Asphalt overlay material and preparation method thereof

Abstract

The invention provides an asphalt overlay material and a preparation method thereof. The asphalt overlay material comprises the following raw materials in parts by mass: 12-18 parts of high-viscosity and high-elasticity modified asphalt, 75-82 parts of aggregate and 0.5-2 parts of an additive, the dynamic viscosity of the high-viscosity and high-elasticity modified asphalt at 60 DEG C is 300,000-500,000 Pas, the ductility at 5 DEG C is 35-45 cm, and the elasticity recovery at 25 DEG C is greater than or equal to 95%; intermittent grading is adopted in the aggregate, and the additives are an anti-stripping agent and a warm mixing agent. The material is suitable for 1.0-1.5 cm ultra-thin overlay engineering, the reflection crack fatigue life is larger than or equal to 1200 times of circulation, the dynamic stability at 60 DEG C is larger than or equal to 4300 times / mm, the low-temperature flexural-tensile strain at-10 DEG C is larger than or equal to 3500 [mu] m, reflection cracks can be effectively inhibited, the service life of a pavement can be effectively prolonged, construction is efficient and energy-saving, and the material is suitable for various scenes such as a dry area, a wet area, a seasonal freezing area and heavy traffic.

Description

Technical Field

[0001] This invention relates to the field of road engineering maintenance materials technology, and in particular to an asphalt overlay material and its preparation method. Background Technology

[0002] In highway maintenance engineering, thin-layer overlay technology is widely used because it can quickly restore pavement function. However, traditional thin-layer overlays (2-3cm thick) have the following limitations: First, reflective cracking is a prominent problem. Displacement from cracks or joints in the old pavement is transmitted to the overlay layer through the interlayer. Due to the thin thickness and insufficient crack resistance of the overlay, reflective cracking is prone to occur (cracking rate exceeds 30% within 1-2 years of opening to traffic). Second, the material performance matching is poor. Ordinary SBS modified asphalt has insufficient low-temperature elasticity (ductility ≤30cm at 5℃), and the mixture skeleton structure is unstable, making it prone to rutting at high temperatures and brittleness at low temperatures. Third, interlayer bonding is weak. Conventional emulsified asphalt has low bond strength (tensile strength ≤0.4MPa), which easily leads to delamination between the overlay and the base layer, exacerbating crack propagation. Fourth, construction technology is limited. Asynchronous construction leads to tack coat contamination or insufficient demulsification, affecting the integrity of the interlayer. Current technologies employ single modified asphalt and continuous gradation, without optimizing the crack-resistant components for extremely thin thicknesses. This results in limited reflective crack suppression (fatigue life ≤ 500 cycles), failing to meet the requirements for long-life maintenance. Therefore, developing a topcoat material that combines high crack resistance, strong adhesion, and adaptability to extremely thin thicknesses is crucial. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides an asphalt overlay material and its preparation method. Through component synergistic optimization and process innovation, it solves the problems of traditional thin-layer overlays, such as susceptibility to reflective cracking, insufficient fatigue resistance, and poor durability due to their thinness. The resulting crack-resistant asphalt overlay material possesses excellent properties, including high crack resistance, strong adhesion, and adaptability to extremely thin thicknesses. This overlay material exhibits excellent comprehensive properties, including a reflective crack fatigue life ≥1200 cycles, dynamic stability at 60℃ ≥4300 cycles / mm, and low-temperature flexural strain at -10℃ ≥3500 μm. It is suitable for extremely thin overlay projects with a thickness of 1.0~1.5 cm, effectively suppressing reflective cracking and extending pavement life.

[0004] In a first aspect, the asphalt overlay material provided by this invention comprises the following raw materials in parts by weight: 12-18 parts modified asphalt, 75-82 parts aggregate, 3-5 parts emulsified asphalt, and 0.5-2 parts additives; the modified asphalt is high-viscosity, high-elasticity modified asphalt; the high-viscosity, high-elasticity modified asphalt has a dynamic viscosity of 300,000 Pa·s to 500,000 Pa·s at 60°C, a ductility of 35-45 cm at 5°C, and an elastic recovery of ≥95% at 25°C; the aggregate adopts a discontinuous gradation; the emulsified asphalt is SBS modified emulsified asphalt; and the additives are an anti-stripping agent and a warm mix agent. This invention, by optimizing the component ratio and using high-viscosity, high-elasticity modified asphalt as the core binder, along with a discontinuously graded aggregate skeleton combined with other raw materials, produces an ultra-thin, crack-resistant asphalt overlay material that solves the problems of reflective cracking, insufficient fatigue resistance, poor interlayer adhesion, and insufficient durability inherent in traditional thin-layer overlays, and achieves a longer pavement service life. Through synergistic optimization of each component, the material retains excellent crack resistance, durability, and interlayer adhesion even at extremely thin thicknesses.

[0005] Preferably, the high-viscosity and high-elasticity modified asphalt has a dynamic viscosity of 300,000~500,000 Pa·s at 60℃, a ductility of 35~45 cm at 5℃, an elastic recovery of ≥95% at 25℃, a softening point of ≥90℃, a residual penetration ratio of ≥70% at 25℃ after TFOT, and a ductility of ≥25 cm at 5℃ after TFOT.

[0006] Preferably, the high-viscosity and high-elasticity modified asphalt comprises the following raw materials in parts by weight: 65-75 parts of base asphalt; 10-15 parts of rubber powder; 6-8 parts of SBS; 2-3 parts of tackifier; 2-3 parts of plasticizer; and 0.3-0.5 parts of crosslinking agent; wherein the SBS is a star-shaped block copolymer, and the S / B block ratio is preferably 30 / 70.

[0007] More preferably, the raw materials include the following parts by weight: 65-75 parts of base asphalt; 10-15 parts of 60-80 mesh activated rubber powder; 6-8 parts of SBS; 2-3 parts of terpene resin; 2-3 parts of dibutyl phthalate; and 0.3-0.5 parts of sulfur. In this invention, by optimizing the composition and dosage of the high-viscosity and high-elasticity modified asphalt components, the base asphalt, rubber powder, SBS, tackifier, plasticizer, and crosslinking agent interact to form a more complete three-dimensional network and bonding system. The synergy between the activated rubber powder and the SBS block structure helps to balance low-temperature toughness and high-temperature stability. The tackifier terpene resin and the plasticizer dibutyl phthalate synergistically improve viscosity and formability, and the crosslinking agent forms a network structure to enhance durability. Furthermore, it better forms a stable skeleton and porosity with the discontinuous graded aggregate, further improving the crack resistance, anti-reflective cracking, fatigue resistance, and durability of the ultra-thin overlay.

[0008] Preferably, the aggregate adopts a discontinuous gradation with a nominal maximum particle size of 4.75mm to 9.5mm to form a stable skeleton structure. Preferably, by mass content, the aggregate includes: 50% to 60% coarse aggregate, 20% to 25% medium aggregate, 15% to 25% fine aggregate, and 3% to 5% mineral powder. The particle sizes d1 of the coarse aggregate, d2 of the medium aggregate, and d3 of the fine aggregate are 4.75mm ≤ d1 < 9.5mm, 2.36mm ≤ d2 < 4.75mm, and 0.075mm ≤ d3 < 2.36mm, respectively. The aggregate is selected from one or more of basalt and diabase, preferably dense basalt. The skeleton of the aggregate gradation provides support and deformation resistance for the extremely thin overburden, while the other aggregate grades work together to better achieve compactness and void control.

[0009] Preferably, the crushing value of the coarse aggregate is ≤26%, and the polishing value is ≥42.

[0010] Further preferred, the coarse aggregate must meet the following requirements: crushing value ≤ 26% (crushing value ≤ 20% for heavy traffic sections), polishing value (PSV) ≥ 42 (≥ 42 in wet areas, ≥ 38 in dry areas), and apparent relative density ≥ 2.60 g / cm³. 3 The material has the following properties: water absorption ≤2.0%, soundness (sodium sulfate solution method) ≤12%, water washing method <0.075mm particle content ≤1.0%, soft stone content ≤3%, and needle-like / flaky content ≤15%. The performance indicators of the medium and fine aggregates are consistent with those of the coarse aggregate (except for particle size). The fine aggregate must additionally meet the following requirements: sand equivalent ≥70%, angularity ≥38s, and methylene blue value ≤25g / kg. The mineral powder is finely ground limestone mineral powder and must meet the following requirement: apparent relative density ≥2.70g / cm³. 3 Hydrophilicity coefficient ≤1.0, plasticity index ≤4, heating stability qualified, and water washing method <0.075mm particle content ≥90%.

[0011] Preferably, the SBS-modified emulsified asphalt comprises the following raw materials in the indicated mass percentages: 65-70 parts SBS-modified asphalt; 2-3 parts emulsifier; 25-30 parts water; and 0.3-0.5 parts stabilizer. The SBS-modified emulsified asphalt ensures strong interlayer adhesion. The stabilizer is preferably calcium chloride, and the emulsifier is preferably an imidazoline emulsifier. The SBS-modified emulsified asphalt has an evaporation residue softening point ≥80℃, an elastic recovery of ≥90% at 25℃, and an adhesion grade to aggregate ≥5. This invention's SBS-modified emulsified asphalt effectively enhances long-term interlayer adhesion, reduces the risk of delamination, and improves stability.

[0012] Preferably, the anti-stripping agent is an amine-based anti-stripping agent and / or a polyamide-based anti-stripping agent; the warm mix agent is Sasobi. The warm mix agent lowers the mixing temperature, reduces aging, and improves construction efficiency; the anti-stripping agent improves the adhesion between aggregate and asphalt, and improves the interlayer interface. The interaction between the anti-stripping agent and the warm mix agent effectively improves adhesion and durability, and improves the construction temperature window and mixing stability, enhancing durability and water penetration resistance in humid environments, while maintaining high fatigue life and freeze-thaw resistance in wet areas.

[0013] Preferably, the crack-resistant asphalt overlay material comprises, by mass content, the following raw materials: 12%~18% high-viscosity, high-elasticity modified asphalt; 75%~82% aggregate; 3%~5% SBS modified emulsified asphalt; 0.5%~1.5% anti-stripping agent, preferably 0.5%~0.8% amine anti-stripping agent and / or 0.8%~1.2% polyamide anti-stripping agent; and 0.5%~1% warm mix agent. More preferably, the composition is: 15%~16% high-viscosity, high-elasticity modified asphalt; 77%~78% aggregate; 4%~5% SBS modified emulsified asphalt; 0.5%~0.8% anti-stripping agent; and 0.5%~0.8% warm mix agent.

[0014] According to the present invention, 12%~18% of high-viscosity and high-elasticity modified asphalt is used as the core binder, which is composed of base asphalt (AH-70) and composite modifier. Rubber powder (60~80 mesh) enhances low-temperature elasticity through surface activation, SBS enhances high-temperature stability, tackifier (terpene resin) increases viscosity (dynamic viscosity at 60℃ ≥ 500,000 Pa·s), plasticizer (dibutyl phthalate) improves low-temperature ductility, and crosslinking agent (sulfur) forms a three-dimensional network structure. The elastic recovery at 25℃ is ≥ 95%, and the ductility at 5℃ is ≥ 60 cm. Aggregate 75%~82%: Intermittent gradation (e.g., STC-7 type) is used. 4.75~9.5mm coarse aggregate forms the skeleton (50%~60%), 2.36~4.75mm medium aggregate fills the skeleton gaps (20%~25%), and fine aggregate (15%~25%) and mineral powder (3%~5%) form a dense filler, ensuring a mixture porosity of 4%~6% and an aggregate porosity ≥17%, improving deformation resistance. SBS modified emulsified asphalt (3%~5%): Interlayer bonding material, made of SBS modified asphalt, imidazoline emulsifier, and stabilizer (calcium chloride), with a solid content ≥65%, ensuring a tensile strength ≥0.6MPa with the base layer, and rapid demulsification during simultaneous construction to form a strong bond. Anti-stripping agent (amine-based) improves the adhesion between aggregate and asphalt (boiling method grade ≥5); warm mix agent (Sasobit) lowers the mixing temperature and reduces asphalt aging.

[0015] Secondly, the present invention provides a method for preparing the asphalt overlay material, comprising the following steps: 1) After heating the base asphalt, SBS, rubber powder, tackifier, plasticizer and crosslinking agent are added. After shear emulsification, swelling and development are obtained to obtain high viscosity and high elasticity modified asphalt.

[0016] 2) The high-viscosity and high-elasticity modified asphalt, additives and aggregates are heated and mixed at 170~185℃ to obtain a mixture.

[0017] 3) Spray emulsified asphalt onto the treated base layer and spread the mixture, then compact it.

[0018] Preferably, in step 1), the base asphalt is heated to 160-170°C, SBS and plasticizer are added, and sheared at 4000-6000 r / min for 30-40 min at a shearing temperature of 185-195°C; rubber powder and tackifier are added, and shearing continues for 20-30 min; a crosslinking agent is added, and swelling treatment is performed at 185-195°C for 60-90 min, followed by cooling to 170-180°C. This ensures that the resulting high-viscosity, high-elasticity modified asphalt possesses more stable mechanical properties and durability, improving the overall performance of the overlay material.

[0019] Preferably, step 2) further includes heating the aggregate to 190~220℃ in stages and mixing it according to the gradation ratio; then mixing the heated aggregate with the high-viscosity and high-elasticity modified asphalt at 170~185℃ for 40~60s, adding additives and continuing to mix for 20~30s, and controlling the discharge temperature to 160~175℃.

[0020] Preferably, in step 3), after milling and cleaning the base layer, the milling depth is 2~3cm, and the surface flatness is ≤3mm; simultaneously, SBS modified emulsified asphalt is sprayed at a rate of 0.8~1.0kg / m³. 2 The mixture is paved with a thickness of 1.0~1.5cm and a paving speed of 5~8m / min. It is compacted with an 11~13t double steel drum roller, with an initial compaction temperature ≥150℃ and a final compaction temperature ≥100℃. Both the initial and final compaction are static compaction, and the secondary compaction is vibrated with a frequency of 30~50Hz. The initial compaction, secondary compaction and final compaction are each performed 1~2 times. The opening temperature is ≤50℃.

[0021] The beneficial effects of this invention are at least as follows: 1) Significantly improved crack resistance. The high-viscosity and high-elasticity modified asphalt, in synergy with discontinuous gradation, achieves an Overlay Test fatigue cycle count of ≥1200 times (conventional materials ≤500 times) and a low-temperature bending tensile strain of ≥3500μm at -10℃, effectively suppressing reflective cracking.

[0022] 2) Enhanced durability. Dynamic stability at 60℃ ≥4300 cycles / mm (rutting resistance), freeze-thaw splitting strength ratio ≥89% (water damage resistance), and service life extended to 5~8 years (traditional thin-layer 3~5 years).

[0023] 3) Strong interlayer bonding. The tensile strength of SBS modified emulsified asphalt is ≥0.6MPa, avoiding interlayer delamination.

[0024] 4) Highly efficient and energy-saving construction. Simultaneous construction reduces the number of steps, lowers the mixing temperature by 10-15℃, and reduces energy consumption by 20%-30%. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0026] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0027] Unless otherwise specified, the techniques or conditions described in the embodiments of this invention shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Devices, instruments, reagents, etc., without specified manufacturers, are all conventional products that can be purchased through legitimate channels. All experimental reagents and raw materials involved are commercially available products, and all reagents are analytical grade products.

[0028] In the following embodiments of the present invention, the anti-stripping agent (amine) used is specifically Wetfix 312R anti-stripping agent from Nouryon. The warm mix agent is H02 warm mix agent from Sasobit. The high-viscosity, high-elasticity modified asphalt used is polymer composite modified emulsified asphalt. The SBS used is specifically a star-shaped block copolymer with an S / B block ratio of 30 / 70. The rubber powder is 60-80 mesh activated rubber powder. The SBS modified emulsified asphalt has an evaporation residue softening point greater than 80°C, an elastic recovery greater than 25% at 25°C, and an adhesion grade of 5 with aggregates. The emulsifier (imidazoline) used is a cationic fast-setting and fast-curing type. The plasticizer used is dibutyl phthalate, purchased from Shandong Lanfan. The crosslinking agent used is sulfur, purchased from Eastman Chemicals, Malaysia. The activated rubber powder is 60-80 mesh activated rubber powder from Changzhou Jiefuxun New Material Technology Co., Ltd.

[0029] All coarse aggregates used are dense basalt, processed by impact crushing, with a crushing value not exceeding 26%, a polishing value greater than 42%, and a particle shape mainly cubic, with a needle-like and flaky content ≤15%. Specific performance parameters are as follows: Table 1

[0030] SBS modified emulsified asphalt is prepared using a "modification followed by emulsification" process. The base asphalt is a blend of SK-90 matrix asphalt and 4% star-shaped SBS (S / B=30 / 70). Specific performance parameters are as follows: Table 2

[0031] Imidazoline emulsifiers are cationic, fast-setting, and quick-setting, suitable for the emulsification requirements of SBS modified asphalt. Specific performance parameters are as follows: Table 3

[0032] The specific performance parameters of the star-shaped SBS (Yueyang Baling Petrochemical YH-792) are as follows: Table 4

[0033] High-viscosity, high-elasticity modified asphalt (polymer-modified emulsified asphalt), specific performance parameters are as follows: Table 5

[0034] Terpene resin (tackifier, Shandong Huakai T-100), specific performance parameters are as follows: Table 6

[0035] Example 1 This embodiment provides an ultra-thin overlay suitable for preventive maintenance of asphalt pavements (dry areas). Addressing the characteristics of dry areas—large temperature differences and susceptibility to microcracks due to temperature stress, but also low rainfall and low risk of water damage—the material's low-temperature crack resistance and high-temperature stability are optimized. Its components and mass percentages are as follows: 15% high-viscosity, high-elasticity modified asphalt (70% base asphalt, 12% 60-80 mesh activated rubber powder, 7% star-shaped SBS, 2% terpene resin, 2% dibutyl phthalate, 0.4% sulfur). The base asphalt is Donghai AH-70 asphalt (softening point 50℃, penetration at 25℃ 63.4×0.1mm, ductility at 15℃ >100cm). The activated rubber powder is a 60-80 mesh product (heat loss 0.8%, ash content 3.8%).

[0036] The aggregate composition is 78% (55% coarse basalt aggregate (4.75~9.5mm), 22% medium basalt aggregate (2.36~4.75mm), 20% fine limestone aggregate (0.075~2.36mm), and 3% limestone mineral powder). The crushing value of the coarse aggregate is 10.7%, the polishing value is 45, the sand equivalent of the fine aggregate is 70%, and the angularity is 38s.

[0037] 4% SBS modified emulsified asphalt (68% SBS modified asphalt, 2.5% imidazoline emulsifier, 29% deionized water, 0.5% calcium chloride). The SBS modified asphalt used is Yueyang Baling Petrochemical YH-792 star-shaped SBS (block ratio S / B=30 / 70, tensile strength ≥12MPa).

[0038] Additives 1% (amine anti-stripping agent 0.5%, Nouryon Wetfix 312R; Sasobit warm mix agent 0.5%, Sasobit H02).

[0039] Specific preparation methods and process parameters 1. Preparation of high-viscosity and high-elasticity modified asphalt Raw material pretreatment: Donghai AH-70 base asphalt is put into a heating tank and heated with heat transfer oil at a controlled heating rate of 5℃ / min until it reaches 165℃ (±2℃). During this period, it is stirred once every 10 minutes (stirring rate 300r / min) to ensure that the asphalt melts evenly and without local overheating. 60~80 mesh activated rubber powder is placed in a 105℃ oven and dried for 2 hours to remove moisture (controlling the moisture content ≤0.5%). It is then cooled to room temperature for later use.

[0040] Component addition and shearing: Step 1: Add star-shaped SBS (S / B=30 / 70) and dibutyl phthalate to the molten base bitumen. Start the high-speed shearing machine (model: FLUKO FA90), set the shearing rate to 5000 r / min and the shearing temperature to 190℃ (±3℃), and shear for 35 min. During this period, take samples every 5 min to ensure that the SBS particles are completely dispersed (no visible agglomerates).

[0041] Step 2: Add the dried activated rubber powder and terpene resin (Shandong Huakai T-100, softening point ≥100℃), adjust the shear rate to 4500r / min, maintain the shear temperature at 190℃ (±3℃), and continue shearing for 25min. Monitor the asphalt viscosity in real time using an online viscometer to ensure that the viscosity at 60℃ is stable in the range of 450000~480000Pa・s.

[0042] Step 3: Add sulfur (Eastman Chemicals, Malaysia, average particle size <30μm), turn off the shearing machine, transfer to a constant temperature swelling tank, set the swelling temperature to 160℃ (±2℃) and the stirring speed to 200r / min, and swell at a constant temperature for 70min. During the swelling period, measure the softening point every 20min to ensure that the softening point is stable in the range of 98~100℃. Finally, cool to 175℃ (±2℃) for later use.

[0043] Performance verification: The prepared high-viscosity and high-elasticity modified asphalt has a dynamic viscosity of 460,000 Pa·s at 60℃, a ductility of 42 cm at 5℃, an elastic recovery of 96.1% at 25℃, and a softening point of 98.3℃, meeting the key control index requirements of Section 3.4 of "Extremely Thin Crack-Resistant 12-30.docx".

[0044] 2. Preparation of SBS-modified emulsified asphalt Soap solution preparation: Add deionized water to the soap solution tank, heat to 75℃ (±2℃), add imidazoline emulsifier (active content ≥65%) and calcium chloride, start the stirrer (speed 500r / min) and stir for 20min to ensure that the emulsifier is completely dissolved; adjust the pH value to 2.0 (±0.1) with 36% hydrochloric acid, and cool to 65℃ (±2℃) for later use.

[0045] Modified asphalt emulsification: SBS modified asphalt (softening point 85.7℃) was heated to 175℃ (±2℃) and simultaneously pumped into a colloid mill (model: JM-80) at a mass ratio of 68:32 with soap solution. The colloid mill speed was set to 3000 r / min and the grinding gap to 0.1 mm. During emulsification, the outlet temperature was controlled to ≤60℃ by cooling water. After emulsification, the asphalt was transferred to a storage tank and stored at a constant temperature of 50℃ (±2℃) for 12 h. The content of evaporation residue was measured to be 68.1% and the amount remaining on the sieve (1.18 mm sieve) was 0.03%, which meets the performance requirements of section 6.3.3 of "Extremely Thin Crack-Resistant 12-30.docx".

[0046] 3. Preparation of the mixture Aggregate heating and gradation control: Coarse aggregate (4.75~9.5mm), medium aggregate (2.36~4.75mm), fine aggregate (0.075~2.36mm), and mineral powder are respectively fed into the four cold aggregate bins of the intermittent mixing plant (model: LB-3000). The flow rate of the cold aggregate is calibrated by belt weighing (80t / h for coarse aggregate, 35t / h for medium aggregate, 25t / h for fine aggregate, and 5t / h for mineral powder).

[0047] The heating temperatures are set as follows: coarse aggregate 210℃ (±5℃), medium aggregate 200℃ (±5℃), fine aggregate 195℃ (±5℃), and mineral powder 190℃ (±5℃). After heating, the aggregates are mixed according to the gradation ratio (55% coarse aggregate, 22% medium aggregate, 20% fine aggregate, and 3% mineral powder). The gradation deviation is controlled by using a vibrating screen (screen size 9.5mm, 4.75mm, 2.36mm, and 0.075mm) to ensure that the passing rate of the 4.75mm screen is 68.3%, the passing rate of the 2.36mm screen is 42.2%, and the passing rate of the 0.075mm screen is 9.2%, which meets the STC-7B gradation requirements.

[0048] Mixing the ingredients: Add high-viscosity, high-elasticity modified asphalt at 175℃ (±2℃) to the mixed aggregate, and dry mix for 10 seconds and wet mix for 50 seconds at 180℃ (±3℃).

[0049] Add amine anti-stripping agent and Sasobit warm mix agent, continue mixing for 25 seconds, control the discharge temperature at 170℃ (±3℃), take samples from each batch during the mixing process to measure the uniformity of the mixture (no white spots, no oil lumps), and finally measure the bulk relative density of the mixture as 2.538 g / cm³, porosity as 4.5%, mineral aggregate void ratio as 17.5%, and stability as 13.26 kN.

[0050] 4. Construction and shaping Base treatment: Mill 2cm of the original asphalt pavement (PCI=85.6, RDI=80.0) in the dry area, sweep it 3 times with a heavy-duty sweeper (model: XS-160), and blow away the surface dust with compressed air (pressure 0.6MPa) to ensure that the flatness of the base surface is ≤3mm and there are no loose particles.

[0051] Simultaneous construction: A synchronous paver was used, with the following settings: SBS modified emulsified asphalt application rate of 0.8 kg / m² (calibrated in real time via a flow sensor), paving thickness of 1.2 cm, paving speed of 7 m / min, screed heating temperature of 165℃ (±5℃), and tamping frequency of 50 Hz.

[0052] The compaction was carried out using a 12t double-drum roller. The initial compaction temperature was 155℃ (one pass of static compaction, travel speed 2.5km / h), the secondary compaction temperature was 140℃ (one pass of 30Hz vibration, travel speed 3km / h), and the final compaction temperature was 105℃ (two passes of static compaction, travel speed 3.5km / h). During the compaction process, mist water spraying (0.2L / m²) was used to prevent the mixture from sticking to the roller.

[0053] Opening to traffic: After compaction, use an infrared thermometer to monitor the road surface temperature. Open to traffic when the temperature drops to ≤50℃. Before opening, trim the edges of the road surface (1.2cm depth and 5cm width) to ensure neat edges.

[0054] Performance testing: Anti-reflective crack performance: Using an Overlay Tester, with a test temperature of 22℃, a maximum opening displacement of 0.65mm, and a cycle period of 10s, the stress attenuation after 1200 cycles was measured to be 28.6%, far exceeding the Texas Department of Transportation's crack resistance standard of 750 cycles.

[0055] High temperature stability: 60℃ rutting test (T 0719-2011), wheel pressure 0.7MPa, loading time 1h, the dynamic stability was measured as 4652 cycles / mm, and the permanent deformation was 1.1mm; Low-temperature crack resistance: -10℃ low-temperature bending test (T 0715-2011), loading rate 50mm / min, the bending tensile strain was measured to be 3507μm and the bending tensile strength was 11.04MPa.

[0056] Interlayer bond performance: The interlayer tensile strength was measured to be 0.65 MPa using a pull-out test (T 0982-2008), which meets the bond performance requirements.

[0057] Anti-skid performance: The pendulum value measured by the pendulum tester (T 0964-2008) was 68 BPN, and the texture depth measured by the manual sand spreading method (T 0961-2008) was 0.97 mm, which meets the anti-skid standard for highways in dry areas.

[0058] Applicable Scenarios The ultra-thin overlay prepared in this embodiment is suitable for preventive maintenance of asphalt pavements in dry areas with annual rainfall <500mm and annual temperature difference ≥30℃. It is especially suitable for road sections where the pavement has been slightly polished (texture depth 0.53mm) but the structural strength has not been reduced (PSSI≥80). It can quickly restore the anti-skid and anti-cracking functions of the pavement. After construction, the initial service performance (PQI) of the pavement is ≥90, and the design service life is 6 years. Compared with the traditional 2.5cm thin overlay, it reduces the amount of stone used by 48% and the construction energy consumption by 37.6%.

[0059] Example 2 This embodiment provides an ultra-thin overlay suitable for cement pavement overlay (in damp areas). Addressing the characteristics of damp areas with annual rainfall of 1000-1500mm, high risk of rainwater infiltration, and susceptibility to reflective cracking due to water damage and temperature stress, the material's water stability and interlayer adhesion are optimized. Its components and mass percentages are as follows: The high-viscosity and high-elasticity modified asphalt contains 16% (base asphalt 68%, 60-80 mesh activated rubber powder 15%, star-shaped SBS 6%, terpene resin 3%, dibutyl phthalate 3%, sulfur 0.5%). The base asphalt is Donghai AH-70 asphalt (softening point 50℃, 25℃ penetration 63.4×0.1mm), and the activated rubber powder is a 60-80 mesh product (bulk density 0.38g / cm³, fiber content 0%).

[0060] The aggregate composition is 77% (50% coarse basalt aggregate of 4.75~9.5mm, 25% medium basalt aggregate of 2.36~4.75mm, 22% fine limestone aggregate of 0.075~2.36mm, and 3% limestone mineral powder), with a coarse aggregate crushing value of 10.7% and a water absorption rate of 0.58%. The fine aggregate has a sand equivalent of 73% and a methylene blue value of ≤25g / kg.

[0061] 5% SBS modified emulsified asphalt (70% SBS modified asphalt, 2% imidazoline emulsifier, 27.5% deionized water, 0.5% calcium chloride), the SBS modified asphalt used is Yueyang Baling Petrochemical YH-792 (block ratio S / B=30 / 70, volatile matter ≤0.5%).

[0062] Additives 2% (amine anti-stripping agent 0.8%, Nouryon Wetfix 312R; Sasobit warm mix agent 0.7%, Sasobit H02).

[0063] Specific preparation methods and process parameters 1. Preparation of high-viscosity and high-elasticity modified asphalt Raw material pretreatment Base asphalt: Add to the heat transfer oil heating tank and heat to 168℃ (±2℃) at 4℃ / min. Stir once every 15 minutes with a stirring paddle (300r / min) to avoid local carbonization and ensure that the asphalt is completely melted and free of impurities.

[0064] Activated rubber powder: Dry in a 105℃ forced-air oven for 2.5 hours, controlling the moisture content to ≤0.4%, and after cooling to room temperature, pass through an 80-mesh sieve to remove agglomerated particles.

[0065] Terpene resins: Crush them to a particle size ≤5mm in advance to avoid agglomeration during shearing.

[0066] Stepwise shearing and swelling: Step 1 (Addition of SBS and Plasticizer): Add star-shaped SBS and dibutyl phthalate to the molten matrix bitumen. Start the FLUKO FA90 high-speed shear mill, set the shear rate to 5500 r / min and the temperature to 192℃ (±3℃), and shear for 38 min. Observe the dispersion state of SBS through a microscope to ensure that there are no agglomerates with a particle size > 0.1 mm.

[0067] Step 2 (Addition of rubber powder and tackifier): Add activated rubber powder and terpene resin, adjust the shear rate to 4800 r / min, maintain the temperature at 192℃ (±3℃), continue shearing for 28 min, monitor the viscosity at 60℃ online, and ensure it is stable at 480000~500000 Pa・s.

[0068] Step 3 (crosslinking and swelling): Add sulfur (Eastman, Malaysia, ash content ≤0.05%), transfer to a constant temperature swelling tank at 160℃ (±2℃), stir at 200r / min for 80min, measure the softening point every 20min, stop when the softening point stabilizes at 99~101℃, cool to 178℃ (±2℃) for later use.

[0069] The modified asphalt obtained by performance verification has a dynamic viscosity of 490,000 Pa·s at 60℃, a ductility of 45 cm at 5℃, an elastic recovery of 96.5% at 25℃, and a softening point of 100.2℃, which meets the key requirements of "softening point ≥ 90℃ and viscosity ≥ 500,000 Pa·s at 60℃".

[0070] 2. Preparation of SBS-modified emulsified asphalt Soap solution preparation: Heat deionized water to 78℃ (±2℃), add imidazoline emulsifier (active content ≥65%) and calcium chloride, and stir with a stirrer at 500r / min for 25min to ensure that the solute is completely dissolved; Adjust the pH value to 1.8 (±0.1) using 36% hydrochloric acid, calibrate in real time using a pH meter, cool to 68℃ (±2℃), and keep stirring (100r / min) during standby to prevent stratification.

[0071] Colloid mill emulsification: SBS modified bitumen was heated to 178℃ (±2℃) and pumped into a JM-80 colloid mill at a mass ratio of 70:30 with soap solution. The grinding gap was set to 0.08mm and the rotation speed to 3200r / min.

[0072] During the emulsification process, the outlet temperature is controlled to ≤58℃ by a double-layer cooling water jacket to avoid emulsified asphalt breaking.

[0073] After emulsification, the product was transferred to a constant temperature storage tank at 55℃ (±2℃) and allowed to stand for 16 hours. The content of evaporation residue was measured to be 69.8%, and the 1-day storage stability was 0.47%, which meets the requirements of Section 6.3.3 of "Extremely Thin Crack-Resistant 12-30.docx" which states "evaporation residue content ≥65% and 1-day storage stability ≤1%".

[0074] 3. Preparation of the mixture Aggregate heating and gradation control: Cold material silo calibration: Using the belt weighing method, the flow rates are set as follows: coarse aggregate (4.75~9.5mm) 75t / h, medium aggregate (2.36~4.75mm) 40t / h, fine aggregate (0.075~2.36mm) 28t / h, and mineral powder 6t / h, to ensure that the gradation deviation is ≤±2%.

[0075] Heating temperatures: coarse aggregate 215℃ (±5℃), medium aggregate 205℃ (±5℃), fine aggregate 200℃ (±5℃), and mineral powder 195℃ (±5℃). After heating, the aggregate is passed through four layers of vibrating screens (9.5mm, 4.75mm, 2.36mm, and 0.075mm) to control the gradation, ensuring a 4.75mm sieve pass rate of 68.3%, a 2.36mm sieve pass rate of 46.0%, and a 0.075mm sieve pass rate of 9.2%, matching the STC-7B gradation design.

[0076] Mixing process: Initial mixing: The mixed aggregate and high-viscosity, high-elasticity modified asphalt at 178℃ (±2℃) are dry-mixed for 12s and wet-mixed for 55s at 182℃ (±3℃).

[0077] Remixing: Add amine anti-stripping agent and Sasobit warm mixing agent, continue mixing for 28 seconds, and control the discharge temperature at 172℃ (±3℃).

[0078] Quality inspection: For each batch, samples were taken to determine the bulk relative density of the mixture (2.54 g / cm³), porosity (5.0%), and aggregate void ratio (18.0%).

[0079] 4. Construction and shaping Base treatment (old cement pavement): Joint treatment: Clean the aged sealant from the joints of the old cement pavement and fill the joints with polyurethane sealant (add anti-crack tape when the joint width is >5mm).

[0080] Milling and cleaning: Mill the surface to remove 3cm of laitance, then clean it 4 times with an XS-160 high-power sweeper, and then blow away the dust in the gaps with 0.7MPa compressed air to ensure that the flatness of the base surface is ≤2.5mm and there is no water accumulation or loose particles.

[0081] Simultaneous paving and compaction: Synchronous construction parameters: Wirtgen SP 1500 paver was used, SBS modified emulsified asphalt application rate was 1.0 kg / m² (calibrated in real time by flow sensor), paving thickness was 1.5 cm, speed was 6 m / min, screed heating temperature was 170℃ (±5℃), and tamping frequency was 55 Hz.

[0082] Compaction process: A 12t double-drum roller is selected. The initial compaction temperature is 158℃ (one static compaction pass, speed 2.2km / h), the secondary compaction temperature is 145℃ (one 35Hz vibration pass, speed 2.8km / h), and the final compaction temperature is 110℃ (two static compaction passes, speed 3.2km / h). The water spraying volume during compaction is controlled at 0.3L / m² (mist) to prevent the mixture from sticking to the roller and to avoid water accumulation.

[0083] Open traffic control: The road surface temperature is monitored every 20 minutes using an infrared thermometer, and traffic is opened when the temperature drops to ≤48℃.

[0084] Special protection for damp areas: If it rains within 48 hours after construction, cover the area with a rainproof cloth in time to prevent rainwater from seeping into the layers.

[0085] Performance testing: Anti-reflective crack performance: Overlay Tester (TTI OT-2000) test, 22℃, 0.65mm opening displacement, 1100 cycles, stress attenuation of 32.1%, crack resistance requirements.

[0086] Water stability: Freeze-thaw splitting test (T 0729-2000), the freeze-thaw splitting strength ratio was measured to be 89.5%, which far exceeds the standard requirement of "≥80%".

[0087] Anti-slip performance: The pendulum value measured by the pendulum meter (T 0964-2008) is 68 BPN, and the texture depth measured by the manual sand spreading method (T 0961-2008) is 1.02 mm, which meets the standard of "pendulum value ≥ 45 BPN and texture depth ≥ 0.55 mm" in humid areas.

[0088] Interlayer bonding performance: The pull-out strength measured by the pull-out test (T 0982-2008) is 0.70 MPa, and the strength retention rate after immersion in water for 72 hours is 85%, which meets the bonding requirements.

[0089] Applicable scenarios: The ultra-thin overlay prepared in this embodiment is suitable for the "white-to-black" conversion of old cement pavement in humid areas with an annual rainfall of 1000~1500mm. It is especially suitable for road sections with PCI=85~90 and DBL (bottom void ratio) ≤3%. It can effectively block rainwater infiltration and suppress reflective cracks. After construction, the pavement PQI≥88 and the design service life is 7 years. Compared with the traditional 2.5cm thin overlay, the amount of stone used is reduced by 52% and the water damage rate is reduced by 60%.

[0090] Example 3 This embodiment provides an ultra-thin overlay suitable for asphalt pavement maintenance in seasonally frozen regions. Considering the frequent freeze-thaw cycles and the susceptibility of pavements to cracking due to frost heave and thaw settlement in these regions, the material composition has been specifically optimized. Its components and mass percentages are as follows: 17% high-viscosity, high-elasticity modified asphalt (65% base asphalt, 14% 60-80 mesh activated rubber powder, 8% star-shaped SBS, 2% terpene resin, 3% dibutyl phthalate, and 0.5% sulfur).

[0091] Aggregate content is 76% (58% coarse basalt aggregate of 4.75~9.5mm, 20% medium aggregate of 2.36~4.75mm, 19% fine aggregate of 0.075~2.36mm, and 3% mineral powder), of which the crushing value of coarse aggregate is 22% and the polishing value is 45.

[0092] SBS modified emulsified asphalt 5% (SBS modified asphalt 69%, imidazoline emulsifier 2.2%, water 28.3%, calcium chloride 0.5%) has an evaporation residue softening point of 83℃ and an elasticity recovery of 92% at 25℃.

[0093] Additives 2% (amine anti-stripping agent 1.2%, Sasobit warm mix agent 0.8%).

[0094] Preparation process Preparation of high-viscosity and high-elasticity modified asphalt: AH-70 base asphalt was heated to 165℃, star-shaped SBS (S / B=30 / 70) and dibutyl phthalate were added, and sheared at 5000 r / min for 35 min at 190℃; then 60~80 mesh activated rubber powder and terpene resin were added, and shearing continued for 25 min; finally, sulfur was added, and the mixture was kept at 190℃ for 80 min to swell, and then cooled to 175℃ for later use. The modified asphalt obtained had a dynamic viscosity of 480000 Pa·s at 60℃ and a ductility of 42 cm at 5℃.

[0095] Mixture preparation: Coarse aggregate, medium aggregate, fine aggregate, and mineral powder were heated to 210℃, 200℃, 195℃, and 190℃ respectively, and mixed evenly according to the gradation ratio; the mixed aggregate was mixed with high-viscosity and high-elasticity modified asphalt at 180℃ for 50s, amine anti-stripping agent and Sasobit warm mix agent were added and mixing was continued for 25s, and the discharge temperature was controlled at 170℃. The bulk relative density of the mixture was measured to be 2.54g / cm³, the porosity was 4.8%, and the aggregate void ratio was 17.8%.

[0096] Construction and shaping: Mill the existing asphalt pavement in the seasonally frozen area to 2.5cm, and after cleaning, ensure the surface flatness is ≤2.5mm; use a synchronous paver to spray SBS modified emulsified asphalt at a rate of 0.9kg / m², and simultaneously pave the mixture with a paving thickness of 1.4cm and a paving speed of 6m / min; use a 12t double-drum roller for compaction, with an initial compaction temperature of 155℃ (one static compaction pass), a secondary compaction temperature of 140℃ (one 35Hz vibration pass), and a final compaction temperature of 105℃ (two static compaction passes). When the road is opened to traffic, the surface temperature is ≤45℃.

[0097] Performance testing Freeze-thaw resistance and crack resistance: According to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), the freeze-thaw splitting strength ratio is 91.2%; the stress decay is 26.8% after 1250 cycles of Overlay Test (22℃, 0.65mm maximum opening displacement), and the bending tensile strain at -10℃ is 3650μm, which can effectively resist the crack propagation caused by freeze-thaw cycles in seasonally frozen areas.

[0098] High temperature and anti-skid performance: The dynamic stability of the rutting test at 60℃ is 4820 times / mm, with no obvious rutting deformation; the pendulum value measured by the pendulum instrument is 70BPN, and the texture depth measured by the manual sand spreading method is 1.02mm, which meets the anti-skid requirements for driving in winter snow and ice weather in the seasonally frozen area.

[0099] Interlayer bonding performance: The interlayer tensile strength was measured to be 0.72 MPa by pull-out test. After 30 freeze-thaw cycles (freezing at -20℃ for 12 h and thawing at 25℃ for 12 h), the tensile strength still remained at 0.65 MPa, indicating excellent interlayer bonding stability and avoiding interlayer delamination caused by freeze-thaw cycles.

[0100] Applicable Scenarios The ultra-thin overlay prepared in this embodiment is suitable for preventive maintenance of asphalt pavements in seasonally frozen areas with an annual extreme low temperature of ≤-30℃ and a freeze-thaw cycle of ≥50 times / year. It is especially suitable for road sections where slight reflective cracks (width ≤2mm) have appeared but the structural strength has not been reduced. It can effectively inhibit the expansion of cracks under freeze-thaw action and extend the service life of the pavement to more than 7 years. Compared with traditional thin overlays (service life of 3~4 years in seasonally frozen areas), the maintenance cycle is significantly extended.

[0101] Example 4 This embodiment provides an ultra-thin overlay suitable for the upgrading and reconstruction of old cement pavement on highways (heavy traffic load). Addressing the characteristics of heavy traffic on highways (daily average truck traffic ≥ 3000 vehicles), large displacement of joints in old cement pavement, and susceptibility to load-induced reflective cracking, the material's fatigue and shear resistance properties are optimized. Its components and mass percentages are as follows: High-viscosity and high-elasticity modified asphalt 16.5% (base asphalt 67%, 60-80 mesh activated rubber powder 13%, star-shaped SBS 7%, terpene resin 2.5%, dibutyl phthalate 3%, sulfur 0.45%).

[0102] The aggregate content is 76.5% (56% coarse aggregate of 4.75~9.5mm diabase, 23% medium aggregate of 2.36~4.75mm, 18% fine aggregate of 0.075~2.36mm, and 3% mineral powder), of which the crushing value of coarse aggregate is 20% and the polishing value is 46, which meets the high requirements of heavy transportation for aggregate strength.

[0103] 5% SBS modified emulsified asphalt (68.5% SBS modified asphalt, 2.4% imidazoline emulsifier, 28.6% water, 0.5% calcium chloride) has an evaporation residue softening point of 85℃, an elastic recovery of 93% at 25℃, and a dynamic viscosity of 620,000 Pa·s at 60℃.

[0104] Additives of 2% (polyamide anti-stripping agent 1.0%, Sasobit warm mix agent 1.0%) enhance the adhesion between aggregate and asphalt and the shear resistance under heavy traffic.

[0105] Preparation process Preparation of high-viscosity and high-elasticity modified asphalt: AH-70 base asphalt was heated to 168℃, star-shaped SBS (S / B=30 / 70) and dibutyl phthalate were added, and the mixture was sheared at 192℃ and 5500 r / min for 38 min to ensure sufficient dispersion of SBS; activated rubber powder and terpene resin were added, and shearing continued for 28 min; finally, sulfur was added, and the mixture was kept at 192℃ for swelling for 75 min, and then cooled to 178℃ for later use. The prepared modified asphalt had a dynamic viscosity of 490000 Pa·s at 60℃, a ductility of 40 cm at 5℃, and an elastic recovery of 96% at 25℃, meeting the fatigue resistance requirements of heavy traffic.

[0106] Mixture preparation: Coarse aggregate, medium aggregate, fine aggregate, and mineral powder were heated to 215℃, 205℃, 200℃, and 195℃ respectively according to the gradation requirements. After being mixed evenly, they were mixed with high-viscosity and high-elasticity modified asphalt at 182℃ for 55 seconds. Polyamide anti-stripping agent and Sasobit warm mix admixture were added, and mixing was continued for 28 seconds, with the discharge temperature controlled at 172℃. The measured bulk relative density of the mixture was 2.56 g / cm³, the porosity was 4.5%, the aggregate void ratio was 18.1%, and the VFA (asphalt saturation) was 79.2%, indicating a dense skeleton and stable structure.

[0107] Construction and shaping: After cleaning and grouting the joints of the old cement pavement, mill the surface to remove 3cm of laitance, and clean the surface to achieve a flatness of ≤2mm. Use a synchronous paver to simultaneously spray SBS modified emulsified asphalt (spraying rate 1.0kg / m²) and pave the mixture, with a paving thickness of 1.5cm and a paving speed of 5.5m / min to ensure timely and effective interlayer bonding. Use a 13t double-drum roller for compaction, with an initial compaction temperature of 158℃ (one static compaction pass), a secondary compaction temperature of 145℃ (one 40Hz vibration pass), and a final compaction temperature of 110℃ (two static compaction passes). After compaction, close the road to traffic until the surface temperature is ≤48℃ before reopening.

[0108] Performance testing Load-resistant reflective cracking performance: Using Overlay Tester to simulate the joint displacement of old cement pavement under heavy traffic load (0.7mm maximum opening displacement), the stress attenuation is 25.3% after 1300 cycles at 22℃, far exceeding the stress attenuation of more than 70% after 500 cycles of traditional thin-layer overlay; the fatigue life of the four-point bending fatigue test (1000μm strain level) reaches 880,000 cycles, and the fatigue resistance meets the long-term load requirements of heavy traffic.

[0109] High-temperature rutting resistance and shear resistance: The dynamic stability of rutting test at 60℃ is 5100 times / mm, and the permanent deformation after 1 hour of loading is only 1.2mm; the interlaminar shear test (60℃) shows a shear strength of 0.95MPa, which can resist the shear force generated by braking and steering of heavy trucks and prevent the overlay from shifting.

[0110] Water stability and skid resistance: The freeze-thaw splitting test (freezing at -18℃ for 16 hours and thawing at 60℃ for 24 hours) showed a freeze-thaw splitting strength ratio of 90.8%, with no obvious water damage; the pendulum value was 72 BPN and the texture depth was 1.05 mm, which met the skid resistance standards for highways and ensured driving safety in rainy weather.

[0111] Applicable Scenarios The ultra-thin overlay prepared in this embodiment is suitable for the "white-to-black" upgrade and reconstruction project of old cement pavement on highways, especially for heavy traffic sections with an average daily equivalent axle load of ≥15,000 times. It can be directly overlaid on the old cement pavement after joint treatment, effectively suppressing the superposition effect of load-type and temperature-type reflective cracks. The pavement design service life reaches 8 years. Compared with the traditional 2.5cm thin overlay (service life of 4-5 years under heavy traffic), it reduces one mid-term maintenance and reduces the total life cycle cost by about 25%.

[0112] Comparative Example 1 This comparative example provides a conventional thin-layer overlay material (2.5 cm thick), using ordinary SBS modified asphalt (SBS content 4%, dynamic viscosity at 60℃ 300000 Pa·s, ductility at 5℃ 30 cm), continuously graded aggregate (AC-10 type, 4.75 mm sieve passing rate 35%), and conventional emulsified asphalt (tensile strength 0.4 MPa). Its performance indicators are compared with those of Examples 1, 2, 3, and 4 of this invention, and the results are shown in the table below: Table 7 Comparison Analysis of Relevant Performance

[0113] The results show that the ultra-thin overlay material provided by the embodiments of the present invention has significantly better comprehensive performance than traditional thin-layer overlay materials in terms of crack resistance (reflective crack fatigue life is 2.2 to 2.6 times that of traditional materials), durability (freeze-thaw splitting strength ratio is increased by 10% to 16%), adhesion (interlaminar tensile strength is increased by 62.5% to 87.5%), and anti-slip properties (pendulum value is increased by 23.6% to 30.9%). Moreover, with a thickness of only 1.0 to 1.5 cm (40% to 60% of that of traditional materials), the design service life is extended by 2 to 3 years, which can better meet the long service life and high performance requirements of ultra-thin overlay projects under different climate zones and traffic loads.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An asphalt cap material, characterized by, The raw materials include the following quality parts: modified asphalt 12-18 parts, aggregate 75-82 parts, and additive 0.5-2 parts; the modified asphalt is high-viscosity and high-elasticity modified asphalt; The high-viscosity and high-elasticity modified asphalt has a 60℃ dynamic viscosity of 300000-500000 Pa・s, a 5℃ ductility of 35-45 cm, and an elastic recovery at 25℃ of ≥95%; the aggregate adopts intermittent gradation, and the additive is anti-stripping agent and warm-mixing agent.

2. The asphalt cap material of claim 1, wherein, The high-viscosity and high-elasticity modified asphalt has a 60℃ dynamic viscosity of 300000-500000 Pa・s, a 5℃ ductility of 35-45 cm, an elastic recovery at 25℃ of ≥95%, a softening point of ≥90℃, a 25℃ residual penetration ratio after TFOT of ≥70%, and a 5℃ ductility after TFOT of ≥25 cm; Preferably, the high-viscosity and high-elasticity modified asphalt includes the following quality parts of raw materials: base asphalt 65-75 parts; rubber powder 10-15 parts; SBS 6-8 parts; tackifier 2-3 parts; plasticizer 2-3 parts; crosslinking agent 0.3-0.5 parts; the SBS is a star-shaped block copolymer, and the S / B block ratio is preferably 30 / 70; More preferably, the raw materials include the following quality parts: base asphalt 65-75 parts; 60-80 mesh activated rubber powder 10-15 parts; SBS 6-8 parts; terpene resin 2-3 parts; dibutyl phthalate 2-3 parts; and sulfur 0.3-0.5 parts.

3. The asphalt cover material according to claim 1 or 2, characterized in that, The aggregate adopts intermittent gradation with a nominal maximum particle size of 4.75 mm-9.5 mm; Preferably, the aggregate includes, in terms of mass content, coarse aggregate 50%-60%, medium aggregate 20%-25%, fine aggregate 15%-25%, and mineral powder 3%-5%; the particle size d1 of the coarse aggregate, the particle size d2 of the medium aggregate, and the particle size d3 of the fine aggregate are respectively 4.75 mm≤d1<9.5 mm, 2.36 mm≤d2<4.75 mm, and 0.075 mm≤d3<2.36 mm; and the aggregate is selected from one or more of basalt and diabase.

4. The asphalt cap material of any one of claims 1-3, wherein, The SBS modified emulsified asphalt includes the following mass contents of raw materials: SBS modified asphalt 65-70 parts; emulsifier 2-3 parts; water 25-30 parts; and stabilizer 0.3-0.5 parts; the stabilizer is preferably calcium chloride, and the emulsifier is preferably imidazoline emulsifier.

5. The asphalt cap material of any one of claims 1-4, wherein, The anti-stripping agent is amine anti-stripping agent and / or polyamide anti-stripping agent; and the warm-mixing agent is Sasobi.

6. The asphalt cap material of any one of claims 1-5, wherein, The raw materials include, in terms of mass content, the following: high-viscosity and high-elasticity modified asphalt 15%-16%; aggregate 77%-78%; SBS modified emulsified asphalt 4%-5%; anti-stripping agent 0.5%-1.5%, preferably 0.5%-0.8% amine anti-stripping agent and / or 0.8%-1.2% polyamide anti-stripping agent; and warm-mixing agent 0.5%-1.0%.

7. A process for the production of an asphalt cover material according to any one of claims 1 to 6, characterized in that The method includes the following steps: 1) After the base asphalt is heated, SBS, rubber powder, tackifier, plasticizer, and crosslinking agent are added, and shear emulsification is performed to swell and develop, thereby obtaining high-viscosity and high-elasticity modified asphalt; 2) mix the high-viscosity and high-elasticity modified asphalt, the additive and the aggregate after heating at 170-185℃ to obtain a mixture; 3) spray the emulsified asphalt on the treated base layer and pave the mixture and then roll and form.

8. The preparation method according to claim 7, characterized in that, In step 1), the base asphalt is heated to 160-170℃, SBS and plasticizer are added, shearing is carried out at 4000-6000r / min for 30-40min, the shearing temperature is 185-195℃, rubber powder and tackifier are added, shearing is continued for 20-30min, crosslinking agent is added, swelling treatment is carried out at 185-195℃ for 60-90min, and cooling is carried out to 170-180℃.

9. The production method according to claim 7 or 8, characterized by, In step 2), the aggregate is also graded and heated to 190-220℃, mixed according to the grading ratio, the heated aggregate is mixed with the high-viscosity and high-elasticity modified asphalt at 170-185℃ for 40-60s, the additive is added and mixed for 20-30s, and the discharge temperature is controlled to 160-175℃.

10. The method of any one of claims 7-9, wherein, In step 3), after the base layer is milled and cleaned, SBS modified emulsified asphalt is sprayed synchronously, with a spraying amount of 0.8-1.0 kg / m 2 The mixture is spread, with a spreading thickness of 1.0-1.5 cm and a spreading speed of 5-8 m / min; a double steel wheel roller is used for rolling, with an initial rolling temperature ≥ 150 ℃ and a final rolling temperature ≥ 100 ℃; both the initial rolling and the final rolling are static rolling, and the re-rolling is vibration with a frequency of 30-50 Hz.

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