Water-blocking polyurethane cold patch asphalt cement, preparation method thereof and mixture

Abstract

The invention discloses a water-blocking polyurethane cold patch asphalt cement, a preparation method thereof and a mixture, and relates to the technical field of preventive maintenance of roads, the water-blocking polyurethane cold patch asphalt cement comprises the following raw materials by mass: 100 parts of 70 # matrix asphalt; 180 to 220 parts of composite polyurethane; 40-48 parts of a curing agent; 15 to 20 parts of a diluent; 8 parts of carbon black; 5-7 parts of an easy compacting agent; 1-5 parts of an anti-settling agent; 2-6 parts of a wetting agent; the molar ratio of-NCO to-OH in the composite polyurethane is in the range of 3.4 to 4.5. Compared with water-based and solvent-based systems which are mostly applied in the market at present, the problems of low strength starting speed, low strength, poor water resistance and the like are solved; the liquid composite polyurethane and the asphalt are blended for modification, the thermoplastic nature of the asphalt is changed by adjusting the proportion of soft and hard sections, and the strength and durability of the mixture are improved.

Description

Technical Field

[0001] The invention relates to the technical field of preventive road maintenance, and more specifically to a water-blocking polyurethane cold-patch asphalt binder and a preparation method and a mixture thereof. Background Art

[0002] With the rapid development of my country's economy, the construction of domestic high-grade highways has gradually reached saturation. With the increase in highway mileage, pothole disease treatment has become one of the important roles in asphalt pavement maintenance projects. At present, the pothole disease repair technology mainly uses hot-mix asphalt mixture, but the hot patch material needs to be heated on site during the construction process, and the amount is difficult to calculate, which is not suitable for small-scale use. Therefore, the existing pothole diseases on the market are mostly maintained with cold patch materials.

[0003] According to the actual use of cold patch materials to repair potholes, the common cold patch materials are mainly emulsified asphalt-based and solvent-based cold patch asphalt. When the rainfall is not large, the mechanical properties and road performance of the repaired road surface basically meet the use requirements of the road surface. However, when the rainfall increases, moisture will accumulate in the cold patch asphalt mixture, and because the repair process is to crush and remove all the damaged original surface layer mixture except the base layer, the moisture cannot be removed. Over time, the continuous accumulation of moisture has greatly reduced the mechanical properties of the cold patch asphalt mixture at this location, and the pothole repair work has to be carried out again, which has increased the amount of road work in vain. The reasons for this are nothing more than the low initial strength of the existing cold patch materials, insufficient water stability, and more pores on the surface of the cold patch asphalt mixture. In order to overcome the problem of low initial strength of cold patch material, the Chinese patent with publication number CN115710098A discloses a long-life, fast-hardening, environmentally friendly water-cured asphalt pavement cold patch material and preparation method, which uses water-cured prepolymer to quickly cure and cross-link when exposed to water to form a three-dimensional network inclusion, which quickly improves the mechanical properties and road performance of the cold patch material. However, this unmodified water-cured polyurethane reacts violently when exposed to water, generating a large number of bubbles, which is not conducive to the compaction of the mixture and makes it easier for moisture to enter the mixture.

[0004] Therefore, in view of the problem that existing cold patch materials cannot balance initial strength, water stability and surface porosity, how to develop a new water-blocking polyurethane cold patch asphalt is an urgent problem to be solved. Summary of the invention

[0005] The purpose of the present invention is to provide a water-blocking polyurethane cold patch asphalt binder and a preparation method and mixture thereof, so as to solve the problems of low initial strength, poor water stability and many surface pores of existing cold patch materials.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention provides a water-blocking polyurethane cold-patch asphalt binder, which comprises the following raw materials, measured by weight: 100 parts of 70# base asphalt; 180-220 parts of composite polyurethane; 40-48 parts of curing agent; 15-20 parts of diluent; 8 parts of carbon black; 5-7 parts of compacting agent; 1-5 parts of anti-settling agent; 2-6 parts of wetting agent; the molar ratio of -NCO / -OH in the composite polyurethane is in the range of 3.4-4.5.

[0008] By adopting the above technical scheme, the present invention adopts isocyanate and polymer polyol to prepare composite polyurethane. Among them, the isocyanate is selected from PAPI, which is a trifunctional isocyanate, and the synthesized polyurethane has a faster curing rate; the polymer polyol is selected from polyoxypropylene glycol with a molecular weight of 1000 and trihydroxy polyoxypropylene ether with a molecular weight of 3000. Doing so on the one hand enhances the compatibility between the composite polyurethane and asphalt, and enhances its early strength to a certain extent; on the other hand, by controlling the molar ratio of -NCO / -OH in the composite polyurethane and the amount of asphalt, the fluidity of the composite polyurethane is improved. When the molar ratio of -NCO / -OH increases, the hydrogen bond interaction weakens, and the viscosity of the polyurethane is significantly reduced. In addition, the increase in free isocyanate also dilutes the viscosity, which helps it to give full play to the cold mix and cold paving characteristics. In addition, under the cooperation of each component, an excellent network structure is smoothly formed in the system, which not only makes the water-blocking polyurethane cold patch asphalt have good early strength, but also can enhance the adhesion between the cold patch liquid and the aggregate, and also effectively improves the problem of poor water damage resistance during the subsequent use of the polyurethane material.

[0009] Moreover, in the present invention, the addition of the compacting agent allows 1,4-cyclohexanedimethanol diglycidyl ether to reduce the viscosity of the cold patch fluid to a certain extent at the initial stage of addition, thereby facilitating compaction during the compaction process, and can be basically completely evaporated in a short time after the compaction is completed, with little effect on the performance of the cold patch fluid. In this way, a more ideal compaction effect can be obtained, so that the strength obtained by compaction is sufficient to support the initial strength required for the cold patch asphalt mixture. At the same time, the porosity caused by the difficulty in compacting the existing cold patch materials is also reduced. Overall, the present invention effectively solves the problems of low initial strength, slow traffic opening, and difficulty in compaction of existing water-based and solvent-based cold patch asphalts, and solves the problem of poor water-blocking performance of existing cold patch asphalts.

[0010] The present invention also provides a method for preparing the water-blocking polyurethane cold patch asphalt binder, which comprises the following steps: according to the above mass parts,

[0011] S1: Composite polyurethane preparation

[0012] Dehydration process of polymer polyol: weigh a certain amount of polyoxypropylene glycol and trihydroxy polyoxypropylene ether, add them into a flask device with a stirring rod, and heat to 120°C, then use a vacuum pump to decompress the system and dehydrate it for 2 hours, then take it out and cool it to room temperature for use;

[0013] A certain mass of trifunctional isocyanate is weighed so that the mass fraction of trifunctional isocyanate to polymer polyol is 1-1.1:1.4-1.6, so that the molar ratio of -NCO / -OH is in the range of 3.4-4.5, and then the weighed and measured isocyanate is poured into a four-necked flask, and the temperature is slowly raised to a predetermined reaction temperature of 140° C., and the dried polymer polyol is added into the flask, and stirred evenly under a nitrogen atmosphere, and the composite polyurethane is obtained after reacting for 2 hours;

[0014] S2: uniformly stirring the carbon black and the composite polyurethane obtained in S1 for a stirring time of not less than 30 minutes, thereby obtaining a composite polyurethane after color change;

[0015] S3: Heat the 70# base asphalt to 145-155℃ to make it flow well, then add the diluent and stir at a speed of 1500r / min for 25-30 minutes to make the two evenly mixed;

[0016] S4: Cool the diluted asphalt prepared in step S3 to 40-50°C, add it to the color-changed composite polyurethane, add an anti-settling agent and a wetting agent, stir at a speed of 2500r / min for 30-40 minutes to evenly mix the components, and finally obtain component A of the water-blocking polyurethane cold patch asphalt after vacuum drying;

[0017] S5: The curing agent is regarded as the B component of the water-blocking polyurethane cold patch asphalt; when finally used, the A component and the B component are evenly mixed in a mass ratio of 4.6-5:1, and then 4-6 parts of the compacting agent are added, and stirred at a speed of 2000r / min for 5-10 minutes to obtain the water-blocking polyurethane cold patch asphalt binder.

[0018] Furthermore, the curing agent is composed of a catalyst, a chain extension cross-linking agent, and a solvent, wherein the catalyst is selected as dibutyltin dilaurate, which is used to improve the reaction efficiency in the reaction process and also promotes the curing process to a certain extent; the chain extension cross-linking agent is selected as dimethylthiotoluene diamine, which not only increases the molecular chain, but also introduces the reaction points of the branched chain in the generated molecular chain, and in the further reaction, the polymer molecules are cross-linked to a certain extent to form a network structure, so that some properties of the polyurethane product are improved and enhanced. The solvent is selected as common ethyl acetate.

[0019] In order to achieve the best curing effect of the curing agent, the mass ratio of dibutyltin dilaurate, dimethylthiotoluenediamine and ethyl acetate should be 1-2:5-10:25-30.

[0020] The present invention also provides a water-blocking polyurethane cold-patch asphalt mixture, which includes the following raw materials in parts by mass: 3000 parts of aggregate; 100 parts of 70# base asphalt; 180-220 parts of composite polyurethane; 40-48 parts of curing agent; 15-20 parts of diluent; 8 parts of carbon black; 5-7 parts of compacting agent; 1-5 parts of anti-settling agent; and 2-6 parts of wetting agent.

[0021] Furthermore, the aggregate should be prepared in sufficient quantity according to the aggregate grading AC-13, and then placed in an oven at 160° C. to dry and remove water for 2.5 hours.

[0022] When the site conditions cannot meet the requirements of good grading, the aggregate can be configured based on experience using 5-10mm crushed stone and machine-made sand in a mass ratio of 6-7:3-4.

[0023] In summary, due to the adoption of the above technical solution, the present invention has at least the following beneficial effects:

[0024] 1. The water-blocking polyurethane cold-patch asphalt provided by the present invention solves the problems of slow strengthening speed, low strength, poor water resistance, etc. compared with the water-based and solvent-based systems that are currently widely used on the market; the present invention adopts liquid composite polyurethane and asphalt for blending and modification, and changes the nature of asphalt thermoplasticity by adjusting the ratio of soft and hard segments, thereby increasing the strength and durability of the mixture.

[0025] 2. The present invention provides a water-blocking polyurethane cold patch asphalt, which solves the problems of low initial strength, slow traffic opening and severe water seepage in existing water-based and solvent-based cold patch asphalt by adjusting the molar ratio of -NCO / -OH and the amount of asphalt and adding a compacting agent.

[0026] 3. The water-blocking polyurethane cold-patch asphalt provided by the present invention, by adding a compacting agent, makes it difficult to compact during on-site construction and prevents the problem of secondary bulging after compaction. At the same time, controlling the porosity and density of the cold-patch asphalt after molding can also increase the water-blocking performance of the cold-patch asphalt during later use.

[0027] 4. The water-blocking polyurethane cold patch asphalt provided by the present invention can be configured as aggregates based on experience using 5-10 mm crushed stone and machine-made sand in a mass ratio of 6-7:3-4 when site conditions cannot meet good grading requirements. DETAILED DESCRIPTION

[0028] The following is a further detailed description of the construction waste roadbed structure and construction method of the present invention in combination with the scheme and embodiments, so as to make the purpose, technical scheme and advantages of the present invention more clear. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] Example 1

[0030] A method for preparing a water-blocking polyurethane cold-patch asphalt binder comprises the following steps:

[0031] (1) Preparation of polymer polyols. First, a dehydration process is performed. A certain amount of polyoxypropylene glycol and trihydroxy polyoxypropylene ether are weighed and added to a flask device with a stirring rod, and heated to 120°C. Then, a vacuum pump is used to decompress the system and dehydrate it for 2 hours. The system is taken out and cooled to room temperature for use.

[0032] (2) Weigh a certain mass of trifunctional isocyanate so that the mass fraction of trifunctional isocyanate to polymer polyol is 1:1.4, so that the molar ratio of -NCO / -OH is 3.4. Then pour the measured isocyanate into a four-necked flask and slowly heat it to a predetermined reaction temperature of 140°C. Add the dried polymer polyol into the flask, stir evenly under a nitrogen atmosphere, and react for 2 hours to obtain a composite polyurethane.

[0033] (3) Preparation of catalyst: The curing agent is composed of a catalyst, a chain extender and a cross-linking agent, and a solvent. The catalyst is selected as dibutyltin dilaurate; the chain extender and cross-linking agent is selected as dimethylthiotoluenediamine; and the solvent is selected as common ethyl acetate. It is required that the mass ratio of dibutyltin dilaurate, dimethylthiotoluenediamine, and ethyl acetate should meet 1:5:25.

[0034] (4) Add 4 parts of carbon black to every 100 parts of the prepared composite polyurethane and stir evenly. The stirring time should be no less than 30 minutes to obtain a black composite polyurethane with a completely changed color.

[0035] (5) Heat the 70# base asphalt to 145-155°C to make it flow well. Then add the diluent and stir at a speed of 1500 r / min for 25-30 minutes to make the two evenly mixed.

[0036] (6) Cool the diluted asphalt prepared in the above step (5) to 40-50°C, add it to the color-changed composite polyurethane, add an anti-settling agent and a wetting agent, and stir at a speed of 2500 r / min for 30-40 minutes to evenly mix the components. After vacuum drying, component A of this type of polyurethane cold patch material is finally obtained.

[0037] (7) The curing agent is regarded as the B component of this type of polyurethane cold patch material. When finally used, the A component and the B component are uniformly mixed in a mass ratio of 4.6:1, and then 5 parts of the easy-to-compact agent are added for every 100 parts of the mass of the solution after the A and B components are mixed, and stirred at a speed of 2000r / min for 5-10 minutes to finally complete the preparation of the binder in the cold patch material.

[0038] A method for preparing a water-blocking polyurethane cold-patch asphalt mixture comprises the following steps:

[0039] (8) The grading of the ore is prepared according to AC-13, as shown in the following table.

[0040]

[0041] (9) After that, sufficient stone material should be prepared according to the aggregate grading, and then placed in an oven at 160°C to dry and remove water for 2.5 hours.

[0042] (10) The cold patch asphalt binder prepared in step (7) is slowly added to the prepared aggregate and stirred evenly using a mixer. The stirring time should be controlled within 10 minutes. The specific stirring time should be based on the site conditions and stirred until there is no white material. This completes the preparation of the water-blocking cold patch asphalt mixture.

[0043] The construction method using the above-mentioned water-blocking cold patch asphalt mixture comprises the following steps:

[0044] (1) Lofting: The principle of straight filling of oblique holes and square filling of round holes should be adopted for lofting. The edge line of the defect repair should exceed the edge line of the defect by more than 5 cm;

[0045] (2) Chiseling: Use a milling machine or pneumatic pick to chisel away the underlying layer defects. The chiseling depth is equal to the original asphalt paving thickness of the road surface.

[0046] (3) Mixing: Mixing is done by cold mixing on site, ready for use;

[0047] (4) Paving: Before paving, the base (i.e. the surface after chiseling) is cleaned with a blower, and then the mixture is spread manually;

[0048] (5) Rolling: Rolling is carried out using a flat plate vibrating rammer, and the number of tamping times is 2 to 3 times;

[0049] (6) Maintenance: After 30 to 60 minutes of maintenance, the construction can be reopened to traffic.

[0050] In the step (2), the chiseling depth is 10 cm to 12 cm;

[0051] In the step (4), the loose paving thickness is 1:1.2;

[0052] In the step (5), the first tamping is performed immediately after paving, and the second and third tamping are performed within about 5-10 minutes after the mixture is discharged.

[0053] Example 2

[0054] A method for preparing a water-blocking polyurethane cold-patch asphalt binder is the same as that in Example 1, except that the mass fraction of trifunctional isocyanate to polymer polyol is 1:1.5, so that the molar ratio of -NCO / -OH is 3.5.

[0055] The preparation method of the curing agent is the same as that of Example 1.

[0056] The preparation method of component A of the water-blocking polyurethane cold patch binder is the same as that of Example 1.

[0057] The preparation method of the final cold patch asphalt binder is the same as that of Example 1. The difference is that the mass ratio of component A to component B is 4.7:1, and they are evenly mixed, and then 6 parts of easy compaction agent are added according to the mass of the solution after mixing components A and B for every 100 parts.

[0058] The preparation method of the water-blocking polyurethane cold patch asphalt mixture is the same as that of Example 1.

[0059] Example 3

[0060] The preparation method of the water-blocking polyurethane cold patch asphalt binder is the same as that of Example 1, except that the mass fraction of trifunctional isocyanate to polymer polyol is 1:1.6, so that the molar ratio of -NCO / -OH is 3.6.

[0061] The preparation method of the curing agent is the same as that of Example 1.

[0062] The preparation method of component A of the water-blocking polyurethane cold patch binder is the same as that of Example 1.

[0063] The preparation method of the final cold patch asphalt binder is the same as that of Example 1. The difference is that the mass ratio of component A to component B is 4.8:1, and they are evenly mixed, and then 7 parts of easy compaction agent are added according to the mass of the solution after mixing components A and B for every 100 parts.

[0064] The preparation method of the water-blocking polyurethane cold patch asphalt mixture is the same as that of Example 1.

[0065] Comparative Example 1 (without introduction of compacting agent)

[0066] The same as Example 2, except that no compacting agent is added when preparing the water-blocking cold patch asphalt binder, so that it does not have the characteristics of easy compaction and compaction.

[0067] Since there are no clear requirements in the cold patch material industry using polyurethane as an adhesive, the cold patch materials prepared in Examples 1-3 and Comparative Example 1 are subjected to freeze-thaw splitting tests (test method T0729) and immersion Marshall stability tests (test method T0709) in accordance with the Highway Asphalt Pavement Design Specifications (JTG D50-2017) to reflect water stability, i.e., hydrophobicity.

[0068] For the mixtures prepared in Examples 1-3 and Comparative Example 1, a variable speed mixing test method was used, that is, the torque used during mixing and the viscosity of the mixture at this time were correlated, and the coefficient R was used to characterize the ease of mixing (the R value range is 0-1, and the smaller the value, the easier it is to mix). The specific test results are shown in Table 2 below.

[0069] Table 2 Performance test results of different cold patch materials

[0070]

[0071] As can be seen from Table 2, there are certain performance differences compared with Examples 1-3, among which Example 2 shows better performance. Considering that the mass fraction of trifunctional isocyanate and polymer polyol is 1:1.5, the molar ratio of -NCO / -OH should be 3.5. When finally used, the mass ratio of component A and component B is 4.7:1, and then 6 parts of easy compacting agent are added according to the mass of the solution after mixing components A and B for every 100 parts.

[0072] The large change in R value of the asphalt mixture between Example 2 and Comparative Example 1, and the more serious impact on the water-immersion Marshall residual stability and freeze-thaw splitting strength of the mixture, also proves the role of the compacting agent from another perspective.

[0073] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A water-blocking polyurethane cold patch asphalt binder, characterized in that: According to the mass percentage, the raw materials include: 100 parts of 70# base asphalt; 180-220 parts of composite polyurethane; 40-48 parts of curing agent; 15-20 parts of diluent; 8 parts of carbon black; 5-7 parts of compacting agent; 1-5 parts of anti-settling agent; 2-6 parts of wetting agent; the molar ratio of -NCO / -OH in the composite polyurethane is in the range of 3.4-4.

5.

2. A method for preparing the water-blocking polyurethane cold patch asphalt binder according to claim 1, characterized in that: The method comprises the following steps: according to the above mass fractions, S1: Composite polyurethane preparation Dehydration process of polymer polyol: weigh a certain amount of polyoxypropylene glycol and trihydroxy polyoxypropylene ether, add them into a flask device with a stirring rod, and heat to 120°C, then use a vacuum pump to decompress the system and dehydrate it for 2 hours, then take it out and cool it to room temperature for use; A certain mass of trifunctional isocyanate is weighed so that the mass fraction of trifunctional isocyanate to polymer polyol is 1-1.1:1.4-1.6, so that the molar ratio of -NCO / -OH is in the range of 3.4-4.5, and then the weighed and measured isocyanate is poured into a four-necked flask, and the temperature is slowly raised to a predetermined reaction temperature of 140° C., and the dried polymer polyol is added into the flask, and stirred evenly under a nitrogen atmosphere, and the composite polyurethane is obtained after reacting for 2 hours; S2: uniformly stirring the carbon black and the composite polyurethane obtained in S1 for a stirring time of not less than 30 minutes, thereby obtaining a composite polyurethane after color change; S3: Heat the 70# base asphalt to 145-155℃ to make it flow well, then add the diluent and stir at a speed of 1500r / min for 25-30 minutes to make the two evenly mixed; S4: Cool the diluted asphalt prepared in step S3 to 40-50°C, add it to the color-changed composite polyurethane, add an anti-settling agent and a wetting agent, stir at a speed of 2500r / min for 30-40 minutes to evenly mix the components, and finally obtain component A of the water-blocking polyurethane cold patch asphalt after vacuum drying; S5: The curing agent is regarded as the B component of the water-blocking polyurethane cold patch asphalt; when finally used, the A component and the B component are evenly mixed in a mass ratio of 4.6-5:1, and then 4-6 parts of the compacting agent are added, and stirred at a speed of 2000r / min for 5-10 minutes to obtain the water-blocking polyurethane cold patch asphalt binder.

3. The method for preparing the water-blocking polyurethane cold patch asphalt binder according to claim 2, characterized in that: The curing agent is composed of a catalyst, a chain extending cross-linking agent, and a solvent, wherein the catalyst is dibutyltin dilaurate, the chain extending cross-linking agent is dimethylthiotoluene diamine, and the solvent is ethyl acetate.

4. The method for preparing the water-blocking polyurethane cold patch asphalt binder according to claim 3, characterized in that: The mass ratio of dibutyltin dilaurate, dimethylthiotoluenediamine and ethyl acetate is 1-2:5-10:25-30.

5. A water-blocking polyurethane cold patch asphalt mixture, characterized in that: According to the mass percentage, the following raw materials are included: 3000 parts of aggregate; 100 parts of 70# base asphalt; 180-220 parts of composite polyurethane; 40-48 parts of curing agent; 15-20 parts of diluent; 8 parts of carbon black; 5-7 parts of compacting agent; 1-5 parts of anti-settling agent; 2-6 parts of wetting agent.

6. The water-blocking polyurethane cold patch asphalt mixture according to claim 5, characterized in that: The aggregates mentioned above should be prepared in sufficient quantity according to the aggregate grading AC-13, and then placed in an oven at 160°C to dry and remove water for 2.5 hours.

7. The water-blocking polyurethane cold patch asphalt mixture according to claim 5, characterized in that: When the site conditions cannot meet the requirements of good grading, the aggregate can be configured based on experience using 5-10mm crushed stone and machine-made sand in a mass ratio of 6-7:3-4.

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