Reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design and preparation method of reinforced and toughened asphalt mixture

Abstract

The invention provides a reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design, the reinforced and toughened asphalt mixture comprises composite modified asphalt and aggregate, the composite modified asphalt is formed by compounding and modifying asphalt through a composite modifier, the total doping amount of the composite modifier in the composite modified asphalt is 10-15% by weight, and the total doping amount of the aggregate is 10-15% by weight. The composite modifier comprises a styrene-ethylene-butylene-styrene block copolymer and a thermoplastic polyolefin elastomer, and the mass ratio of the styrene-ethylene-butylene-styrene block copolymer to the thermoplastic polyolefin elastomer is 47: 53; the aggregate comprises coarse aggregate, fine aggregate and mineral powder, namely coarse aggregate gt; 4.75 mm and < = 15 mm, 67-78% by weight, where gt; 15-25% by weight of particles with the particle size of 4.75 mm and less than or equal to 9.5 mm, and fine aggregate 1t; 2.36 mm, 12-25% by weight, and 7-10% by weight of mineral powder; the asphalt-aggregate ratio of the composite modified asphalt to the aggregate is 5.6-5.8%. The reinforced and toughened asphalt mixture disclosed by the invention is excellent in fatigue resistance, good in low-temperature crack resistance and high in storage stability.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering materials, in particular to the technical field of asphalt materials for asphalt pavement top layers, and specifically refers to an enhanced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design and a preparation method thereof. Background Art

[0002] Road engineering materials form the material foundation of engineering structures such as roads, bridges, and tunnels. They primarily include stone and aggregate, organic binders, cement concrete, and asphalt mixtures. These materials play a vital role in road engineering. The scientific and rational selection and use of these materials can improve the service performance of structures, extend their service life, and reduce construction costs.

[0003] Asphalt mixture is the most common material used in road construction, used for paving roads. Its composition and dosage vary depending on the materials and processes used. Asphalt mixtures generally include coarse aggregate, fine aggregate, mineral filler, asphalt, and other materials.

[0004] Traditional SBS-SMA13 asphalt mixture is widely used in road surface layers in southern China due to its excellent high-temperature stability and water damage resistance. However, it has the following drawbacks:

[0005] Insufficient fatigue resistance: A single modifier system results in insufficient viscoelasticity of asphalt mortar, which is prone to fatigue cracks under long-term cyclic loading;

[0006] Limited low-temperature crack resistance: SBS modified asphalt has poor low-temperature ductility and cannot meet the road crack resistance requirements in cold regions;

[0007] Poor storage stability: Single modifiers are prone to phase separation and segregation problems during construction;

[0008] Limitations of gradation design: The fine aggregate range of traditional dense-graded mixtures is narrow (e.g., 2.36mm passing rate is 15% to 20%), the mortar filling is insufficient, and the ability to resist reflective cracks is weak.

[0009] Existing technologies include fiber-reinforced SBS-modified asphalt mixtures, which improve crack resistance. However, the addition of fiber increases costs and complicates the construction process. Other studies have attempted composite modification technologies, but these have failed to address the issues of gradation optimization and binder synergy, resulting in limited performance improvements in actual projects.

[0010] Therefore, it is hoped to provide an asphalt mixture with excellent fatigue resistance, good low-temperature crack resistance, high storage stability, convenient construction, economy and environmental protection. Summary of the Invention

[0011] In order to overcome the shortcomings of the above-mentioned prior art, one purpose of the present invention is to provide a reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open grading design, which has excellent fatigue resistance, good low-temperature crack resistance, high storage stability, and is suitable for large-scale promotion and application.

[0012] Another object of the present invention is to provide a method for preparing a reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open grading design, which has a clever design, simple steps, convenient construction, economy and environmental protection, and is suitable for large-scale promotion and application.

[0013] To achieve the above objectives, in a first aspect of the present invention, a reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design is provided, comprising composite modified asphalt and aggregate, which is characterized in that:

[0014] The composite modified asphalt is prepared by composite-modifying asphalt with a composite modifier, wherein the total amount of the composite modifier in the composite modified asphalt is 10% by weight to 15% by weight, and the composite modifier comprises a first elastomer and a second elastomer, wherein the first elastomer and the second elastomer are styrene-ethylene-butylene-styrene block copolymer and a thermoplastic polyolefin elastomer, respectively, and the mass ratio of the first elastomer to the second elastomer is 47:53;

[0015] The aggregate comprises coarse aggregate, fine aggregate and mineral powder, wherein the particle size of the coarse aggregate is greater than 4.75 mm and ≤ 15 mm, and the coarse aggregate accounts for 67% by weight to 78% by weight, wherein the coarse aggregate with a particle size greater than 4.75 mm and ≤ 9.5 mm accounts for 15% by weight to 25% by weight, the particle size of the fine aggregate is less than 2.36 mm, and the fine aggregate accounts for 12% by weight to 25% by weight, and the mineral powder accounts for 7% by weight to 10% by weight;

[0016] The asphalt-to-stone ratio of the composite modified asphalt and the aggregate is 5.6% to 5.8%.

[0017] Preferably, the total content of the composite modifier in the composite modified asphalt is 10.5% by weight; and the asphalt-to-stone ratio of the composite modified asphalt and the aggregate is 5.8%.

[0018] Preferably, among the aggregates, the coarse aggregate with a particle size greater than 9.5 mm and ≤ 15 mm accounts for 54% by weight, the coarse aggregate with a particle size greater than 4.75 mm and ≤ 9.5 mm accounts for 20% by weight, the fine aggregate accounts for 19% by weight, and the mineral powder accounts for 7% by weight.

[0019] Preferably, the total content of the composite modifier in the composite modified asphalt is 15% by weight; and the asphalt-to-stone ratio of the composite modified asphalt and the aggregate is 5.7%.

[0020] Preferably, among the aggregates, the coarse aggregate with a particle size greater than 9.5 mm and ≤ 15 mm accounts for 52% by weight, the coarse aggregate with a particle size greater than 4.75 mm and ≤ 9.5 mm accounts for 15% by weight, the fine aggregate accounts for 25% by weight, and the mineral powder accounts for 8% by weight.

[0021] Preferably, the total content of the composite modifier in the composite modified asphalt is 10% by weight; and the asphalt-to-stone ratio of the composite modified asphalt and the aggregate is 5.6%.

[0022] Preferably, among the aggregates, the coarse aggregate with a particle size greater than 9.5 mm and ≤ 15 mm accounts for 53% by weight, the coarse aggregate with a particle size greater than 4.75 mm and ≤ 9.5 mm accounts for 25% by weight, the fine aggregate accounts for 12% by weight, and the mineral powder accounts for 10% by weight.

[0023] In a second aspect of the present invention, a method for preparing a reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design is provided, which is characterized by comprising the following steps:

[0024] (1) adding the composite modifier to the asphalt, and mixing uniformly by high-temperature shearing and stirring to obtain a composite modified asphalt;

[0025] (2) The aggregate is heated to a first high temperature, the composite modified asphalt is heated to a second high temperature, and the aggregate and the composite modified asphalt are mixed evenly to obtain the reinforced and toughened asphalt mixture based on the composite modification and discontinuous semi-open grading design.

[0026] Preferably, in step (1), the high temperature is 160° C. to 180° C., the shear stirring rate is 3000 rpm to 4000 rpm, and the shear stirring time is 30 minutes to 40 minutes.

[0027] Preferably, in step (2), the first high temperature is 180°C to 190°C, the second high temperature is 160°C to 170°C, the mixing time is 90 seconds to 120 seconds, and the mixing speed is 45 rpm to 55 rpm.

[0028] The beneficial effects of the present invention are mainly:

[0029] 1. The reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open grading design of the present invention comprises composite modified asphalt and aggregate, wherein the composite modified asphalt is formed by composite modified asphalt with a composite modifier, wherein the total amount of the composite modifier in the composite modified asphalt is 10% by weight to 15% by weight, and the composite modifier comprises a first elastomer and a second elastomer, wherein the first elastomer and the second elastomer are styrene-ethylene-butylene-styrene block copolymer and a thermoplastic polyolefin elastomer, respectively, and the mass ratio of the first elastomer to the second elastomer is 47:53; the aggregate comprises Including coarse aggregate, fine aggregate and mineral powder, the particle size of the coarse aggregate is >4.75mm and ≤15mm, the coarse aggregate accounts for 67% by weight to 78% by weight, of which the coarse aggregate with a particle size >4.75mm and ≤9.5mm accounts for 15% by weight to 25% by weight, the particle size of the fine aggregate is <2.36mm, the fine aggregate accounts for 12% by weight to 25% by weight, and the mineral powder accounts for 7% by weight to 10% by weight; the oil-stone ratio of the composite modified asphalt and aggregate is 5.6% to 5.8%, it has excellent fatigue resistance, good low-temperature crack resistance, and high storage stability, and is suitable for large-scale promotion and application.

[0030] 2. The preparation method of the reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design of the present invention comprises the following steps: (1) adding a composite modifier to asphalt, shearing and stirring at high temperature to mix uniformly, and obtaining a composite modified asphalt; (2) heating the aggregate to a first high temperature, heating the composite modified asphalt to a second high temperature, and mixing the aggregate and the composite modified asphalt uniformly to obtain a reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design. The method has an ingenious design, simple steps, convenient construction, is economical and environmentally friendly, and is suitable for large-scale promotion and application.

[0031] These and other objects, features and advantages of the present invention are fully reflected in the following detailed description and can be achieved by the means, devices and their combinations particularly pointed out in the summary of the invention. DETAILED DESCRIPTION

[0032] In order to improve the low-temperature crack resistance and fatigue resistance of asphalt mixture, balance the high and low temperature performance and storage stability, simplify the construction process, avoid fiber addition, and reduce the overall cost, the inventors selected a combination of asphalt composite modifiers and optimized the aggregate gradation, thereby proposing a reinforced and toughened asphalt mixture (CMA-ARHM13) based on composite modification and discontinuous semi-open gradation design and a preparation method thereof. The reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design has excellent fatigue resistance, good low-temperature crack resistance, and high storage stability. The preparation method of the reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design is cleverly designed, with simple steps, convenient construction, and is economical and environmentally friendly. The present invention was completed on this basis.

[0033] The present invention first provides a reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design, comprising composite modified asphalt and aggregate, wherein:

[0034] The composite modified asphalt is prepared by composite-modifying asphalt with a composite modifier, wherein the total amount of the composite modifier in the composite modified asphalt is 10% by weight to 15% by weight, and the composite modifier comprises a first elastomer and a second elastomer, wherein the first elastomer and the second elastomer are styrene-ethylene-butylene-styrene block copolymer and a thermoplastic polyolefin elastomer, respectively, and the mass ratio of the first elastomer to the second elastomer is 47:53;

[0035] The aggregate comprises coarse aggregate, fine aggregate and mineral powder, wherein the particle size of the coarse aggregate is greater than 4.75 mm and ≤ 15 mm, and the coarse aggregate accounts for 67% by weight to 78% by weight, wherein the coarse aggregate with a particle size greater than 4.75 mm and ≤ 9.5 mm accounts for 15% by weight to 25% by weight, the particle size of the fine aggregate is less than 2.36 mm, and the fine aggregate accounts for 12% by weight to 25% by weight, and the mineral powder accounts for 7% by weight to 10% by weight;

[0036] The asphalt-to-stone ratio of the composite modified asphalt and the aggregate is 5.6% to 5.8%.

[0037] The total amount of the composite modifier in the composite modified asphalt and the oil-stone ratio of the composite modified asphalt and the aggregate can be determined as needed. Preferably, the total amount of the composite modifier in the composite modified asphalt is 10.5% by weight; the oil-stone ratio of the composite modified asphalt and the aggregate is 5.8%.

[0038] In the aggregate, the weight percentages of the coarse aggregate with a particle size >9.5mm and ≤15mm, the coarse aggregate with a particle size >4.75mm and ≤9.5mm, the fine aggregate and the mineral powder can be determined as needed. Preferably, in the aggregate, the coarse aggregate with a particle size >9.5mm and ≤15mm accounts for 54% by weight, the coarse aggregate with a particle size >4.75mm and ≤9.5mm accounts for 20% by weight, the fine aggregate accounts for 19% by weight, and the mineral powder accounts for 7% by weight.

[0039] The total amount of the composite modifier in the composite modified asphalt and the oil-stone ratio of the composite modified asphalt and the aggregate can be determined as needed. Preferably, the total amount of the composite modifier in the composite modified asphalt is 15% by weight; the oil-stone ratio of the composite modified asphalt and the aggregate is 5.7%.

[0040] In the aggregate, the weight percentages of the coarse aggregate with a particle size >9.5mm and ≤15mm, the coarse aggregate with a particle size >4.75mm and ≤9.5mm, the fine aggregate and the mineral powder can be determined as needed. Preferably, in the aggregate, the coarse aggregate with a particle size >9.5mm and ≤15mm accounts for 52% by weight, the coarse aggregate with a particle size >4.75mm and ≤9.5mm accounts for 15% by weight, the fine aggregate accounts for 25% by weight, and the mineral powder accounts for 8% by weight.

[0041] The total amount of the composite modifier in the composite modified asphalt and the oil-stone ratio of the composite modified asphalt and the aggregate can be determined as needed. Preferably, the total amount of the composite modifier in the composite modified asphalt is 10% by weight; the oil-stone ratio of the composite modified asphalt and the aggregate is 5.6%.

[0042] In the aggregate, the weight percentages of the coarse aggregate with a particle size >9.5mm and ≤15mm, the coarse aggregate with a particle size >4.75mm and ≤9.5mm, the fine aggregate and the mineral powder can be determined as needed. Preferably, in the aggregate, the coarse aggregate with a particle size >9.5mm and ≤15mm accounts for 53% by weight, the coarse aggregate with a particle size >4.75mm and ≤9.5mm accounts for 25% by weight, the fine aggregate accounts for 12% by weight, and the mineral powder accounts for 10% by weight.

[0043] The present invention also provides a method for preparing a reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design, comprising the following steps:

[0044] (1) adding the composite modifier to the asphalt, and mixing uniformly by high-temperature shearing and stirring to obtain a composite modified asphalt;

[0045] (2) The aggregate is heated to a first high temperature, the composite modified asphalt is heated to a second high temperature, and the aggregate and the composite modified asphalt are mixed evenly to obtain the reinforced and toughened asphalt mixture based on the composite modification and discontinuous semi-open grading design.

[0046] In the step (1), the high temperature, the shear stirring rate and the time can be determined as needed. Preferably, in the step (1), the high temperature is 160°C to 180°C, the shear stirring rate is 3000rpm to 4000rpm, and the shear stirring time is 30 minutes to 40 minutes.

[0047] In the step (2), the first high temperature, the second high temperature, the mixing time and speed can be determined as needed. Preferably, in the step (2), the first high temperature is 180°C to 190°C, the second high temperature is 160°C to 170°C, the mixing time is 90 seconds to 120 seconds, and the mixing speed is 45 rpm to 55 rpm.

[0048] In order to more clearly understand the technical content of the present invention, the following examples are specifically described in detail. It should be understood that the specific examples described herein are merely illustrative of the present invention and are not intended to limit the present invention. Unless otherwise stated, the instruments, drugs, reagents, etc. used in the following examples can be obtained by conventional commercial means.

[0049] The test methods used in each embodiment are as follows:

[0050] Dynamic stability test: Tested in accordance with JTG E20-2011 T 0719 "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering - Rutting Test for Asphalt Mixtures";

[0051] Water-soaked residual stability ratio: According to JTG E20-2011 T 0709 "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering - Marshall Stability Test for Asphalt Mixtures":

[0052] SCB fracture energy test: Refer to JTG E20-2011 T 0734 "Test procedures for asphalt and asphalt mixtures in highway engineering - semicircular bending test (SCB)":

[0053] Penetration test: According to GB / T 4509-2010 "Determination of Penetration of Asphalt":

[0054] Softening point test: According to GB / T 4507-2014 "Determination of softening point of asphalt (ring and ball method)".

[0055] Low temperature ductility test: According to GB / T 4508-2010 "Asphalt ductility test method":

[0056] 135℃ kinematic viscosity test: GB / T 265-1988 "Determination of kinematic viscosity of petroleum products":

[0057] Target void ratio, VMA, and VFA tests: Determined in accordance with JTG E20-2011 T 0705 "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering - Density Test of Compacted Asphalt Mixtures".

[0058] Example 1

[0059] 1. Aggregate:

[0060] 10-15 mm gneiss crushed stone: 54% by weight;

[0061] 5-10 mm gravel: 20% by weight;

[0062] 0-3mm machine-made sand: 19% by weight;

[0063] Mineral powder: 7% by weight; limestone mineral powder, fineness (0.075mm sieve passing rate) ≥88%.

[0064] 2. Preparation of composite modified asphalt:

[0065] 2.1 Composite modifier

[0066] The mass ratio of the first elastomer SEBS (styrene-ethylene-butylene-styrene block copolymer) to the second elastomer TPO (thermoplastic polyolefin elastomer) is 47:53.

[0067] 2.3 Preparation process

[0068] The composite modifier was preheated at 170°C for 10 minutes and added to the asphalt. The total dosage of the composite modifier was 10.5% by weight. A high-speed shearing machine was used to shear at 3500 rpm for 40 minutes. The temperature was maintained at 165°C to 175°C to obtain the composite modified asphalt. The needle penetration and softening point were tested to see if they met the technical requirements.

[0069] The composite modified asphalt has a needle penetration of 45×0.1mm, a softening point of 93℃, a low-temperature ductility (5℃) of 36cm, and a kinematic viscosity of 2.9Pa.s at 135℃.

[0070] 3. Asphalt mixture mixing:

[0071] Heat the aggregate to 185°C, heat the composite modified asphalt to 165°C, and mix the aggregate and composite modified asphalt in a forced mixer at 55 rpm for 105 seconds, with an oil-stone ratio of 5.8% and a discharge temperature of 170±5°C. 4. Construction application

[0072] Construction on the upper surface of the expressway in Changchun City, Jilin Province:

[0073] 4.1 Paving: Paving temperature ≥ 155°C, paving speed 3m / min;

[0074] 4.2 Compaction: Use rotary compactor (SGC) for compaction, 50 times, initial compaction temperature 150℃, final compaction temperature 135℃, compaction degree ≥97%;

[0075] 4.3 Performance Verification:

[0076] On-site core sampling test dynamic stability of 6,500 times / mm, water immersion residual stability ratio of 83.5%; SCB fracture energy of 6,200J / m2 , meeting the design requirements.

[0077] Target void ratio (VV): measured result: 5.2%, aggregate void ratio (VMA): measured result: 17.5% (design requirement ≥17%), asphalt saturation (VFA): calculated result: 70%.

[0078] Example 2

[0079] 1. Aggregate:

[0080] 10-15 mm gneiss crushed stone: 52% by weight;

[0081] 5-10 mm gravel: 15% by weight;

[0082] 0-3mm machine-made sand: 25% by weight;

[0083] Mineral powder: 8% by weight; limestone mineral powder, fineness (0.075mm sieve pass rate) ≥88%.

[0084] 2. Preparation of composite modified asphalt:

[0085] 2.1 Composite modifier

[0086] The mass ratio of the first elastomer SEBS to the second elastomer TPO is 47:53.

[0087] 2.3 Preparation process

[0088] The composite modifier was preheated at 180°C for 10 minutes and added to the asphalt. The total dosage of the composite modifier was 15% by weight. A high-speed shearing machine was used to shear at 3000 rpm for 35 minutes. The temperature was maintained at 175°C to 180°C to obtain the composite modified asphalt. The penetration and softening point were then tested to see if they met the technical requirements.

[0089] The composite modified asphalt has a needle penetration of 46×0.1mm, a softening point of 92.5℃, a low-temperature ductility (5℃) of 36cm, and a kinematic viscosity of 2.9Pa.s at 135℃.

[0090] 3. Asphalt mixture mixing:

[0091] Heat the aggregate to 180℃, heat the composite modified asphalt to 170℃, and stir the aggregate and composite modified asphalt in a forced mixer at 45 rpm for 90 seconds, with an oil-to-stone ratio of 5.7% and a discharge temperature of 170±5℃. 4. Construction application

[0092] Construction on the upper surface of the expressway in Changchun City, Jilin Province:

[0093] 4.1 Paving: Paving temperature ≥ 155°C, paving speed 3m / min;

[0094] 4.2 Compaction: Use rotary compactor (SGC) for compaction, 60 times, initial compaction temperature 150℃, final compaction temperature 130℃, compaction degree ≥98%;

[0095] 4.3 Performance Verification:

[0096] On-site core sampling test dynamic stability of 6725 times / mm, water immersion residual stability ratio of 85.3%; SCB fracture energy of 6,300J / m 2 , meeting the design requirements.

[0097] Target void ratio (VV): measured result: 4.8%, aggregate void ratio (VMA): measured result: 18.1% (design requirement ≥17%), asphalt saturation (VFA): calculated result: 73%.

[0098] Example 3

[0099] 1. Aggregate:

[0100] 10-15 mm gneiss crushed stone: 53% by weight;

[0101] 5-10 mm gravel: 25% by weight;

[0102] 0-3mm machine-made sand: 12% by weight;

[0103] Mineral powder: 10% by weight; limestone mineral powder, fineness (0.075mm sieve passing rate) ≥88%.

[0104] 2. Preparation of composite modified asphalt:

[0105] 2.1 Composite modifier

[0106] The mass ratio of the first elastomer SEBS to the second elastomer TPO is 47:53.

[0107] 2.3 Preparation process

[0108] The composite modifier was preheated at 160°C for 10 minutes and added to the asphalt. The total dosage of the composite modifier was 10% by weight. A high-speed shearing machine was used to shear at 4000 rpm for 30 minutes. The temperature was maintained at 160°C to 165°C to obtain the composite modified asphalt. The penetration and softening point were then tested to see if they met the technical requirements.

[0109] The composite modified asphalt has a needle penetration of 45×0.1mm, a softening point of 93℃, a low-temperature ductility (5℃) of 36cm, and a kinematic viscosity of 2.9Pa.s at 135℃.

[0110] 3. Asphalt mixture mixing:

[0111] Heat the aggregate to 190℃, heat the composite modified asphalt to 160℃, and mix the aggregate and composite modified asphalt in a forced mixer at 50 rpm for 120 seconds, with an oil-stone ratio of 5.6% and a discharge temperature of 170±5℃; 4. Construction application

[0112] Construction on the upper surface of the highway in Harbin, Heilongjiang Province:

[0113] 4.1 Paving: Paving temperature ≥ 155°C, paving speed 3m / min;

[0114] 4.2 Compaction: Use rotary compactor (SGC) for compaction, 75 times, initial compaction temperature 150℃, final compaction temperature 140℃, compaction degree ≥99%;

[0115] 4.3 Performance Verification:

[0116] On-site core sampling test dynamic stability of 6,240 times / mm, water immersion residual stability ratio of 86.5%; SCB fracture energy of 6,500J / m 2 , meeting the design requirements.

[0117] Target void ratio (VV): measured result: 5.5%, aggregate void ratio (VMA): measured result: 17.2%, asphalt saturation (VFA): calculated result: 68%.

[0118] Therefore, the present invention conducts collaborative design from two dimensions: binder modification and aggregate gradation optimization, and proposes a reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design:

[0119] (1) Composite modification design of binder

[0120] 1. Selection of composite modifier:

[0121] First elastomer (SEBS): gives asphalt high elastic recovery ability and improves crack resistance;

[0122] Second elastomer (TPO): Enhances high-temperature viscoelasticity and improves anti-rutting performance.

[0123] 2. Optimization of composite modifier ratio (mass ratio):

[0124] The mass ratio of the first elastomer to the second elastomer is 47:53, and the total amount of the first elastomer in the composite modified asphalt is 10% to 15% by weight;

[0125] 3. Key performance indicators of composite modified asphalt:

[0126] Needle penetration (25℃): 45×0.1mm;

[0127] Softening point ≥93℃;

[0128] Low temperature ductility (5℃)≥40cm;

[0129] Kinematic viscosity at 135℃≤3Pa·s.

[0130] (2) Grading optimization design

[0131] Discontinuous semi-open gradation design

[0132] 1. Grading characteristics:

[0133] The key sieve holes (4.75-9.5 mm) are set with gradation breaks to reduce the proportion of intermediate size aggregates. The content of this grade should not exceed 25% by weight, and can generally be 15% to 25% by weight;

[0134] Coarse aggregate (>4.75mm and ≤15mm) accounts for 67% to 78% by weight, forming a skeleton embedded structure;

[0135] Fine aggregate (<2.36mm) accounts for 12% to 25% by weight, filling the gaps in the skeleton and increasing the mortar content.

[0136] 2. Design parameters:

[0137] Target void ratio 4% to 6%;

[0138] Mineral void ratio (VMA) ≥ 17%;

[0139] Asphalt saturation (VFA) 65% to 75%.

[0140] (3) Preparation process

[0141] Aggregate pretreatment: Coarse and fine aggregates and mineral powder fillers are heated to 180℃~190℃ to ensure the surface is dry;

[0142] Asphalt mixing:

[0143] Heat the composite modified asphalt to 160℃~170℃ and add aggregate at an asphalt to stone ratio of 5.6%~5.8%;

[0144] Mix at 45 rpm to 55 rpm for 90 to 120 seconds to ensure even coating;

[0145] Forming and compaction:

[0146] The specimens were formed using a rotary compactor (SGC) with 50 to 75 compaction times;

[0147] The final pressing temperature should be ≥130℃ to avoid aging of the binder.

[0148] The present invention is used to solve the following technical problems:

[0149] 1. Improve the low-temperature crack resistance and fatigue resistance of asphalt mixture;

[0150] 2. Optimize the selection of composite modifiers and aggregate gradation design to balance high and low temperature performance and storage stability;

[0151] 3. Simplify the construction process, avoid fiber addition, and reduce overall costs.

[0152] The present invention can achieve the following advantages:

[0153] 1. Excellent fatigue resistance: The four-point bending fatigue life of the beam reaches 89,810 times (compared to 26,270 times for traditional SMA13), which is nearly three times higher;

[0154] 2. Significantly improved low-temperature crack resistance: SCB fracture energy is 6200J / m 2 ~6500J / m 2 (SMA13 is 2,631J / m 2 ), low temperature strain capacity is enhanced;

[0155] 3. Stable high temperature performance: dynamic stability 6240 times / mm~6725 times / mm, meeting the requirements of the specification;

[0156] 4. Convenient construction: no need to add fiber, simplified mixing process, and reduced construction costs;

[0157] 5. Environmental protection and economy: The dosage of composite modifier is optimized, and the cost is reduced by 15% to 20% compared with the SBS modification solution.

[0158] The reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design of the present invention significantly improves the fatigue resistance, low-temperature crack resistance and high-temperature stability of the asphalt mixture through the coordinated design of elastomer composite modification and discontinuous semi-open gradation, while taking into account construction controllability and economy. It is particularly suitable for road surface structures in low-temperature environments, heavy-load traffic and complex climatic conditions.

[0159] In summary, the reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open grading design of the present invention has excellent fatigue resistance, good low-temperature crack resistance, and high storage stability. Its preparation method is cleverly designed, with simple steps, convenient construction, economy and environmental protection, and is suitable for large-scale promotion and application.

[0160] It can be seen that the objectives of the present invention have been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and illustrated in the embodiments. The embodiments may be modified as desired without departing from the principles described. Therefore, the present invention includes all variations within the spirit and scope of the claims.

Claims

1. A reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design, comprising composite modified asphalt and aggregate, characterized in that: The composite modified asphalt is prepared by composite-modifying asphalt with a composite modifier, wherein the total amount of the composite modifier in the composite modified asphalt is 10% by weight to 15% by weight, and the composite modifier comprises a first elastomer and a second elastomer, wherein the first elastomer and the second elastomer are styrene-ethylene-butylene-styrene block copolymer and a thermoplastic polyolefin elastomer, respectively, and the mass ratio of the first elastomer to the second elastomer is 47:53; The aggregate comprises coarse aggregate, fine aggregate and mineral powder, wherein the particle size of the coarse aggregate is greater than 4.75 mm and ≤ 15 mm, and the coarse aggregate accounts for 67% by weight to 78% by weight, wherein the coarse aggregate with a particle size greater than 4.75 mm and ≤ 9.5 mm accounts for 15% by weight to 25% by weight, the particle size of the fine aggregate is less than 2.36 mm, and the fine aggregate accounts for 12% by weight to 25% by weight, and the mineral powder accounts for 7% by weight to 10% by weight; The asphalt-to-stone ratio of the composite modified asphalt and the aggregate is 5.6% to 5.8%.

2. The reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design according to claim 1, characterized in that: The total content of the composite modifier in the composite modified asphalt is 10.5% by weight; the asphalt-to-stone ratio of the composite modified asphalt and the aggregate is 5.8%.

3. The reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design according to claim 1, characterized in that: Among the aggregate, the coarse aggregate with a particle size of >9.5mm and ≤15mm accounts for 54% by weight, the coarse aggregate with a particle size of >4.75mm and ≤9.5mm accounts for 20% by weight, the fine aggregate accounts for 19% by weight, and the mineral powder accounts for 7% by weight.

4. The reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design according to claim 1, characterized in that: The total content of the composite modifier in the composite modified asphalt is 15% by weight; the asphalt-to-stone ratio of the composite modified asphalt and the aggregate is 5.7%.

5. The reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design according to claim 1, characterized in that: Among the aggregate, the coarse aggregate with a particle size of >9.5mm and ≤15mm accounts for 52% by weight, the coarse aggregate with a particle size of >4.75mm and ≤9.5mm accounts for 15% by weight, the fine aggregate accounts for 25% by weight, and the mineral powder accounts for 8% by weight.

6. The reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design according to claim 1, characterized in that: The total content of the composite modifier in the composite modified asphalt is 10% by weight; the asphalt-to-stone ratio of the composite modified asphalt to the aggregate is 5.6%.

7. The reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design according to claim 1, characterized in that: Among the aggregates, the coarse aggregates with a particle size of >9.5 mm and ≤15 mm account for 53% by weight, the coarse aggregates with a particle size of >4.75 mm and ≤9.5 mm account for 25% by weight, the fine aggregates account for 12% by weight, and the mineral powder accounts for 10% by weight.

8. A method for preparing a reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design as claimed in claim 1, characterized in that: The following steps are involved: (1) adding the composite modifier to the asphalt, and mixing them uniformly by high-temperature shearing and stirring to obtain a composite modified asphalt; (2) The aggregate is heated to a first high temperature, the composite modified asphalt is heated to a second high temperature, and the aggregate and the composite modified asphalt are mixed evenly to obtain the reinforced and toughened asphalt mixture based on the composite modification and discontinuous semi-open grading design.

9. The method for preparing a reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design according to claim 8, characterized in that: In the step (1), the high temperature is 160° C. to 180° C., the shear stirring rate is 3000 rpm to 4000 rpm, and the shear stirring time is 30 minutes to 40 minutes.

10. The method for preparing a reinforced and toughened asphalt mixture based on composite modification and discontinuous semi-open gradation design according to claim 8, characterized in that: In the step (2), the first high temperature is 180°C to 190°C, the second high temperature is 160°C to 170°C, the mixing time is 90 seconds to 120 seconds, and the mixing speed is 45 rpm to 55 rpm.