A method for preparing a water-promoted self-healing modified asphalt

Abstract

The application provides a preparation method of water-promoted self-healing modifier modified asphalt, and specifically comprises the following steps: first, polyol is dehydrated, and then polymerized with diisocyanate to obtain a prepolymer; the prepolymer is uniformly mixed with a disulfide chain extender, a gel monomer, a crosslinking agent, an initiator, a promoter and a solvent to obtain a reaction copolymer; the copolymer is heated and solidified; the solidified copolymer is uniformly mixed with a base asphalt to obtain a reaction mixture; and the reaction mixture is heated and solidified to obtain the modified asphalt with the water-promoted self-healing modifier. The application aims to provide a kind of modified asphalt which synchronously polymerizes polyurethane with dynamic covalent bond and hydrogel with high water absorption, and is used as an asphalt modifier, and prepares modified asphalt with water-promoted self-healing. The hydrogel with water absorption is introduced into the polyurethane system, through the dynamic exchange of disulfide bond and the water absorption performance of the hydrogel, so that the modified asphalt has excellent water-promoted self-healing performance.

Description

Technical Field

[0001] This invention belongs to the field of road engineering material preparation technology, specifically relating to a method for preparing water-promoted self-healing modified asphalt. Background Technology

[0002] Petroleum asphalt is currently the most widely used type of asphalt in my country, but it has the disadvantage of poor temperature sensitivity. Specifically, it is prone to rutting and swelling in the high temperatures of summer, and cracking in the low temperatures of winter. This cracking damage will seriously reduce the road surface's traffic capacity over time. Therefore, research on how to inhibit the formation of microcracks in asphalt pavements and reduce crack propagation is of great significance for improving road safety and extending road service life.

[0003] Currently, polyurethane-modified asphalt mainly employs in-situ polymerization technology. Asphalt modified with polyurethane exhibits better road performance, such as durability and high-temperature stability, significantly reducing maintenance frequency and costs. Research on self-healing polyurethane is becoming increasingly in-depth and mature. Introducing self-healing polyurethane technology into the field of asphalt pavement materials not only retains the excellent mechanical properties of modified asphalt but also utilizes the dynamic exchange function of the dynamic bond crosslinking network to achieve the self-healing properties of asphalt materials. Patent CN116426138A proposes a polyurethane-modified asphalt material with a dynamic covalent bond structure and its preparation method. From the perspective of material molecular structure, it introduces dynamic covalent bonds into the molecular structure of polyurethane-modified asphalt, endowing the asphalt with self-healing and regenerative properties. However, the self-healing index in this patent is not significantly improved compared to ordinary polyurethane-modified asphalt, and its rheological properties lack detailed description. Therefore, new methods need to be explored to address these issues and improve the practical application effect of modified asphalt.

[0004] Currently, there are no blends of materials with opposite hydrophilic and hydrophobic properties used as asphalt modifiers. However, this invention proposes a novel method to achieve water-promoted self-healing properties in modified asphalt by introducing hydrogels into a polyurethane system with self-healing properties. Hydrogels possess a highly hydrated three-dimensional network structure containing numerous polar hydrophilic groups, allowing them to swell rapidly in water while retaining a large amount of moisture. Strong hydrogen bonds exist between the molecular chains of hydrogels and polyurethanes; the introduction of the hydrogel crosslinking network can improve the crystallinity of the polyurethane phase, thereby enhancing thermal stability and mechanical properties. Since hydrogels are highly hydrophilic polymers and polyurethanes are hydrophobic polymers, copolymerizing them to prepare copolymers with unique structures exhibits excellent swelling effects in water. Water molecules penetrate the material and disrupt the hydrogen bonds between polymer chains, promoting polymer chain fluidity and thus enhancing the material's repair effect. This invention combines the water absorption of hydrogels with the dynamic exchange of dynamic covalent bonds in polyurethane, enabling modified asphalt to possess water-promoted self-healing properties. This polyurethane-hydrogel copolymer modifier has significant application value for improving pavement durability and reducing maintenance work. Summary of the Invention

[0005] This invention aims to provide a method for simultaneously polymerizing dynamically covalently bonded polyurethane with a highly absorbent hydrogel as an asphalt modifier, and preparing modified asphalt with water-promoted self-healing properties. This not only lowers the temperature required for asphalt preparation and significantly reduces energy consumption, but also, by utilizing the high hydrophilicity of the introduced hydrogel and the inherent dynamic covalent bonds of the polyurethane, not only are the rheological properties of the asphalt improved, but the modified asphalt is also endowed with water-promoted repair properties, thereby extending the service life of roads. Furthermore, this invention can solve the problems of unstable road structures, high repair costs, and demanding construction requirements caused by traditional repair methods, making it suitable for high-traffic and highway-like special road conditions.

[0006] To achieve the above objectives, the present invention employs the following scheme: a method for preparing water-promoting self-healing modified asphalt, wherein the modified asphalt comprises base asphalt and polyurethane-hydrogel, specifically including the following steps:

[0007] (1) The diol is dried in a vacuum oven to remove water, and then polymerized with diisocyanate to obtain a prepolymer;

[0008] (2) The prepolymer obtained in step (1) is uniformly mixed with disulfide chain extender, gel monomer, crosslinking agent, initiator, accelerator and solvent to obtain a reactive copolymer;

[0009] (3) The copolymer obtained in step (2) is cured by heating;

[0010] (4) Heat the base asphalt to 100-130°C to soften it, and mix the copolymer obtained by curing in step (3) with the base asphalt at a certain temperature and for a certain time until they are uniformly mixed.

[0011] (5) The mixture prepared in step (4) is heated and cured to obtain the water-promoted self-healing modified asphalt.

[0012] Furthermore, the mass ratio of the base asphalt to the polyurethane-hydrogel is 100:1 to 50. This is because the density of polyurethane differs from that of the base asphalt; excessive addition can easily lead to uneven dispersion of polyurethane in the base asphalt, increasing the difficulty of preparation; insufficient addition, on the other hand, cannot effectively improve the high and low temperature properties and self-healing properties of the asphalt.

[0013] Preferably, in step (1), the diol is one of PTMEG (polytetrahydrofuran ether diol), PPG (polypropylene glycol), or PEG (polyethylene glycol), and the diisocyanate is one of IPDI (isophorone diisocyanate), HDI (hexamethylene diisocyanate), HMDI (dicyclohexylmethane diisocyanate), or MDI (diphenylmethane diisocyanate).

[0014] Preferably, in step (1), the drying temperature of the vacuum oven is 100-140°C and the drying time is 2-6 hours.

[0015] Preferably, in step (1), the molar ratio of the diisocyanate to the diol is 3:1, the reaction temperature is 60-80°C, the reaction time is 2-4 hours, and the reaction is carried out in an inert gas atmosphere.

[0016] Preferably, in step (2), the chain extender is one or more of 2,2-diaminodiphenyl disulfide, 4,4-diaminodiphenyl disulfide, bis(2-hydroxyethyl) disulfide, and bis(4-hydroxyphenyl) disulfide; the gel monomer is one or more of AA (acrylic acid), NIPAM (N-isopropylacrylamide), and AM (acrylamide); the crosslinking agent is BIS (N,N'-methylenebis(acrylamide)); the initiator is one or more of APS (ammonium persulfate) and KPS (potassium persulfate); the accelerator is one or more of TEMED (tetramethylethylenediamine) and AIBN (azobisisobutyronitrile); and the solvent is one or more of DMF (N,N'-dimethylformamide) and DMAc (N,N'-dimethylacetamide).

[0017] Preferably, in step (2), the mass ratio of the polyurethane to the gel monomer is 4:1 to 1:1, the reaction temperature is 40 to 80°C, the reaction time is 2 to 12 hours, and the reaction is carried out in an inert gas atmosphere.

[0018] Preferably, in step (3), the heating and curing temperature is 60-120°C and the curing time is 3-7 days.

[0019] Preferably, in step (4), the base asphalt is 70# or 90# base asphalt.

[0020] Preferably, in step (5), the heating and curing temperature is 60-120°C and the curing time is 2-6 hours.

[0021] Based on the same technical concept, another aspect of the present invention is to provide a method for preparing water-promoting self-healing modifier-modified asphalt obtained by the above preparation method, comprising the following steps:

[0022] (1) Heat the base asphalt to 70-100℃ to soften it.

[0023] (2) Take a certain amount of fully cured polyurethane-hydrogel copolymer, and use a high-speed multi-functional pulverizer to obtain rice-grain-sized material for later use.

[0024] (3) Add the material prepared in step (2) to the base asphalt to obtain a mixture, heat it to 100-140°C, and then turn on the constant temperature high-speed shearing to obtain the water-promoting self-healing modifier modified asphalt material.

[0025] Furthermore, the stirring speed in step (3) is 500 to 10000 rpm, and the stirring time is 30 to 120 min.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The modified asphalt in this invention utilizes a water-promoting self-healing material as a modifier. This modifier, prepared by copolymerizing polyurethane containing a dynamic covalent bond structure with a water-absorbing hydrogel, endows the modified asphalt with water-promoting self-healing properties. This modifier possesses water-absorbing properties; when cracks or damage exist in the asphalt pavement, the hydrogel can absorb moisture from the surrounding environment or provide the necessary moisture through a sprinkler system. Simultaneously, the dynamic covalent bond structure in the polyurethane is reversible; when the hydrogel absorbs water, it can cause changes in the structure of the dynamic bonds in the polyurethane, reconnecting and repairing the damaged parts of the asphalt. Therefore, this water-promoting self-healing modifier enables the modified asphalt to automatically repair itself after damage, filling cracks and restoring its original strength and durability. This has significant application value in improving the long-term maintenance of asphalt pavements and reducing maintenance work.

[0028] Although many studies have proposed novel methods for promoting self-healing of asphalt pavements, these methods often suffer from problems such as high cost, complex construction, difficult maintenance, environmental issues, and a lack of standardization and regulations. Therefore, when selecting new asphalt materials, these issues need to be comprehensively considered and a reasonable decision made. The asphalt material modified with a water-promoting self-healing modifier provided by this invention has significant application value. This material can significantly improve pavement durability and reduce the frequency and cost of maintenance. By introducing a water-promoting self-healing modifier, this material can automatically repair itself when pavement damage occurs, restoring its original performance and function. This is of considerable significance for extending pavement service life and improving pavement stability and reliability. Therefore, this water-promoting self-healing modifier-modified asphalt material has broad application prospects and significant economic benefits. Attached Figure Description

[0029] Figure 1 This is a flowchart of a method for modifying asphalt using polyurethane-hydrogel copolymer as a modifier, as described in this invention.

[0030] Figure 2 The graph shows the relationship between the storage modulus G'-frequency of the modified asphalt in Examples 1-2 and Comparative Examples 1-2 at 60°C.

[0031] Figure 3 The graph shows the relationship between the complex modulus |G*|-frequency of the modified asphalt in Examples 1-2 and Comparative Examples 1-2 at 60°C.

[0032] Figure 4 The diagram shows the phase angle δ-frequency relationship between the modified asphalt of Examples 1-2 and Comparative Examples 1-2 at 60°C.

[0033] Figure 5 The images show the Fourier transform infrared spectra of the modified asphalt in Examples 1-2 and Comparative Examples 1-2 of this invention.

[0034] Figure 6 These are microscopic images of the modified asphalt in Examples 1-2 and Comparative Examples 1-2 of the present invention under an optical microscope.

[0035] Figure 7 The images show the self-healing properties of the modified asphalt in Examples 1-2 and Comparative Examples 1-2 of this invention in an oven at 60°C.

[0036] Figure 8 The diagram shows the self-healing properties of the modified asphalt in Examples 1-2 and Comparative Examples 1-2 of this invention in water at 60°C. Detailed Implementation

[0037] The present invention will now be described in detail with reference to embodiments and comparative examples:

[0038] I. A method for preparing water-promoted self-healing modified asphalt using PU-PNIPAM copolymer as a modifier

[0039] Example 1

[0040] A method for preparing water-promoted self-healing modified asphalt using PU-PNIPAM copolymer as a modifier;

[0041] The specific steps are as follows:

[0042] First, 20g of PTMEG with a number average molecular weight of 2000 was weighed into a three-necked flask and vacuum dried for 120 minutes at 120℃. The flask was then transferred to an 80℃ water bath, and 6.89g of IPDI and 0.03g of DBTDL (approximately 0.1% of the total mass of PTMEG and IPDI) were added. The mixture was reacted under nitrogen protection with a stirrer at 200 rpm for 2 hours to obtain a diisocyanate prepolymer. Then, 4.97g of chain extender DTDA was dissolved in 15ml of water. After the DMF solvent was stirred evenly, it was added to a three-necked flask. Then, 15.93g of monomer NIPAM, 0.194g of crosslinking agent BIS, 0.097g of initiator APS, and 0.2ml of accelerator TEMED were dissolved in DMF solvent and stirred evenly before being added to the three-necked flask. The DMF accounted for more than 50% of the total mass, and the mass ratio of polyurethane to NIPAM monomer was 2:1. The reaction was continued at 70℃ for 3 hours. The resulting material was then cast into a polytetrafluoroethylene tray and dried in a vacuum oven at 80℃ under normal pressure for 72 hours to obtain a polyurethane-hydrogel copolymer with water-promoted self-healing function, named PU-PNIPAM.

[0043] Place 50g of base asphalt in a container, heat to 120℃ and keep warm for 30 minutes. Cut the cured PU-PNIPAM into rice-grain-sized pieces, weigh 12.5g and add it to the container. Turn on the constant temperature stirring at 1000rpm for 30min. Then transfer it to a heat-insulating oven and keep it at 80℃ for 2h to obtain PU-PNIPAM copolymer modified asphalt.

[0044] Example 2

[0045] A method for preparing water-promoted self-healing modified asphalt using PU-PNIPAM copolymer as a modifier;

[0046] The specific steps are as follows:

[0047] First, 20g of PTMEG with a number average molecular weight of 2000 was weighed into a three-necked flask and vacuum dried for 120 minutes at 120℃. The flask was then transferred to an 80℃ water bath, and 6.89g of IPDI and 0.03g of DBTDL (approximately 0.1% of the total mass of PTMEG and IPDI) were added. The mixture was reacted under nitrogen protection with a stirrer at a stirring rate of 200 rpm for 2 hours to obtain a diisocyanate prepolymer. Then, 4.97g of chain extender DTDA was dissolved in 15ml of water. After the DMF solvent was stirred evenly, it was added to a three-necked flask. Then, 15.93g of monomer NIPAM, 0.194g of crosslinking agent BIS, 0.097g of initiator APS, and 0.2ml of accelerator TEMED were dissolved in DMF solvent and stirred evenly before being added to the three-necked flask. The DMF accounted for more than 50% of the total mass, and the mass ratio of polyurethane to NIPAM monomer was 2:1. The reaction was continued at 70℃ for 3 hours. The resulting material was then cast into a polytetrafluoroethylene tray and dried in a vacuum oven at 80℃ under normal pressure for 72 hours to obtain a polyurethane-hydrogel copolymer with water-promoted self-healing function, named PU-PNIPAM.

[0048] Place 50g of base asphalt in a container, heat to 120℃ and keep warm for 30 minutes. Cut the cured PU-PNIPAM into rice-grain-sized pieces, weigh 25g and add it to the container. Turn on constant temperature stirring at 1000rpm for 30 minutes. Then transfer it to a heat-insulating oven and keep it at 80℃ for 2 hours to obtain PU-PNIPAM copolymer modified asphalt.

[0049] Comparative Example 1

[0050] A modified asphalt is composed of the following raw materials in parts by weight: 100 parts of 70# base asphalt and 4 parts of SBS (styrene-butadiene-styrene block copolymer); and is prepared by the following method:

[0051] (1) Heat the 70# base asphalt to 100℃ to soften it.

[0052] (2) Add SBS to the base asphalt, heat to 180°C, start constant temperature low speed stirring, stirring speed is 500 rpm, stirring time is 30 min, and then at the same temperature, further perform high speed shearing on the asphalt, shearing speed is 5000 rpm, shearing time is 2 h, and thus obtain the modified asphalt.

[0053] Comparative Example 2

[0054] A high-performance polyurethane-modified asphalt that self-heals at room temperature is prepared using the following method:

[0055] (1) First, dehydrate 21g of polypropylene glycol, add 45ml of N,N′-dimethylacetamide solvent, and then heat it with 3.336g of isoflurane diisocyanate and 2.568g of hexamethylene diisocyanate to 80℃ for 4h under a nitrogen atmosphere to obtain a prepolymer.

[0056] (2) The prepolymer was polymerized with 3.835g of isoflurane diamine and reacted for 30min in a vacuum low temperature environment (0℃), and then reacted for 24h at 60℃. After being taken out, it was cured at 80℃ for 12h to obtain a polyurethane with multiple hydrogen bonds.

[0057] (3) The polyurethane with multiple hydrogen bonds in (2) is shredded and crushed by a high-speed multi-functional pulverizer to obtain polyurethane with multiple hydrogen bonds of rice grain size. Then, it is added to the matrix asphalt, heated to 120°C, and high-speed shearing is started. The shearing speed is 5000 rpm and the shearing time is 0.5 h to obtain the reaction mixture.

[0058] (4) The reaction mixture is heated and cured to obtain the high-performance polyurethane modified asphalt material that is self-healing at room temperature.

[0059] (5) This high-performance polyurethane modified asphalt that is self-healing at room temperature is composed of the following raw materials in parts by weight: 100 parts of 70# base asphalt and 25 parts of polyurethane.

[0060] II. Performance Testing

[0061] 1. The modified asphalt prepared in Examples 1-2 and Comparative Example 1 were subjected to rheological property testing using a dynamic shear rheometer (DSR). The temperature was maintained at 60°C, which is generally considered the highest temperature for asphalt pavements. The strain was fixed at 1%. Dynamic frequency scanning was used, with a frequency scanning range of 100–0.01 Hz, scanning from high frequency to low frequency to determine the high-temperature rheological properties of the modified asphalt. The storage modulus G' reflects the asphalt material's resistance to elastic deformation, while the composite modulus |G*| reflects the asphalt material's resistance to rutting. The larger the |G*| value, the better the resistance to rutting. The phase angle δ reflects the viscoelasticity of the material, with a value between 0 and 90°. When δ = 0°, the material exhibits pure elasticity; when δ = 90°, the material exhibits pure viscosity. For asphalt under high-temperature conditions, an excessively high δ value will lead to a sticky pavement and a decrease in rutting resistance. The lower the δ value, the better the elasticity, i.e., the greater the deformation recovery ability, and the better the rutting resistance.

[0062] The storage modulus G' of different modified asphalts varies with frequency as follows: Figure 2As shown, it can be found that the storage modulus of the modified asphalt is in the following order across the entire scanning frequency range: Example 2 > Comparative Example 2 > Comparative Example 1 > Example 1. The storage modulus of Example 1 is slightly smaller than that of Comparative Example 1. When the copolymer content is 25 parts, the elastic deformation resistance of the corresponding modified asphalt is slightly lower than that of SBS modified asphalt. When the copolymer content is 50 parts, the elastic deformation resistance of the corresponding modified asphalt is much better than that of SBS modified asphalt and better than that of general self-healing polyurethane modified asphalt.

[0063] The variation of the complex modulus |G*| of different modified asphalts with frequency is as follows: Figure 3 As shown, it can be observed that across the entire scanning frequency range, the complex modulus of the modified asphalt follows the order: Example 2 > Comparative Example 2 > Example 1 ≈ Comparative Example 1. The complex modulus of Example 1 is approximately equal to that of Comparative Example 1. When the copolymer content is 25 parts, the rutting resistance of the corresponding modified asphalt is consistent with that of SBS modified asphalt. When the copolymer content is 50 parts, the rutting resistance of the corresponding modified asphalt is significantly better than that of SBS modified asphalt and general self-healing polyurethane modified asphalt. This indicates that the copolymer-modified asphalt has better rutting resistance, and its effect on improving the rutting resistance of asphalt is superior to that of SBS, with Example 2 exhibiting the most outstanding rutting resistance.

[0064] The phase angle δ of different modified asphalts varies with frequency as follows: Figure 4 As shown, in the low-frequency region, the magnitude of the δ value satisfies Example 1 > Comparative Example 1 > Example 2 > Comparative Example 2, and the deformation resistance of the modified asphalt increases accordingly. In the high-frequency region, the magnitude of the δ value satisfies Example 1 > Comparative Example 2 > Example 2 > Comparative Example 1, and the deformation resistance of the modified asphalt increases accordingly.

[0065] 2. The modified asphalts prepared in Examples 1-2 and Comparative Examples 1-2 were characterized for their characteristic functional groups using Fourier transform infrared spectroscopy (FTIR) in the wavenumber range of 400-4000 cm⁻¹. -1 The resolution is 4cm. -1 .

[0066] Depend on Figure 5 It can be obtained that the value is between 3300-3400cm. -1 The nearby absorption peak is due to the stretching vibration of the –N–H bond, 2922 cm⁻¹. -1 and 2849cm -1 The vibrations at 1598 cm⁻¹ are caused by antisymmetric and symmetric stretching vibrations of –CH₃ and –CH₂, respectively. -1 The absorption peak at 1626 cm⁻¹ represents the bending vibration of –NH; since no C=C absorption peak appears in the PU-PNIPAM curve, it can be considered that the N-isopropylacrylamide monomer has completely reacted. -1 and 1561cm -1These are the characteristic absorption peaks of amide I and amide II, respectively, at 1359 cm⁻¹. -1 and 1308cm -1 The bimodal peak at 1626 cm⁻¹ is formed by the symmetrical deformation vibrational coupling splitting of the dimethyl group on the isopropyl group, indicating that the copolymer contains N-isopropylacrylamide structural units. Comparing the curves of Examples 1-2 with those of PU-PNIPAM and matrix bitumen, the curve at 1626 cm⁻¹ shows a higher peak due to the introduction of PU-PNIPAM in the examples. -1 and 1561cm -1 The absorption peak becomes stronger and broader.

[0067] Examples 1-2 and Comparative Example 2 and the PU-PNIPAM curves are at 1103 cm⁻¹ -1 The stretching vibration peak at the C–O–C group is characterized by the soft segment providing molecular chain extension. (3300 cm⁻¹) -1 The peak at this location is the –N–H stretching vibration peak. As can be seen from the figure, polyurethane contains this peak, while asphalt does not. Figure 5 Curves from Examples 1-2 and Comparative Examples 1-2 and Comparative Example 2 show that –NCO at 2270 cm⁻¹ -1 The disappearance of nearby vibration signals indicates that the polymerization reaction is complete and the polyurethane has been successfully prepared. In summary, no new peaks were generated in the curves of Examples 1-2, the base asphalt, and PU-PNIPAM, suggesting that the modifier and the base asphalt may be a simple physical blend.

[0068] 3. The film samples of modified asphalt prepared in Comparative Examples 1-2 and Examples 1-2 were observed using an optical microscope. Figure 6 The microstructures of the modified asphalt prepared in Comparative Examples 1-2 and Examples 1-2 are shown in the transmitted light mode, respectively. Figure 6 It can be observed that when the admixture content is 4%, SBS exhibits a sea-island structure in asphalt, while the polyurethane-hydrogel of the present invention is partially randomly dispersed in the matrix asphalt, and the overall mixture is relatively uniform.

[0069] 4. The self-healing test of this invention was conducted under 60℃ oven conditions, and the healing changes were as follows: Figure 7 As shown, strips of similar length and width were cut from Comparative Examples 1-2 and Examples 1-2, cut in the middle with a blade, and spliced ​​together. The modified asphalt was then placed in a 60℃ oven for 5 minutes. After removal from the oven, the healing of the fracture surfaces was observed. It can be seen that Examples 1 and 2 showed a certain degree of healing, while Comparative Examples 1 and 2 showed no significant healing effect. This indicates that the self-healing performance of polyurethane-hydrogel modified asphalt is superior to that of traditional SBS modified asphalt, and also superior to that of general self-healing polyurethane modified asphalt.

[0070] A self-healing test was conducted under 60℃ water conditions, and the changes before and after healing were as follows: Figure 8 As shown, strips of similar length and width were cut from Comparative Examples 1-2 and Examples 1-2, respectively. These strips were then cut in half with a blade, joined together, and the modified asphalt was soaked in 60°C water for 5 minutes. The water was then drained, and the healing of the fracture surfaces of the modified asphalt was observed. Figure 8 It was observed that Comparative Examples 1-2 and Examples 1-2 all showed different degrees of healing. The healing degree of Comparative Examples 1 and 2 was poor, and fracture marks could also be observed. Examples 1 and 2 had already swelled, and the healing degree was better than that of Comparative Examples 1 and 2. This indicates that the asphalt modified with polyurethane-hydrogel as a modifier has better healing performance in water than traditional SBS modified asphalt, and is also better than asphalt modified with general polyurethane modifier.

[0071] Will Figure 7 and Figure 8 In comparison, no difference was observed in the degree of healing between Comparative Example 1 and Comparative Example 2 in water and in air, and the degree of healing was poor. The degree of healing in water was better than that in air in Example 1 and Example 2, which proves that the modified asphalt has water-promoting healing properties after the introduction of polyurethane-hydrogel.

[0072] In summary, the modified asphalt of Example 2 has excellent high-temperature rutting resistance and deformation resistance, as well as excellent self-healing ability and water-promoted self-healing properties. Its comprehensive performance is the most outstanding and superior to traditional modified asphalt with an admixture of 4% SBS.

[0073] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention. The technologies, shapes, and structures not described in detail in the present invention are all known technologies.

Claims

1. A method for preparing water-promoted self-healing modified asphalt, characterized in that, Specifically, the following steps are included: (1) The diol is dried in a vacuum oven to remove water, and then polymerized with diisocyanate to obtain a prepolymer; (2) The prepolymer obtained in step (1) is mixed uniformly with a chain extender, a gel monomer, a crosslinking agent, an initiator, a accelerator, and a solvent to obtain a reactive copolymer; the chain extender is one or more of 2,2-diaminodiphenyl disulfide, 4,4-diaminodiphenyl disulfide, bis(2-hydroxyethyl) disulfide, and bis(4-hydroxyphenyl) disulfide; the gel monomer is one or more of acrylic acid, N-isopropylacrylamide, and acrylamide; the mass ratio of the prepolymer to the gel monomer is 4:1 to 1:

1. (3) The copolymer obtained in step (2) is cured by heating; (4) Heat the base asphalt to 100~130 ℃ to soften it. The cured copolymer obtained in step (3) is shredded and crushed by a high-speed multi-functional pulverizer to obtain a material the size of rice grains. Then, it is mixed evenly with the base asphalt at a constant temperature and high speed for a certain period of time. (5) The mixture prepared in step (4) is heated and cured to obtain the water-promoted self-healing modified asphalt.

2. The method for preparing water-promoted self-healing modified asphalt according to claim 1, characterized in that... In step (1), the diol is one of polytetrahydrofuran ether diol, polypropylene glycol, and polyethylene glycol, and the diisocyanate is one of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and diphenylmethane diisocyanate.

3. The method for preparing water-promoted self-healing modified asphalt according to claim 1, characterized in that... In step (1), the molar ratio of the diisocyanate to the diol is 3:1, the reaction temperature is 60~80 ℃, the reaction time is 2~4h, and the reaction is carried out in an inert gas atmosphere.

4. The method for preparing water-promoted self-healing modified asphalt according to claim 1, characterized in that... In step (2), the crosslinking agent is N,N'-methylenebis(acrylamide), the initiator is one or more of ammonium persulfate and potassium persulfate, the accelerator is one or more of tetramethylethylenediamine and azobisisobutyronitrile, and the solvent is one or more of N,N'-dimethylformamide and N,N'-dimethylacetamide.

5. The method for preparing water-promoted self-healing modified asphalt according to claim 1, characterized in that... In step (2), the reaction temperature is 40~80 ℃, the reaction time is 2~12h, and the reaction environment is an inert gas atmosphere.

6. The method for preparing water-promoted self-healing modified asphalt according to claim 1, characterized in that... The heating and curing temperature in step (3) is 60~120 ℃, and the curing time is 3~7 days.

7. The method for preparing water-promoted self-healing modified asphalt according to claim 1, characterized in that... The base asphalt mentioned in step (4) is 70# or 90# base asphalt.

8. The method for preparing water-promoted self-healing modified asphalt according to claim 1, characterized in that... In step (4), the mass ratio of the cured copolymer to the base asphalt is 3:7 to 7:3, the stirring speed is 500 to 10000 rpm, the stirring time is 30 to 120 min, and the heating temperature is 100 to 140 ℃.

9. The method for preparing water-promoted self-healing modified asphalt according to claim 1, characterized in that... In step (5), the heating and curing temperature is 60~120 ℃ and the curing time is 2~6h.

10. A water-promoted self-healing modified asphalt obtained by the preparation method according to any one of claims 1 to 9.

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