Asphalt-like binder based on waste materials and preparation method thereof

Abstract

The present invention relates to the field of preparing asphalt-like polymer materials, and more specifically, to an asphalt-like binder based on waste materials and a method for preparing the same. The present invention utilizes waste rubber, waste PET plastic, and waste grease to prepare an asphalt-like binder. This method utilizes a large amount of waste materials and achieves a high utilization rate, providing an efficient and feasible method for preparing an asphalt-like binder from waste materials. The binder's conventional technical performance and key road performance meet the standards for actual construction use, and compared to traditional asphalt binders, it offers superior performance, particularly under conditions of high or low ambient temperatures.

Description

Technical Field

[0001] The present invention relates to the field of preparation of asphalt-like polymer materials, and in particular to an asphalt-like binder based on waste materials and a preparation method thereof. Background Art

[0002] Hot-mix asphalt pavement technology is currently the most common method used in asphalt pavement construction both domestically and internationally. However, with growing awareness of environmental protection, the high energy consumption and pollution associated with hot-mix asphalt production and construction have become increasingly prominent. While cold-mix emulsified asphalt meets the environmental demands of reducing energy consumption and air pollution, its performance is insufficient and cannot meet the performance standards for high-grade highways. Consequently, some researchers have proposed replacing asphalt with polyurethane adhesives as a binder or adhesive.

[0003] Polyurethane has high bonding strength and can cure at room temperature, eliminating the need for heating and effectively protecting the environment. However, its manufacturing cost and construction difficulty are major obstacles hindering its replacement of asphalt. Consequently, numerous studies have been conducted to reduce the cost of polyurethane manufacturing, particularly the recycling of waste materials to produce polyurethane materials, which has attracted considerable attention.

[0004] Currently reported patents for using waste materials to manufacture binders range from synthesizing certain key materials used in polyurethane synthesis using waste to modifying existing binder materials using waste materials. For example, Chinese patent CN116970362A discloses a method for preparing a novel water-based polyurethane adhesive based on waste PET. By introducing a para-benzoate structure, typically found in PET, into the polyol molecular chain, this method not only improves the molecular chain's order and rigidity but also enables the recycling of PET waste, resulting in a water-based polyurethane adhesive with high bonding strength and high-temperature resistance. Chinese patent CN109320981A discloses a solid waste phosphogypsum composite modified asphalt and its preparation method. By fully utilizing solid waste phosphogypsum and rubber powder to modify asphalt, this method not only addresses the disposal issues of solid wastes such as phosphogypsum and rubber powder, reducing environmental pollution, but also further improves the pavement performance of road asphalt and reduces raw material costs for road construction, thereby achieving the multiple goals of waste utilization, environmental protection, and improved road performance. This process is simple and easy to operate, making it suitable for industrial production.

[0005] In summary, existing inventions focus on using waste materials to prepare a certain additive material or using waste materials as additives for application in pavement adhesives or binder materials. However, there are no reports on the use of waste materials as the main raw materials for the preparation of binder materials, and there is no demonstration of the feasibility of using waste materials to prepare binder materials to replace asphalt. Summary of the Invention

[0006] Based on the above-mentioned problems, the present invention provides an asphalt-like binder based on waste materials and a preparation method thereof. The main feature of the present invention is that the asphalt-like binder is prepared by using waste materials as the main raw materials. The conventional performance and road performance of the asphalt-like binder meet the technical standards and can be used as an alternative material to asphalt binder. The specific technical solution is as follows:

[0007] A method for preparing an asphalt-like binder based on waste materials comprises the following steps:

[0008] S1: Pre-processing of recycled waste rubber, waste plastic PET and waste grease;

[0009] S2: using the waste oil pretreated in S1 to prepare dimer acid via the intermediate synthesis pathway of fatty acid methyl ester;

[0010] S3: Use the waste plastic PET pretreated in S1 to prepare a polyurethane binder via the synthesis path from BHET to BHETPP;

[0011] S4: using the waste rubber particles pretreated in S1 to pre-disperse the polyurethane binder prepared in S3, and at the same time, performing anti-hydrolysis and surface adhesion improvement treatments on the polyurethane binder prepared in S3;

[0012] S5: The waste rubber particles pre-treated in S1 are added to the polyurethane binder treated in S4 to complete the preparation of the asphalt-like binder.

[0013] The method for pre-treating waste rubber and waste plastic PET described in S1 comprises:

[0014] The recycled waste rubber and waste plastic PET are washed and crushed separately, wherein the waste rubber is crushed into rubber particles with a particle size of 0.5-1.5 mm and screened through a 20-40 mesh sieve, and the waste plastic PET is crushed to a maximum diameter of less than 3 cm;

[0015] The waste oil and fat pretreatment method described in S1 comprises:

[0016] After filtering out particulate impurities from the recovered waste grease, add 0.1wt% phosphoric acid and stir in a 60℃ water bath for 45min. Then add 3wt% distilled water and continue stirring for 30min. After completion, wash with water 3-5 times and then perform reduced pressure distillation with a vacuum degree of 0.85-0.95MPa and a heating temperature of 100℃. Distill until no bubbles are generated.

[0017] The preparation of dimer acid in S2 includes two steps of preparing fatty acid methyl ester from waste oil pretreated in S1 and preparing dimer acid from fatty acid methyl ester;

[0018] The method for preparing fatty acid methyl ester comprises:

[0019] Glycerol was added to the waste oil pretreated in S1 at an alcohol-to-acid molar ratio of 0.5, and then 0.59 wt% of a magnetic catalyst was added for vacuum distillation. The reaction temperature was set at 220°C and the reaction time was 2.5 hours. After the reaction was completed, 2.1 wt% of a magnetic solid base catalyst was added, and then methanol was added at an alcohol-to-oil molar ratio of 10:1. The mixture was heated and stirred at 70°C for 1.5 hours, and the mixed liquid was allowed to stand and separate into crude glycerol and fatty acid methyl esters.

[0020] The method for preparing dimer acid from fatty acid methyl ester comprises:

[0021] 10 wt % of an active catalyst was added to the prepared fatty acid methyl ester, and the mixture was heated at 240° C. for 6 h under a nitrogen atmosphere. The obtained mixture was molecularly distilled to obtain dimer acid methyl ester, and then the dimer acid methyl ester was conventionally hydrolyzed to obtain dimer acid.

[0022] The magnetic catalyst is Al2O3-ZrO2 / Fe3O4, the magnetic solid base catalyst is K2CO3-Al2O3 / Fe3O4, and the active catalyst is activated clay.

[0023] S3 uses the waste plastic PET pretreated in S1 to prepare a polyurethane binder, including four steps of preparing BHET, preparing BHETPP, preparing a polyurethane prepolymer, and chain extension to obtain a polyurethane binder;

[0024] The method for preparing BHET comprises:

[0025] Ethylene glycol and zinc acetate catalyst were added to the waste plastic PET pretreated in S1, and the mixture was reacted at 200°C for 3 hours, then cooled to 70°C, diluted with deionized water and stirred for 30 minutes. After filtering, the filtrate was cooled below 0°C to precipitate white crystals, which were washed and dried by centrifugation to obtain diethylene glycol terephthalate (BHET);

[0026] The method for preparing BHETPP comprises:

[0027] The prepared BHET and the dimer acid prepared by S2 were mixed, and DBTDL catalyst and solvent NMP were added, and heated at 190°C under nitrogen atmosphere for 10 hours to obtain BHET-based polyester polyol (BHETPP);

[0028] The method for preparing a polyurethane prepolymer comprises:

[0029] Butanone was added to the prepared BHETPP and dissolved at 70°C, followed by the addition of hexamethylene diisocyanate (HDI) and DBTDL catalyst, and the reaction was carried out at 70°C for 1.5 hours. Then, a blocking agent, methyl ethyl ketoxime (MEKO), was added and reacted for 1 hour to obtain a polyurethane prepolymer.

[0030] The method for preparing the polyurethane binder by chain extension comprises:

[0031] The polyurethane prepolymer and the chain extender diethylenetriamine (DETA) are mixed evenly in proportion to prepare a polyurethane binder.

[0032] The mass ratio of the pretreated waste plastic PET and ethylene glycol is 1:4, and the amount of zinc acetate added is 5wt% of the pretreated waste plastic PET; the alkyd acid mixing ratio of BHET and dimer acid is 3:1, and the mixing ratio of the polyurethane prepolymer and chain extender diethylenetriamine (DETA) is 80:3.

[0033] The method of using the waste rubber particles pretreated in S1 to pre-disperse the polyurethane binder prepared in S3 includes:

[0034] Take out 5wt% of the modified polyurethane binder, add the rubber particles treated with S1 at a ratio of 1:1, and then add a dispersant. After ultrasonic treatment of the mixture for 15 minutes, stir for 30 minutes, and then mix the treated mixture into the original untreated polyurethane binder. Stir all the polyurethane binders for 1 hour.

[0035] The method for improving the anti-hydrolysis and surface adhesion properties of the polyurethane binder prepared in S3 includes:

[0036] Toluenesulfonyl isocyanate and silane coupling agent KH550 were added to the polyurethane binder prepared in S3, and the modification was completed after uniform dispersion.

[0037] The dispersant is 0.0005 wt% of PVP, the addition amount of the toluenesulfonyl isocyanate is 0.5 wt% to 2 wt%, and the addition amount of the silane coupling agent KH550 is 1 wt% to 3 wt%.

[0038] Preferably, the added amount of the toluenesulfonyl isocyanate is 1 wt %, and the added amount of the silane coupling agent KH550 is 2 wt %.

[0039] The S5 preparation method specifically includes: adding the waste rubber particles pretreated in S1 to the polyurethane binder modified in S4, the volume ratio of the polyurethane binder to the pretreated waste rubber particles is 4:1, and mixing them thoroughly to complete the preparation of the asphalt-like binder.

[0040] A bituminous binder based on waste materials is prepared by any of the above-mentioned methods for preparing bituminous binders based on waste materials.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The present invention uses waste materials as the main raw materials to prepare asphalt-like binders, which has a large amount of waste materials and a high utilization rate, and provides an efficient and feasible method for preparing asphalt-like binders using waste materials;

[0043] (2) The conventional technical performance and key technical performance of the asphalt-like binder prepared by the present invention meet the standards for actual construction use, and its performance is better than that of traditional asphalt binders, especially under road conditions with high or low ambient temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a flow chart for preparing asphalt-like binder based on waste materials according to the present invention;

[0045] Figure 2 This is a mineral aggregate gradation curve diagram used to compare the road performance of the present invention with that of asphalt binder. DETAILED DESCRIPTION

[0046] The following examples further illustrate and describe the technical solutions of the present invention. It is particularly noted that each specific embodiment is intended to be a concretization and explanation of the technical solutions and should not be construed as limiting the scope of protection of the present invention. Persons of ordinary skill in the art are entitled to modify the technical solutions of these embodiments and to substitute equivalent features for some or all of the technical features. Such modifications or substitutions do not alter the essence of the corresponding technical solutions and do not deviate from the scope of the technical solutions described in the present invention.

[0047] The reagents and instruments used in the examples can be purchased from the market, and the detection method adopts the conventional method well known in the art; based on the need to verify the performance of the binder prepared using waste materials and compare the performance with the existing asphalt binder, the detection is mainly carried out on the water absorption rate of the binder, tensile strength and elongation at break after immersion in water, contact angle, adhesion, needle penetration and softening point, force ductility test, and road performance (high temperature stability, low temperature crack resistance, water stability).

[0048] 1. Water absorption test:

[0049] The water absorption rate specimens of the binder were made according to the standard "Polyurethane Waterproof Coating" (GB / T 19250-2013). The mass change of the sample in a constant temperature water bath at 70°C was measured. The water absorption rate of the sample was calculated based on the mass difference before and after water absorption. The calculation formula is as follows:

[0050]

[0051] Where W ar - water absorption rate of the sample, %; M1- mass of the sample before water absorption, g; M2- mass of the sample after water absorption, g.

[0052] 2. Tensile strength and elongation at break test after immersion in water:

[0053] According to the standard "Determination of Tensile Properties of Plastics" (GB / T 1040.2-2006), the specimen is dumbbell-shaped with dimensions of 115×25×2mm. After the binder specimen is cured, it is immersed in a constant temperature water bath at 70°C for 3 days. Then, the test is performed using a universal tensile material testing machine with a tensile speed set at 200mm / min. The formulas for calculating tensile strength and elongation at break are as follows:

[0054]

[0055] TL is the tensile strength of the sample, MPa; F is the maximum tensile force corresponding to the fracture of the sample, N; b is the width of the fracture surface of the sample, mm; c is the thickness of the fracture surface of the sample, mm;

[0056]

[0057] E is the elongation at break of the specimen, %; L is the gauge length of the specimen at break, mm; L0 is the original gauge length of the specimen, mm.

[0058] 3. Contact angle measurement:

[0059] Referring to the sessile drop method, a tablet press was used to make the test sample into a disc, and ethylene glycol, distilled water, and formamide were used as test media to measure the sample. The optical system was combined with a CCD camera to capture a picture every 1 second, and the baseline was found. The contact angle of the imaged picture was measured within the system, and the average value was taken after multiple measurements.

[0060] 4. Binder adhesion evaluation:

[0061] The binder sample adhered to the limestone aggregate was first boiled in water for 10 minutes and then cleaned in an ultrasonic cleaner for 10 minutes. The boiling temperature was set at 80-85°C and the ultrasonic temperature was 80°C. The residual mass ratio was used to quantitatively evaluate the adhesion of the binder. The residual mass was calculated as follows:

[0062]

[0063] Where: M Ris the residual mass of the sample, g; M1 is the mass of the binder, g; M2 is the mass of the binder before ultrasonic cleaning, g; M3 is the mass of the binder after ultrasonic cleaning, g.

[0064] 5. Needle penetration and softening point test:

[0065] The penetration and softening point of the binder samples were measured with reference to JTG E20-2011 “Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering”, and the hardness and high-temperature stability of the binder and asphalt were compared and evaluated.

[0066] 6. Force ductility test

[0067] Universal tensile testing equipment was used to test the binder. The binder was formed into an "eight"-shaped mold. The specimen was placed in a 10°C water bath for two hours before testing. The test temperature was 10°C and the tensile speed was 10 mm / min. The test was terminated when the tensile force reached "0." The same sample was tested three times in parallel, and the results were averaged.

[0068] 7. Determination of road performance of cementitious materials

[0069] To facilitate comparison with asphalt binders, the mix design of the improved binder was carried out based on the current Marshall design method for asphalt mixtures and relevant specifications. The three most important road performance indicators, high-temperature stability, low-temperature crack resistance, and water stability, were also tested and compared.

[0070] High-temperature stability was determined by referring to JTG E20-2011, "Test Procedures for Asphalt and Mixtures in Highway Engineering." Binder specimens were formed using the wheel rolling method and subjected to rutting tests under standard operating conditions. Dynamic stability and rutting depth were used to evaluate the high-temperature stability of the binder. Each binder was tested three times in parallel and the average value was taken. The specimen dimensions were 300mm (length) × 300mm (width) × 50mm (thickness). The standard rutting test conditions were: test temperature 60°C ± 1°C, wheel pressure 0.7MPa ± 0.05MPa, and wheel rolling speed 42 times / min. The rutting depths at 45 minutes (t1) and 60 minutes (t2) were recorded and recorded as d1 and d2, respectively. The dynamic stability calculation formula is as follows:

[0071]

[0072] Where DS is the dynamic stability of the specimen, times / mm; d1 is the deformation corresponding to time t1, mm; d2 is the deformation corresponding to time t2, mm; C1 is the testing machine type coefficient, which is 1.0 for the crank-connecting rod-driven reciprocating operation of the loading wheel; C2 is the specimen coefficient, which is 1.0 for the 300 mm wide specimen prepared in the laboratory; and N is the reciprocating rolling speed of the test wheel, 42 times / min.

[0073] Low-temperature crack resistance was determined using the asphalt mixture bending test method outlined in JTG E20-2011, "Test Procedures for Asphalt and Mixtures in Highway Engineering." Rutting specimens of the binder were formed using the wheel rolling method and then cut into prismatic beams measuring 250 mm ± 2.0 mm (length) × 30 mm ± 2.0 mm (width) × 35 mm ± 2.0 mm (height). The stress-strain curves were measured using a UTM universal testing machine at a temperature of -10°C ± 0.5°C, with a loading rate of 50 mm / min and a beam span of 200 mm ± 0.5 mm. The flexural tensile strength, maximum flexural tensile strain, and flexural modulus were then calculated to evaluate the binder's low-temperature crack resistance. Each sample mixture was tested three times in parallel, and the average value was taken. The formulas for calculating the flexural tensile strength, maximum flexural tensile strain, and flexural modulus of the low-temperature flexural beam test are as follows:

[0074]

[0075] Where R B is the flexural tensile strength of the sample at failure, MPa; ε B is the maximum bending strain of the sample when it fails, με; S B is the bending modulus of the sample when it fails, MPa; b is the width of the cross-section sample, mm; h is the height of the cross-section sample, mm; L is the span of the sample, mm; P B is the maximum load when the specimen fails, N; d is the mid-span deflection when the specimen fails, mm.

[0076] The water stability was tested with reference to the Marshall test (T07092011) and freeze-thaw splitting strength (T07292011) of asphalt mixtures in JTG E20-2011 "Test Procedures for Asphalt and Mixtures in Highway Engineering". Marshall cylinder specimens of the binder were formed using the Marshall compaction method. The specimen size was 101.6 mm ± 0.25 mm (diameter) × 63.5 mm ± 1.3 mm (height). Among them, the immersion Marshall test divided the specimens into two groups, with 3 in each group, and placed them in a 60℃ constant temperature water bath for 30 minutes and 48 hours respectively, and then the splitting test was carried out using a UTM universal testing machine; the freeze-thaw splitting test specimens were also set up with 3. After vacuum saturation treatment, they were placed in a -18℃ environment and frozen for 16 hours, then transferred to a 60℃ constant temperature water bath for 24 hours, and finally placed in a 25℃ constant temperature water bath for no less than 2 hours, and then the splitting test was carried out using a UTM universal testing machine.

[0077] Example 1

[0078] A method for preparing an asphalt-like binder based on waste materials is as follows:

[0079] S1: Pretreatment of waste materials:

[0080] S11: washing and crushing the recycled waste rubber and waste PET respectively, wherein the waste rubber is crushed into rubber particles with a particle size of 0.5-1.5 mm, and screened through a 20-40 mesh sieve, and the waste PET is crushed into a maximum diameter of less than 3 cm;

[0081] S12: After filtering out particulate impurities from the recovered waste grease (mainly catering waste grease), add 0.1wt% phosphoric acid and stir in a 60℃ water bath for 45min, then add 3wt% distilled water and continue stirring for 30min. After completion, wash with water 3-5 times, and then perform reduced pressure distillation, set the vacuum degree to 0.85-0.95MPa, heat to 100℃, and distill until no bubbles are generated.

[0082] S2: Preparation of dimer acid:

[0083] S21: Glycerol is added to the waste oil pretreated in S12, with an alcohol-acid molar ratio of 0.5, and then 0.59wt% of Al2O3-ZrO2 / Fe3O4 magnetic catalyst is added for vacuum distillation, and the reaction temperature is set to 220°C and the reaction time is 2.5h; after the reaction is completed, 2.1wt% of K2CO3-Al2O3 / Fe3O4 magnetic solid base catalyst is added, and then methanol is added at a ratio of alcohol to oil molar ratio of 10:1, heated at 70°C and stirred for 1.5h, and then the mixed liquid is allowed to stand for stratification, the separated crude glycerol is purified and recycled, and the separated fatty acid methyl ester is set aside;

[0084] S22: 10 wt % of an activated clay catalyst is added to the fatty acid methyl ester, and the mixture is heated at 240° C. for 6 h under a nitrogen atmosphere. The obtained mixture is molecularly distilled to obtain dimer acid methyl ester, and the dimer acid methyl ester is then subjected to conventional ester hydrolysis to obtain dimer acid.

[0085] S3: Preparation of polyurethane binder:

[0086] S31: adding ethylene glycol and zinc acetate catalyst to the waste plastic PET treated in S11, wherein the mass ratio of the waste plastic PET to the ethylene glycol is 1:4, and the amount of zinc acetate added is 5 wt% of the waste plastic PET; reacting the mixture at 200° C. for 3 hours, then cooling to 70° C., adding deionized water to dilute and stirring for 30 minutes, filtering, and cooling the filtrate below 0° C. to precipitate white crystals, washing and drying by centrifugation to obtain diethylene glycol terephthalate (BHET);

[0087] S32: BHET and the dimer acid obtained in S22 were mixed in an alcohol-acid ratio of 3:1, and DBTDL catalyst and NMP solvent were added. The mixture was heated at 190°C under a nitrogen atmosphere for 10 h to obtain BHET-based polyester polyol (BHETPP);

[0088] S33: Add butanone to BHETPP and dissolve it at 70°C. Then add hexamethylene diisocyanate (HDI) and DBTDL catalyst, and react at 70°C for 1.5 hours. Then, add blocking agent methyl ethyl ketone oxime (MEKO) and react for 1 hour to obtain a polyurethane prepolymer.

[0089] S34: The polyurethane prepolymer and the chain extender diethylenetriamine (DETA) are uniformly mixed in a ratio of 80:3 to prepare a polyurethane binder.

[0090] S4: Modification of polyurethane binder:

[0091] S41: Take out 5wt% of the modified polyurethane binder, add the rubber particles treated in S11, and add 0.0005wt% of PVP dispersant. After ultrasonic treatment of the mixture for 15 minutes, stir for 30 minutes, and then mix the treated mixture into the original untreated polyurethane binder. Stir all the polyurethane binders for 1 hour.

[0092] S42: adding 1 wt% of toluenesulfonyl isocyanate and 2 wt% of silane coupling agent KH550 to the polyurethane binder treated in S41, and dispersing them evenly to complete the modification.

[0093] S5: Preparation of asphalt-like binder: Add the rubber particles processed in S11 to the polyurethane binder modified in S42, with the volume ratio of polyurethane binder to rubber particles being 4:1. Mix well to complete the preparation of asphalt-like binder.

[0094] The main polyurethane component of the prepared binder is a closed single-component type, which can be stored for a long time. When the binder is mixed for use, it only needs to be heated to 140°C to unseal. After heating, it is mixed with aggregate and powder and poured for construction. It can be initially solidified after 4-6 hours and completely solidified after 24-72 hours.

[0095] Example 2

[0096] A method for preparing an asphalt-like binder based on waste materials, wherein the preparation steps are substantially the same as those in Example 1, except that step S41 is omitted in S4.

[0097] The binders prepared in Example 1 and Example 2 were compared by contact angle measurement test (after heating and unsealing at 140°C), and the results are as follows:

[0098] Table 1 Comparison of contact angle test of binders prepared in Example 1 and Example 2

[0099]

[0100] By comparison, it can be seen that the sample plane formed by the binder prepared in Example 1 has a larger contact angle when the liquid medium is dropped on it, which proves that its surface energy is smaller, and also makes it more waterproof and the dispersion effect of rubber particles in the system is better.

[0101] Examples 3-6

[0102] A method for preparing an asphalt-like binder based on waste materials, wherein the preparation steps are basically the same as those in Example 1, except that the amounts of toluenesulfonyl isocyanate added in step S42 are 0%, 0.5%, 1.5%, and 2%, respectively.

[0103] The water absorption test, tensile strength and elongation at break were compared (after heating and unsealing at 140°C). The results are as follows:

[0104] Table 2 Comparison of the effects of different toluenesulfonyl isocyanate additions on water absorption

[0105]

[0106] Table 3 Comparison of the effects of different toluenesulfonyl isocyanate additions on tensile strength and elongation at break

[0107]

[0108] Based on the above test results, the effect of different toluenesulfonyl isocyanate addition amounts on water absorption presents a trend of first decreasing and then increasing, while the effect on tensile strength after immersion in water presents a trend of first increasing and then decreasing. The minimum water absorption occurs at a mixing ratio of 1.5%, and the maximum tensile strength occurs at a mixing ratio of 0.5%. For the elongation at break, except for the case of no addition, the effect of the amount of addition is minimal and can be ignored. Overall, selecting a 1% toluenesulfonyl isocyanate addition amount can achieve the best effect.

[0109] Examples 7-9

[0110] A method for preparing an asphalt-like binder based on waste materials, wherein the preparation steps are substantially the same as those in Example 1, except that the amounts of KH550 added in step S42 are 0%, 1%, and 3%, respectively.

[0111] Comparison was made through a binder adhesion evaluation test (after heating and unsealing at 140°C, adhering to limestone aggregate), and the results are as follows:

[0112] Table 4 Comparison of the effects of different KH550 addition amounts on the adhesion of the binder

[0113]

[0114] The test results show that the silane coupling agent KH550 significantly improves the adhesion of the binder, and the addition amount shows a trend of first increasing and then decreasing, with the optimal addition amount being 2wt%.

[0115] The asphalt-like binder prepared by the present invention uses various types of waste materials as its primary raw materials and can be used as an alternative to asphalt binder. The following comparative evaluation of key asphalt binder performance measures the substitutability of the present binder for asphalt binder. 70#A-grade petroleum asphalt, currently used in the market, was selected as a comparative example. Its conventional technical specifications are as follows:

[0116] Table 570# General Technical Specifications of Grade A Road Petroleum Asphalt

[0117]

[0118] The three conventional indicators (penetration, softening point and ductility) of the asphalt-like binder prepared in Example 1 were compared with those of the above-mentioned asphalt binder:

[0119] Table 6 Comparison of conventional indicators of the binder of the present invention and asphalt binder

[0120]

[0121]

[0122] From the comparison results, it can be seen that the asphalt-like binder prepared by the present invention can meet the performance standards of road construction binders in terms of conventional indicators. Compared with the commonly used 70#A-grade petroleum asphalt binder, it is more excellent in resisting temperature changes and load pressure.

[0123] In terms of the form of a single binder, the asphalt-like binder prepared by the present invention can replace the traditional asphalt binder. The following further demonstrates its performance and feasibility of replacement from the perspective of road performance. For the sake of comparison, the surface mixture gradation type (SMA-13) of the 70#A-grade road petroleum asphalt binder in the asphalt pavement is referenced. The specific test indicators of various aggregates and the mineral gradation are as follows:

[0124] Table 7 Coarse aggregate test indicators

[0125]

[0126]

[0127] Table 8 Fine aggregate detection indicators

[0128]

[0129] Table 9 Mineral powder detection indicators

[0130]

[0131] Table 10 Ore gradation range (gradation curve as attached Figure 2 shown)

[0132]

[0133] Based on the gradation range for SMA-13 ​​asphalt mixtures in JTG F40-2004, "Technical Specifications for Highway Asphalt Pavement Construction," the median gradation was selected as the design gradation for the comparison asphalt binder, and 6.1% was selected as the optimal asphalt binder dosage based on empirical data. Referring to the aforementioned asphalt binder gradation range, with a porosity of ≤20% as the limit, and considering the road performance characteristics of polyurethane itself, the dosage range for the binder of the present invention can be determined to be between 5% and 8%. For ease of comparison, 6.1% was also selected as the dosage for the asphalt binder of the present invention.

[0134] Comparison of high temperature stability performance, the results are as follows:

[0135] Table 11 Comparison of high temperature stability of the binder of the present invention and asphalt binder for road use

[0136]

[0137] Since polyurethane materials have a certain ability to resist high temperatures after curing, they can resist loads without significant deformation and can effectively recover the deformation caused by loads. Therefore, the high-temperature stability of polyurethane mixtures has a greater advantage over asphalt binders.

[0138] Comparison of low temperature crack resistance performance, the results are as follows:

[0139] Table 12 Comparison of low temperature crack resistance of the binder of the present invention and asphalt binder for road use

[0140]

[0141]

[0142] From the comprehensive results, the stress resistance of the binder of the present invention at low temperature is better than that of traditional asphalt materials.

[0143] The water stability performance comparison results are as follows:

[0144] Table 13 Comparison of road water stability between the present binder and asphalt binder

[0145]

[0146] From the comprehensive results, the binder of the present invention performs better than traditional asphalt materials in terms of water erosion resistance.

[0147] According to the results of comprehensive inspection and comparative tests, the performance of the asphalt-like binder prepared by the present invention meets the performance requirements of road binders, and is superior to traditional asphalt binders in both conventional binder performance and road performance. In addition, the present invention utilizes waste materials as the main raw materials, which greatly reduces the preparation cost and road use cost of polyurethane materials, and to a certain extent narrows the gap in application cost with traditional asphalt binders, especially in low-temperature environments.

Claims

1. A method for preparing an asphalt-like binder based on waste materials, characterized in that: The steps include: S1: Pre-processing of recycled waste rubber, waste plastic PET and waste grease; S2: using the waste oil pretreated in S1 to prepare dimer acid via the intermediate synthesis pathway of fatty acid methyl ester; S3: using the waste plastic PET pretreated in S1 to prepare a polyurethane binder through a synthesis path from BHET to BHET-based polyester polyol, specifically comprising four steps of preparing BHET, preparing BHET-based polyester polyol, preparing a polyurethane prepolymer, and chain extending to obtain the polyurethane binder; wherein the method for preparing the polyurethane prepolymer comprises: adding butanone to the prepared BHET-based polyester polyol and dissolving it at 70°C, then adding hexamethylene diisocyanate and DBTDL catalyst, reacting at a constant temperature of 70°C for 1.5 hours, and then adding a blocking agent methyl ethyl ketone oxime to react for 1 hour to obtain the polyurethane prepolymer; and the method for preparing the polyurethane binder by chain extension comprises: uniformly mixing the polyurethane prepolymer and the chain extender diethylenetriamine in proportion to obtain the polyurethane binder; S4: using the waste rubber particles pre-treated in S1 to pre-disperse the polyurethane binder prepared in S3, and simultaneously performing anti-hydrolysis and surface adhesion improvement treatments on the polyurethane binder prepared in S3; the anti-hydrolysis and surface adhesion improvement treatments specifically include: adding toluenesulfonyl isocyanate and silane coupling agent KH550 to the polyurethane binder prepared in S3, and dispersing them uniformly; S5: The waste rubber particles pre-treated in S1 are added to the polyurethane binder treated in S4 to complete the preparation of the asphalt-like binder.

2. The method for preparing an asphalt-like binder based on waste materials according to claim 1, wherein: The method for pre-treating waste rubber and waste plastic PET described in S1 comprises: The recycled waste rubber and waste PET are washed and crushed separately. The waste rubber is crushed into rubber particles with a particle size of 0.5-1.5 mm and screened through a 20-40 mesh sieve. The waste PET is crushed to a maximum diameter of less than 3 cm. The waste oil and fat pretreatment method described in S1 comprises: After filtering out particulate impurities from the recovered waste grease, add 0.1wt% phosphoric acid and stir in a 60℃ water bath for 45 minutes. Then add 3wt% distilled water and continue stirring for 30 minutes. After completion, wash with water 3 to 5 times and then perform reduced pressure distillation with a vacuum degree of 0.85 to 0.95MPa and a heating temperature of 100℃. Distill until no bubbles are generated.

3. The method for preparing an asphalt-like binder based on waste materials according to claim 1, wherein: The preparation of dimer acid in S2 includes two steps of preparing fatty acid methyl ester from waste oil pretreated in S1 and preparing dimer acid from fatty acid methyl ester; The method for preparing fatty acid methyl esters from waste oils and fats pretreated in S1 comprises: Glycerol was added to the waste oil pretreated by S1 at an alcohol-to-acid molar ratio of 0.5, and 0.59 wt% of a magnetic catalyst was added for vacuum distillation. The reaction temperature was set at 220°C and the reaction time was 2.5 h. After the reaction was completed, 2.1 wt% of a magnetic solid base catalyst was added, and then methanol was added at an alcohol-to-oil molar ratio of 10:

1. The mixture was heated and stirred at 70°C for 1.5 h, and the mixed liquid was allowed to stand for stratification to separate crude glycerol and fatty acid methyl esters. The method for preparing dimer acid from fatty acid methyl ester comprises: 10 wt % of an active catalyst was added to the prepared fatty acid methyl ester, and the mixture was heated at 240° C. for 6 h under a nitrogen atmosphere. The obtained mixture was molecularly distilled to obtain dimer acid methyl ester, and then the dimer acid methyl ester was conventionally hydrolyzed to obtain dimer acid.

4. The method for preparing an asphalt-like binder based on waste materials according to claim 3, wherein: The magnetic catalyst is Al2O3-ZrO2 / Fe3O4, the magnetic solid base catalyst is K2CO3-Al2O3 / Fe3O4, and the active catalyst is activated clay.

5. The method for preparing an asphalt-like binder based on waste materials according to claim 1, wherein: The method for preparing BHET comprises: Ethylene glycol and zinc acetate catalyst were added to the waste plastic PET pretreated in S1, and the mixture was reacted at 200°C for 3 hours, then cooled to 70°C, diluted with deionized water and stirred for 30 minutes. After filtering, the filtrate was cooled below 0°C to precipitate white crystals, which were then washed and dried by centrifugation to obtain BHET. The method for preparing BHET-based polyester polyol comprises: The prepared BHET and the dimer acid prepared by S2 were mixed, and DBTDL catalyst and NMP solvent were added, and the mixture was heated at 190° C. under a nitrogen atmosphere for 10 h to obtain a BHET-based polyester polyol; The mixing ratio of the polyurethane prepolymer and the chain extender diethylenetriamine is 80:

3.

6. The method for preparing an asphalt-like binder based on waste materials according to claim 5, characterized in that: The mass ratio of waste plastic PET to ethylene glycol added to the pretreated waste plastic PET is 1:4, and the amount of zinc acetate catalyst added is 5wt% of the pretreated waste plastic PET; the alkyd acid mixing ratio of BHET and dimer acid in the mixture of the prepared BHET and the dimer acid prepared by S2 is 3:

1.

7. The method for preparing an asphalt-like binder based on waste materials according to claim 1, wherein: The method of using the waste rubber particles pretreated in S1 to pre-disperse the polyurethane binder prepared in S3 includes: Take out 5wt% of the modified polyurethane binder, add the rubber particles treated with S1 at a ratio of 1:1, and then add a dispersant. After ultrasonic treatment of the mixture for 15 minutes, stir for 30 minutes, and then mix the treated mixture into the untreated original polyurethane binder. Stir all the polyurethane binders for 1 hour; The method for improving the anti-hydrolysis and surface adhesion properties of the polyurethane binder prepared in S3 includes: Toluenesulfonyl isocyanate and silane coupling agent KH550 were added to the polyurethane binder prepared in S3, and the modification was completed after uniform dispersion.

8. The method for preparing an asphalt-like binder based on waste materials according to claim 7, wherein: The dispersant is 0.0005 wt% of PVP, the addition amount of the toluenesulfonyl isocyanate is 0.5 wt% to 2 wt%, and the addition amount of the silane coupling agent KH550 is 1 wt% to 3 wt%.

9. The method for preparing an asphalt-like binder based on waste materials according to claim 1, wherein: The polyurethane binder processed in S4 is added to the waste rubber particles pretreated in S1, and the volume ratio of the polyurethane binder to the pretreated waste rubber particles is 4:

1.

10. An asphalt-like binder based on waste materials, characterized in that: The preparation method is described in any one of claims 1 to 9.

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