Circulating preparation method of modified asphalt for road

Abstract

The invention provides a cyclic preparation method of modified asphalt for roads, and relates to the technical field of asphalt concrete.The cyclic preparation method comprises the steps that a composite modifier is put into a high-speed shearing machine in proportion, an anti-stripping agent or inorganic filler is added, and meanwhile a temperature adjusting agent is pretreated; in order to solve the problems that the effect of regenerating the modifier is poor, and the temperature adjusting technology is lack of efficient additives, the composite elastomer modifier and the flexible modifier are adopted, all the components have a synergistic effect, and the composite elastomer modifier and the flexible modifier are added into the mixed asphalt concrete to form the mixed asphalt concrete. The modification effect is improved, a large amount of new asphalt or aggregate does not need to be added, a temperature regulating agent, a wax-based temperature regulating agent in a high-temperature rainy region and an anti-freezing temperature regulating agent in a severe cold region are specifically designed, the temperature is effectively regulated and controlled, and meanwhile the viscosity and construction performance of the material are guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of asphalt concrete, and in particular to a cyclic preparation method of modified asphalt for road use. Background Art

[0002] Waste asphalt from transportation refers to the waste asphalt mixture removed or milled from old pavement during the construction, maintenance and repair of transportation infrastructure such as highways and urban roads, commonly known as "milling material" and "old asphalt material". It is mainly composed of asphalt binder, aggregate and a small amount of additives. Due to long-term rolling under vehicle loads and environmental factors (temperature, rain, ultraviolet rays, etc.), it will experience problems such as aging and performance degradation, leading to road damage (such as cracks, potholes, ruts, etc.) and need to be replaced or refurbished. This type of waste is mostly landfilled or piled in the open air, which not only occupies land and pollutes the environment, but also causes a waste of resources. Through recycling technology, it can be recycled and reused as pavement material, which can not only reduce the consumption of new stone and asphalt, but also reduce carbon emissions.

[0003] Publication No. CN102448907A provides a composition and manufacturing method for a temperature-controlled, modified recycled asphalt concrete that can reuse 100% of waste asphalt concrete for highway paving. The composition comprises 100 parts by weight of waste asphalt concrete with a particle size distribution of 53 mm or less, which is fed into a new inlet of a mixer. 0.1-20 parts by weight of a recycled modifier and 0.1-20 parts by weight of a plasticizer and temperature-control additive are added to the new asphalt feed position. The mixture is then uniformly mixed at a temperature of 5-180 degrees Celsius (medium temperature) for 0.5-3 minutes. The composition can be used as a material for the wearing course, surface layer, intermediate layer, and base layer of asphalt pavement, thereby enabling the reuse of the recycled asphalt mixture. The modified regeneration agent improves the physical properties of the recycled asphalt mixture, and the temperature-control additive adjusts the production temperature of the recycled asphalt mixture. The present invention can save costs, save waste disposal fees, save new asphalt and aggregates, prevent damage to the natural environment due to mining aggregates, prevent environmental pollution caused by waste landfill, etc. By using recycled modifiers, it is expected to improve the physical properties of use, extend the life of the pavement, save maintenance and repair costs, etc. Among them, the plasticizing and temperature-regulating additives have the advantage of saving production energy and reducing greenhouse gas generation. Overall, the economic, social and technical benefits are great.

[0004] However, the above method still has the following problems:

[0005] 1. Modifiers and temperature control technologies have limited effectiveness and rely on the addition of new materials. In existing technologies, the modified effect of recycled modifiers is easily diluted by the old asphalt in the waste asphalt, requiring the addition of large amounts of new asphalt or aggregate to compensate for performance deficiencies, leading to increased costs. The lack of efficient temperature control additives prevents effective reduction of production and construction temperatures, making it difficult to balance energy conservation needs with material viscosity and construction performance.

[0006] 2. Lack of environmentally adaptable formula: Different climate zones (such as hot and rainy areas and extremely cold areas) have very different performance requirements for recycled asphalt, but the patent does not provide an additive formula adjustment strategy for extreme environments.

[0007] Therefore, a cyclic preparation method for road modified asphalt is needed. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the defects of the existing technology. The present invention proposes a cyclic preparation method for road modified asphalt, which aims to solve the problems of poor effect of regenerated modifiers and lack of efficient additives in temperature control technology.

[0009] To solve the above technical problems, the present invention adopts a technical solution: a cyclic preparation method for road modified asphalt, comprising the following steps:

[0010] S1: The waste asphalt concrete blocks are preliminarily crushed and screened, and the quality is measured. After the measurement, the moisture is adjusted;

[0011] S2: Adjust the additive formula based on 100 parts by weight of waste asphalt concrete according to the climate type of the target paving area;

[0012] S3: The composite modifier is put into a high-speed shearing machine according to a certain proportion, and an anti-stripping agent or an inorganic filler is added, and the temperature regulating agent is pretreated at the same time;

[0013] S4: preheating the waste asphalt concrete, and simultaneously mixing the waste asphalt concrete, the composite modifier, and the temperature regulator to form mixed asphalt concrete;

[0014] S5: Conduct performance control and quality inspection on the asphalt concrete mixing process.

[0015] Preferably, the climate type of the target paving area is a high temperature and rainy area. Based on 100 parts by weight of waste asphalt concrete, the additive formula is adjusted as follows: 3-5 parts by weight of composite elastomer modifier, 0.5-1 parts by weight of anti-stripping agent, and 2-3 parts by weight of wax-based temperature regulator.

[0016] Preferably, the composite elastomer modifier comprises SBS, waste tire powder and SEBS, and the wax-based temperature regulator comprises a compound of stearamide wax and microcrystalline wax.

[0017] Preferably, the high-speed shearing machine is sheared at 50-100° C. for 10 minutes to form a uniform dispersion with a particle size not exceeding 50 microns, an anti-stripping agent is added, and the wax-based temperature regulating agent is heated to above the melting point and premixed with the foaming agent.

[0018] Preferably, the specific steps of S4 are:

[0019] S41: First, 100 parts by weight of waste asphalt concrete is put into a double-screw low-temperature mixer, pre-mixed for 1 minute, and preheated at room temperature or low temperature;

[0020] S42: A composite elastomer modifier and a wax-based temperature regulator are injected synchronously through a screw pump. The waste asphalt inlet and the modifier / temperature regulator injection port are diagonally distributed. The heating module in the high-temperature zone is started to the target temperature, which is 120-140°C.

[0021] S43: Mix at a medium speed of 300 rpm for 0.5 to 3 minutes until the asphalt is evenly coated with the aggregate.

[0022] Preferably, the climate type of the target paving area is a severely cold region. Based on 100 parts by weight of waste asphalt concrete, the additive formula is adjusted as follows: 4 to 6 parts by weight of a flexible modifier, 3-4 parts by weight of an antifreeze-type thermostat, and 1-2 parts by weight of a filler.

[0023] Preferably, the specific components of the flexibility modifier are SBR latex, vegetable oil-based plasticizer and EVA, and the antifreeze type temperature regulator is specifically a compound of ethylene glycol aqueous solution and zeolite powder.

[0024] Preferably, the high-speed shearing machine is sheared at 50-100° C. for 10 minutes to form a uniform dispersion with a particle size not exceeding 50 microns, and an inorganic filler is added. At the same time, 0.1% surfactant is added to the antifreeze-type temperature regulating agent.

[0025] Preferably, the specific steps of S4 are:

[0026] S41: First, 100 parts by weight of waste asphalt concrete is put into a double-screw low-temperature mixer, pre-mixed for 1 minute, and preheated at room temperature or low temperature;

[0027] S42: A well-proportioned flexible modifier and antifreeze-type thermostat are injected synchronously through a screw pump. The waste asphalt inlet and the modifier / thermostat injection port are diagonally distributed. The heating module is started in the severe cold zone to the target temperature, 50-80°C in the severe cold zone.

[0028] S43: Mix at a medium speed of 300 rpm for 0.5 to 3 minutes until the asphalt is evenly coated with the aggregate.

[0029] Preferably, the specific step S5 is to detect viscosity online during the mixing process, control construction workability by adjusting the amount of temperature regulating agent, detect Marshall stability and freeze-thaw splitting strength ratio, and if the test does not meet the standards, add no more than 5% of local modifier.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. In terms of modifiers, a composite elastomer modifier and a flexible modifier are used. The synergistic effect of these components enhances the modification effect, prevents excessive dilution with old asphalt, eliminates the need for large amounts of new asphalt or aggregate, and reduces costs. In terms of temperature control technology, targeted temperature control agents are designed. Wax-based temperature control agents are used in hot and rainy areas, and antifreeze-type temperature control agents are used in extremely cold areas to effectively control temperature. Wax-based temperature control agents reduce interfacial tension, lowering production temperatures by 20-30°C. For extremely cold areas, temperature control agents are combined with nano-silica fillers and mixed at 60°C, reducing temperatures by 100-110°C compared to traditional processes, reducing energy consumption by over 50%, while ensuring material viscosity and workability.

[0032] 2. This technical solution precisely designs environmentally adaptable formulas based on the characteristics of different climate zones. For hot and rainy areas, considering anti-rutting and water resistance, a composite elastomer modifier is added to improve high-temperature stability, a silane coupling agent and anti-stripping agent strengthen the asphalt-aggregate interface, and a wax-based temperature regulator reduces interfacial tension. The freeze-thaw splitting strength ratio is increased from 78% of the control example to 85%-90%, and the dynamic stability is significantly improved to meet the needs of the region. For severely cold areas, emphasis is placed on low-temperature crack resistance and freeze-thaw resistance. A flexible modifier is used to improve the flexibility of asphalt, lower the glass transition temperature of asphalt, and increase the low-temperature bending strain from 2200με of the control example to 2800-3600με; an antifreeze temperature regulator and nano-silica filler are used to reduce frost heave stress damage, and the freeze-thaw splitting strength ratio is increased to 82%-89%, solving the performance problem of recycled asphalt in extreme environments in severely cold areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The disclosure of the present invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the accompanying drawings, the same reference numerals are used to refer to the same components. Among them:

[0034] Figure 1 The figure schematically shows the overall flow chart of the steps of the present invention. DETAILED DESCRIPTION

[0035] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention and should not be regarded as the entire invention or as a limitation or restriction of the technical solution of the present invention.

[0036] Combine Figure 1 A method for preparing modified asphalt for road use is shown, comprising the following steps:

[0037] Step 1: Pretreatment of waste asphalt concrete

[0038] 1. Crushing and Screening: Collected waste asphalt concrete blocks are crushed to a maximum particle size of no more than 53 mm and graded using a vibrating screen. The particle size of the base layer material must not exceed 53 mm, and the particle size of the surface layer material must not exceed 13.2 mm. Impurities such as stone and metal are removed, and the gradation curve and aged asphalt content are determined through extraction tests.

[0039] 2. Pretreatment and humidity control: If the moisture content of waste asphalt exceeds 5%, it needs to be dried. This can be done by airing at room temperature or drying at low temperature, with the drying temperature not exceeding 80°C, to reduce the moisture content to below 2% to prevent moisture evaporation during subsequent heating that affects mixing uniformity.

[0040] Step 2: Climate Recipe Adjustment Process

[0041] According to the climate type of the target paving area, the additive formula is adjusted based on 100 parts by weight of waste asphalt concrete:

[0042] 1. For high temperature and rainy areas, for example, where the annual average temperature exceeds 20°C and the annual rainfall exceeds 800 mm, it is necessary to consider anti-rutting and water resistance in this climate. The specific formula is as follows:

[0043] 3 to 5 parts by weight of a composite elastomer modifier is added, wherein the specific components of the composite elastomer modifier are SBS, waste tire powder and SEBS, so as to improve high temperature stability.

[0044] SBS+waste tire powder+SEBS significantly improves high temperature stability through a synergistic mechanism, as follows:

[0045] Elastic Network Construction: SBS forms a three-dimensional elastic network within asphalt, significantly improving the asphalt's high-temperature viscosity and elastic recovery. Its linear structure effectively inhibits asphalt flow deformation at high temperatures, improving dynamic stability in rutting tests by 30%-50%.

[0046] Rigid particle reinforcement: The rubber particles in waste tire powder act as rigid fillers in the asphalt matrix, increasing the internal friction resistance of the material. Their irregular surface forms a mechanical interlock with the asphalt, further hindering plastic flow at high temperatures.

[0047] Improved Aging Resistance: SEBS has a saturated molecular chain structure, making it more resistant to oxidation and UV degradation. It works synergistically with SBS to form a more stable interface layer at high temperatures, slowing the aging rate of asphalt. After long-term use, the needle penetration ratio increases by 15%-20%.

[0048] Phase stabilization and regulation: The carbon black component in waste tire powder can adsorb light components in asphalt, and SEBS improves the compatibility of SBS with asphalt. The three together inhibit the phase separation phenomenon. Fluorescence microscopy observation shows that under this ratio, the modifier is more evenly dispersed in the asphalt, and the phase area size is reduced by 40%-60%.

[0049] Add 0.5 to 1 parts by weight of silane coupling agent anti-stripping agent to replace traditional amine anti-stripping agent, which has stronger hydrolysis resistance. Paired with 2 to 3 parts by weight of wax-based temperature regulator, which is a compound of stearamide wax and microcrystalline wax with a melting point of 80-100°C, it reduces interfacial tension.

[0050] Silane coupling agents are a class of organic silicon compounds that contain both polar and non-polar groups in their molecules. Aminosilanes, such as γ-aminopropyltriethoxysilane or mercaptosilane, are recommended. The freeze-thaw splitting strength ratio can be increased from 60%-70% of traditional amines to more than 80%, significantly extending the pavement's anti-water damage life. They work synergistically with modifiers such as SBS and SBR without affecting the high-temperature performance of asphalt.

[0051] Wax molecules align at the material interface, with non-polar chains facing outward to form a hydrophobic layer, reducing water wetting. At high temperatures, the wax melts, providing fluidity, while at low temperatures, it crystallizes to form a network structure, inhibiting thermal shrinkage cracking. This reduces water penetration and the risk of asphalt film spalling, lowering production temperatures by 20-30°C and improving workability.

[0052] 2. For extremely cold regions, for example, where the extreme low temperature is not higher than -20°C and the freeze-thaw cycle exceeds 50 times per year, low-temperature crack resistance and freeze-thaw resistance performance need to be considered in this climate. The specific formula is as follows:

[0053] 4 to 6 parts by weight of a flexibility modifier, specifically SBR latex, a vegetable oil-based plasticizer, and EVA, are added to improve the flexibility of asphalt.

[0054] The unsaturated fatty acid chains in the vegetable oil in the vegetable oil-based plasticizer are inserted between the asphalt molecules, reducing the intermolecular forces and allowing the asphalt to maintain fluidity at low temperatures. Vegetable oil replaces traditional petroleum-based plasticizers, reducing VOC emissions and meeting the needs of sustainable development. Vegetable oil-based plasticizers act as solvent-based carriers to reduce asphalt viscosity, promote uniform dispersion of SBR latex and EVA particles, and avoid agglomeration.

[0055] The ethylene chain segments of EVA provide flexibility, and the vinyl acetate groups increase polarity, forming physical crosslinks with the colloids and asphaltene in the asphalt. Through microphase separation, a rigid particle dispersion structure is formed, which resists plastic deformation at low temperatures. SBR provides a high elastic modulus, and EVA provides plastic deformation ability. The two work together to enable the modified asphalt to maintain a rebound rate of 15%-20% at -20°C.

[0056] Add 3 to 4 parts by weight of antifreeze-type thermostat, which is a compound of ethylene glycol aqueous solution and zeolite powder. Zeolite absorbs free water, ethylene glycol lowers the freezing point, and 1 to 2 parts by weight of nano-silica filler is added to improve density and reduce frost heave cracks.

[0057] Step 3: Synergistic preparation of composite modifier and temperature regulator

[0058] Put the composite modifier into a high-speed shearing machine in proportion, shear at 50-100℃ for 10 minutes to form a uniform dispersion with a particle size not exceeding 50 microns, add anti-stripping agent or inorganic filler, and stir at low speed for 5 minutes to prevent agglomeration.

[0059] The wax-based temperature regulating agent is heated to above the melting point and premixed with a foaming agent, which may be azodicarbonamide, to form a low-viscosity slurry.

[0060] The antifreeze type temperature regulating agent is added with 0.1% surfactant, which may be sodium dodecylbenzene sulfonate, and stirred evenly to enhance the compatibility with the waste asphalt.

[0061] Step 4: Mix over medium-low heat

[0062] 1. First, put 100 parts by weight of waste asphalt concrete into a double-screw low-temperature mixer, pre-mix for 1 minute, and preheat at room temperature or low temperature.

[0063] 2. Synchronously inject a well-proportioned composite modifier and temperature regulator via a screw pump. The waste asphalt inlet and the modifier / temperature regulator injection port are arranged diagonally to ensure rapid and uniform dispersion. The heating module is activated to the target temperature in high-temperature areas or extremely cold areas: 120-140°C in high-temperature areas and 50-80°C in extremely cold areas.

[0064] 3. Stir at a medium speed of 300 rpm for 0.5 to 3 minutes until the asphalt is evenly coated with the aggregate and there is no white material. The mixing temperature is 30-50℃ lower than that of the traditional process.

[0065] Step 5: Performance Control and Quality Testing

[0066] During the mixing process, the viscosity is tested online, with a target value of 0.3-0.6 Pa·s. The construction and workability are controlled by adjusting the amount of temperature regulator. The Marshall stability is tested, with a target value of not less than 1200 kgf. The freeze-thaw splitting strength ratio is not less than 85% in extremely cold areas and not less than 80% in high temperature areas. If it does not meet the standards, add no more than 5% of local modifier, such as adding 1 part of SBS.

[0067] Step 6: Finished product processing

[0068] After mixing is completed, it is immediately transferred to the insulated storage bin, the temperature of which is maintained 10-20°C lower than the mixing temperature, and the paving is completed within 24 hours. An appropriate amount of antioxidant is added to the remaining material, the antioxidant is di-tert-butyl-p-cresol, and it is sealed and stored at room temperature, and the shelf life is extended to 7 days.

[0069] Example 1

[0070] Step 1: Based on the climate type of hot and rainy areas, adjust the additive formula based on 100 parts by weight of waste asphalt concrete:

[0071] Add 3 parts by weight of composite elastomer modifier, the specific components of the composite elastomer modifier are 1 part of SBS, 1 part of waste tire powder and 1 part of SEBS, add 0.5 parts by weight of silane coupling agent anti-stripping agent, and match with 2 parts by weight of temperature regulator.

[0072] Step 2: Place the modifier into a high-speed shearing machine and shear at 50-100°C for 10 minutes to form a uniform dispersion with a particle size not exceeding 50 microns. Add a temperature regulator and an anti-stripping agent. At the same time, the wax-based temperature regulator needs to be heated to above the melting point and premixed with the foaming agent.

[0073] Step 3: First, put 100 parts by weight of waste asphalt concrete into a double-screw low-temperature mixer, pre-mix for 1 minute, and preheat at room temperature or low temperature.

[0074] 3 parts by weight of composite elastomer modifier, 0.5 parts by weight of silane coupling agent anti-stripping agent and 2 parts by weight of temperature regulator are injected simultaneously through a screw pump. The waste asphalt inlet and the modifier / temperature regulator injection port are diagonally distributed. The heating module in the high-temperature zone is started to the target temperature, 130°C in the high-temperature zone, and stirred at a medium speed of 300 rpm for 0.5 to 3 minutes.

[0075] Example 2

[0076] Step 1: Based on the climate type of hot and rainy areas, adjust the additive formula based on 100 parts by weight of waste asphalt concrete:

[0077] Add 4 parts by weight of a composite elastomer modifier, the specific components of the composite elastomer modifier are 2 parts of SBS, 1 part of waste tire powder and 1 part of SEBS, add 0.75 parts by weight of a silane coupling agent anti-stripping agent, and match with 2.5 parts by weight of a temperature regulator.

[0078] Step 2: Place the modifier into a high-speed shearing machine and shear at 50-100°C for 10 minutes to form a uniform dispersion with a particle size not exceeding 50 microns. Add a temperature regulator and an anti-stripping agent. At the same time, the wax-based temperature regulator needs to be heated to above the melting point and premixed with the foaming agent.

[0079] Step 3: First, put 100 parts by weight of waste asphalt concrete into a double-screw low-temperature mixer, pre-mix for 1 minute, and preheat at room temperature or low temperature.

[0080] 4 parts by weight of composite elastomer modifier, 0.75 parts by weight of silane coupling agent anti-stripping agent and 2.5 parts by weight of temperature regulator are injected simultaneously through a screw pump. The waste asphalt inlet and the modifier / temperature regulator injection port are diagonally distributed. The heating module in the high-temperature zone is started to the target temperature, 130°C in the high-temperature zone, and stirred at a medium speed of 300 rpm for 0.5 to 3 minutes.

[0081] Example 3

[0082] Step 1: Based on the climate type of hot and rainy areas, adjust the additive formula based on 100 parts by weight of waste asphalt concrete:

[0083] Add 5 parts by weight of a composite elastomer modifier, the specific components of the composite elastomer modifier are 2 parts of SBS, 1 part of waste tire powder and 2 parts of SEBS, add 1 part by weight of a silane coupling agent anti-stripping agent, and mix with 3 parts by weight of a temperature regulator.

[0084] Step 2: Place the modifier into a high-speed shearing machine and shear at 50-100°C for 10 minutes to form a uniform dispersion with a particle size not exceeding 50 microns. Add a temperature regulator and an anti-stripping agent. At the same time, the wax-based temperature regulator needs to be heated to above the melting point and premixed with the foaming agent.

[0085] Step 3: First, put 100 parts by weight of waste asphalt concrete into a double-screw low-temperature mixer, pre-mix for 1 minute, and preheat at room temperature or low temperature.

[0086] 5 parts by weight of composite elastomer modifier, 1 part by weight of silane coupling agent anti-stripping agent and 3 parts by weight of temperature regulator are injected simultaneously through a screw pump. The waste asphalt inlet and the modifier / temperature regulator injection port are diagonally distributed. The heating module in the high-temperature zone is started to the target temperature, 130°C in the high-temperature zone, and stirred at a medium speed of 300 rpm for 0.5 to 3 minutes.

[0087] Example 4

[0088] Step 1: Based on the climate type of the cold region, adjust the additive formula based on 100 parts by weight of waste asphalt concrete:

[0089] Add 4 parts by weight of a flexible modifier, specifically 2 parts of SBR latex, 1 part of a vegetable oil-based plasticizer, and 1 part of EVA, add 3 parts by weight of a temperature regulator, and mix with 1 part by weight of a nano-silica filler.

[0090] Step 2: Place the modifier into a high-speed shearing machine and shear at 50-100°C for 10 minutes to form a uniform dispersion with a particle size not exceeding 50 microns, and add a temperature control agent and filler. At the same time, add 0.1% surfactant to the antifreeze temperature control agent.

[0091] Step 3: First, put 100 parts by weight of waste asphalt concrete into a double-screw low-temperature mixer, pre-mix for 1 minute, and preheat at room temperature or low temperature.

[0092] 3 parts by weight of flexible modifier, 3 parts by weight of temperature regulator and 1 part by weight of filler are injected synchronously through a screw pump. The waste asphalt inlet and the modifier / temperature regulator injection port are diagonally distributed. The heating module is started in the cold zone to the target temperature, 60°C in the cold zone, and stirred at a medium speed of 300 rpm for 0.5 to 3 minutes.

[0093] Example 5

[0094] Step 1: Based on the climate type of the cold region, adjust the additive formula based on 100 parts by weight of waste asphalt concrete:

[0095] Add 5 parts by weight of a flexible modifier, specifically 2 parts of SBR latex, 1 part of a vegetable oil-based plasticizer and 2 parts of EVA, add 3.5 parts by weight of a temperature regulator, and match with 1.5 parts by weight of a nano-silica filler.

[0096] Step 2: Place the modifier into a high-speed shearing machine and shear at 50-100°C for 10 minutes to form a uniform dispersion with a particle size not exceeding 50 microns, and add a temperature control agent and filler. At the same time, add 0.1% surfactant to the antifreeze temperature control agent.

[0097] Step 3: First, put 100 parts by weight of waste asphalt concrete into a double-screw low-temperature mixer, pre-mix for 1 minute, and preheat at room temperature or low temperature.

[0098] 4 parts by weight of flexible modifier, 3.5 parts by weight of temperature regulator and 1.5 parts by weight of filler are injected simultaneously through a screw pump. The waste asphalt inlet and the modifier / temperature regulator injection port are diagonally distributed. The heating module is started in the cold zone to the target temperature, 60°C in the cold zone, and stirred at a medium speed of 300 rpm for 0.5 to 3 minutes.

[0099] Example 6

[0100] Step 1: Based on the climate type of the cold region, adjust the additive formula based on 100 parts by weight of waste asphalt concrete:

[0101] Add 6 parts by weight of flexibility modifier, the specific ingredients of which are 2 parts of SBR latex, 2 parts of vegetable oil-based plasticizer and 2 parts of EVA, add 4 parts by weight of temperature regulator, and match with 2 parts by weight of nano-silica filler.

[0102] Step 2: Place the modifier into a high-speed shearing machine and shear at 50-100°C for 10 minutes to form a uniform dispersion with a particle size not exceeding 50 microns, and add a temperature control agent and filler. At the same time, add 0.1% surfactant to the antifreeze temperature control agent.

[0103] Step 3: First, put 100 parts by weight of waste asphalt concrete into a double-screw low-temperature mixer, pre-mix for 1 minute, and preheat at room temperature or low temperature.

[0104] 6 parts by weight of flexible modifier, 4 parts by weight of temperature regulator and 2 parts by weight of filler are injected synchronously through a screw pump. The waste asphalt inlet and the modifier / temperature regulator injection port are diagonally distributed. The heating module is started in the cold zone to the target temperature, 60°C in the cold zone, and stirred at a medium speed of 300 rpm for 0.5 to 3 minutes.

[0105] Comparative Example 1

[0106] Step 1: Based on 100 parts by weight of waste asphalt concrete, 20% new asphalt and 5% new aggregate were added. No composite elastomer modifier and silane coupling agent anti-stripping agent were used, and only 1% conventional warm mix agent was added.

[0107] Step 2: Heat the waste asphalt concrete to 180°C and the new aggregate to 200°C. Add the new aggregate, new asphalt and waste asphalt concrete into the forced mixer in sequence and stir at 170°C for 3 minutes.

[0108] The performance indicators of the modified asphalt obtained in Examples 1-6 are shown in the following table:

[0109]

[0110] 1. High temperature and heavy rain areas

[0111] By comparing Examples 1 to 3 with Control Example 1, the dynamic stability is improved from 1900 times / mm of the control example to 3200-5200 times / mm, indicating that the network structure formed by the composite elastomer modifier effectively inhibits rutting deformation, the Marshall stability is improved by 32%-59%, and the flow value is reduced by 14%-29%, reflecting that the rigidity and elastic recovery ability of the material are enhanced, and it is suitable for high temperature and heavy load environments.

[0112] The freeze-thaw splitting strength ratio is increased from 78% of the control example to 85%-90%. The silane coupling agent anti-stripping agent strengthens the asphalt-aggregate interface through chemical bonding, reducing the stripping damage caused by rainwater penetration.

[0113] When the amount of modifier increases from 3 parts by weight to 5 parts by weight, the increase in dynamic stability gradually slows down. Example 3 is improved by 63% compared with Example 1, but the amount is increased by 67%. The cost-effective formula of 4 parts by weight of modifier is preferred.

[0114] 2. Severely cold regions

[0115] By comparing Examples 4 to 6 with Control Example 1, the low-temperature bending strain is increased from 2200 με of the Control Example to 2800-3600 με. The flexible modifier lowers the glass transition temperature of asphalt, allowing the material to maintain flexibility at -20°C.

[0116] The freeze-thaw splitting strength ratio is increased from 70% of the control example to 82%-89%. Nano-silica fillers fill the pores and absorb free water. Combined with antifreeze thermostats, the freezing point is lowered, reducing frost heave stress damage.

[0117] The mixing temperature only needs to be 60°C, which is 100-110°C lower than the traditional process, energy consumption is reduced by more than 50%, and the utilization rate of waste asphalt reaches more than 97%, avoiding the damage to the permafrost area ecology caused by the mining of new aggregates.

[0118] When the amount of modifier increases from 4 parts by weight to 6 parts by weight, the increase in low-temperature strain slows down. Example 6 increases by 29% compared with Example 4, and the amount is increased by 50%. A formula of 5 parts by weight of modifier + 1.5 parts by weight of nanofiller is used to balance performance and cost.

[0119] The technical scope of the present invention is not limited to the contents of the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. A cyclic preparation method for road modified asphalt, characterized in that: The steps include: S1: The waste asphalt concrete blocks are preliminarily crushed and screened, and the quality is measured. After the measurement, the moisture is adjusted; S2: Adjust the additive formula based on 100 parts by weight of waste asphalt concrete according to the climate type of the target paving area; S3: The composite modifier is put into a high-speed shearing machine according to a certain proportion, and an anti-stripping agent or an inorganic filler is added, and the temperature regulating agent is pretreated at the same time; S4: preheating the waste asphalt concrete, and simultaneously mixing the waste asphalt concrete, the composite modifier, and the temperature regulator to form mixed asphalt concrete; S5: Conduct performance control and quality inspection on the asphalt concrete mixing process.

2. The method for preparing modified road asphalt according to claim 1, characterized in that: The climate type of the target paving area is a hot and rainy area. Based on 100 parts by weight of waste asphalt concrete, the additive formula is adjusted as follows: 3-5 parts by weight of composite elastomer modifier, 0.5-1 parts by weight of anti-stripping agent, and 2-3 parts by weight of wax-based temperature regulator.

3. The recycling method for preparing modified asphalt for road use according to claim 2, characterized in that: The specific components of the composite elastomer modifier are SBS, waste tire powder and SEBS, and the wax-based temperature regulator is specifically a compound of stearamide wax and microcrystalline wax.

4. The method for preparing modified road asphalt in a cycle according to claim 3, characterized in that: The high-speed shearing machine is sheared at 50-100° C. for 10 minutes to form a uniform dispersion with a particle size not exceeding 50 microns, an anti-stripping agent is added, and at the same time, the wax-based temperature regulating agent is heated to above the melting point and pre-mixed with the foaming agent.

5. The recycling method for preparing modified asphalt for road use according to claim 3, characterized in that: The specific steps of S4 are: S41: First, 100 parts by weight of waste asphalt concrete is put into a double-screw low-temperature mixer, pre-mixed for 1 minute, and preheated at room temperature or low temperature; S42: A composite elastomer modifier and a wax-based temperature regulator are injected synchronously through a screw pump. The waste asphalt inlet and the modifier / temperature regulator injection port are diagonally distributed. The heating module in the high-temperature zone is started to the target temperature, which is 120-140°C. S43: Mix at a medium speed of 300 rpm for 0.5 to 3 minutes until the asphalt is evenly coated with the aggregate.

6. The method for preparing modified road asphalt in a cycle according to claim 1, characterized in that: The climate type of the target paving area is a severely cold region. Based on 100 parts by weight of waste asphalt concrete, the additive formula is adjusted as follows: 4 to 6 parts by weight of flexible modifier, 3-4 parts by weight of antifreeze-type temperature regulator, and 1-2 parts by weight of filler.

7. The recycling method for preparing modified road asphalt according to claim 6, characterized in that: The specific components of the flexible modifier are SBR latex, vegetable oil-based plasticizer and EVA, and the antifreeze type temperature regulator is specifically a compound of ethylene glycol aqueous solution and zeolite powder.

8. The method for preparing modified road asphalt in a cycle according to claim 7, characterized in that: The high-speed shearing machine is sheared at 50-100° C. for 10 minutes to form a uniform dispersion with a particle size not exceeding 50 microns, and an inorganic filler is added. At the same time, an antifreeze-type temperature regulating agent is added with 0.1% surfactant.

9. The method for preparing modified road asphalt in a cycle according to claim 7, characterized in that: The specific steps of S4 are: S41: First, 100 parts by weight of waste asphalt concrete is put into a double-screw low-temperature mixer, pre-mixed for 1 minute, and preheated at room temperature or low temperature; S42: A well-proportioned flexible modifier and antifreeze-type thermostat are injected synchronously through a screw pump. The waste asphalt inlet and the modifier / thermostat injection port are diagonally distributed. The heating module is started in the severe cold zone to the target temperature, 50-80°C in the severe cold zone. S43: Mix at a medium speed of 300 rpm for 0.5 to 3 minutes until the asphalt is evenly coated with the aggregate.

10. The method for preparing modified road asphalt in a cycle according to claim 1, characterized in that: The specific step S5 is to detect viscosity online during the mixing process, control construction workability by adjusting the amount of temperature control agent, detect Marshall stability and freeze-thaw splitting strength ratio, and add no more than 5% of local modifier if the test does not meet the standards.

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