A concrete bridge guardrail salt freeze disease repairing material and method

Abstract

This invention discloses a material and method for repairing salt-frost damage to concrete bridge railings, belonging to the field of civil engineering materials technology. The raw materials include: 30-34 parts composite cement, 16-20 parts mineral admixtures, 38-40 parts quartz sand, 1-3 parts nano-reinforcing agent, 1-3 parts steel reinforcement corrosion inhibitor, 2-4 parts expansion agent, 1-3 parts self-healing component, 2-4 parts polymer powder, 1-3 parts fiber, 5-7 parts solid functional repair component, and 14-17 parts water; wherein the solid functional repair component includes: powder water-reducing agent, powder water-retaining agent, powder antifreeze agent, and powder retarder. Through precise multi-component proportioning, the overall mechanical properties and impermeability are improved, salt-frost resistance is enhanced, crack propagation is prevented, the long-term integrity of the repair layer is ensured, steel corrosion is prevented, and on-site operation is adapted.

Description

Technical Field

[0001] This invention belongs to the field of civil engineering materials technology, specifically relating to a material and method for repairing salt frost damage to concrete bridge railings. Background Technology

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

[0003] As a key structure for ensuring traffic safety, reinforced concrete bridge railings are exposed to a salt-freezing environment for a long time, making them susceptible to a vicious cycle of damage caused by "salt penetration - freeze-thaw expansion - steel corrosion", resulting in surface peeling, crack development, exposed steel bars and other defects.

[0004] Repair materials need to balance bonding strength with old concrete, resistance to salt freezing, resistance to salt penetration, and the ability to deform with the substrate. Existing conventional repair materials struggle to achieve all these properties, and they are prone to sagging in vertical application scenarios, resulting in insufficient adaptability to different construction methods. Therefore, there is an urgent need for a bridge railing salt freezing damage repair material that combines multiple performance characteristics. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a material and method for repairing salt-frost damage to concrete bridge railings.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a material for repairing salt-frost damage to concrete bridge railings, comprising the following raw materials in parts by weight: The composition consists of 30-34 parts composite cement, 16-20 parts mineral admixture, 38-40 parts quartz sand, 1-3 parts nano-reinforcing agent, 1-3 parts steel rust inhibitor, 2-4 parts expansion agent, 1-3 parts self-healing component, 2-4 parts polymer powder, 1-3 parts fiber, 5-7 parts solid functional repair component, and 14-17 parts water. The solid functional repair components include: 35-45 parts of powder water-reducing agent, 10-15 parts of powder water-retaining agent, 25-30 parts of powder antifreeze agent, and 8-12 parts of powder retarder.

[0007] Secondly, a repair method based on the aforementioned repair material for salt-frost damage of concrete bridge railings includes the following steps: Clean the area to be repaired, dry mix all raw materials except water, add water and stir to obtain the repair material, cover the area to be repaired with the repair material, and cure until the set age.

[0008] The beneficial effects of this invention are as follows: This invention specifically addresses the complex needs of concrete bridge railings suffering from salt-frost damage. Through precise multi-component formulation, it achieves synergistic effects. The composite cement provides both rapid early hardening and long-term stable strength; while the optimized gradation density of mineral admixtures and quartz sand fills macroscopic voids, synergistically forming a dense matrix with cement hydration products, enhancing overall mechanical properties and impermeability. The pozzolanic activity of the mineral admixtures, combined with the microscopic filling effect of the nano-reinforcing agent, significantly refines the pore structure, blocking the penetration of moisture and salt ions; the antifreeze agent in the solid functional repair component directly enhances resistance to freeze-thaw cycles, and the enhanced impermeability further reduces the intrusion of salt-frost media, synergistically improving salt-frost resistance. The expansion agent reduces crack formation at the source, while the fiber and polymer powder form an elastic network, bridging interface gaps and enhancing toughness, adapting to substrate deformation. The self-healing component repairs microcracks upon contact with water. These four components work synergistically to achieve an integrated "prevention-inhibition-repair" system, effectively preventing crack propagation and ensuring the long-term integrity of the repair layer. Mineral admixtures and nano-reinforcing agents enhance interfacial bonding strength, while polymer powder forms a continuous film layer that synergistically improves crack resistance and steel reinforcement adhesion to the substrate being repaired, in conjunction with fibers. Meanwhile, the steel reinforcement corrosion inhibitor forms a passivation film on the steel reinforcement surface, synergistically preventing corrosion. Water-reducing agents improve fluidity, water-retaining agents ensure sufficient hydration, retarder adjusts setting time to suit on-site operations, and antifreeze agents directly address low-temperature environments. These factors collectively optimize the material's workability and environmental adaptability, making repair work efficient and convenient, and ultimately resulting in stable and durable performance. Detailed Implementation

[0009] A typical embodiment of the present invention provides a material for repairing salt-frost damage to concrete bridge railings, comprising the following raw materials in parts by weight: The composition consists of 30-34 parts composite cement, 16-20 parts mineral admixture, 38-40 parts quartz sand, 1-3 parts nano-reinforcing agent, 1-3 parts steel rust inhibitor, 2-4 parts expansion agent, 1-3 parts self-healing component, 2-4 parts polymer powder, 1-3 parts fiber, 5-7 parts solid functional repair component, and 14-17 parts water. The solid functional repair components include: 35-45 parts of powder water-reducing agent, 10-15 parts of powder water-retaining agent, 25-30 parts of powder antifreeze agent, and 8-12 parts of powder retarder.

[0010] Among the above components, composite cement, mineral admixtures, and quartz sand form a dense matrix, improving overall mechanical properties and impermeability; they also block the penetration of water and salt ions and, together with antifreeze agents, enhance salt-freezing resistance; the expansion agent reduces crack formation at the source, and the fibers and polymer powder form an elastic network that adapts to substrate deformation and prevents crack propagation; the self-healing component repairs micro-cracks upon contact with water, effectively preventing repair material failure due to crack damage; the mineral admixtures, nano-reinforcing agents, and polymer powders jointly enhance the ability to encapsulate steel bars, while the steel bar corrosion inhibitor forms a passivation film on the steel bar surface, synergistically blocking corrosion; water-reducing agents, water-retaining agents, and other components work together to make repair construction efficient and convenient, and ultimately achieve stable and durable performance; thus, it achieves an integrated effect of rapid repair, high impermeability, salt-freezing resistance, crack resistance, steel bar protection, and long-term durability.

[0011] Optionally, the composite cement comprises silicate cement and rapid-hardening sulfoaluminate cement in a mass ratio of (65~75):(25~35); preferably 70:30; both are solid powders, balancing strength and rapid-hardening performance, and using P The composite of O42.5 grade silicate cement and 42.5 grade rapid hardening sulfoaluminate cement can precisely control the 28-day compressive strength at around 45MPa, which is compatible with common guardrail substrates (C30~C40).

[0012] Optionally, the mineral admixture includes microsilica, fly ash, slag powder and metakaolin in a mass ratio of (10~20):(25~35):(35~45):(5~15), preferably 15:30:40:10; the pore structure is optimized by “micro-aggregate filling + volcanic ash reaction” to improve impermeability and salt freeze resistance, while enhancing interfacial adhesion.

[0013] Optionally, the nano-reinforcing agent comprises nano-silica and nano-calcium carbonate in a mass ratio of (55~65):(35~45); nano-SiO2 promotes the formation of hydration products through pozzolanic reaction, while nano-CaCO3 fills the pores, and the two synergistically optimize the microstructure of the mortar. Durability is also significantly improved; the combined use can reduce water absorption and drying shrinkage, and enhance resistance to sulfate attack. Especially under freeze-thaw cycles, the composite-reinforced mortar exhibits better volume stability. In terms of cost-effectiveness, the price advantage of nano-CaCO3 can balance the overall cost, reducing material costs while ensuring performance improvement, and the durability of the nano-reinforcing agent is stronger than that of conventional epoxy binder powder.

[0014] Optionally, the steel reinforcement rust inhibitor comprises a calcium nitrite rust inhibitor and an amine-carboxylate composite rust inhibitor in a mass ratio of (60~70):(30~40), preferably 65:35; the amine-carboxylate composite rust inhibitor refers to a composite rust inhibitor obtained by mixing octadecylamine acetate and ammonium citrate in a ratio of (50~60):(50~40), which, after being evenly dispersed, can form a passivation film on the steel reinforcement surface to block salt corrosion; the calcium nitrite rust inhibitor is an anodic rust inhibitor that inhibits corrosion by promoting the formation of a dense oxide film on the steel reinforcement surface; while the amine-carboxylate composite rust inhibitor is an adsorption rust inhibitor that can form a hydrophobic adsorption layer on the metal surface to block corrosive media; after the two are combined, a dual protection of "passivation + shielding" is achieved, which not only significantly improves the resistance to corrosive factors such as chloride ions, but also broadens the applicable environmental range and reduces the potential risks of a single component (such as the possibility of local failure of calcium nitrite), thereby making the protection more comprehensive, durable and reliable.

[0015] Optionally, the expanding agent is a CSA type solid expanding agent (ettringite expanding agent) with a 28-day restricted expansion rate of 0.02~0.05%, used to compensate for shrinkage, reduce cracks, improve density, and indirectly enhance bond stability.

[0016] Optionally, the self-healing component comprises a Bacillus pasteurellium inoculant and a metakaolin-gypsum composite mineral self-healing agent in a mass ratio of (50~60):(40~50), preferably 55:45; wherein, Bacillus pasteurellium (… Sporocarcinoma pasteursAs highly efficient mineralizing microorganisms, the urease they secrete can rapidly decompose urea to generate carbonate ions, which combine with calcium ions in the cement matrix to form calcium carbonate precipitate, thus achieving rapid filling of cracks; while the metakaolin-gypsum composite mineral system further fills and closes cracks through volcanic ash reaction and expansion effect. The synergistic effect of the two can achieve the dual effect of "rapid initial repair + deep and continuous repair": the mineralization reaction of Bacillus pasteurellii can generate a large amount of calcium carbonate in a short time (such as within 7 days), filling the surface of cracks and shallow pores, preventing further crack expansion; the metakaolin-gypsum composite system is continuously consumed through the volcanic ash reaction, generating more CSH gel, which penetrates deep into the crack to fill the micropores, while the micro-expansion effect of ettringite can promote crack closure, achieving deep repair; as a micro-carrier, metakaolin's porous structure can provide a good living environment for Bacillus pasteurellii, reducing the inhibitory effect of the highly alkaline environment of the cement matrix on microorganisms and improving the long-term activity of microorganisms; on the other hand, the presence of gypsum can adjust the pH value of the cement matrix, providing a more suitable mineralization environment for microorganisms (such as neutral or weakly alkaline), further promoting the continuous mineralization reaction; and the CSH gel generated by the metakaolin-gypsum composite system and ettringite can form a denser microstructure, enhancing the crack resistance of the cement matrix and reducing the recurrence of cracks after repair. Specifically, metakaolin-gypsum composite mineral self-healing agent is a high-performance self-healing material based on natural mineral modification. Through the synergistic effect of the high pozzolanic activity of metakaolin and the cementing and expansion properties of gypsum, it achieves self-healing of cracks, strength recovery, and durability improvement in cement-based materials (such as concrete and mortar). The technical document "Cantero B, Seara-Paz S, Cuenca E, et al. Self-Healing Mechanisms in Concrete Cured in CO2-Saturated Environments: Synergistic Effects of BiomassForest Ash and Metakaolin[J]. Cement and Concrete Composites, 2025.DOI:10.2139 / ssrn.5158157" elucidates the mechanism of metakaolin-gypsum composite mineral self-healing agent.

[0017] Optionally, the polymer powder includes VAE-type redispersible latex powder with a glass transition temperature of -5 to 5°C; it is the core bonding and reinforcing component, forming a continuous elastic polymer film during hydration, bridging the interface gap between the repair layer and the old concrete, while filling the internal pores, replacing the bonding function of solid epoxy adhesive powder, and ensuring a bonding strength ≥3.2MPa; in addition, the polymer film can also improve the flexibility of the material, adapt to the deformation of the substrate, and reduce cracking caused by temperature stress.

[0018] Optionally, the fibers include one or more of polypropylene fibers and basalt fibers, preferably polypropylene fibers and basalt fibers in a mass ratio of 6:4. The composite of polypropylene fibers (low elastic modulus, high ductility) and basalt fibers (high elastic modulus, high strength) can optimize the mechanical properties of mortar through a "rigid-flexible" load transfer mechanism: the high hydrophilicity of polypropylene fibers in the early stage can absorb free water in cement paste, reducing plastic cracks caused by surface evaporation; basalt fibers limit the shrinkage deformation of the paste through their rigid structure; the high elastic modulus of basalt fibers in the later stage can constrain the long-term shrinkage of cement paste, while the "bridging" effect of polypropylene fibers can prevent... To reduce the propagation of shrinkage cracks, polypropylene fibers can fill tiny pores, reducing the number of interconnected pores; basalt fibers, through their rigid structure, refine the pore size. Together, they reduce the permeability coefficient of the mortar by 30% to 40% compared to a single fiber group, and the strength loss of the composite fiber group during freeze-thaw cycles (50 times) is reduced by 25% to 30% compared to a single fiber group. The flexibility of polypropylene fibers can reduce the friction between fibers and reduce agglomeration; the rigidity of basalt fibers can prevent fiber settling. Together, they improve the workability of the mortar by 10% to 15% compared to a single fiber group, which is used to inhibit crack propagation, enhance toughness, and work synergistically with polymer films to improve crack resistance and ensure long-term stability of the bonding interface.

[0019] Optionally, the powder water-reducing agent is a polycarboxylate high-efficiency water-reducing agent powder, which has good dispersibility and dissolves quickly after adding water to exert its water-reducing effect, reducing the water-cement ratio to 0.35~0.45, reducing capillary porosity, and improving density and bonding strength. The powder water-retaining agent is a calcium lignosulfonate water-retaining agent powder, which has both water-retaining and dispersing functions, reducing water loss, preventing early cracking, and has good compatibility with other solid components, ensuring sufficient hydration and enhancing structural integrity. The powder antifreeze agent is an organosilicon antifreeze agent powder, which hydrolyzes after adding water to form a hydrophobic film, enhancing low-temperature freeze-thaw resistance, while improving impermeability and reducing the damage of salt intrusion to the bonding interface. The retarder powder includes sodium tripolyphosphate retarder powder, used to control the setting time, preventing the dry powder from setting too quickly after mixing, which would affect construction, and ensuring full contact and bonding between the repair layer and the base layer.

[0020] Optionally, the solid functional repair components include: powder water-reducing agent, powder water-retaining agent, powder antifreeze agent and powder retarder in a mass ratio of 40:12:28:10, and all of them have a particle size of less than 100 μm.

[0021] A typical embodiment of the present invention provides a repair method based on the above-mentioned repair material for salt frost damage of concrete bridge railings, comprising the following steps: Clean the area to be repaired, dry mix all raw materials except water, add water and stir to obtain repair material, cover the area to be repaired with the repair material, and cure until the set age.

[0022] Optionally, cleaning the area to be repaired includes: removing loose concrete, loose rust, and oil stains from the damaged area; removing rust from exposed rebar areas until no oxide scale remains; keeping the base layer moist but without standing water after rinsing with a high-pressure water gun; and applying an epoxy interface agent when the crack width is ≥0.3mm.

[0023] Optionally, the covering method includes: spraying 2-3 coats using a high-pressure airless sprayer; or manually applying the coating to the vertical surface, following the method of applying thin layers first and then thickening them, compacting each layer, with the first layer being 2-3 mm thick, and each subsequent layer being 3-5 mm thick, until the total thickness is 5-20 mm.

[0024] The present invention will be further described below with reference to specific embodiments.

[0025] Example 1 A repair material for salt-frost damage to concrete bridge railings, composed of premixed powder and water.

[0026] The premixed powder comprises the following components in parts by weight: 30 parts composite cement, 18 parts mineral admixture, 40 parts quartz sand, 2 parts nano-reinforcing agent, 2 parts steel rust inhibitor, 2 parts expansion agent, 2 parts self-healing component, 3 parts polymer powder, 2 parts fiber, and 6 parts solid functional repair component.

[0027] The premixed powder and water are in a mass ratio of 100:14, with 15 parts water.

[0028] The solid functional repair components include: 40 parts of powder water-reducing agent, 12 parts of powder water-retaining agent, 28 parts of powder antifreeze agent, and 10 parts of powder retarder.

[0029] Composite cement consists of P in a mass ratio of 70:30 It is composed of O42.5 grade silicate cement and 42.5 grade rapid hardening sulfoaluminate cement.

[0030] The mineral admixture consists of silica fume, grade I fly ash, S95 grade slag powder and metakaolin in a mass ratio of 15:30:40:10.

[0031] The quartz sand is 100-mesh high-purity solid quartz sand with a mud content of ≤0.5%.

[0032] The nano-reinforcing agent is composed of nano-silica powder and nano-calcium carbonate powder in a mass ratio of 6:4.

[0033] The steel reinforcement rust inhibitor is composed of calcium nitrite and amine-carboxylate composite rust inhibitor in a mass ratio of 65:35. The amine-carboxylate composite rust inhibitor is obtained by mixing octadecylamine acetate and ammonium citrate in a ratio of 55:45.

[0034] The expanding agent is a CSA type solid expanding agent with a 28-day restricted expansion rate of 0.03% and a particle size of 120μm.

[0035] The self-healing component consists of a 55:45 mass ratio of Bacillus pasteurellium inoculant and a metakaolin-gypsum composite mineral self-healing agent, wherein the spore concentration of the Bacillus pasteurellium inoculant is ≥10. 9 CFU / g.

[0036] The polymer powder is a VAE-type redispersible latex powder with a glass transition temperature of 0℃ and a solid content of 99%.

[0037] The fiber is composed of polypropylene fiber and basalt fiber in a mass ratio of 6:4, with a diameter of 15±5μm and a length of 4mm.

[0038] The solid functional repair components include a solid polycarboxylate superplasticizer, calcium lignosulfonate water-retaining agent, solid organosilicon antifreeze agent, and solid sodium tripolyphosphate retarder in a mass ratio of 40:12:28:10. Among them, the solid polycarboxylate superplasticizer is a spray-dried solid powder with a water reduction rate of ≥38%, a moisture content of 4%, and a particle size of 80μm; the solid organosilicon antifreeze agent is a powdered organosilicon complex with an effective component of 92% and a particle size of 90μm; the solid sodium tripolyphosphate retarder is an anhydrous solid powder with a particle size of ≤100μm, and the setting time is controlled to 2~4h for initial setting and 4~8h for final setting.

[0039] Repair methods include: Base treatment: Remove loose concrete, rust, and oil stains from the affected areas; remove rust from exposed rebar areas until no oxide scale remains; after rinsing with a high-pressure water gun, keep the base moist but without standing water; apply epoxy interface agent when cracks are ≥0.3mm.

[0040] On-site mixing: Mix composite cement, mineral admixtures, quartz sand, nano-reinforcing agent, solid functional repair components, steel reinforcement rust inhibitor, expansion agent, self-healing components, polymer powder, and fiber according to the specified ratio. Mix with a dry powder mixer for ≥5 minutes to ensure that all solid components are evenly dispersed, without lumps or stratification, to obtain premixed powder. Seal and package the powder and transport it to the site. On-site, add water at a ratio of 14 kg to 100 kg of premixed powder and mix with a portable mixer for 4 minutes until the slurry is uniform, fine, and free of dry powder lumps. Adjust the consistency according to the construction method: adjust to a slump of 100~120 mm for spraying and 50~80 mm for manual application.

[0041] Spraying: When using spraying, use a high-pressure airless sprayer (working pressure 0.3~0.6MPa), with the nozzle 25cm away from the substrate. Spray three coats evenly, each 4±1mm thick, with an interval of ≥2 hours between coats, for a total thickness of 5~20mm. When using manual application, first apply to the vertical surface with a trowel / scraper, following the principle of "thin first, then thick, layered compaction." The first layer is 2.5±0.5mm (interface layer). After initial setting, apply subsequent layers, each 4±1mm thick, again after initial setting, until the total thickness reaches 20mm, ensuring no sagging or air bubbles. Initial setting refers to the point at which the cement paste gradually thickens after mixing with water, begins to lose plasticity, and can no longer be shaped. At this point, the cement paste has transformed from a fluid state into a pre-hardened network structure, but has not yet developed significant strength.

[0042] Subsequent maintenance: Cover with geotextile or apply curing agent within 1-2 hours after construction. Cure for ≥7 days at normal temperature (5-35℃). Take heat preservation measures at low temperature (<5℃) to keep the base layer moist and ensure cement hydration, polymer film formation and activation of self-healing components.

[0043] Example 2 A repair material for salt-frost damage to concrete bridge railings, composed of premixed powder and water.

[0044] The premixed powder comprises the following components in parts by weight: 32 parts composite cement, 20 parts mineral admixture, 38 parts quartz sand, 1.5 parts nano-reinforcing agent, 1.5 parts steel reinforcement rust inhibitor, 4 parts expansion agent, 1.5 parts self-healing component, 2.5 parts polymer powder, 1 part fiber, and 7 parts solid functional repair component.

[0045] The premixed powder and water were mixed at a mass ratio of 100:15, with 16.3 parts water.

[0046] The solid functional repair components include: 35 parts of powder water-reducing agent, 15 parts of powder water-retaining agent, 30 parts of powder antifreeze agent, and 12 parts of powder retarder.

[0047] The requirements for each raw material and the repair method are the same as in Example 1.

[0048] Example 3 A repair material for salt-frost damage to concrete bridge railings, composed of premixed powder and water.

[0049] The premixed powder comprises the following components in parts by weight: 34 parts composite cement, 16 parts mineral admixture, 39 parts quartz sand, 2.5 parts nano-reinforcing agent, 2.5 parts steel reinforcement rust inhibitor, 3.5 parts expansion agent, 2.5 parts self-healing component, 4 parts polymer powder, 3 parts fiber, and 5 parts solid functional repair component.

[0050] The premixed powder and water were mixed at a mass ratio of 100:13, with 14.5 parts water.

[0051] The solid functional repair components include: 45 parts of powder water-reducing agent, 10 parts of powder water-retaining agent, 25 parts of powder antifreeze agent, and 8 parts of powder retarder.

[0052] The requirements for each raw material and the repair method are the same as in Example 1.

[0053] Comparative Example 1 A conventional cement-based repair material comprises the following components in parts by weight: 40 parts ordinary silicate cement, 40 parts medium sand, 10 parts fly ash, 1.5 parts liquid polycarboxylate superplasticizer, 8.5 parts water, 1 part fiber, and 20 parts water.

[0054] In the repair method, the dry powder is mixed on-site, and then the liquid raw materials are mixed and added to the mixed dry powder. The mixture is stirred evenly before repair.

[0055] The requirements for other raw materials and the repair methods are the same as in Example 1.

[0056] Comparative Example 2 A repair material for salt-frost damage to concrete bridge railings, composed of premixed powder and water.

[0057] The premixed powder comprises the following components in parts by weight: 32 parts composite cement, 18 parts mineral admixture, 38 parts quartz sand, 1.5 parts nano-reinforcing agent, 1.5 parts steel reinforcement rust inhibitor, 4 parts expansion agent, 1.5 parts self-healing component, 2.5 parts polymer powder, 1 part fiber, and 7 parts solid functional repair component.

[0058] The difference from Example 1 is that metakaolin is not added to the mineral admixture.

[0059] The requirements for other raw materials and the preparation methods are the same as in Example 1.

[0060] Comparative Example 3 A repair material for salt-frost damage to concrete bridge railings, composed of premixed powder and water.

[0061] The premixed powder comprises the following components in parts by weight: 32 parts composite cement, 18 parts mineral admixture, 38 parts quartz sand, 0.9 parts nano-reinforcing agent, 1.5 parts steel reinforcement rust inhibitor, 4 parts expansion agent, 1.5 parts self-healing component, 2.5 parts polymer powder, 1 part fiber, and 7 parts solid functional repair component.

[0062] The difference from Example 1 is that no nano-calcium carbonate is added to the nano-reinforcing agent.

[0063] The requirements for other raw materials and the preparation methods are the same as in Example 1.

[0064] Comparative Example 4 A repair material for salt-frost damage to concrete bridge railings, composed of premixed powder and water.

[0065] The premixed powder comprises the following components in parts by weight: 32 parts composite cement, 18 parts mineral admixture, 38 parts quartz sand, 0.9 parts nano-reinforcing agent, 1.5 parts steel reinforcement rust inhibitor, 4 parts expansion agent, 1.5 parts self-healing component, 2.5 parts polymer powder, 1 part fiber, and 6.2 parts solid functional repair component.

[0066] The difference from Example 1 is that no sodium tripolyphosphate retarder is added to the solid functional repair component.

[0067] The requirements for other raw materials and the preparation methods are the same as in Example 1.

[0068] Performance tests were conducted in accordance with JG / T 336-2011 "Polymer Cement Mortar for Concrete Structure Repair", GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", GB / T 50164-2011 "Standard for Quality Control of Concrete", and GB / T8076-2025 "Concrete Admixtures". The results are shown in Table 1.

[0069] Table 1 Performance Test Results

[0070] It can be seen that the all-solid powder-type repair materials in each embodiment have the following advantages: Excellent strength adaptability: 28-day compressive strength of 43~47MPa, matching the strength of conventional guardrail substrates (C30~C40), avoiding stress imbalance cracking and meeting the load-bearing requirements of the repair structure. Superior salt and frost resistance: Resistant to salt freeze-dry-wet cycles >200 times, far exceeding conventional materials (≤100 times), providing long-term resistance to salt and frost erosion with a low recurrence rate. Excellent impermeability: 28-day permeability coefficient ≤1.0×10⁻⁶. -¹¹m / s effectively blocks the intrusion of salt and moisture, breaking the "penetration-freeze-thaw-corrosion" chain and inhibiting the development of diseases from the source. High bonding strength: The bonding strength with the old concrete interface is ≥3.2MPa, which is 40% higher than that of conventional materials. The repair layer is firmly bonded to the substrate and is not easy to fall off. Good flexibility and crack resistance: The polymer powder and fiber work together to reduce the brittleness of the material, adapt to the deformation of the substrate and temperature stress, and reduce the generation of secondary cracks. Low shrinkage + micro-expansion synergy: 28-day drying shrinkage ≤220με, combined with the micro-expansion effect of CSA expansion agent, further reduces cracks and ensures the integrity of the anti-seepage. Significant rust prevention effect on steel bars: The dual rust-inhibiting components work together to reduce the rust rate of steel bars to ≤0.001mm / a, effectively inhibiting exposed steel bar corrosion. Micro-crack self-repair capability: 7-day micro-crack self-repair efficiency ≥80%, which can actively repair micro-cracks in the salt-freeze environment, further sealing the seepage channels and extending the service life of the structure. Simultaneously, the synergistic effect of VAE latex powder and other components ensures high adhesion, effectively blocking the chain of salt-freezing damage and guaranteeing the long-term safe service of bridge railings. The absence of metakaolin in the mineral admixture reduces the 7-day self-healing efficiency from 85% to 50%. The absence of nano-calcium carbonate in the nano-reinforcing agent reduces density and increases shrinkage and permeability coefficients. The absence of sodium tripolyphosphate retarders in the solid functional repair components primarily affects the on-site construction speed, thus impacting construction quality, but has little impact on material properties themselves.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A material for repairing salt-frost damage to concrete bridge railings, characterized in that, The raw materials include the following parts by weight: The composition consists of 30-34 parts composite cement, 16-20 parts mineral admixture, 38-40 parts quartz sand, 1-3 parts nano-reinforcing agent, 1-3 parts steel rust inhibitor, 2-4 parts expansion agent, 1-3 parts self-healing component, 2-4 parts polymer powder, 1-3 parts fiber, 5-7 parts solid functional repair component, and 14-17 parts water. The solid functional repair components include: 35-45 parts of powder water-reducing agent, 10-15 parts of powder water-retaining agent, 25-30 parts of powder antifreeze agent, and 8-12 parts of powder retarder.

2. The material for repairing salt-frost damage to concrete bridge railings as described in claim 1, characterized in that, The composite cement comprises silicate cement and rapid-hardening sulfoaluminate cement in a mass ratio of (65~75):(25~35); preferably 70:

30.

3. The material for repairing salt-frost damage to concrete bridge railings as described in claim 1, characterized in that, The mineral admixture includes 12-22 parts of microsilica powder, 8-15 parts of nano-calcium carbonate, 28-38 parts of fly ash, and 28-38 parts of slag powder.

4. The material for repairing salt-frost damage to concrete bridge railings as described in claim 1, characterized in that, The mineral admixture comprises silica fume, fly ash, slag powder and metakaolin in a mass ratio of (10~20):(25~35):(35~45):(5~15), preferably 15:30:40:

10.

5. The material for repairing salt-frost damage to concrete bridge railings as described in claim 1, characterized in that, The nano-reinforcing agent comprises nano-silica and nano-calcium carbonate in a mass ratio of (55~65):(35~45).

6. The material for repairing salt-frost damage to concrete bridge railings as described in claim 1, characterized in that, The steel reinforcement rust inhibitor comprises calcium nitrite rust inhibitor and amine-carboxylate composite rust inhibitor in a mass ratio of (60~70):(30~40), preferably 65:35; the amine-carboxylate composite rust inhibitor comprises octadecylamine acetate and ammonium citrate in a mass ratio of (50~60):(50~40).

7. The material for repairing salt-frost damage to concrete bridge railings as described in claim 1, characterized in that, The self-healing component comprises a Bacillus pasteurization agent and a metakaolin-gypsum composite mineral self-healing agent in a mass ratio of (50~60):(40~50), preferably 55:45; Alternatively, the polymer powder may include VAE-type redispersible latex powder with a glass transition temperature of -5 to 5°C; Alternatively, the fibers may include one or more of polypropylene fibers and basalt fibers, preferably polypropylene fibers and basalt fibers in a mass ratio of 6:

4.

8. The material for repairing salt-frost damage to concrete bridge railings as described in claim 1, characterized in that, The powder water-reducing agent is polycarboxylate high-efficiency water-reducing agent powder, the powder water-retaining agent is calcium lignosulfonate water-retaining agent powder, the powder antifreeze agent is organosilicon antifreeze agent powder, and the retarder powder includes sodium tripolyphosphate retarder powder. Alternatively, the solid functional repair component may include: a powder water-reducing agent, a powder water-retaining agent, a powder antifreeze agent, and a powder retarder in a mass ratio of 40:12:28:

10.

9. A repair method based on the concrete bridge railing salt frost damage repair material as described in any one of claims 1-8, characterized in that, The steps include: cleaning the area to be repaired, mixing all raw materials except water dry, adding water and stirring to obtain the repair material, covering the area to be repaired with the repair material, and curing it until the set age.

10. The repair method as described in claim 8, characterized in that, Cleaning the areas to be repaired includes: removing loose concrete, loose rust, and oil stains from the damaged areas; removing rust from exposed rebar areas until no oxide scale remains; rinsing with a high-pressure water gun and keeping the base layer moist but without standing water; and applying an epoxy interface agent when the crack width is ≥0.3mm. Alternatively, the covering methods include: spraying with a high-pressure airless sprayer, or manually applying the coating to the vertical surface.

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