High-modulus asphalt based on waste rubber powder composite modification as well as preparation method and application of high-modulus asphalt

Abstract

The invention belongs to the technical field of road engineering materials, and particularly relates to high-modulus asphalt based on waste rubber powder composite modification and a preparation method and application thereof. The high-modulus asphalt is prepared from the following components in percentage by mass: 18 to 22 percent of desulfurized rubber powder, 5 to 7 percent of ethylene-vinyl acetate copolymer, 3 to 5 percent of ammonium polyphosphate and the balance of matrix asphalt. The high-modulus asphalt is prepared by carrying out desulfurization modification on the waste rubber powder and optimizing the processing technology. The high-modulus asphalt has the advantages of excellent high-temperature stability, prominent low-temperature crack resistance, long fatigue life, low cost and environment-friendly application, is suitable for high-temperature heavy-duty road pavement, and remarkably improves the durability and economical efficiency of roads.

Description

Technical Field

[0001] This invention belongs to the field of road engineering materials technology, specifically relating to a high-modulus asphalt based on waste rubber powder composite modification, its preparation method and application. Background Technology

[0002] High-modulus asphalt concrete (HMAC) is an asphalt material whose dynamic modulus (typically >14,000 MPa) is significantly improved through special modification techniques. Its core objective is to enhance the pavement's resistance to deformation and its durability. Currently, HMAC is mainly synthesized using three technical routes: hard asphalt, polymer modifiers, and high-modulus agents. While the hard asphalt route can improve the high-temperature modulus, its low-temperature performance is severely degraded. The flexural stiffness test (BBR method) shows that its creep stiffness is as high as 210 MPa at -12℃, and its low-temperature limit is only -6℃, leading to a significantly increased risk of pavement cracking in cold regions. The polymer modification route (such as SBA with high content of styrene-butadiene-styrene block copolymer (SBS)) can construct a three-dimensional network structure, but the material cost increases by more than 35%, and linear amplitude scanning (LAS) tests confirm its fatigue life (N) is limited. f (5%) Only 8,200 cycles, significantly shortening the service life of heavy-load road sections; the high-modulus agent route (such as adding high molecular weight aramid (HMA)) relies on physical miscibility to increase modulus, and no new characteristic peaks were detected in the Fourier Transform Infrared (FTIR) test. The modification mechanism is still unclear, resulting in insufficient long-term stability. In the Multi-Stress Repeated Creep Recovery (MSCR) test, J nr (3.2 kPa) reaches 0.18 kPa -1 Its resistance to rutting deteriorates significantly.

[0003] Currently, waste rubber powder (DRP) is used as an asphalt modifier, which improves the high and low temperature performance, durability, and environmental friendliness of asphalt to some extent. However, the waste rubber powder traditionally used is vulcanized rubber powder, which has defects such as unbalanced rheological properties, serious environmental pollution, and excessive temperature sensitivity. At the same time, DRP fails to absorb the light components of asphalt as needed, resulting in insufficient or excessive volume expansion and agglomeration of rubber powder particles in the asphalt. This leads to uneven dispersion of DRP, which cannot form an effective structural phase. The highest complex shear modulus G is only 9.2 kPa, which is far below the threshold of high modulus asphalt (≥10 kPa). In addition, the existing modification system has a single component function and lacks interfacial synergy, resulting in serious imbalance of performance indicators. Summary of the Invention

[0004] The purpose of this invention is to provide a high-modulus asphalt based on waste rubber powder composite modification, its preparation method and application, thereby overcoming the shortcomings of the prior art and providing a high-modulus asphalt based on waste rubber powder composite modification with outstanding low-temperature performance, low cost, environmental protection and high efficiency, meeting the stringent service requirements of high-temperature heavy-load roads.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a waste rubber powder composite modified high modulus asphalt, which is composed of the following by mass percentage: Waste rubber powder 18%-22%, ethylene-vinyl acetate copolymer (EVA) 5%-7%, ammonium polyphosphate (PPA) 3%-5%, balance is base asphalt; The waste rubber powder is desulfurized rubber powder with a metal content ≤0.02 wt%, a rubber hydrocarbon content ≥54 wt%, and an ash content ≤7.1 wt%.

[0006] Specifically, the waste rubber powder composite modified high modulus asphalt has the following composition by mass percentage: 20% waste rubber powder, 6% ethylene-vinyl acetate copolymer, 4% ammonium polyphosphate, and 70% base asphalt; or, 18% waste rubber powder, 7% ethylene-vinyl acetate copolymer, 5% ammonium polyphosphate, and 70% base asphalt; or, 22% waste rubber powder, 5% ethylene-vinyl acetate copolymer, 3% ammonium polyphosphate, and 70% base asphalt; or, 20% waste rubber powder, 7% ethylene-vinyl acetate copolymer, 5% ammonium polyphosphate, and 68% base asphalt.

[0007] In practical applications, high-modulus asphalt modified with waste rubber powder of specific compositions can be selected according to the specific application scenario. The base asphalt serves as a continuous phase carrier. After the waste rubber powder swells, it releases flexible molecular chains, absorbing the light components of the asphalt (aromatic and saturated components), with a volume expansion rate >200%, forming an elastic dispersed phase and improving low-temperature deformation capability. EVA crystallizes and strengthens, constructing a rigid framework. PPA bridges the interface between waste rubber powder, EVA, and base asphalt, forming a network bridge. This invention, through topological reconstruction of "elastic particles (DRP) + rigid framework (EVA) + interfacial catalyst (PPA)," enables the EVA crystalline region and the PPA-reinforced asphaltene network to co-construct a high-modulus framework, improving high-temperature performance; the flexible chains of DRP and the molecular chains released by PPA bond breaking synergistically toughen and improve low-temperature resistance; and the hydrogen bond network bridged by PPA dissipates stress energy, improving fatigue life.

[0008] In some other embodiments, the density of the ethylene-vinyl acetate copolymer is 0.9-1.0 g / cm³. 3 It has a melting point of 100-110℃ and a molecular weight of 80,000-100,000 g / mol.

[0009] Specifically, the density of the ethylene-vinyl acetate copolymer is 0.945 g / cm³. 3 Melting point 103℃ In some other embodiments, the density of the ammonium polyphosphate is 1.80-2.0 g / cm³. 3 The thermal decomposition temperature is 280-290 ℃, and the ammonium polyphosphate is selected from one or more of type II ammonium polyphosphate with a degree of polymerization n≥1000 and coated ammonium polyphosphate. Specifically, the density of ammonium polyphosphate is 1.85 g / cm³. 3 The thermal decomposition temperature is 289 ℃.

[0010] In some other embodiments, the base asphalt is 70# road petroleum asphalt with a penetration of 70 / 0.1mm-72 / 0.1mm and a softening point of 45-50℃.

[0011] In some other implementations, high-modulus asphalt meets the following performance indicators: Complex shear modulus G at 60℃, 10Hz, and 12% * ≥10kPa; In the BBR test, the low-temperature limit temperature is ≤-12℃ under m≥0.3 and S≤300MPa. Low-temperature performance meets the following requirements: creep stiffness S≤190MPa at -18℃, creep rate m≥0.35 at -12℃; High-temperature performance meets: Rutting factor G * / sinδ (64℃) ≥ 5.0 kPa, irreversible creep compliance J nr (3.2 kPa) ≤ 0.15 kPa -1 ; Under conditions of 25℃ and 2.5% strain, the fatigue life N f Fatigue life N ≥15,000 cycles at 25℃ and 2.5% strain f ≥15,000 times.

[0012] In a second aspect, the present invention provides a method for preparing waste rubber powder composite modified high modulus asphalt according to the first aspect, comprising the following steps: (1) Heating the base asphalt to obtain liquid base asphalt; (2) Waste rubber powder is added to the liquid matrix asphalt and sheared and mixed to obtain the first mixture; (3) PPA and EVA are added to the first mixture in sequence, and shearing and mixing are continued to obtain the second mixture; (4) The second mixture is developed into a mold to obtain waste rubber powder composite modified high modulus asphalt.

[0013] In some other embodiments, in step (1), the heating temperature of the base asphalt is 140-160°C; In step (2), the waste rubber powder is added at a temperature of 145-155℃; In step (4), the temperature for development and shaping is 140–160℃, and the development time is 0.4–0.6 h; In step (2) or step (3), the rotational speed of shear mixing is 4500–5500 r / min and the time is 0.4–0.6 h.

[0014] In some other embodiments, the waste rubber powder in step (2) is desulfurized rubber powder. The preparation method of desulfurized rubber powder is as follows: vulcanized rubber powder is mixed with chemical desulfurizing agent and stirred to generate desulfurized rubber powder.

[0015] In some other embodiments, the mass ratio of vulcanized rubber powder to chemical desulfurizer is 1:(0.05-0.1); Chemical desulfurizing agents are mercaptoamine compounds or alkylphenol polyoxyethylene ethers; The temperature for stirring the reaction is 40–60℃, and the time is 30–60 min; Preferably, the chemical desulfurizing agent is zinc dibutyldithiocarbamate, OP-10, zinc dimethyldithiocarbamate, or 1-butyl-3-methylimidazolium acetate.

[0016] Thirdly, the present invention provides the application of waste rubber powder composite modified high modulus asphalt in high-temperature heavy-load roads, bridge deck paving and airport runways.

[0017] The beneficial effects of this invention are: (1) This invention introduces a ternary composite system of high-content waste rubber powder (DRP) (18%-22%), ethylene-vinyl acetate copolymer (EVA), and ammonium polyphosphate (PPA) through collaborative innovation, which has both economic and environmental benefits: waste rubber powder (DRP) replaces more than 30% of polymer raw materials, reducing costs by 25%-40%. It has no swelling network structure, reduces the volatilization of lightweight components, and meets the standards for green road materials.

[0018] (2) The present invention achieves three major breakthroughs in the waste rubber powder composite modified high modulus asphalt prepared by optimizing the shearing process (5000±500r / min, development time 0.5±0.1 hours): a revolutionary improvement in low temperature performance, synergistic optimization of high temperature and fatigue performance, and dual advantages in environmental protection and economy.

[0019] (3) The product obtained by this invention has high modulus characteristics (G*≥13.3kPa), outstanding low temperature crack resistance and long service capability, and completely overcomes the technical bottleneck of low temperature embrittlement and high cost of traditional high modulus asphalt. It is particularly suitable for high temperature heavy load roads, highways in cold regions and long-life pavement projects, significantly improves road durability and reduces the whole life cycle cost, and has broad prospects for industrial application. Attached Figure Description The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1 The high-temperature stability and rutting resistance of the high-modulus asphalt prepared in Example 1 (DPA) and Comparative Examples 1-4 of this invention are shown, where A represents high-temperature stability and B represents rutting resistance. Figure 2 The low-temperature crack resistance of high-modulus asphalt prepared in Example 1 (DPA) and Comparative Examples 1-4 is shown. A is a comparison of creep stiffness at -18℃, B is a comparison of creep rate at -12℃, and C is the low-temperature limit temperature. Figure 3 The images show the FTIR test results of high-modulus asphalt prepared in Example 1 (DPA) and Comparative Examples 1-4 of this invention. Figure 4 The images show fluorescence microscopy test results of high modulus bitumen prepared in Example 1 (DPA) and Comparative Examples 1-4 of this invention; where (a) HGA, (b) DPA, (c) SBA, and (d) HMA. in, Figure 1 - Figure 4 In this context, VA represents unmodified base asphalt, HGA represents hard asphalt, DPA represents waste rubber powder modified asphalt of this invention, SBA represents SBS modified asphalt, and HMA represents aramid high modulus agent asphalt. Detailed Implementation

[0021] Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Specific conditions not specified in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Components not explicitly named as manufacturers are all commercially available conventional products. The specifications of the base bitumen, waste rubber powder (DRP), ethylene-vinyl acetate copolymer (EVA), and ammonium polyphosphate (PPA) used are as follows: Base asphalt: 70# road petroleum asphalt, penetration 71.5 / 0.1mm, softening point 46.7℃.

[0022] Desulfurized rubber powder (DRP): Particle size 80 mesh, metal content ≤0.02 wt%, rubber hydrocarbon content ≥54 wt%, ash content ≤7.1 wt%.

[0023] Ethylene-vinyl acetate copolymer (EVA): transparent granules, density 0.945 g / cm³ 3 Melting point 103℃.

[0024] Ammonium polyphosphate (PPA): White powder, density 1.85 g / cm³ 3 The thermal decomposition temperature is 289℃.

[0025] This invention addresses the technical bottleneck in existing high-modulus asphalt technologies, which is the difficulty in overcoming the technical limitations of "high content of 20% waste rubber powder + chemical cross-linking + low-temperature performance (-18℃)," resulting in the inability to simultaneously meet the technical requirements of high-modulus asphalt in terms of high-temperature stability, low-temperature crack resistance, and economic and environmental protection.

[0026] This invention pretreats the sulfur in rubber powder through chemical desulfurization, thereby destroying the cross-linking structure of the sulfur in the rubber powder and solving the problems of high viscosity at high temperatures, poor ductility at low temperatures, and environmental pollution of traditional vulcanized rubber powder. At the same time, by optimizing the raw material composition and processing technology of high modulus asphalt, the low-temperature crack resistance, environmental protection and economy of high modulus asphalt are synergistically optimized.

[0027] The present invention will be further described below with reference to specific embodiments: Example 1 A high-modulus asphalt based on waste rubber powder composite modification and its preparation method 1. The basic formula, by mass fraction, consists of the following: Desulfurized rubber powder (DRP): 20%, ethylene-vinyl acetate copolymer (EVA, molecular weight 80,000): 6%, ammonium polyphosphate (PPA, type II ammonium polyphosphate with degree of polymerization n=1000): 4%, base bitumen: 70%.

[0028] The preparation method of desulfurized rubber powder (DRP) is as follows: Mix 80-mesh vulcanized rubber powder with mercaptoamine desulfurizing agent (zinc dibutyldithiocarbamate) at a mass ratio of 1:0.08, and mechanically stir in a constant temperature water bath at 50℃ for 40 minutes to destroy the sulfur cross-linking structure and obtain the reaction product. After washing with deionized water three times, vacuum dry at 80℃ to constant weight, and pulverize through an 80-mesh sieve, the desulfurized rubber powder is obtained.

[0029] 2. A method for preparing high-modulus asphalt, comprising the following steps: (1) Pretreatment of base asphalt: Heat the base asphalt to a fluid state at 150±2℃; (2) Waste rubber powder compounding: Add desulfurized rubber powder (DRP) and shear at a shearing speed of 5000 r / min for 0.5 h; (3) Addition of modifier: Ammonium polyphosphate (PPA) and ethylene-vinyl acetate copolymer (EVA) were added in sequence and sheared at a shearing speed of 5000 r / min for 0.4 h; (4) Development and shaping: Develop at 150℃ for 0.4 h to form homogeneous composite asphalt.

[0030] 3. Performance Testing The performance test results of the high modulus asphalt prepared in this embodiment are shown in Table 1, where G * The test method for (60℃, 10Hz, 12%) refers to standard JT / T 860.6-2016 "Road Use Waste Tire Rubber Powder Asphalt Part 6: Dynamic Shear Rheology Test, Low Temperature Limit Temperature Test Method" and standard JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" T 0627, G * The test method for / sinδ (64℃) refers to the standard ASTM D7175-15 "Standard Test Method for Dynamic Shear Rheometer of Bituminous Binders", J nr The test method for (3.2 kPa) is based on the standard AASHTO T 350-19 "Multi-stress creep recovery test".

[0031] Table 1. Performance of high modulus asphalt in Example 1

[0032] As shown in Table 1, the high modulus asphalt DPA prepared in Example 1 meets the standard requirements.

[0033] Example 2 In this embodiment, 1. the high-modulus asphalt, by mass fraction, has the following composition: Desulfurized rubber powder (DRP): 18%, ethylene-vinyl acetate copolymer (EVA, molecular weight 100,000): 7%, ammonium polyphosphate (PPA, type II polyphosphate with degree of polymerization n=1000): 5%, base bitumen: 70%. The preparation method of desulfurized rubber powder (DRP) is the same as in Example 1.

[0034] 2. In the preparation method of high modulus asphalt, the shearing time in step (2) is extended to 0.6 hours; in step (3), PPA is added and sheared for 0.3 hours first, and then EVA is added and sheared for 0.3 hours. Other preparation steps are the same as in Example 1.

[0035] 3. Performance Testing The test method for creep stiffness or reference standard JT / T 860.5-2016 "Road Waste Tire Rubber Powder Asphalt Bending Beam Rheological Test", and the test method for fatigue life or reference standard AASHTO TP 101-14 "Linear Amplitude Scan Test".

[0036] The results showed that, compared with Example 1, the creep stiffness of Example 2 decreased to 165 MPa at -18℃, while the fatigue life increased to 17,200 cycles.

[0037] Example 3 1. A special formula for low-temperature environments (severely cold regions), composed of the following by mass fraction: Desulfurized rubber powder (DRP): 22%, ethylene-vinyl acetate copolymer (EVA, molecular weight 90,000): 5%, ammonium polyphosphate (PPA, type II polyphosphate with degree of polymerization n=1000): 3%, base asphalt: 70%. The preparation method of desulfurized rubber powder (DRP) is the same as in Example 1.

[0038] 2. In the preparation method of high modulus asphalt, the shear speed in step (2) is reduced to 4500 r / min; the development time in step (4) is extended to 0.6 hours, and the other preparation steps are the same as in Example 1.

[0039] 3. Low temperature performance The results of low-temperature performance tests on the high-modulus asphalt prepared in this embodiment are shown in Table 3.

[0040] Table 2 Low-temperature performance of high-modulus asphalt in Example 3

[0041] As shown in Table 2, the high modulus asphalt prepared in Example 3 has good low-temperature performance.

[0042] Example 4 1. The formula for high-temperature, heavy-duty road use, by mass fraction, consists of the following: Desulfurized rubber powder (DRP): 20%, ethylene-vinyl acetate copolymer (EVA, molecular weight 80,000): 7%, ammonium polyphosphate (PPA, type II polyphosphate with degree of polymerization n=1000): 5%, base bitumen: 68%. The preparation method of desulfurized rubber powder (DRP) is the same as in Example 1.

[0043] 2. The preparation method of high-modulus asphalt includes the following steps: (1) Pretreatment of base asphalt: Heat the base asphalt to a fluid state at 150±2℃; (2) Waste rubber powder compounding: Add ammonium polyphosphate (PPA) and shear at a shearing speed of 5500 r / min for 0.5 h; (3) Addition of modifier: Desulfurized rubber powder (DRP) and ethylene-vinyl acetate copolymer (EVA) are added in sequence and sheared at a shearing speed of 5500 r / min for 0.4 h; (4) Development and shaping: Develop at 150℃ for 0.4 h to form homogeneous composite asphalt.

[0044] 3. Performance Testing The high-modulus asphalt prepared in this embodiment was subjected to performance testing, including the rutting factor G. * / sinδ (64℃) Test method reference standard ASTM D7175-15 "Standard Test Method for Dynamic Shear Rheology of Bituminous Binders", J nr The test method for (3.2 kPa) is based on the standard AASHTO T 350-19 "Multi-stress creep recovery test".

[0045] The test results showed that the rutting factor G measured in Example 4 of this embodiment was... * / sinδ (64℃) = 6.2kPa, rutting resistance J nr =0.10kPa -1 The rutting factor G compared to Example 1 * / sinδ (64℃) increases, but rutting resistance J nr reduce.

[0046] Comparative Example 1 Hard asphalt (HGA) is prepared as follows: 70# road petroleum asphalt (penetration 71.5 / 0.1mm, softening point 46.7°C) is heated to 150°C without adding any modifiers and directly molded. This represents the traditional hard asphalt technology route.

[0047] Comparative Example 2 SBS-modified bitumen (SBA) is prepared as follows: 12% SBS (styrene-butadiene-styrene block copolymer, molecular weight 150,000 g / mol) is added to 70# base bitumen, sheared at 5000 r / min for 0.5 hours, and then grown at 150°C for 0.5 hours. This represents a polymer modification route.

[0048] Comparative Example 3 Unmodified base asphalt (VA) was prepared as follows: 70# road petroleum asphalt (penetration 71.5 / 0.1 mm, softening point 46.7°C) was used directly without any treatment. It served as a blank control group.

[0049] Comparative Example 4 The preparation method of high-modulus aramid asphalt (HMA) is as follows: 8% high molecular weight aramid (HMA, density 1.4 g / cm³) is added to 70# base asphalt. 3( ), sheared at 5000 r / min for 0.5 hours, and developed at 150°C for 0.5 hours. This represents the high-modulus agent route.

[0050] Comparative Example 5 Unlike Example 1, no modification treatment was performed on the vulcanized rubber powder; the formulation and preparation method were the same as in Example 1.

[0051] Comparative Example 6 Unlike Example 1, PPA was replaced with an equal amount of EVA, and the formulation, by mass fraction, was as follows: Desulfurized rubber powder (DRP): 20%, ethylene-vinyl acetate copolymer (EVA): 10%, base bitumen: 70%. The preparation method was the same as in Example 1, resulting in a DRP / EVA composite system (without added PPA).

[0052] The study found that the DRP / EVA composite system (without PPA) had a ductility of only 19.7 cm and failed to meet the low-temperature performance standards.

[0053] Comparative Example 7 Unlike Example 1, EVA was replaced with an equal amount of PPA, and the formulation, by mass fraction, was as follows: Desulfurized rubber powder (DRP): 20%, ammonium polyphosphate (PPA): 10%, and base asphalt: 70%. The preparation method was the same as in Example 1, resulting in a DRP / PPA composite system (without added EVA).

[0054] The study found that the DRP / PPA composite system (without EVA) had a G of only 11.3 kPa, with limited improvement in high-temperature modulus.

[0055] Comparative Example 8 The conventional processing method for DRP-modified asphalt is as follows: vulcanized rubber powder (undesulfurized) is directly added to the base asphalt, sheared at 3000 r / min (without PPA / EVA), and allowed to develop for 0.2 hours. This represents the traditional waste rubber powder modification route.

[0056] Performance testing: Comparative example 8's G* is only 8.5 kPa (lower than the standard ≥10 kPa), and Jnr reaches 0.20 kPa. -1 The fatigue life N ≤ 10,000 cycles. This is because low shear leads to uneven dispersion, and the cross-linked structure of the undesulfurized rubber powder remains intact.

[0057] Performance testing and mechanism verification The properties and modification mechanism of the high-modulus asphalt prepared in Example 1 (DPA) and Comparative Examples 1-4 of this invention are described below: (1) High temperature stability and rutting resistance: Figure 1The high-temperature stability and rutting resistance of the high-modulus asphalt prepared in Example 1 (DPA) and Comparative Examples 1-4 are shown, where A represents high-temperature stability and B represents rutting resistance. * / sinδ (64℃) ≥ 5.0 kPa, meeting the PG88 high-temperature rating. Rutting resistance is close to that of polymer-modified asphalt (such as SBA). J nr (3.2 kPa) ≤ 0.15 kPa -1 .

[0058] Depend on Figure 1 As shown in Figure A (High-Temperature Stability), the rutting factor G* / sinδ (64°C) of DPA reaches 5.8 kPa, far exceeding the standard (≥5.0 kPa). This is because the crystalline framework of EVA and the interfacial catalysis of PPA form a rigid network, while HGA (Comparative Example 1) lacks a modifier, resulting in a G* / sinδ of only 4.2 kPa; SBA (Comparative Example 2) reaches 5.5 kPa, but its cost is higher; HMA (Comparative Example 4) has a G* / sinδ of only 4.8 kPa due to uneven physical miscibility. Figure B (Rutting Resistance): The irreversible creep compliance J of DPA nr( 3.2kPa) is 0.12 kPa -1 Below the threshold (≤0.15 kPa) -1 PPA reinforces the asphaltene network and reduces permanent deformation. HMA (Comparative Example 4) shows J... nr Up to 0.18 kPa -1 The poor dispersibility of aramid fibers leads to a deterioration in rutting resistance.

[0059] (2) Low-temperature crack resistance: Figure 2 This section compares the low-temperature crack resistance of high-modulus asphalt prepared in Example 1 (DPA) with that prepared in Comparative Examples 1-4. Figure A (creep stiffness S comparison, -18℃): DPA's S value is ≤150 MPa (far lower than the standard ≤190 MPa), while HGA (Comparative Example 1) has an S value as high as 210 MPa, and VA (Comparative Example 3) has an S value of 195 MPa. Desulfurized rubber powder (DRP) releases flexible molecular chains, absorbs lightweight components, and improves elasticity. Figure B (creep rate m comparison, -12℃): DPA's m value is ≥0.38 (higher than the standard ≥0.35), while SBA (Comparative Example 2) has an m value of only 0.28. The molecular chains released by PPA bond breaking synergistically toughen with DRP. Figure C (low-temperature limit temperature): DPA's low-temperature limit is ≤-14.2℃, superior to HGA (-6℃) and SBA (-6℃). The ternary system (DRP / EVA / PPA) optimizes temperature sensitivity.

[0060] As can be seen, the low-temperature limit of Example 1 (DPA) is ≤-12℃, which is significantly better than that of hard asphalt (HGA) and polymer-modified asphalt (SBA / HMA). BBR tests show that S≤180MPa at -18℃ and m≥0.35 at -12℃.

[0061] (3) Long fatigue life and environmental friendliness: Fatigue life N f ≥15,000 cycles, superior to hard asphalt.

[0062] (4) The modification mechanism was further verified by FTIR detection and fluorescence microscopy as follows: Figure 3 For the comparison of FTIR spectra of Examples 1-4 (DPA) and Comparative Examples 1-4, the focus is on observing the characteristic region of the esterification reaction (900–1200 cm⁻¹). -1 ).Depend on Figure 3 It can be seen that Example 1 (DPA) is at 1024±5cm -1 The presence of a CO stretching vibration characteristic peak at this location confirms that PPA undergoes an esterification reaction with asphalt, enhancing long-term stability. Example 1 (DPA): At 1024±5 cm⁻¹ -1 A significant CO stretching vibration peak (peak intensity ≥ 0.85) was observed at 1022 cm⁻¹, confirming that PPA and asphalt carboxyl groups underwent esterification, forming a covalent network. Example 2 (DPA+SBR): At 1022 cm⁻¹... -1 The CO peak intensity decreased slightly (0.78) due to SBR competing for crosslinking sites, but the reaction requirements were still met. Comparative Example 1 (HGA): only at 1038 cm⁻¹ -1 A weak absorption (intensity 0.15) was observed at this location, which is due to the oxygen-containing groups in the asphalt itself, without the formation of ester bonds. Comparative Example 2 (SBA): 1040–1050 cm⁻¹ -1 A broad peak (intensity 0.32) appears in the region, originating from the COC bond of SBS, and is unrelated to the esterification reaction. Comparative Example 4 (HMA): at 1070 cm⁻¹ -1 The presence of a CN peak (intensity 0.65) and the absence of a CO characteristic peak at the location indicate that the aramid did not participate in the chemical reaction.

[0063] Microstructure analysis was performed using fluorescence microscopy. Figure 4 It is known that DRP is uniformly dispersed in the form of filled particles (non-polymer network structure), which improves low-temperature ductility through interlocking effect, while avoiding the swelling defects of high-cost polymers.

[0064] The properties obtained in Example 1 and Comparative Examples 1-2 or 4, 8 are shown in Tables 3 and 4. The test method for the low-temperature limit temperature (°C) refers to standard JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" T0627; the test method for fatigue life (cycles) refers to standard AASHTO TP101-14 "Linear Amplitude Scanning Test"; the test method for sulfur dioxide emission reduction rate refers to standard GB / T 16157 "Determination of Particulate Matter and Sampling Methods for Gaseous Pollutants in Exhaust Gas from Stationary Sources"; and the test method for low-temperature ductility (5°C ductility, cm) refers to standard JT / T 860.3-2016 "Road Waste Tire Rubber Powder Asphalt Part 3: Ductility Test". Table 3. Properties of the asphalt prepared in Example 1 and Comparative Examples 1-2, 8

[0065] As can be seen from Table 3, Example 1 (DPA) has significantly better low-temperature performance, cost and fatigue life than comparative documents 1, 2 and 8.

[0066] Table 4 shows the performance of the samples obtained in Example 1 and Comparative Examples 4 and 8.

[0067] As shown in Table 4, the introduction of desulfurized rubber powder significantly improves environmental friendliness and rheological properties: based on the optimization of the desulfurization process, sulfur dioxide emissions in asphalt fumes are reduced by 74% (from 11.25% (baseline) to 2.87%), hydrogen sulfide emissions are reduced by 38% (from 1.55% (baseline) to 0.96%), while workability is improved (viscosity at 180°C decreases from 4.2 Pa·s to 2.1 Pa·s, a reduction of 50%) and low-temperature ductility is improved (ductility at 5°C increases from 19.7 cm to 28.4 cm, an increase of 44%).

[0068] In summary, this invention, through synergistic innovation, introduces a ternary composite system of high-content (18%-22%) waste rubber powder (DRP), ethylene-vinyl acetate copolymer (EVA), and ammonium polyphosphate (PPA), and optimizes the shearing process (5000±500 r / min, development time 0.5±0.1 hours) to produce composite modified high-modulus asphalt, achieving three major breakthroughs: a revolutionary improvement in low-temperature performance, synergistic optimization of high-temperature and fatigue performance, and dual advantages in environmental protection and economy; this product also possesses high modulus characteristics (G... * With a strength of ≥13.3kPa, it highlights low-temperature crack resistance and long-term service capability, completely overcoming the technical bottlenecks of traditional high-modulus asphalt's low-temperature embrittlement and high cost. It is particularly suitable for high-temperature heavy-load roads, highways in frigid regions, and long-life pavement projects, significantly improving road durability and reducing the total life cycle cost, and has broad prospects for industrial application. The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A waste rubber powder composite modified high-modulus asphalt, characterized in that, Composition by weight percentage is as follows: Waste rubber powder 18%-22%, ethylene-vinyl acetate copolymer 5%-7%, ammonium polyphosphate 3%-5%, The remainder is base asphalt; The waste rubber powder is desulfurized rubber powder with a metal content ≤0.02 wt%, a rubber hydrocarbon content ≥54 wt%, and an ash content ≤7.1 wt%.

2. The waste rubber powder composite modified high modulus asphalt according to claim 1, characterized in that, The density of the ethylene-vinyl acetate copolymer is 0.9-1.0 g / cm³. 3 It has a melting point of 100-110℃ and a molecular weight of 80,000-100,000 g / mol.

3. The waste rubber powder composite modified high-modulus asphalt according to claim 1, characterized in that, The density of the ammonium polyphosphate is 1.80-2.0 g / cm³. 3 The thermal decomposition temperature is 280-290 ℃, and the ammonium polyphosphate is selected from one or more of type II ammonium polyphosphate and coated ammonium polyphosphate with a degree of polymerization n≥1000.

4. The waste rubber powder composite modified high modulus asphalt according to claim 1, characterized in that, The base asphalt is 70# road petroleum asphalt with a penetration of 70 / 0.1mm-72 / 0.1mm and a softening point of 45-50℃.

5. The waste rubber powder composite modified high-modulus asphalt according to claim 1, characterized in that, The high-modulus asphalt meets one or more of the following performance indicators: Complex shear modulus G at 60℃, 10Hz, and 12% * ≥10kPa; In the BBR test, the low-temperature limit temperature is ≤-12℃ under m≥0.3 and S≤300MPa. Low-temperature performance meets the following requirements: creep stiffness S≤190MPa at -18℃, creep rate m≥0.35 at -12℃; High-temperature performance meets: Rutting factor G at 64℃ * / sinδ≥5.0kPa, irreversible creep compliance J at 3.2kPa nr ≤0.15kPa -1 ; Under conditions of 25℃ and 2.5% strain, the fatigue life N f Fatigue life N ≥15,000 cycles at 25℃ and 2.5% strain f ≥15,000 times.

6. A method for preparing waste rubber powder composite modified high modulus asphalt according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Heating the base asphalt to obtain liquid base asphalt; (2) Waste rubber powder is added to the liquid matrix asphalt and sheared and mixed to obtain the first mixture; (3) Add ethylene-vinyl acetate copolymer and ammonium polyphosphate to the first mixture in sequence, and continue to shear and mix to obtain the second mixture; (4) The second mixture is developed into a mold to obtain waste rubber powder composite modified high modulus asphalt.

7. The method for preparing waste rubber powder composite modified high-modulus asphalt according to claim 6, characterized in that, In step (1), the heating temperature of the base asphalt is 140-160℃; In step (2), the waste rubber powder is added at a temperature of 145-155℃; In step (4), the temperature for development and shaping is 140–160℃, and the development time is 0.4–0.6 h; In step (2) or step (3), the rotational speed of shear mixing is 4500–5500 r / min and the time is 0.4–0.6 h.

8. The method for preparing waste rubber powder composite modified high modulus asphalt according to claim 6, characterized in that, In step (2), the waste rubber powder is desulfurized rubber powder. The preparation method of desulfurized rubber powder is as follows: mix vulcanized rubber powder with chemical desulfurizing agent and stir to generate desulfurized rubber powder.

9. The method for preparing waste rubber powder composite modified high-modulus asphalt according to claim 8, characterized in that, The mass ratio of the vulcanized rubber powder to the chemical desulfurizing agent is 1:(0.05-0.1); The chemical desulfurizing agent is a mercaptoamine compound or an alkylphenol polyoxyethylene ether; The stirring reaction was carried out at a temperature of 40–60°C for 30–60 min. Preferably, the chemical desulfurizing agent is zinc dibutyldithiocarbamate, OP-10, zinc dimethyldithiocarbamate, or 1-butyl-3-methylimidazolium acetate.

10. The application of waste rubber powder composite modified high modulus asphalt according to any one of claims 1-5 in high-temperature heavy-load roads, bridge deck paving and airport runways.

Images