred for 2.5 minutes. The resulting slurry after stirring is the composite material for road repair and can be directly used for pouring and paving.

[0082] Example 2:

[0083] This embodiment provides a composite material for road surface repair and its preparation method, including the following steps:

[0084] Preparation of dry powder components:

[0085] 60 kg of fully dried sulfoaluminate cement clinker, 20 kg of ordinary silicate cement, 5 kg of anhydrous calcium sulfate, 1.5 kg of zinc sulfate heptahydrate and 0.5 kg of sodium tetraborate decahydrate are put into a plow-type dry powder mixer and mixed at room temperature for 15 minutes to make the inorganic powder uniformly distributed. The mixture is then discharged, sealed and packaged to obtain the dry powder components.

[0086] On-site compounding process:

[0087] The dry powder component prepared above and the liquid component A2 obtained in Preparation Example 2 are added into a forced mixer at a liquid-solid mass ratio of 0.28 and continuously stirred for 2.0 minutes. The resulting slurry after stirring is the composite material for road repair and can be directly used for pouring and paving.

[0088] Example 3:

[0089] This embodiment provides a composite material for road surface repair and its preparation method, including the following steps:

[0090] Preparation of dry powder components:

[0091] 70 kg of fully dried sulfoaluminate cement clinker, 30 kg of ordinary silicate cement, 10 kg of anhydrous calcium sulfate, 2.5 kg of zinc sulfate heptahydrate and 1.0 kg of sodium tetraborate decahydrate are put into a plow-type dry powder mixer and mixed at room temperature for 20 minutes to make the inorganic powder uniformly distributed. The mixture is then discharged, sealed and packaged to obtain the dry powder components.

[0092] On-site compounding process:

[0093] The dry powder component prepared above and the liquid component A3 obtained in Preparation Example 3 are added into a forced mixer at a liquid-solid mass ratio of 0.32 and continuously stirred for 3.0 minutes. The resulting slurry after stirring is the composite material for road repair and can be directly used for pouring and paving.

[0094] Example 4:

[0095] This embodiment provides a composite material for road surface repair and its preparation method, including the following steps:

[0096] Preparation of dry powder components:

[0097] 70 kg of fully dried sulfoaluminate cement clinker, 20 kg of ordinary silicate cement, 10 kg of anhydrous calcium sulfate, 1.5 kg of zinc sulfate heptahydrate and 1.0 kg of sodium tetraborate decahydrate are put into a plow-type dry powder mixer and mixed at room temperature for 18 minutes to make the inorganic powder uniformly distributed. The material is then discharged, sealed and packaged to obtain the dry powder components.

[0098] On-site compounding process:

[0099] The dry powder component prepared above and the liquid component A2 obtained in Preparation Example 2 are added into a forced mixer at a liquid-solid mass ratio of 0.30 and continuously stirred for 2.5 minutes. The resulting slurry after stirring is the composite material for road repair and can be directly used for pouring and paving.

[0100] Comparative Example 1:

[0101] Compared with Example 1, the difference is that zinc sulfate heptahydrate was not added in the preparation of the dry powder component, but all other aspects are the same.

[0102] Comparative Example 2:

[0103] Compared with Example 1, the difference is that sodium tetraborate decahydrate was not added in the preparation of the dry powder component, but all other aspects are the same.

[0104] Comparative Example 3:

[0105] Compared with Example 1, the difference is that glacial acetic acid is not used to adjust the pH value during the preparation of the liquid component. Instead, polyvinyl alcohol, sodium gluconate and γ-glycidoxypropyltrimethoxysilane are added directly to deionized water in sequence and stirred. All other aspects are the same.

[0106] Comparative Example 4:

[0107] Compared with Example 1, the difference is that the liquid component A1 of Preparation Example 1 was not used in the on-site compounding process. Instead, the same mass of deionized water was used for mixing. At the same time, 0.15 kg of tartaric acid was added to the dry powder component as a conventional retarder. Zinc sulfate heptahydrate and sodium tetraborate decahydrate were not added to the dry powder. All other aspects are the same.

[0108] Comparative Example 5:

[0109] Compared with Example 1, the difference is that the liquid component A1 of Preparation Example 1 was not used in the on-site compounding process. Instead, commercially available styrene-butadiene rubber latex with the same mass ratio was used for mixing, and zinc sulfate heptahydrate and sodium tetraborate decahydrate were not added to the dry powder. All other aspects are the same.

[0110] Test Example 1:

[0111] 1. Extract the liquid component A1 obtained from Preparation Example 1 and the liquid phase sample from the preparation process of Comparative Example 3, and inject them into 500mL standard sealed glass storage bottles for later use. Place all the above samples in a constant temperature and humidity chamber set at 25℃ for static storage. Using an NDJ series rotational viscometer, samples were taken on the 1st, 7th, 14th, 21st and 28th days of storage to test their dynamic viscosity values ​​at room temperature.

[0112] 2. Following the dry powder material ratios of Example 1 and Comparative Example 2 (without borax), sodium tetraborate decahydrate was extracted from the liquid component of Example 1 and dissolved completely in liquid component A1 to prepare test sample 1, simulating the actual mixing liquid phase environment of Example 1; the original liquid component A1 was directly used as test sample 2 for Comparative Example 2. The test samples were injected into the sample cell of a rheometer with a temperature-controlled jacket. The initial temperature was set to 20°C, and the temperature was slowly increased to 50°C at a heating rate of 2°C / min. Under a constant shear rate, the apparent viscosity data of the system at different temperature nodes (20°C to 50°C, in 5°C intervals) were recorded.

[0113] Table 1. Dynamic viscosity test data of liquid phase samples stored at 25℃ and under different temperature conditions.

[0114] Storage time / day Viscosity of liquid component A1 (mPa·s) Comparative Example 3: Liquid phase viscosity (mPa·s) Test temperature / ℃ Viscosity of sample 1 (mPa·s) Viscosity of sample 2 (mPa·s) 1 148 152 20 4125 315 7 143 321 25 3890 298 14 151 856 30 3140 282 21 149 2430 35 1765 265 28 154 Unable to detect (gelation). 40 610 251 - - - 45 305 238 - - - 50 275 224

[0115] Based on the data in Table 1 and the appendix Figure 1, under the conventional process without pH adjustment, the liquid-phase sample of Comparative Example 3 showed a continuous deterioration of viscosity at the initial stage of standing at room temperature. As the storage time extended, the silane molecules in the system underwent an irreversible condensation reaction and formed a disordered siloxane cross-linking network due to the lack of an inhibitory environment, directly causing the sample to completely lose its fluidity on the 28th day. After introducing the weak acid buffer system into Liquid Component A1, its apparent viscosity only showed a slight fluctuation up and down after one month of storage at room temperature, proving that this component process effectively locked the early deterioration path of the chemical reaction and met the requirements of industrial production for long-term storage of materials.

[0116] Observing the rheological law when the system is thermally excited, it can be found that Test Sample 1 simulating the complete environment of Example 1 maintained a high blocking state of over 3800 mPa·s below 25°C. When the external heat accumulation pushed the local temperature across the critical line of 30°C, the viscosity curve of this sample showed a sharp cliff-like drop and basically dropped to the normal sol level at 45°C. This process verified that thermally reversible covalent bonds were formed between tetrahydroxyborate and substances such as polyvinyl alcohol depending on temperature. In contrast, Test Sample 2 lacking the participation of this ion maintained the characteristics of a low-viscosity fluid from beginning to end and was not sensitive to temperature differences. The comparison of the above physical and chemical parameters confirmed the mechanism of the material system inhibiting the diffusion of water and retarders through the microgel network in the early stage, and this temporarily formed physical and chemical restraint could be precisely released by the trace hydration heat release of cement in the early stage, thereby realizing the transformation of the blockade and解封 of fluidity.

[0117] Test Example 2:

[0118] 1. Extract the materials of Example 1, Comparative Example 1, and Comparative Example 4 as test objects. Mix the dry powders of each component with the corresponding liquid phase at a set liquid-solid ratio using a planetary mixer at room temperature of 24°C for 2.5 minutes. After mixing, quickly take 800 grams of the slurry and put it into a standard adiabatic calorimeter test cylinder lined with a polytetrafluoroethylene film in advance. Insert a K-type thermocouple probe with thermal grease into the geometric center of the slurry and seal the upper cover of the calorimeter.

[0119] 2. Start the multi-channel data acquisition system and set the sampling frequency to once every 10 seconds. The system runs continuously for 120 minutes, synchronously recording the change in the internal center temperature of the system over time. Using the analysis software supporting the calorimeter, perform differential processing on time based on the adiabatic temperature rise data to calculate the test results of the hydration heat release rate at the corresponding time nodes.

[0120] Table 2. Test data of adiabatic temperature rise and hydration heat release rate of the composite material mixture within 120 minutes

[0121] Test time / min Example 1: Center temperature / °C <![CDATA[Example 1 Heat release rate / (J·g -1 ·h -1 )]]> Comparative Example 1: Center Temperature / °C <![CDATA[Exemplary Comparative Case 1 Heat Release Rate / (J·g -1 ·h -1 )]]> Comparative Example 4: Center Temperature / °C <![CDATA[Exothermic rate of Comparative Example 4 / (J·g -1 ·h -1 )]]> 0 24.3 2.1 24.5 18.5 24.2 1.2 15 25.1 4.6 38.6 145.2 24.8 3.5 30 26.8 8.2 52.4 86.4 25.6 4.8 45 31.5 45.7 56.1 24.5 26.3 5.2 60 49.3 128.5 57.8 12.1 27.5 6.4 75 56.4 64.2 58.5 8.6 28.6 8.1 90 58.1 21.6 58.9 4.3 29.8 9.3 105 58.7 10.2 59.2 3.1 31.2 12.5 120 59 5.4 59.3 2.5 32.7 15.6

[0122] Based on the data in Table 2 and the appendix Figure 2 The sulfoaluminate cement clinker system exhibits drastically different hydration kinetics under the intervention of different admixtures. Comparative Example 1, due to the removal of zinc salt components and the lack of a physical barrier formed by initial precipitation, shows a violent exothermic reaction within 15 minutes of contact with water, with a peak exothermic rate as high as 145.2 J·g. -1 ·h -1 This premature heat release causes the slurry to lose its fluidity instantly during actual construction, making it impossible to complete the smoothing and paving of road defects. In contrast, tartaric acid used in Comparative Example 4 is a typical traditional organic retarder. Although it avoids early rapid setting, it indiscriminately inhibits the hydration process over a long period. Data shows that its core temperature only slowly rises to 32.7℃ within two hours, the exothermic curve is flat and there is no obvious breakthrough in the induction period, which means that the material cannot establish early mechanical strength suitable for traffic in a short time.

[0123] Example 1, which introduces a dual-lock mechanism, exhibits a clear time-phased characteristic in its exothermic behavior. Within the test interval of 0 to 30 minutes, the system's exothermic rate remains at 10 J·g⁻¹. -1 ·h -1 In the following low-temperature state, the temperature only slightly increased from 24.3℃ to 26.8℃. Combined with material ratio analysis, at this point, the calcium zincate passivation film formed by the co-precipitation of zincate and calcium ions effectively encapsulated the cement particles, blocking the hydration process and reserving sufficient operating time for on-site construction. As the weak heat of hydration accumulated internally caused the system temperature to exceed the thermodynamic unlocking threshold of 30℃, the borate ester microgel network disintegrated, releasing a high concentration of gluconate into the liquid phase and actively peeling off the passivation film. This microscopic chemical behavior is manifested in the macroscopic calorimetric curve as a sharp increase in the exothermic rate between 45 and 60 minutes, reaching 128.5 J·g at 60 minutes. -1 ·h -1 The secondary exothermic peak causes the internal temperature to jump to nearly 50°C. This artificially designed "dormant-awakening" cascade reaction path forces the material to enter the accelerated hydration stage after the safe construction period, ensuring the dual requirements of rapid pavement formation and early strength acquisition in macro-engineering.

[0124] Test Example 3:

[0125] 1. Select the dry powder and liquid raw materials specified in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 4, and place them in a constant temperature and humidity test chamber at 20±2℃ and 60% relative humidity for 24 hours to balance the material temperature. According to the set liquid-solid ratio, put each group of test objects into a cement paste mixer, first slowly mix for 1 minute, then stop the machine and scrape the pot, and continue to mix rapidly for 1.5 minutes. Immediately after discharge, put a portion of the mixture into a truncated cone mold, and use an NLD-3 type cement mortar flowability tester to test and record its initial flowability according to the standard jump table method.

[0126] 2. Seal and cover the remaining slurry and place it on the test bench to stand. After standing for 30 minutes and 45 minutes respectively, take samples again, mold them, and test their flowability data over time using the same method. If the slurry has lost its plasticity and cannot be molded, record the flowability as 0.

[0127] A portion of the initial mixture was extracted and injected into a standard mold of the Vicat apparatus. After the surface was smoothed, the mold was placed in a standard curing chamber. Using an automatic Vicat apparatus, the penetration depth of the probe was measured every 3 minutes according to the standard consistency water requirement and setting time test method for cement, thereby obtaining the initial setting time and final setting time of each group of samples.

[0128] Table 3. Test data on the change in flowability of composite material mixtures over time and setting time.

[0129] Test sample Initial flowability / mm 30min flowability / mm Flowability in 45 min / mm Initial setting time / min Final setting time / min Example 1 286 273 148 52 67 Comparative Example 1 243 0 0 12 19 Comparative Example 2 291 262 234 108 134 Comparative Example 4 268 215 162 87 122

[0130] Based on the data in Table 3 and the appendix Figure 3 The rheological state and setting time of composite materials under different intervention mechanisms showed significant differences in evolution during the construction period. Comparative Example 1, lacking zinc sulfate heptahydrate, exhibited extreme early rapid setting characteristics, with an initial flowability of only 243 mm, and completed the alternation of initial and final setting within a dozen minutes after mixing. This phenomenon in the construction site means that the material begins to consume a large amount of free water to form crystals as soon as it comes into contact with water, completely losing the necessary time for pouring and smoothing for road repair. Observation of Comparative Example 2 without sodium tetraborate shows that although sodium gluconate is still present in the system, due to the lack of physical restraint of the microgel network, the high concentration of retarder is released without hindrance and strongly adsorbed on the surface of unhydrated cement particles, resulting in the sample maintaining a flowability of up to 234 mm even after standing for 45 minutes, and the final setting time is indefinitely postponed to 134 minutes. This uncontrolled retarding effect not only prolongs the traffic closure period, but also easily causes shrinkage cracking of the repair surface under air drying. The conventional tartaric acid retarding system used in Comparative Example 4 showed obvious linear decay characteristics, with the fluidity gradually decreasing over time. It still failed to break out of the traditional technical trap of "extending the working time inevitably leads to slow solidification".

[0131] The test data from Example 1 clearly verify the invention's ability to precisely intervene in the hydration process across time and space. During the first 30 minutes of settling, the hydration kinetics within the system were forcibly suspended thanks to the dual support of the calcium zincate passivation film and the polymer borate microgel network. The fluidity decreased only slightly from 286 mm to 273 mm, providing construction workers with ample time for paving and compaction. When the settling time reached approximately 45 minutes, the accumulated heat triggered the depolymerization of the thermally reversible gel. The released gluconate ions began to competitively disintegrate the passivation film, causing the macroscopic slurry to thicken rapidly, and the fluidity to plummet to 148 mm. The system then completed a rapid transition from initial setting (52 minutes) to final setting (67 minutes) within a mere 15 minutes. This nonlinear rheological behavior, characterized by high slump retention in the early stages and rapid hardening in the later stages, successfully decouples the material's operability window from its curing time, perfectly meeting the stringent requirements of road repair projects that demand both ample operating time and rapid restoration of traffic.

[0132] Test Example 4:

[0133] 1. The dry powder components and corresponding liquid phase substances of Examples 1, 2, and 4 were selected as test objects. In an indoor environment of 20±2℃, the weighed raw materials were added to a forced mortar mixer at a predetermined liquid-solid ratio and mixed for 2.5 minutes. After mixing, the flowing slurry was poured into a triple standard mold (40mm×40mm×160mm) pre-coated with a release agent, and compacted on a vibrating table for 15 seconds to remove air bubbles. The surface was then smoothed with a scraper and covered with plastic wrap to prevent premature evaporation of moisture.

[0134] 2. For specimens with a test age of 2 hours, after pouring, they were allowed to stand until close to the test time point before being pre-pressed in the mold, and then demolded to complete the preparation. For long-term test specimens with an age of 24 hours and 28 days, they were demolded uniformly after standing and curing in the mold for 2 hours, and then moved as a whole into a standard curing room with a temperature set at 20±1℃ and a relative humidity maintained at more than 95% for continuous hydration curing.

[0135] After the specimens reached the corresponding specified ages (2 hours, 24 hours, 28 days), they were removed and their surface moisture was wiped dry. Using a microcomputer-controlled electro-hydraulic servo universal testing machine, a three-point flexural strength test was first performed at a loading rate of 50 N / s, and the ultimate load at fracture was recorded. Then, half of the fractured specimen was taken and placed in a compression fixture, and an axial load of 2.4 kN / s was applied to perform a compressive strength test. The test results for each sample at each age were taken as the arithmetic mean of three sets of parallel data.

[0136] Table 4. Test data of flexural and compressive strength of composite materials at different ages

[0137] Test sample 2-hour compressive strength / MPa 24-hour compressive strength / MPa 28-day compressive strength / MPa 2-hour flexural strength / MPa 24-hour flexural strength / MPa 28-day flexural strength / MPa Example 1 33.6 51.4 74.8 6.5 8.8 12.3 Comparative Example 2 1.2 37.5 63.2 0.4 6.1 9.4 Comparative Example 4 14.3 41.6 61.5 2.8 7.3 9.8

[0138] Based on the data in Table 4 and the appendix Figure 4 In actual road repair scenarios, the ability of a material to establish a framework network to resist traffic loads within a very short time after pouring is a core indicator for evaluating its practical value. Comparative Example 2, lacking organic gel binding, exhibited near-collapse in mechanical performance in the very early 2 hours, with a compressive strength of only 1.2 MPa. This extremely low value demonstrates that the high concentration of free sodium gluconate severely interfered with the initial crystal nucleation kinetics, causing the slurry to remain in a fluid state for an extended period, completely missing the critical timeframe for rapid road reopening. In Comparative Example 4, using a conventional tartaric acid system, although the material achieved a compressive strength of 14.3 MPa within 2 hours, its long-term mechanical properties showed significant stagnation. This traditional carboxylic acid retarder, while delaying the hydration reaction, irreversibly poisoned the crystal growth end faces of the hydration product, ettringite, resulting in a severe imbalance in the aspect ratio of the later-formed needle-like crystals and a loosening of the interlocking structure between crystals. Ultimately, this manifested in significantly lower-than-expected compressive and flexural strengths at 28 days.

[0139] Example 1 breaks free from the correlation between early inhibition and later strength decay through the path of microstructure establishment. Thanks to the cascade unlocking mechanism of the temperature-responsive gel and passivation film, after overcoming the early dormancy period, the system undergoes a forced secondary hydration, generating extremely high-density hydrated calcium silicate gel and ettringite crystals internally. Macroscopic data vividly demonstrate this aggressive hydration benefit; the specimen broke through the 33.6 MPa compressive strength barrier in just 2 hours, fully possessing the compressive strength to withstand heavy truck traffic. The released silane molecules rapidly undergo hydrolysis and condensation reactions in a strongly alkaline environment, generating flexible organosiloxane segments that interweave within the inorganic rigid framework, significantly reducing internal micro-defect stress concentration, resulting in the 28-day flexural strength of Example 1 climbing to 12.3 MPa. This achieves the ideal form of "steep early leap followed by steady later gain" in the strength development curve, using robust engineering mechanics data to corroborate the performance of the thermodynamic unlocking triggering mechanism in balancing construction tolerance and ultimate structural strength.

[0140] Test Example 5:

[0141] 1. The dry powder and liquid raw materials corresponding to Example 1, Comparative Example 3, and Comparative Example 5 were selected as the test objects for this interface. A standard C40 concrete cube specimen with dimensions of 100mm × 100mm × 100mm and cured for up to 6 months was prepared in advance to simulate the aging old pavement substrate. One test surface of the cube specimen was deeply roughened using a high-pressure water jet device to remove the surface laitance until the coarse aggregate was exposed. Then, the surface dust was blown away with an air gun and moderately moistened to ensure the interface was surface-dry and internally saturated.

[0142] 2. Place the treated old concrete block into a specially designed steel mating mold. Mix the test materials of Example 1, Comparative Example 3, and Comparative Example 5 at room temperature according to the set proportions. Pour the highly fluid mixture into the remaining cavity of the mold, directly contacting the rough, aged concrete block surface. Use a small vibrator to gently vibrate and remove any air bubbles that may have accumulated at the interface, and smooth the surface of the repair layer.

[0143] 3. After the composite specimens are poured and allowed to cure indoors for 24 hours, they are demolded and transferred to a standard constant temperature and humidity curing room for continuous curing. Specimens are collected at 1 day, 7 days, and 28 days of age for interfacial mechanical testing. The testing platform uses a computer-controlled electronic universal testing machine equipped with a dedicated interfacial shear fixture. During testing, the line of action of the shear force is strictly aligned with the interface between the new and old concrete. A parallel shear stress is applied at a constant loading rate of 0.5 MPa / s until shear failure occurs along the interface. The system automatically records the ultimate shear load at which slip fracture occurs and calculates the macroscopic interfacial shear strength at each age.

[0144] Table 5. Test data on macroscopic shear bond strength at the interface between new and old concrete.

[0145] Test sample 1-day interfacial shear strength / MPa 7-day interfacial shear strength / MPa 28-day interfacial shear strength / MPa Example 1 2.15 3.42 4.87 Comparative Example 3 1.23 1.56 1.68 Comparative Example 5 1.45 1.98 2.12

[0146] Based on the data in Table 5 and the appendix Figure 5The weak bond at the interface between new and old concrete remains a core engineering challenge limiting the service life of repair materials. Comparative Example 5 uses traditional styrene-butadiene rubber latex modification, whose adhesion mechanism highly relies on the physical film formation and mechanical interlocking of polymer particles at the old interface after moisture evaporation. This non-reactive adhesion method provides a small amount of adhesion in the early stages of pouring, with data showing a 1-day shear strength of 1.45 MPa. However, in subsequent long-term service environments, the purely physical film is prone to interfacial microcracks and peeling due to continuous shrinkage stress from the substrate. Its 28-day ultimate shear strength is only 2.12 MPa, insufficient to withstand the enormous horizontal shear fatigue exerted on the road surface by heavy-duty trucks during starting and braking. Comparative Example 3, by abandoning the constraints of the glacial acetic acid buffer system in the early liquid-phase preparation stage, allows the highly reactive silane molecules to irreversibly undergo spontaneous hydrolysis and disordered polycondensation during the weeks-long material storage period. Silane oligomer clusters that have completely lost their silanol activity become inactive suspended particles, unable to effectively diffuse to the old road substrate and generate interfacial reactions at the pouring site. This ultimately leads to a degradation of their bonding performance to the level of the most common silicate cement, with a 28-day test value of only 1.68 MPa.

[0147] The test results of Example 1 demonstrate the significant advantages of synchronizing the condensation kinetics of silane molecules with the hydration process of inorganic cement in time and space. Relying on well-controlled liquid-phase storage stability, silane molecules in the mixture, in a free monomer state, undergo deep penetration into the rough capillaries of dry, aged concrete under the dual stimulation of instantaneous transition from a slightly acidic to a strongly alkaline environment and spontaneous heating of the system, accompanied by free water. Under the high-temperature and high-alkali catalysis of secondary burst hydration, the epoxy end groups of the silane molecules intertwine with the inorganic hydration products, while the silanol groups at the other end are densely adsorbed onto the surface of the exposed aggregate and hydrated calcium silicate gel of the old substrate, undergoing a vigorous dehydration condensation reaction. This in-situ reaction network constructs continuous and highly resilient Si-O-Si covalent bonds at the microscopic cross-section within the same growth cycle of the macroscopic repair layer's curing strength, completely transforming the simple physical friction contact between the old and new phases into a continuous chemical whole. This cross-interface chemical anchoring resulted in a stepwise increase in the shear strength of Example 1 at all ages, with a 28-day shear strength as high as 4.87 MPa. This completely eliminated the engineering hazard of interlayer delamination of the pavement repair body under complex stress conditions from the microscopic reaction level.

[0148] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite material for road surface repair, characterized in that, It is made by mixing dry powder components and liquid components; The dry powder component comprises the following raw materials in parts by weight: 60-70 parts of sulfoaluminate cement clinker, 20-30 parts of ordinary silicate cement, 5-10 parts of anhydrous calcium sulfate, 1.5-2.5 parts of zinc sulfate heptahydrate, and 0.5-1.0 parts of sodium tetraborate decahydrate. The liquid component comprises the following raw materials in parts by weight: 40-50 parts deionized water, 2-4 parts polyvinyl alcohol, 0.5-1.0 parts sodium gluconate, 1-2 parts γ-glycidoxypropyltrimethoxysilane, and glacial acetic acid in an amount such that the pH of the liquid component system is 4.5-5.

0.

2. The composite material for road surface repair according to claim 1, characterized in that, The preferred ratio of raw materials is: Dry powder composition: 65 parts of sulfoaluminate cement clinker, 25 parts of ordinary Portland cement, 8 parts of anhydrous calcium sulfate, 2 parts of zinc sulfate heptahydrate, and 0.8 parts of sodium tetraborate decahydrate; Liquid components: 45 parts deionized water, 3 parts polyvinyl alcohol, 0.8 parts sodium gluconate, and 1.5 parts γ-glycidoxypropyltrimethoxysilane.

3. The composite material for road surface repair according to claim 1, characterized in that, The raw materials have the following parameters and characteristics: The specific surface area of ​​the sulfoaluminate cement clinker is controlled at 350-450 m². 2 / kg; The ordinary Portland cement has a strength grade of P·O42.5 and a specific surface area of ​​330-380 m². 2 / kg; The degree of alcoholysis of the polyvinyl alcohol is 87%-89%, and the average degree of polymerization is 1700-2000.

4. The composite material for road surface repair according to claim 1, characterized in that, The anhydrous calcium sulfate particles have a particle size where the residue on a 200-mesh standard sieve is less than 1.0%. The particle size of the sodium tetraborate decahydrate powder is no greater than 150 μm.

5. A composite material for road surface repair according to claim 1, characterized in that, The liquid-to-solid mass ratio of the dry powder component to the liquid component during on-site mixing is 0.28-0.

32.

6. A method for preparing a composite material for road repair, applied to the method for preparing a composite material for road repair as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of dry powder components: Fully dried sulfoaluminate cement clinker, ordinary silicate cement, anhydrous calcium sulfate, zinc sulfate heptahydrate and sodium tetraborate decahydrate are added into a dry powder mixer according to the proportion and mixed. The dry powder components are then discharged. S2. Preparation of liquid component: Deionized water is injected into a reaction vessel equipped with a heating and stirring device and the temperature is raised. Polyvinyl alcohol is added and stirred continuously until a transparent homogeneous solution is formed. After the solution is cooled, sodium gluconate is added and stirred until dissolved. Then, glacial acetic acid is added dropwise to adjust the pH value of the system. Finally, γ-glycidoxypropyltrimethoxysilane is added dropwise and stirred continuously. The liquid component is then discharged. S3. On-site compounding process: The dry powder component prepared in step S1 and the liquid component prepared in step S2 are put into a forced mixer according to the set liquid-solid mass ratio for mixing. The resulting slurry after mixing is the composite material used for road repair.

7. A method for preparing a composite material for road repair according to claim 6, characterized in that, In step S1, a plow-type dry powder mixer is used to mix the powder for 15-20 minutes at room temperature.

8. A method for preparing a composite material for road repair according to claim 6, characterized in that, The specific process parameters for step S2 are as follows: Inject deionized water into the reactor, turn on the stirrer, set the speed to 150-200 rpm, and heat to 80-85℃; Add polyvinyl alcohol granules at a uniform rate and stir continuously at a constant temperature for 1.5-2 hours until the liquid is a transparent homogeneous solution; then cool the solution to 20-30℃. Add sodium gluconate and stir at room temperature for 15-20 minutes until completely dissolved; slowly add glacial acetic acid dropwise, and stop adding when the pH of the system stabilizes at 4.5-5.0; Add γ-glycidoxypropyltrimethoxysilane dropwise at a uniform rate and stir continuously for 2-2.5 hours under sealed conditions at room temperature.

9. A method for preparing a composite material for road repair according to claim 6, characterized in that, In step S3, the dry powder component and the liquid component are added into a forced mixer at a liquid-to-solid mass ratio of 0.28-0.32 and stirred continuously at room temperature for 2.0-3.0 minutes.

10. A method for preparing a composite material for road repair according to claim 6, characterized in that, After step S3, the obtained slurry is poured directly onto the road surface to be repaired, vibrated to remove air bubbles, and the surface is smoothed. Before pouring, the road surface base is roughened and moistened until the surface is dry and the interior is saturated.

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