Rubber asphalt pouring sealant for asphalt concrete pavement crack repair and preparation method thereof

Abstract

The present application relates to the technical field of road engineering materials, and particularly relates to a rubber asphalt sealant for repairing cracks in asphalt concrete pavement and a preparation method thereof, which comprises, by weight fraction, 100 parts of road petroleum asphalt, 25-45 parts of a composite rubber system, 8-18 parts of double-modified nano-silicon dioxide, 25-42 parts of softening oil, 2-5 parts of an interface compatibilizer, 4-7 parts of a vulcanization system, 1.5-4 parts of a rubber activator, 0.8-2.5 parts of an antioxidant, and 4-9 parts of a tackifier. The present application solves the core technical defects of existing pavement sealants by optimizing the performance of the sealant from the two dimensions of material composition and preparation process through the synergistic effect of the composite rubber system, double-modified nano-filler and multiple compounded additives, and in combination with a gradient preparation process.

Description

Technical Field

[0001] This invention relates to the field of road engineering materials technology, specifically to a rubber asphalt sealant for repairing cracks in asphalt concrete pavements and its preparation method. Background Technology

[0002] Asphalt concrete pavements are prone to various cracks under the combined effects of long-term traffic loads and the natural environment. Crack repair is a key technical measure to ensure the integrity of the pavement structure and extend the service life of the road. Rubber asphalt sealant is currently the mainstream material for pavement crack repair.

[0003] Most existing road sealant uses a single rubber powder to modify asphalt. The rubber component has poor compatibility with the asphalt matrix, and the components in the system are difficult to disperse evenly. This can easily lead to imbalances in performance at high and low temperatures. The material is prone to brittleness at low temperatures and flow and slippage at high temperatures, making it unsuitable for road repair operations in complex climate zones.

[0004] Some existing technologies attempt to add nanofillers to optimize performance, but modifying nanofillers using only a single method can lead to agglomeration of nanoparticles, making it difficult to fully utilize the reinforcing effect of the fillers, and resulting in limited improvement in the mechanical properties and aging resistance of the materials.

[0005] Existing potting compounds generally use a single vulcanization system, making it difficult to achieve uniform and controllable crosslinking reactions. This results in weak elastic recovery and rapid performance degradation after thermal aging. Furthermore, traditional potting compound preparation often employs a one-step blending process, lacking gradient crosslinking and isothermal curing stages. This fails to effectively eliminate residual stress within the material, leading to cracking defects after molding, insufficient bond strength with the pavement substrate, poor water resistance, and poor construction adaptability. Such potting compounds have a short actual service life and are prone to detachment, cracking, and failure in the later stages, failing to meet the requirements for long-term stable use on high-grade highways. Therefore, the industry urgently needs to develop a potting compound with superior comprehensive performance and strong environmental adaptability for repairing cracks in asphalt concrete pavements. Summary of the Invention

[0006] The primary objective of this invention is to provide a rubber asphalt sealant for repairing cracks in asphalt concrete pavements and its preparation method.

[0007] A further objective of this invention is to provide a rubber asphalt sealant for repairing cracks in asphalt concrete pavements, characterized in that, by weight, it comprises: 100 parts of road petroleum asphalt, 25 to 45 parts of a composite rubber system, 8 to 18 parts of double-modified nano-silica, 25 to 42 parts of softening oil, 2 to 5 parts of an interface compatibilizer, 4 to 7 parts of a vulcanization system, 1.5 to 4 parts of a rubber activator, 0.8 to 2.5 parts of an antioxidant, and 4 to 9 parts of a tackifier; wherein the rubber activator is a compound of allicin and diphenyl disulfide compound in a mass ratio of 1:1.5; the antioxidant is a compound of antioxidant 4010NA and antioxidant RD in a mass ratio of 1:1; and the tackifier is a compound of hydrogenated rosin and liquid coumarone in a mass ratio of 3:2.

[0008] Preferably, the road petroleum asphalt is No. 70 road petroleum asphalt, or a compound asphalt of No. 70 road petroleum asphalt and No. 90 road petroleum asphalt.

[0009] Preferably, the composite rubber system is composed of waste tire rubber powder and recycled nitrile rubber; the waste tire rubber powder is activated by a compound of allicin and diphenyl disulfide compound as an activator, and is activated at a high temperature of 200°C to 210°C for 40 to 50 minutes; the recycled nitrile rubber is subjected to a low temperature mechanical thermal desulfurization degradation treatment at 90°C to 95°C.

[0010] Preferably, the dual-modified nano-silica is prepared by stepwise surface modification with silane coupling agent KH-550 and octadecyltrichlorosilane; The modification process is as follows: nano-silica is first ultrasonically dispersed in anhydrous ethanol, KH-550 is added and refluxed at 75°C for 3 hours, then octadecyltrichlorosilane is added and reacted at 60°C for 2.5 hours. After drying, double-modified nano-silica is obtained.

[0011] Preferably, the softening oil is a compound of naphthenic oil and aromatic oil; the interface compatibilizer is a compound of chlorosulfonated polyethylene and ethylene vinyl acetate copolymer; and the vulcanization system is a compound of sulfur, accelerator D and accelerator TMTD.

[0012] A method for preparing a rubber asphalt sealant for repairing cracks in asphalt concrete pavement includes the following steps: raw material pretreatment, compound rubber kneading and activation, gradient vulcanization and crosslinking, asphalt compound blending, and constant temperature curing and discharge.

[0013] Preferably, the raw material pretreatment involves: pulverizing the composite rubber system to 90 mesh; vacuum drying the double-modified nano-silica at 90°C for 3 hours; and heating and melting the road petroleum asphalt at 150°C to 155°C while stirring to remove impurities and air bubbles.

[0014] Preferably, the compound rubber is kneaded and activated: the compound rubber system and the rubber activator are added to a 0.4 MPa high-temperature meshing mixer and kneaded at 280°C to 310°C for 70 to 90 minutes.

[0015] Preferred method: gradient vulcanization crosslinking: first add softening oil and knead at 200°C to 215°C for 55 to 70 minutes, then add the vulcanization system and knead at the same temperature for 40 to 50 minutes.

[0016] Preferably, the asphalt composite blend is stirred and blended at 175°C to 185°C for 150 to 190 minutes; constant temperature curing and discharge is carried out at 150°C for 75 to 85 minutes, and then discharged after filtration through a 100-mesh filter.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention optimizes the performance of the potting compound from two dimensions: material composition and preparation process, through the synergistic effect of the composite rubber system, dual-modified nanofillers and multiple compounding additives, combined with a gradient preparation process, thus solving the core technical defects of existing road potting compounds. The composite rubber system, after activation and desulfurization treatment, has significantly improved compatibility with the asphalt matrix, effectively balances the high and low temperature performance of the material, enhances the elasticity and deformation recovery ability of the material, and can adapt to the crack resistance and repair needs of road surfaces in different climate regions.

[0018] 2. The dual-modified nano-silica of this invention is uniformly dispersed within the system, forming a stable reinforcing structure that significantly improves the material's mechanical properties, aging resistance, and water resistance, effectively slowing down the performance degradation rate after long-term use. The compounded vulcanization system allows for a mild and uniform cross-linking reaction, enhancing the material's high-temperature stability and structural strength, and avoiding the inherent drawbacks of uneven cross-linking with a single vulcanizing agent.

[0019] 3. The gradient vulcanization crosslinking and constant temperature curing process of this invention can fully eliminate the internal stress of the material, improve the overall uniformity and molding stability of the system, avoid cracking after the material cools down, and ensure stable and consistent product performance.

[0020] 4. The sealant prepared by this invention has a strong bond with the asphalt concrete pavement substrate, excellent water resistance and anti-aging properties, good construction adaptability, and can maintain the crack repair effect for a long time, greatly extending the pavement repair cycle.

[0021] 5. The material formula and preparation process of this invention are flexible and adjustable, and can be optimized and adjusted according to actual engineering needs, taking into account both performance and production cost. It can be adapted to various asphalt concrete pavement crack repair projects and has extremely strong engineering practical value. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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. Example

[0023] Raw materials, by weight: 100 parts of No. 70 road petroleum asphalt with a penetration of 80 × 0.1 mm and a softening point of 48 degrees Celsius; 30 parts of a composite rubber system, composed of 20-mesh waste tire rubber powder and recycled nitrile rubber, wherein the waste tire rubber powder is activated at 200 degrees Celsius for 40 minutes, and the recycled nitrile rubber is desulfurized and degraded at 90 degrees Celsius; 10 parts of double-modified nano-silica, prepared by stepwise surface modification with silane coupling agent KH-550 and octadecyltrichlorosilane, with a particle size of 35 nanometers and a specific surface area of ​​180 square meters per gram; softening oil. 30 parts, composed of naphthenic oil and aromatic oil in a mass ratio of 1.5:1; 3 parts, composed of chlorosulfonated polyethylene and ethylene vinyl acetate copolymer in a mass ratio of 2:1; 5 parts, composed of sulfur, accelerator D and accelerator TMTD in a mass ratio of 5:2:1; 2 parts, composed of allicin and diphenyl disulfide compound in a mass ratio of 1:1.5; 1 part, composed of antioxidant 4010NA and antioxidant RD in a mass ratio of 1:1; 6 parts, composed of hydrogenated rosin and liquid coumarone in a mass ratio of 3:2.

[0024] Preparation process: The first step is raw material pretreatment. The activated waste tire rubber powder is mixed with the desulfurized recycled nitrile rubber and crushed in a high-speed pulverizer at 2500 rpm for 8 minutes to obtain a composite rubber powder with a particle size of 90 mesh. The double-modified nano silica is placed in a vacuum drying oven and dried at 90 degrees Celsius for 3 hours to remove surface moisture. The No. 70 base asphalt is placed in a heating kettle, heated and melted at 150 degrees Celsius, and stirred at a constant speed of 400 rpm for 25 minutes to remove impurities and air bubbles before use.

[0025] The second step involves kneading and activating the composite rubber. The composite rubber powder and rubber activator are added to a high-temperature meshing internal mixer with a pressure of 0.4 MPa, heated to 280 degrees Celsius, and kneaded for 70 minutes. During this period, the mixture is stirred once every 20 minutes for 10 minutes each time, at a stirring speed of 900 revolutions per minute, to obtain a semi-fluid dynamic composite rubber composition.

[0026] The third step involves gradient vulcanization and crosslinking. Softening oil is added to the semi-fluid dynamic composite rubber composition, the temperature is lowered to 200 degrees Celsius, and kneading is performed for 55 minutes to fully integrate the softening oil with the composite rubber. Subsequently, the vulcanization system is added, and the mixture is kneaded at this temperature for 40 minutes with the stirring rate controlled at 1000 rpm to obtain the vulcanized modified rubber mixture.

[0027] The fourth step is asphalt compound blending. The pretreated base asphalt is heated to 175 degrees Celsius, and an interface compatibilizer and tackifier are added. The mixture is kept at this temperature and stirred for 45 minutes at a stirring speed of 650 rpm to ensure that the compatibilizer and tackifier are fully dissolved in the asphalt. Then, the vulcanized modified rubber mixture and double-modified nano silica are slowly added, and the stirring speed is adjusted to 1200 rpm. The mixture is kept at this temperature and stirred for 160 minutes. During this period, samples are taken every 30 minutes to test the uniformity of the system to ensure that each component is uniformly dispersed and free from agglomeration.

[0028] The fifth step is constant temperature curing and discharge. The blended material is cooled to 150 degrees Celsius and cured at a constant temperature for 75 minutes to eliminate internal stress and prevent cracking after cooling. Then it is cooled to 110 degrees Celsius and filtered through a 100-mesh filter to remove impurities. After discharge, it is naturally cooled to room temperature to obtain rubber asphalt potting compound. Example

[0029] Based on the technical solution of Example 1, this example focuses on optimizing the amount of double-modified nano-silica and improving the dispersion process, while keeping the other raw material parameters, raw material amounts and basic process parameters consistent.

[0030] Raw materials by weight: 100 parts of No. 70 road petroleum asphalt with a penetration of 80×0.1 mm and a softening point of 48 degrees Celsius; 30 parts of composite rubber system; 15 parts of double-modified nano silica; 30 parts of softening oil; 3 parts of interface compatibilizer; 5 parts of vulcanization system; 2 parts of rubber activator; 1 part of antioxidant; and 6 parts of tackifier.

[0031] Preparation process: The process parameters for the raw material pretreatment, compound rubber kneading and activation, gradient vulcanization and crosslinking, and constant temperature curing and discharge steps are completely consistent with those in Example 1; in the asphalt compound blending step, the blending time is extended to 180 minutes to ensure uniform dispersion of double-modified nano-silica, and the remaining parameters are consistent with those in Example 1. Example

[0032] Based on Example 2, this embodiment adjusts the amount and ratio of the composite rubber system, and simultaneously optimizes the amount of softening oil and various additives. The remaining raw material parameters and process parameters continue the basic settings of Example 2.

[0033] Raw materials, by weight: 100 parts of No. 70 road petroleum asphalt with a penetration of 80 × 0.1 mm and a softening point of 48 degrees Celsius; 35 parts of a composite rubber system, composed of 30-mesh waste tire rubber powder and recycled nitrile rubber, wherein the waste tire rubber powder is activated at 200 degrees Celsius for 40 minutes, and the recycled nitrile rubber is desulfurized and degraded at 90 degrees Celsius; 15 parts of double-modified nano-silica; 32 parts of softening oil, composed of naphthenic oil and aromatic oil in a mass ratio of 1.5:1; interface... The compatibilizer consists of 4 parts, which is a compound of chlorosulfonated polyethylene and ethylene vinyl acetate copolymer in a mass ratio of 2:1; the vulcanization system consists of 6 parts, which is a compound of sulfur, accelerator D and accelerator TMTD in a mass ratio of 5:2:1; the rubber activator consists of 2.5 parts, which is a compound of allicin and diphenyl disulfide compound in a mass ratio of 1:1.5; the antioxidant consists of 1.5 parts, which is a compound of antioxidant 4010NA and antioxidant RD in a mass ratio of 1:1; and the tackifier consists of 7 parts, which is a compound of hydrogenated rosin and liquid coumarone in a mass ratio of 3:2.

[0034] Preparation process: The process parameters for raw material pretreatment, asphalt compound blending, and constant temperature curing and discharge are completely consistent with those in Example 2; In the compound rubber kneading and activation step, the kneading temperature is adjusted to 290 degrees Celsius, the kneading time is extended to 80 minutes, and the remaining parameters are consistent with those in Example 2; In the gradient vulcanization and crosslinking step, the vulcanization and crosslinking temperature is adjusted to 210 degrees Celsius, the kneading time is extended to 60 minutes, the vulcanization holding time is extended to 45 minutes, and the remaining parameters are consistent with those in Example 2. Example

[0035] Based on Example 3, this example optimizes the amount of vulcanization system and the stirring rate, while keeping the other raw material parameters, raw material amounts and process parameters unchanged.

[0036] Raw materials by weight: 100 parts of No. 70 road petroleum asphalt with a penetration of 80×0.1 mm and a softening point of 48 degrees Celsius; 35 parts of composite rubber system; 15 parts of double-modified nano silica; 32 parts of softening oil; 4 parts of interface compatibilizer; 6.5 parts of vulcanization system, which is composed of sulfur, accelerator D and accelerator TMTD in a mass ratio of 5:2:1; 2.5 parts of rubber activator; 1.5 parts of antioxidant; and 7 parts of tackifier.

[0037] Preparation process: The process parameters for the raw material pretreatment, compound rubber kneading and activation, asphalt compound blending, and constant temperature curing and discharge steps are completely consistent with those in Example 3; in the gradient vulcanization and crosslinking step, the vulcanization and crosslinking stirring rate is adjusted to 1100 rpm, the vulcanization holding time is extended to 50 minutes, and the remaining parameters are consistent with those in Example 3. Example

[0038] Based on Example 4, this example uses a blend of No. 70 and No. 90 base asphalt, adjusts the amount of each core raw material to the upper limit of the protection scope of this invention, and simultaneously optimizes the corresponding process parameters.

[0039] The raw materials, by weight, are: 60 parts of No. 70 road petroleum asphalt with a penetration of 80 × 0.1 mm and a softening point of 48 degrees Celsius; 40 parts of No. 90 road petroleum asphalt with a penetration of 90 × 0.1 mm and a softening point of 46 degrees Celsius; 45 parts of a composite rubber system, composed of 40-mesh waste tire rubber powder and recycled nitrile rubber, wherein the waste tire rubber powder is activated at 210 degrees Celsius for 50 minutes, and the recycled nitrile rubber is desulfurized and degraded at 95 degrees Celsius; and 18 parts of double-modified nano-silica, prepared by stepwise surface modification with silane coupling agent KH-550 and octadecyltrichlorosilane, with a particle size of 30 nanometers. The specific surface area is 190 square meters per gram; 42 parts of softening oil, which is a compound of naphthenic oil and aromatic oil in a mass ratio of 1.8:1; 5 parts of interface compatibilizer, which is a compound of chlorosulfonated polyethylene and ethylene vinyl acetate copolymer in a mass ratio of 2:1; 7 parts of vulcanization system, which is a compound of sulfur, accelerator D and accelerator TMTD in a mass ratio of 5:2:1; 4 parts of rubber activator, which is a compound of allicin and diphenyl disulfide compound in a mass ratio of 1:1.5; 2.5 parts of antioxidant, which is a compound of antioxidant 4010NA and antioxidant RD in a mass ratio of 1:1; and 9 parts of tackifier, which is a compound of hydrogenated rosin and liquid coumarone in a mass ratio of 3:2.

[0040] Preparation process: The first step is raw material pretreatment. The activation temperature of waste tire rubber powder is adjusted to 210 degrees Celsius, and the activation time is extended to 50 minutes. After mixing with recycled nitrile rubber, the crushing parameters are the same as in Example 1. The drying parameters of double-modified nano-silica are the same as in Example 1. The heating temperature of the compound matrix asphalt is 155 degrees Celsius, the stirring rate is 450 revolutions per minute, and the stirring time is 28 minutes.

[0041] The second step involves kneading and activating the composite rubber. The kneading temperature is adjusted to 310 degrees Celsius, and the kneading time is extended to 90 minutes. The remaining parameters are the same as in Example 3.

[0042] The third step is gradient vulcanization crosslinking. The vulcanization crosslinking temperature is adjusted to 215 degrees Celsius, the kneading time is extended to 70 minutes, and the vulcanization holding time is extended to 48 minutes. The remaining parameters are the same as in Example 4.

[0043] The fourth step is asphalt compound blending. The asphalt compounding temperature is adjusted to 185 degrees Celsius, the stirring time of the compatibilizer and thickener is extended to 55 minutes, and the blending time is extended to 190 minutes. The remaining parameters are the same as in Example 4.

[0044] The fifth step is constant temperature curing and discharge. The constant temperature curing time is extended to 85 minutes, and the remaining parameters are the same as in Example 1. Example

[0045] Based on Example 5, this example optimizes the softening oil ratio and the dosage of various additives, adjusts the raw material dosage to the lower-middle level of the protection range, and simultaneously adjusts the corresponding process parameters.

[0046] Raw materials, by weight: 60 parts of No. 70 road petroleum asphalt with a penetration of 80×0.1 mm and a softening point of 48 degrees Celsius; 40 parts of No. 90 road petroleum asphalt with a penetration of 90×0.1 mm and a softening point of 46 degrees Celsius; 25 parts of a composite rubber system, composed of 25-mesh waste tire rubber powder and recycled nitrile rubber, wherein the waste tire rubber powder is activated at 210 degrees Celsius for 50 minutes, and the recycled nitrile rubber is desulfurized and degraded at 95 degrees Celsius; 8 parts of double-modified nano-silica; 25 parts of softening oil, composed of naphthenic oil and aromatics. The oil is compounded in a mass ratio of 1.2:1; the interface compatibilizer is 2 parts, which is compounded in a mass ratio of 2:1 by chlorosulfonated polyethylene and ethylene vinyl acetate copolymer; the vulcanization system is 4 parts, which is compounded in a mass ratio of 5:2:1 by sulfur, accelerator D and accelerator TMTD; the rubber activator is 1.5 parts, which is compounded in a mass ratio of 1:1.5 by allicin and diphenyl disulfide compound; the antioxidant is 0.8 parts, which is compounded in a mass ratio of 1:1 by antioxidant 4010NA and antioxidant RD; and the tackifier is 4 parts, which is compounded in a mass ratio of 3:2 by hydrogenated rosin and liquid coumarone.

[0047] Preparation process: The process parameters for the raw material pretreatment, compound rubber kneading and activation, gradient vulcanization and crosslinking, and constant temperature curing and discharge steps are completely consistent with those in Example 5; In the asphalt compound blending step, the blending stirring rate is adjusted to 1300 rpm, the blending time is shortened to 150 minutes, and the remaining parameters are consistent with those in Example 5.

[0048] Comparative Example 1: The composite rubber system of the present invention was replaced by 30 parts of 20-mesh waste tire rubber powder. The waste tire rubber powder was activated at 200 degrees Celsius for 40 minutes. At the same time, the double-modified nano silica was eliminated. The other raw material parameters, raw material dosage and process parameters were completely consistent with those of Example 1, so as to simulate the conventional scheme of single rubber powder modification in the prior art.

[0049] Comparative Example 2: Ten parts of single silane coupling agent KH-550 modified nano silica were used to replace the double-modified nano silica of the present invention. The nano silica had a particle size of 35 nanometers and a specific surface area of ​​180 square meters per gram. The other raw material parameters, raw material dosage and process parameters were completely consistent with those of Example 1, thereby simulating the conventional scheme of single filler modification in the prior art.

[0050] Comparative Example 3: Five parts of single sulfur were used to replace the composite vulcanization system of the present invention. The remaining raw material parameters, raw material dosage and process parameters were completely consistent with those of Example 1, thereby simulating the conventional scheme of crosslinking with a single vulcanizing agent in the prior art.

[0051] Comparative Example 4: The constant temperature curing step of the present invention is omitted. After the blending is completed, the temperature is directly reduced to 110 degrees Celsius, and impurities are removed by filtering through a 100-mesh filter. After discharge, the material is naturally cooled to room temperature. The remaining raw material parameters, raw material dosage and process parameters are completely consistent with those of Example 1, thereby simulating the conventional scheme of one-step blending without curing process in the prior art.

[0052] Comparative Example 5: The existing conventional potting compound formulation uses the following raw materials by weight: 100 parts of No. 70 road petroleum asphalt with a penetration of 80 × 0.1 mm and a softening point of 48 degrees Celsius; 30 parts of 20-mesh waste tire rubber powder (unactivated); 10 parts of ordinary nano-silica with a particle size of 35 nanometers (unmodified); 30 parts of naphthenic oil; 3 parts of chlorosulfonated polyethylene; 5 parts of sulfur; 2 parts of rubber activator (allicin); 1 part of antioxidant (antioxidant 4010NA); and 6 parts of hydrogenated rosin. The preparation process employs an existing one-step blending process, involving stirring at 175 degrees Celsius at 1000 rpm for 180 minutes, followed by direct cooling to 110 degrees Celsius, filtration, and natural cooling to room temperature, thus simulating the technical solution of existing conventional potting compounds.

[0053] Comparative Example 6: The technical solutions of Comparative Example 2 and Comparative Example 3 were simply combined, using 10 parts of single silane coupling agent KH-550 modified nano-silica and 5 parts of single sulfur. The remaining raw material parameters, raw material dosage and process parameters were completely consistent with those of Example 1, thereby simulating the technical solution of simple combination of existing technologies.

[0054] To enable those skilled in the art to fully implement this invention, the core modification process and auxiliary components are hereby disclosed as follows: Preparation process of double-modified nano-silica: Nano-silica is dispersed in anhydrous ethanol at a solid-liquid mass ratio of 1:10 and ultrasonically dispersed for 30 min; first, silane coupling agent KH-550 is added at a mass ratio of 1:10 to nano-silica, and the mixture is refluxed at 75℃ for 3 h, then filtered and washed; then octadecyltrichlorosilane is added at a mass ratio of 1:12 to nano-silica, and the mixture is reacted at 60℃ for 2.5 h, filtered, and vacuum dried to obtain double-modified nano-silica.

[0055] Activation and desulfurization process of composite rubber system: High-temperature activation of waste tire rubber powder uses a compound of allicin and diphenyl disulfide as the activator, with the mass ratio of activator to rubber powder being 1:15; Low-temperature desulfurization and degradation of recycled nitrile rubber adopts a combination of mechanical desulfurization and thermal degradation. No external desulfurizing agent is added during the desulfurization process, and the degradation of rubber molecular chains is achieved only by low-temperature insulation at 90℃-95℃.

[0056] The specific components of the core additives are as follows: the rubber activator is a mixture of allicin and diphenyl disulfide compound in a mass ratio of 1:1.5; the antioxidant is a mixture of antioxidant 4010NA and antioxidant RD in a mass ratio of 1:1; and the tackifier is a mixture of hydrogenated rosin and liquid coumarone in a mass ratio of 3:2.

[0057] Performance testing and results analysis: Test basis and items: All rubber asphalt sealants prepared in the examples and comparative examples were tested for performance in accordance with the relevant methods of the industry standard JT / T740-2024 for road rubber asphalt crack sealant and national standards such as GB / T4507 and GB / T15332. The test conditions were clear and repeatable, and the overall performance of the sealant was comprehensively evaluated.

[0058] The test items include cone penetration, softening point, low-temperature tensile elongation, compression rebound rate, viscosity at 190 degrees Celsius, heat aging cone penetration change rate, bond strength, water resistance strength retention rate, and construction adaptability.

[0059] The low-temperature tensile elongation test was conducted at a temperature of -20 degrees Celsius and a tensile rate of 50 mm per minute; the bond strength test used asphalt concrete specimens with a bond area of ​​100 square millimeters and a test rate of 10 mm per minute; the thermal aging test was conducted under constant temperature aging conditions of 163 degrees Celsius for 72 hours.

[0060] The test results are shown in Table 1 below: Table 1: Group Cone penetration (0.1 mm) Softening point (degrees Celsius) Low-temperature tensile elongation (percentage) Compression rebound rate (percentage) Viscosity at 190 degrees Celsius (Pa·s) Change rate of cone penetration during thermal aging (percentage) Bond strength (MPa) Water resistance strength retention rate (percentage) Construction adaptability Example 1 85 88 280 58 2.3 12.1 1.85 89.5 good Example 2 82 92 305 62 2.5 10.3 1.98 91.2 good Example 3 88 89 320 65 2.4 11.5 2.02 90.8 good Example 4 80 94 290 60 2.6 9.8 1.92 90.1 good Example 5 78 95 310 63 2.7 9.5 2.05 91.5 good Example 6 86 87 275 56 2.2 12.5 1.80 88.9 good Comparative Example 1 65 75 150 35 3.8 28.6 1.20 72.3 Poor Comparative Example 2 72 80 200 45 3.0 19.8 1.50 80.5 generally Comparative Example 3 70 82 180 42 3.2 22.5 1.45 78.8 generally Comparative Example 4 83 85 230 50 2.4 16.7 1.65 85.2 generally Comparative Example 5 60 72 120 30 4.2 35.3 1.10 68.7 Poor Comparative Example 6 71 81 190 43 3.1 21.2 1.48 79.6 generally Results analysis: The test results above show that the rubber asphalt potting compound prepared in each embodiment of the present invention has excellent comprehensive performance, meeting industry standards and engineering application requirements, and is significantly superior to each comparative example. It exhibits good high and low temperature performance, bonding performance, aging resistance, and construction adaptability. Example 1, as the base formulation, meets all standard requirements: cone penetration of 85 × 0.1 mm, softening point of 88 degrees Celsius, low-temperature tensile elongation of 280%, bond strength of 1.85 MPa, water resistance strength retention rate of 89.5%, and good construction adaptability. Compared with existing conventional potting compounds, it has achieved a significant performance improvement.

[0061] Example 2 increased the amount of double-modified nano-silica based on Example 1, which increased the softening point to 92 degrees Celsius, the low-temperature tensile elongation to 305%, and the thermal aging cone penetration change rate to 10.3%. This shows that optimizing the amount of double-modified nano-silica can further improve the mechanical properties and aging resistance of the potting compound without affecting its construction adaptability.

[0062] In Example 3, after optimizing the composite rubber system, the low-temperature tensile elongation increased to 320%, the compression rebound rate reached 65%, and the bond strength exceeded 2.0 MPa. This highlights that the optimized ratio of the composite rubber system can significantly improve the elasticity and bonding performance of the potting compound, making it suitable for the crack resistance requirements of roads in cold regions.

[0063] In Example 4, after adjusting the amount of vulcanization system and the stirring rate, the softening point increased to 94 degrees Celsius, the change rate of thermal aging cone penetration decreased to 9.8%, and the high-temperature stability was significantly enhanced. This indicates that the optimization of the composite vulcanization system can achieve a full and uniform cross-linking reaction, effectively improving the high-temperature anti-flow performance of the potting compound.

[0064] Example 5 uses a compound matrix asphalt with the raw material dosage reaching the upper limit of the protection range, and all properties are still excellent. The softening point is 95 degrees Celsius, the low-temperature tensile elongation is 310%, and the bond strength is 2.05 MPa. This verifies the rationality of the raw material ratio range of the present invention. Even at the upper limit of the ratio, the potting compound can still ensure good comprehensive performance, further proving the applicability of the wide ratio protection range.

[0065] Example 6 optimizes the ratio of additives to asphalt, reducing production costs while ensuring performance meets standards. Although the performance of each component is slightly lower than that of Examples 2 to 5, it is still superior to all comparative examples, demonstrating the flexibility of the formulation of this invention. It can be adjusted according to actual engineering needs, taking into account both performance and cost control.

[0066] The performance of each comparative example was significantly inferior to that of the embodiments of the present invention. Among them, comparative example 1, due to the lack of composite rubber system and double-modified nano silica, had a significant decrease in various properties, with a low-temperature tensile elongation of only 150% and a thermal aging cone penetration change rate as high as 28.6%, resulting in poor construction adaptability. This fully demonstrates that the composite rubber system and double-modified nano silica are the core of the present invention to improve the performance of potting compound, and that single rubber powder modification cannot solve the core defects of the prior art.

[0067] Comparative Example 2 uses single-modified nano-silica, but the problem of nanoparticle agglomeration is not completely solved, resulting in insufficient mechanical properties and water resistance, highlighting the significant advantages of dual-modification process compared to single modification.

[0068] Comparative Example 3, which used a single vulcanizing agent, resulted in uneven cross-linking reaction, decreased high-temperature stability and elastic recovery rate, and accelerated aging rate. This demonstrates that the composite vulcanization system can achieve mild and controllable cross-linking reaction, avoiding the inherent defects of a single vulcanizing agent.

[0069] In Comparative Example 4, the internal stress of the system could not be eliminated after the isothermal curing step was removed. The system was prone to cracking after cooling, resulting in poor moldability and a decline in all properties. This indicates that the isothermal curing step is a key process to ensure the stability of the potting compound's performance, and the existing one-step blending process cannot replace the role of this step.

[0070] Comparative Example 5 represents an existing conventional potting compound solution, which has the worst performance in all aspects and cannot meet the long-term use requirements of high-grade highways, further highlighting the technical superiority of the present invention.

[0071] Comparative Example 6 combines existing single filler modification with single vulcanizing agent technology in a simple way. Although the performance is slightly better than that of Comparative Examples 2 to 4, it is still far inferior to the embodiments of the present invention. This shows that the simple combination of existing technologies cannot achieve the technical effect of the present invention. The composite modification system and gradient process of the present invention are irreplaceable.

[0072] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A rubber asphalt sealant for repairing cracks in asphalt concrete pavements, characterized in that, The product comprises, by weight parts: 100 parts road petroleum asphalt, 25 to 45 parts composite rubber system, 8 to 18 parts double-modified nano silica, 25 to 42 parts softening oil, 2 to 5 parts interface compatibilizer, 4 to 7 parts vulcanization system, 1.5 to 4 parts rubber activator, 0.8 to 2.5 parts antioxidant, and 4 to 9 parts tackifier; wherein the rubber activator is a compound of allicin and diphenyl disulfide compound in a mass ratio of 1:1.5; wherein the antioxidant is a compound of antioxidant 4010NA and antioxidant RD in a mass ratio of 1:1; and wherein the tackifier is a compound of hydrogenated rosin and liquid coumarone in a mass ratio of 3:

2.

2. The rubber asphalt potting compound according to claim 1, characterized in that, The road petroleum asphalt is No. 70 road petroleum asphalt, or a compound asphalt of No. 70 road petroleum asphalt and No. 90 road petroleum asphalt.

3. The rubber asphalt potting compound according to claim 1, characterized in that, The composite rubber system is composed of waste tire rubber powder and recycled nitrile rubber. The waste tire rubber powder is activated by a compound of allicin and diphenyl disulfide compound, and is activated at a high temperature of 200°C to 210°C for 40 to 50 minutes. The recycled nitrile rubber is desulfurized by mechanical thermal desulfurization at a low temperature of 90°C to 95°C.

4. The rubber asphalt potting compound according to claim 1, characterized in that, The dual-modified nano-silica was prepared by stepwise surface modification with silane coupling agent KH-550 and octadecyltrichlorosilane. The modification process is as follows: nano-silica is first ultrasonically dispersed in anhydrous ethanol, KH-550 is added and refluxed at 75°C for 3 hours, then octadecyltrichlorosilane is added and reacted at 60°C for 2.5 hours. After drying, double-modified nano-silica is obtained.

5. The rubber asphalt potting compound according to claim 1, characterized in that, The softening oil is a compound of naphthenic oil and aromatic oil; the interface compatibilizer is a compound of chlorosulfonated polyethylene and ethylene vinyl acetate copolymer; the vulcanization system is a compound of sulfur, accelerator D and accelerator TMTD.

6. A method for preparing a rubber asphalt sealant for repairing cracks in asphalt concrete pavement as described in any one of claims 1-5, characterized in that, The process involves the following steps in sequence: raw material pretreatment, compound rubber kneading and activation, gradient vulcanization and crosslinking, asphalt compound blending, and constant temperature curing and discharge.

7. The preparation method according to claim 6, characterized in that, Raw material pretreatment: The composite rubber system is crushed to 90 mesh; the double-modified nano silica is vacuum dried at 90℃ for 3 hours; the road petroleum asphalt is heated and melted at 150℃ to 155℃ and stirred to remove impurities and air bubbles.

8. The preparation method according to claim 6, characterized in that, Compound rubber kneading activation: Add the compound rubber system and rubber activator to a 0.4 MPa high-temperature meshing mixer and knead at 280°C to 310°C for 70 to 90 minutes.

9. The preparation method according to claim 6, characterized in that, Gradient vulcanization crosslinking: First, add softening oil and knead at 200℃ to 215℃ for 55 to 70 minutes, then add the vulcanization system and knead at the same temperature for 40 to 50 minutes.

10. The preparation method according to claim 6, characterized in that, asphalt Compound blending: Stir and blend at 175℃ to 185℃ for 150 to 190 minutes; Constant temperature curing and discharge: Curing at 150℃ for 75 to 85 minutes, then filtering through a 100-mesh filter before discharge.