Preparation method of high-temperature-resistant asphalt concrete

Abstract

The invention discloses a preparation method of high-temperature-resistant asphalt concrete, belongs to the technical field of road engineering materials, and aims to solve the technical problems that existing asphalt concrete is easy to generate ruts and cracks and poor in stability in a high-temperature heavy-load environment. According to the method, the high-temperature-resistant and heavy-load-resistant asphalt concrete is prepared through four core links of accurately selecting high-temperature-resistant raw materials, optimizing aggregate gradation (adjusting the proportion of coarse aggregate to fine aggregate to mineral powder to construct a stable skeleton structure), controlling a fiber pretreatment and mixing process and optimizing paving and compacting parameters. The high-temperature dynamic stability of the prepared asphalt concrete is greater than or equal to 3000 times / mm, the low-temperature bending strain is greater than or equal to 2800mu epsilon, the residual stability is greater than or equal to 85%, high-temperature softening and heavy-load fatigue damage can be effectively resisted, the service life of a pavement is prolonged, and the asphalt concrete is particularly suitable for summer high-temperature areas such as south China and East China and expressways and urban main roads busy in freight transportation. And the method has remarkable engineering application value and economic benefit.

Description

Technical Field

[0001] This invention relates to the field of road engineering materials technology, specifically to a method for preparing high-temperature resistant asphalt concrete. Background Technology

[0002] Asphalt concrete is widely used in highway and urban road pavement engineering due to its advantages such as driving comfort, convenient construction, and good noise reduction. However, under the dual effects of high temperature and heavy load, asphalt concrete is prone to serious deterioration of its road performance: on the one hand, the high temperature environment causes the asphalt binder to soften and the cohesion to decrease, making it prone to permanent deformation (i.e., rutting) under repeated rolling by heavy vehicles, affecting road smoothness and driving safety; on the other hand, the fatigue load of heavy traffic will exacerbate the initiation and expansion of micro-cracks inside the asphalt mixture, leading to pavement cracking and shortening the service life of the road.

[0003] In existing technologies, the main methods for improving the high-temperature resistance of asphalt concrete fall into three categories: First, using modified asphalt (such as SBS modified or rubber modified) to enhance the heat resistance of the binder itself. However, it is difficult for a single modified asphalt to simultaneously meet the balance between high-temperature stability and low-temperature crack resistance, and the cost is relatively high. Second, adding fiber reinforcing agents (such as lignin fiber and polyester fiber). However, lignin fiber has poor high-temperature resistance (it is easy to decompose at high temperatures), and polyester fiber has poor dispersibility and is prone to agglomeration, resulting in fluctuations in the performance of the mixture. Third, optimizing the aggregate gradation. However, traditional gradation design focuses on the single concept of "coarse aggregate skeleton" or "fine aggregate filling," without forming a gradation system that takes into account both skeleton stability and density. At high temperatures, aggregate segregation or excessive porosity is likely to occur.

[0004] Furthermore, existing preparation processes have relatively crude controls on mixing temperature and compaction parameters: if the mixing temperature is too low, the asphalt and aggregate will not bond sufficiently; if the temperature is too high, the asphalt will easily age; improper compaction temperature or insufficient compaction passes will lead to low mixture density and reduced impermeability and fatigue resistance. Therefore, there is an urgent need for a preparation method that can synergistically optimize raw materials, gradation, and processes to address the performance defects of existing asphalt concrete under high temperature and heavy loads. Summary of the Invention

[0005] The purpose of this application is to overcome the defects of poor high-temperature stability, insufficient heavy load resistance, and easy cracking of asphalt concrete in the prior art, and to provide a method for preparing high-temperature resistant asphalt concrete. Through precise selection of raw materials, synergistic optimization of gradation, and refined control of process parameters, the high-temperature resistance and heavy load resistance of asphalt concrete can be improved simultaneously.

[0006] To achieve the above objectives, the present invention provides a method for preparing high-temperature resistant asphalt concrete, comprising the following steps:

[0007] (1) Raw material selection: Modified asphalt was selected as the binder, high-strength coarse aggregate, wear-resistant fine aggregate and active mineral powder were selected as the aggregate system, and high-temperature resistant fiber was selected as the reinforcing agent.

[0008] (2) Aggregate gradation optimization: Adjust the mass ratio of coarse aggregate, fine aggregate and mineral powder in the aggregate system to construct a skeleton-dense gradation structure;

[0009] (3) Fiber pretreatment and mixing: After drying and pretreating the high-temperature resistant fiber, the pretreated high-temperature resistant fiber is mixed with the heated aggregate and modified asphalt in sequence, and the mixing temperature and mixing time are controlled to obtain asphalt mixture;

[0010] (4) Paving and compaction: The asphalt mixture is paved at a preset temperature and compacted using a layered compaction process to obtain high-temperature resistant asphalt concrete.

[0011] As a further improvement to the technical solution of the present invention, the high-temperature resistant fiber mentioned in step (1) is at least one of basalt fiber, polyester fiber, and glass fiber.

[0012] As a further improvement to the technical solution of the present invention, based on the total mass of the asphalt mixture, the content of the high-temperature resistant fiber is 0.3-0.6%; wherein, the content of basalt fiber is 0.4-0.6%, the content of polyester fiber is 0.3-0.5%, and the content of glass fiber is 0.35-0.55%.

[0013] As a further improvement to the technical solution of the present invention, the mass ratio of the skeleton-dense gradation structure in step (2) is as follows: coarse aggregate with a particle size of 4.75-13.2mm accounts for 50-55%, fine aggregate with a particle size of 0.3-4.75mm accounts for 39-46%, and mineral powder with a particle size ≤0.075mm accounts for 4-6%; and fine aggregate with a particle size ≤0.3mm accounts for 17-26% of the total mass of the fine aggregate.

[0014] As a further improvement to the technical solution of the present invention, the high-strength coarse aggregate in step (1) is basalt aggregate or granite aggregate, with a crushing value ≤18% and Los Angeles abrasion loss ≤20%; the wear-resistant fine aggregate is limestone aggregate, with an angularity ≥30s; the active mineral powder is limestone ground mineral powder, with a specific surface area ≥350m² / kg and a hydrophilicity coefficient ≤1.0.

[0015] As a further improvement to the technical solution of the present invention, the mixing process parameters in step (3) are as follows: the heating temperature of modified asphalt is 160-180℃, the heating temperature of aggregate is 170-190℃; the aggregate is first dry-mixed for 30-60s, then the pretreated high-temperature resistant fiber is added and stirred for 15-30s, and finally the modified asphalt is added and wet-mixed for 45-90s until the mixture is uniform in color and free of fiber clumps.

[0016] As a further improvement to the technical solution of the present invention, the paving and compaction process parameters in step (4) are as follows: paving temperature 155-170℃, paving speed 2-4m / min; compaction is divided into three steps: initial compaction, intermediate compaction and final compaction. The initial compaction temperature is 150-160℃, and a steel wheel roller is used for static compaction 1-2 times; the intermediate compaction temperature is 140-150℃, and a vibratory roller is used for high-frequency low-amplitude vibration compaction 2-3 times; the final compaction temperature is 130-140℃, and a steel wheel roller is used for static compaction 1-2 times, with a final compaction degree ≥96% (Marshall standard density).

[0017] As a further improvement to the technical solution of the present invention, the modified asphalt in step (1) is at least one of SBS modified asphalt or rubber modified asphalt, with a penetration of 60-80 (0.1 mm) at 25°C and a kinematic viscosity of 135°C. Softening point ≥60℃.

[0018] As a further improvement to the technical solution of the present invention, the fiber pretreatment process in step (3) is as follows: the high temperature resistant fiber is placed in an oven at 60-80℃ and dried for 2-4 hours to make the fiber moisture content ≤1%; and the length of the high temperature resistant fiber is 3-6mm and the diameter of the single filament is 10-20μm.

[0019] As a further improvement to the technical solution of the present invention, the performance indicators of the high-temperature resistant asphalt concrete meet the following requirements: dynamic stability at 60℃ ≥ 3000 times / mm, bending strain at -10℃ ≥ 2800με, Marshall residual stability after 48h immersion in water ≥ 85%, and water permeability coefficient ≤ 100mL / min.

[0020] The method for preparing high-temperature resistant asphalt concrete in this application has the following advantages compared with the prior art:

[0021] Significantly improved high-temperature resistance: Through the synergistic effect of modified asphalt and high-temperature resistant fibers, as well as the support of skeleton-dense gradation, the prepared asphalt concrete has a dynamic stability of ≥3000 times / mm at 60℃, which is 40-60% higher than that of traditional asphalt concrete, and can effectively resist high-temperature rutting.

[0022] Excellent resistance to heavy loads and cracks: The high strength of basalt fiber (tensile strength ≥3000MPa) and the interlocking skeleton of aggregates enable the mixture to have a bending strain ≥2800με at -10℃ and a Marshall residual stability ≥85% after 48h immersion in water. It can withstand heavy fatigue loads and reduce crack initiation.

[0023] High construction stability: Step-by-step mixing and precise compaction parameter control ensure uniform fiber dispersion (agglomeration rate ≤5%) and the required density of the mixture (≥96%), avoiding performance fluctuations during construction.

[0024] Economical and widely applicable: The raw materials are all commonly used engineering materials, requiring no special equipment; the prepared asphalt concrete is suitable for road sections with high summer temperatures (maximum temperature ≥35℃) and annual heavy traffic volume (axle load ≥100kN) ≥1 million times, and its service life can be extended by 3-5 years, reducing later maintenance costs. Attached Figure Description

[0025] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0026] Figure 1 This is an exemplary flowchart of a method for preparing high-temperature resistant asphalt concrete according to the present invention. Detailed Implementation

[0027] The present invention will be described in detail below with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0028] Reference Figure 1 A method for preparing high-temperature resistant asphalt concrete includes the following steps:

[0029] (1) Raw material selection: Modified asphalt was selected as the binder, high-strength coarse aggregate, wear-resistant fine aggregate and active mineral powder were selected as the aggregate system, and high-temperature resistant fiber was selected as the reinforcing agent.

[0030] (2) Aggregate gradation optimization: Adjust the mass ratio of coarse aggregate, fine aggregate and mineral powder in the aggregate system to construct a skeleton-dense gradation structure;

[0031] (3) Fiber pretreatment and mixing: After drying and pretreating the high-temperature resistant fiber, the pretreated high-temperature resistant fiber is mixed with the heated aggregate and modified asphalt in sequence, and the mixing temperature and mixing time are controlled to obtain asphalt mixture;

[0032] (4) Paving and compaction: The asphalt mixture is paved at a preset temperature and compacted using a layered compaction process to obtain high-temperature resistant asphalt concrete.

[0033] In practice, the preparation of high-temperature resistant asphalt concrete is achieved through four core processes, forming a systematic technical solution. The first step, raw material selection, involves selectively using modified asphalt as a binder, leveraging its modifying components to enhance heat resistance and adhesion; selecting high-strength coarse aggregate, wear-resistant fine aggregate, and active mineral powder to construct the aggregate system, ensuring the aggregate's own load-bearing capacity; and introducing high-temperature resistant fibers as a reinforcing agent to compensate for the insufficient tensile strength of the asphalt mixture. The second step, aggregate gradation optimization, involves adjusting the mass ratio of coarse aggregate, fine aggregate, and mineral powder to construct a skeleton-dense gradation structure. The coarse aggregate forms a rigid skeleton to resist heavy-load shear deformation, while the fine aggregate and mineral powder fill the gaps in the skeleton to ensure structural density, avoiding the performance defects of a single skeleton or single-filler structure. The third step, fiber pretreatment and mixing, involves drying the high-temperature resistant fibers to remove moisture and prevent segregation in the mixture. Then, the mixture is mixed in the following sequence: dry aggregate mixing, fiber incorporation, and wet asphalt mixing. Mixing temperature and time are controlled to ensure uniform fiber dispersion in the mixture and to prevent asphalt aging due to excessively high temperatures or insufficient coating due to excessively low temperatures. The fourth step, paving and compaction, involves paving the asphalt mixture at a preset temperature to avoid difficulties in subsequent compaction due to low temperatures. A layered compaction process is used: initial compaction to fix the aggregate skeleton, secondary compaction to increase density, and final compaction to ensure a smooth surface, ensuring the mixture meets density standards and reducing internal voids.

[0034] This invention optimizes the entire process from raw material selection, gradation design, mixing technology to construction, systematically solving the technical problems of rutting, cracking, and poor stability in existing asphalt concrete under high-temperature and heavy-load conditions. Through the synergistic effect of a skeleton-dense gradation, high-temperature resistant fibers, and modified asphalt, the prepared asphalt concrete possesses both excellent high-temperature deformation resistance and heavy-load fatigue resistance. Control of process parameters throughout the entire process ensures the stability of the mixture's performance and the reliability of construction quality, providing highly adaptable pavement materials for high-temperature and heavy-load road sections (such as highways and main freight roads in high-temperature areas during summer), extending pavement service life, and reducing later maintenance costs.

[0035] In some embodiments, the high-temperature resistant fiber mentioned in step (1) is at least one of basalt fiber, polyester fiber, and glass fiber. It should be noted that the specific type range of high-temperature resistant fiber is clearly defined to meet the reinforcement requirements of asphalt concrete under high-temperature and heavy-load environments. Basalt fiber is an inorganic fiber with high-temperature resistance (temperature tolerance ≥600℃) and high mechanical strength (tensile strength ≥3000MPa), maintaining structural stability under high-temperature conditions and effectively inhibiting the initiation and expansion of micro-cracks within the mixture. Polyester fiber is an organic fiber with good flexibility and dispersibility, easily mixing evenly with asphalt and aggregates, enhancing the cohesion of the mixture, and reducing asphalt leakage. Glass fiber combines certain high-temperature resistance (temperature tolerance ≥300℃) and tensile strength, serving as an auxiliary reinforcing component to further optimize the mechanical properties of the mixture. In practical applications, a single fiber type or multiple fibers can be selected and used in combination according to the specific needs such as the highest temperature and heavy traffic volume in the project area to ensure that the fiber reinforcement effect is precisely matched to the engineering scenario.

[0036] This invention provides flexible fiber selection solutions for different engineering scenarios by specifying the specific types of high-temperature resistant fibers, avoiding reinforcement failure caused by inappropriate fiber selection. The introduction of basalt fiber can significantly improve the high-temperature stability and crack resistance of asphalt concrete, making it suitable for road sections with severe high temperatures and heavy loads; the dispersibility advantage of polyester fiber can reduce construction difficulty and ensure the uniformity of mixture performance; glass fiber can serve as a cost-effective auxiliary reinforcement option, balancing material cost and performance requirements. The coverage of these three fiber types can meet the engineering needs under different climates and traffic load conditions, improving the universality of the technical solution.

[0037] In some embodiments, based on the total mass of the asphalt mixture, the content of the high-temperature resistant fiber is 0.3-0.6%; wherein, the content of basalt fiber is 0.4-0.6%, the content of polyester fiber is 0.3-0.5%, and the content of glass fiber is 0.35-0.55%. It should be noted that the content range of different types of high-temperature resistant fibers is limited based on the overall performance requirements of the asphalt mixture to avoid performance defects caused by insufficient or excessive content. Based on the total mass of the asphalt mixture, the basalt fiber content is set at 0.4-0.6%. Because basalt fiber has a high density and high mechanical strength, if the content is too low, an effective reinforcing network cannot be formed, making it difficult to resist heavy-load shear deformation; if the content is too high, fiber agglomeration is likely to occur, damaging the bonding interface between asphalt and aggregate and reducing the overall strength of the mixture. The polyester fiber content is set at 0.3-0.5%. Polyester fiber has good flexibility but its strength is slightly lower than that of basalt fiber. A lower content is sufficient to improve cohesion, while excessive content may increase the viscosity of the mixture, affecting the mixing and paving effect. The glass fiber content is set at 0.35-0.55%, balancing its high-temperature resistance and dispersibility. The content range is between that of basalt fiber and polyester fiber, ensuring that crack resistance is improved without affecting the workability of the mixture.

[0038] The precise fiber dosage range of this invention achieves a balance between fiber reinforcement and workability of the mixture. On the one hand, it avoids the problem of insufficient improvement in high-temperature stability and crack resistance due to insufficient dosage, ensuring that the fibers can effectively play their reinforcing and toughening roles. On the other hand, it prevents problems such as fiber clumping and construction difficulties caused by excessive dosage, ensuring the performance stability of the mixture during mixing, paving, and compaction. The differentiated settings for different fiber dosages can further adapt to the performance characteristics of various fibers, maximizing the advantages of each fiber and improving the overall road performance of asphalt concrete under high-temperature and heavy-load environments.

[0039] In some embodiments, the mass ratio of the skeleton-dense gradation structure in step (2) is as follows: 50-55% of coarse aggregate with a particle size of 4.75-13.2mm, 39-46% of fine aggregate with a particle size of 0.3-4.75mm, and 4-6% of mineral powder with a particle size ≤0.075mm; and the fine aggregate with a particle size ≤0.3mm accounts for 17-26% of the total mass of the fine aggregate.

[0040] In practice, by defining the specific mass ratio of the skeleton-dense gradation structure, a synergistic system of coarse aggregate skeleton support + fine aggregate-mineral powder filling and compaction is constructed. Of the aggregates, coarse aggregates with a particle size of 4.75-13.2mm account for 50-55%. Coarse aggregates in this size range can interlock to form a rigid skeleton, providing core support for the mixture to resist heavy-load shear deformation and preventing rutting deformation caused by a weak skeleton at high temperatures. Fine aggregates with a particle size of 0.3-4.75mm account for 39-46%. This portion of fine aggregates can fill the gaps between coarse aggregate skeletons, reduce the voids inside the skeleton, and enhance the interlocking force between aggregates, preventing the skeleton from becoming loose. Mineral powder with a particle size ≤0.075mm accounts for 4-6%. As a microfiller, mineral powder can further fill the tiny voids between fine aggregates, improve the density of the mixture, and its active components can react with the asphalt binder at the interface, enhancing the bond strength between asphalt and aggregates. In addition, controlling the proportion of fine aggregates with a particle size ≤0.3mm to 17-26% of the total mass of fine aggregates can avoid the increased high-temperature fluidity caused by excessive fine aggregates, preventing rutting. This gradation design simultaneously achieves the dual functions of "heavy-load-resistant skeleton support" and "high-temperature-resistant, dense, and stable" properties for the mixture. The rigid skeleton formed by coarse aggregate effectively resists the shear force generated by repeated compaction by heavy vehicles, reducing the risk of permanent deformation. The proper filling of fine aggregate and mineral powder ensures the density of the mixture, reduces internal voids, and prevents performance degradation due to excessive voids after asphalt softens at high temperatures. It also improves the mixture's skid resistance and impermeability. Compared to traditional gradation designs, this ratio significantly improves the high-temperature stability and heavy-load resistance of asphalt concrete, reducing the probability of road surface rutting, aggregate segregation, and other defects.

[0041] In some embodiments, the high-strength coarse aggregate in step (1) is basalt aggregate or granite aggregate, with a crushing value ≤18% and Los Angeles abrasion loss ≤20%; the wear-resistant fine aggregate is limestone aggregate, with an angularity ≥30s; the active mineral powder is limestone ground mineral powder, with a specific surface area ≥350m² / kg and a hydrophilicity coefficient ≤1.0.

[0042] In practice, by limiting the performance indicators of each component in the aggregate system, the overall strength and durability of asphalt concrete are guaranteed from the raw material level. High-strength coarse aggregates are selected from basalt or granite aggregates, with a crushing value ≤18% to ensure that the coarse aggregates are not easily broken under heavy compaction, maintaining the stability of the skeleton structure; Los Angeles abrasion loss ≤20% ensures that the coarse aggregates are not easily worn during construction mixing and long-term use, avoiding skeleton loosening due to changes in aggregate particle morphology. Abrasion-resistant fine aggregates are selected from limestone aggregates, with an angularity ≥30s, which enhances the interlocking force between fine aggregates, increases the internal friction angle of the mixture, and reduces plastic deformation at high temperatures; at the same time, limestone fine aggregates have good adhesion to asphalt, which can enhance the bond strength at the asphalt-aggregate interface. The active mineral powder is made from finely ground limestone, with a specific surface area ≥350m² / kg. This increases the contact area between the mineral powder and asphalt, enhancing adsorption capacity and reducing asphalt leakage. A hydrophilicity coefficient ≤1.0 ensures the mineral powder does not easily absorb water, preventing water damage to the mixture. Simultaneously, its active components can chemically react with acidic components in the asphalt to form a stable interfacial bonding layer, further enhancing adhesion. Strictly limiting aggregate performance indicators allows for control of raw material quality from the source, providing a fundamental guarantee for high-performance asphalt concrete. The selection of high-strength coarse aggregate extends the service life of the skeleton structure, preventing pavement structure failure due to skeleton breakage under heavy loads. The high angularity of abrasion-resistant fine aggregate improves the anti-skid performance and deformation resistance of the mixture. The high specific surface area and low hydrophilicity coefficient of the active mineral powder enhance the water stability and adhesion strength of the mixture, reducing water damage, asphalt aging, and other defects. The synergistic effect of the various aggregate components significantly improves the durability and reliability of asphalt concrete under high-temperature and heavy-load environments.

[0043] In some embodiments, the mixing process parameters in step (3) are: the heating temperature of modified asphalt is 160-180℃, the heating temperature of aggregate is 170-190℃; the aggregate is first dry-mixed for 30-60s, then the pretreated high-temperature resistant fiber is added and stirred for 15-30s, and finally the modified asphalt is added and wet-mixed for 45-90s until the mixture is uniform in color and free of fiber clumps.

[0044] In practice, by clearly defining the mixing process parameters, the uniformity and performance stability of the asphalt mixture are ensured. The heating temperature of the modified asphalt is controlled at 160-180℃. This temperature range allows the modified asphalt to reach its optimal viscosity, ensuring that the asphalt fully coats the aggregate surface while preventing the modifier from aging and the asphalt performance from deteriorating due to excessively high temperatures. The aggregate heating temperature is 170-190℃, which is 10-20℃ higher than the modified asphalt heating temperature. This compensates for the temperature loss of the mixture after the asphalt is added, ensuring that the mixture temperature is maintained within a reasonable range during the mixing process and preventing insufficient asphalt coating due to excessively low temperatures. The mixing sequence follows a step-by-step approach: dry mixing of aggregates for 30-60 seconds, adding fibers and mixing for 15-30 seconds, then wet mixing of asphalt for 45-90 seconds. Dry mixing ensures uniform aggregate temperature, preventing uneven mixing due to localized temperature differences. Adding fibers and mixing allows for initial dispersion on the aggregate surface, preventing fiber clumping during subsequent asphalt mixing. Wet mixing ensures the asphalt fully coats the aggregates and fibers, forming a homogeneous mixture. Simultaneously, controlling the dry mixing time to no more than 60 seconds prevents aggregate wear due to over-mixing, maintaining the original particle shape and skeletal support capacity. This refined control of mixing process parameters effectively solves problems such as fiber clumping, uneven asphalt coating, and aggregate wear that exist in traditional mixing processes. The step-by-step mixing mode ensures uniform fiber dispersion in the mixture, maximizing its reinforcing effect; reasonable temperature control prevents asphalt aging and insufficient coating, guaranteeing the bond strength of the mixture; and the limited dry mixing time maintains the skeletal support capacity of the aggregates. The final mixture exhibits uniform and stable performance, with no localized clumping, aging, or coating defects, laying a solid foundation for subsequent paving and compaction processes and further ensuring the overall road performance of the asphalt concrete.

[0045] In some embodiments, the paving and compaction process parameters in step (4) are as follows: paving temperature 155-170℃, paving speed 2-4m / min; compaction is divided into three steps: initial compaction, intermediate compaction and final compaction. The initial compaction temperature is 150-160℃, and a steel wheel roller is used for static compaction 1-2 times; the intermediate compaction temperature is 140-150℃, and a vibratory roller is used for high-frequency low-amplitude vibration compaction 2-3 times; the final compaction temperature is 130-140℃, and a steel wheel roller is used for static compaction 1-2 times, with a final compaction degree ≥96% (Marshall standard density).

[0046] In practice, by optimizing paving and compaction parameters, a dense and smooth pavement structure is ensured from the asphalt mixture. During the paving process, the paving temperature is controlled at 155-170℃. This temperature ensures good workability of the mixture during paving and prevents it from becoming stiff and difficult to pave smoothly due to excessively low temperatures. The paving speed is controlled at 2-4 m / min. Uniform paving avoids uneven pavement thickness caused by speed fluctuations, ensuring that the road surface smoothness meets standards. The compaction process employs a layered compaction technique: Initial compaction at 150-160℃, using a steel-drum roller for 1-2 passes of static compaction. This high-temperature static compaction helps to initially stabilize the aggregate skeleton, preventing displacement or damage caused by subsequent vibratory compaction. Secondary compaction at 140-150℃, using a vibratory roller for 2-3 passes of high-frequency, low-amplitude vibration. High-frequency vibration rearranges the aggregate particles, filling internal voids and increasing density, while low-amplitude vibration prevents excessive segregation. Final compaction at 130-140℃, using a steel-drum roller for 1-2 passes of static compaction, eliminates wheel tracks from the secondary compaction process, ensuring a smooth road surface. Simultaneously, controlling the density after compaction to ≥96% (Marshall standard density) reduces internal voids in the mixture, improving impermeability and fatigue resistance. This layered compaction process and parameter control achieve the construction goals of stable aggregate skeleton, adequate density, and a smooth surface. The initial compaction stabilizes the aggregate, ensuring its resistance to deformation under heavy loads. The high-frequency, low-amplitude vibration of the secondary compaction significantly improves density, reduces internal voids, and lowers the risk of water damage and high-temperature aging. The final compaction ensures surface smoothness and improves driving comfort. Compared to traditional compaction processes, this method effectively avoids problems such as insufficient density due to improper compaction temperature or insufficient compaction passes, or aggregate damage due to unreasonable vibration parameters, further improving the construction quality and long-term performance of asphalt concrete pavements.

[0047] In some embodiments, the modified asphalt in step (1) is at least one of SBS modified asphalt or rubber modified asphalt, with a penetration of 60-80 (0.1 mm) at 25°C and a kinematic viscosity of 135°C. Softening point ≥60℃.

[0048] In practice, by limiting the type and performance indicators of modified asphalt, a balance between high-temperature resistance and high- and low-temperature performance is ensured in the binder layer. SBS-modified asphalt or rubber-modified asphalt is selected. SBS (styrene-butadiene-styrene block copolymer) is used as a modifier, forming an interpenetrating network structure with the asphalt, increasing its softening point and viscosity, and enhancing its high-temperature resistance. Simultaneously, the elastic properties of SBS improve the low-temperature flexibility of the asphalt, preventing low-temperature brittleness. Rubber-modified asphalt utilizes the elasticity and heat resistance of rubber particles to improve the asphalt's resistance to deformation and aging. Regarding performance indicators, a penetration of 60-80 (0.1mm) at 25℃ ensures that the asphalt has suitable hardness at room temperature, guaranteeing the road surface's load-bearing capacity while avoiding brittleness caused by excessive hardness; the kinematic viscosity at 135℃... This invention ensures that asphalt maintains good fluidity at mixing temperatures, facilitating aggregate coating; a softening point ≥60℃ significantly improves the high-temperature resistance of asphalt, preventing rutting caused by asphalt softening in summer. By selecting SBS modified asphalt or rubber modified asphalt that meets performance specifications, this invention addresses the insufficient high-temperature resistance of traditional petroleum asphalt at the core of the binder. A higher softening point ensures that the asphalt does not easily soften in high-temperature environments, reducing rutting; suitable penetration and kinematic viscosity balance the asphalt's room-temperature load-bearing capacity and workability; simultaneously, the elastic properties of the modified asphalt improve the low-temperature crack resistance of the mixture, preventing road surface cracking caused by low winter temperatures. This solution achieves a balance between the high and low-temperature performance of asphalt binders, providing a reliable binder guarantee for asphalt concrete used in high-temperature, heavy-load, and large-temperature-difference environments.

[0049] In some embodiments, the fiber pretreatment process in step (3) is as follows: the high-temperature resistant fiber is placed in an oven at 60-80℃ and dried for 2-4 hours to make the fiber moisture content ≤1%; and the length of the high-temperature resistant fiber is 3-6mm and the diameter of the single filament is 10-20μm.

[0050] In practice, the fiber pretreatment process and morphological parameters are optimized to ensure that the fibers fully exert their reinforcing effect in asphalt mixtures. Fiber pretreatment involves drying in an oven at 60-80℃ for 2-4 hours. This temperature range effectively removes adsorbed moisture from the fibers without causing aging of their properties. Controlling the fiber moisture content after drying to ≤1% prevents water evaporation during mixing, which can form air bubbles, leading to voids in the mixture, causing water damage or reduced density. The fiber length is controlled at 3-6mm. This length allows the fibers to form a continuous reinforcing network in the mixture without tangling or clumping due to excessive length. The monofilament diameter is controlled at 10-20μm. A finer diameter increases the contact area between the fiber and the asphalt and aggregates, improving interfacial bond strength, while ensuring fiber flexibility and preventing a decrease in workability due to excessive diameter. It should be noted that optimizing the fiber pretreatment process and morphological parameters significantly improves fiber dispersibility and reinforcing effect. Drying removes moisture, preventing the formation of voids within the mixture and improving its impermeability and density. Suitable fiber length and diameter ensure uniform fiber dispersion and the formation of an effective reinforcing network, maximizing tensile and crack resistance. Compared to untreated or improperly shaped fibers, the fibers in this solution more stably enhance the high-temperature stability and fatigue resistance of asphalt concrete, reducing performance fluctuations caused by uneven fiber dispersion or unsuitable morphology, and further ensuring the reliability of the mixture's performance.

[0051] In some embodiments, the performance indicators of the high-temperature resistant asphalt concrete meet the following requirements: dynamic stability at 60℃ ≥ 3000 cycles / mm, bending strain at -10℃ ≥ 2800με, Marshall residual stability after 48h immersion in water ≥ 85%, and water permeability coefficient ≤ 100mL / min.

[0052] In practical implementation, a performance evaluation system directly corresponding to the requirements of high-temperature heavy-duty road use is established by clearly defining the core performance indicators of high-temperature resistant asphalt concrete. These indicators include: 60℃ high-temperature dynamic stability ≥ 3000 cycles / mm (simulating the scenario of repeated crushing by heavy vehicles in summer high-temperature environments; higher dynamic stability indicates stronger resistance to permanent deformation (rutting); -10℃ low-temperature flexural strain ≥ 2800με (simulating the low-temperature environment in winter; higher flexural strain indicates better low-temperature flexibility and stronger crack resistance); 48h water immersion Marshall residual stability ≥ 85% (simulating the rainwater immersion environment; higher residual stability indicates better water stability and stronger resistance to water damage); and a permeability coefficient ≤ 100mL / min (directly reflecting the impermeability of the mixture; a lower permeability coefficient indicates less difficulty for rainwater to penetrate the mixture, reducing pavement peeling, loosening, and other defects caused by water damage). These indicators work synergistically to address core road use requirements such as high-temperature rutting resistance, low-temperature crack resistance, and water-stable impermeability, forming a comprehensive performance assurance system. It should be noted that clearly defined performance indicators provide quantitative standards for the quality control and engineering application of asphalt concrete, ensuring that the prepared mixture is fully adaptable to high-temperature and heavy-load environments. The high requirement for dynamic stability at 60℃ directly solves the problem of rutting in summer; the limitation of bending strain at -10℃ avoids low-temperature cracking in winter; and the control of Marshall residual stability and permeability coefficient after 48 hours of immersion reduces the risk of water damage. The synergistic effect of these indicators can significantly extend the service life of asphalt concrete pavements, reduce the frequency and cost of maintenance caused by high temperatures, heavy loads, and water damage, and provide a reliable and long-lasting pavement material solution for high-temperature and heavy-load road sections.

[0053] To provide a clearer understanding of the invention, the invention is further described below:

[0054] This application provides a method for preparing high-temperature resistant asphalt concrete, the specific technical solution of which is as follows:

[0055] 1. Raw material selection

[0056] Modified asphalt: SBS modified asphalt or rubber modified asphalt are selected, preferably a blend of both (mass ratio 7:3-8:2). This type of asphalt improves compatibility with polymer modifiers, achieving a softening point ≥60℃ and a kinematic viscosity at 135℃. It can resist softening at high temperatures and ensure flexibility at low temperatures (ductility ≥20cm at -10℃).

[0057] Aggregate system:

[0058] Coarse aggregate: Basalt or granite is selected, with a crushing value ≤18% and Los Angeles abrasion loss ≤20% to ensure high strength to withstand heavy loads; the particle size is graded as 4.75-9.5mm and 9.5-13.2mm to avoid skeletal voids caused by a single particle size.

[0059] Fine aggregate: Limestone is selected with angularity ≥30s (to increase the interlocking force between aggregates). The particle size is classified as 0.3-2.36mm and 2.36-4.75mm. The proportion of fine material below 0.3mm is controlled (≤10%) to avoid rutting caused by the flow of fine material at high temperature.

[0060] Mineral powder: Finely ground limestone mineral powder is selected, with a specific surface area ≥350m² / kg and a hydrophilicity coefficient ≤1.0. Its active component (CaO) can react with the acidic components in asphalt to enhance the bonding force and fill the gaps between aggregates to improve the density.

[0061] High-temperature resistant fibers: Basalt fiber (high temperature resistance ≥600℃), polyester fiber (high temperature resistance ≥250℃) or glass fiber (high temperature resistance ≥300℃) are selected, with priority given to the blending of basalt fiber and polyester fiber (mass ratio 6:4-7:3) to balance heat resistance and dispersibility.

[0062] 2. Aggregate gradation optimization adopts the "skeleton-dense" gradation design concept, which constructs a coarse aggregate skeleton + fine aggregate - mineral powder filling structure by adjusting the aggregate ratio:

[0063] Coarse aggregates with a particle size of 4.75-13.2mm account for 50-55% and form the main skeleton to resist shear deformation under heavy loads.

[0064] Fine aggregates with a particle size of 0.3-4.75mm account for 39-46% to fill the gaps between coarse aggregates and prevent the skeleton from becoming loose;

[0065] Mineral powder with a particle size ≤0.075mm accounts for 4-6%, which further fills the micro-voids and improves the bonding strength between asphalt and aggregate.

[0066] Fine aggregates with a particle size ≤0.3mm should account for 17-26% of the total mass of fine aggregates to prevent excessive fine aggregates from causing high-temperature fluidity.

[0067] 3. Fiber pretreatment and mixing

[0068] Fiber pretreatment: Place the fiber in an oven at 60-80℃ and dry for 2-4 hours to make the moisture content ≤1% (to avoid segregation of the mixture caused by moisture); if the fiber length exceeds 6mm, it needs to be crushed to 3-6mm (to ensure uniform dispersion).

[0069] Mix in stages:

[0070] Aggregate heating: Coarse aggregate and fine aggregate are heated to 170-190℃ respectively (10-20℃ higher than the asphalt heating temperature to ensure sufficient asphalt coating);

[0071] Dry mixing: Put the heated aggregate into the mixing pot and dry mix for 30-60 seconds to make the aggregate temperature uniform;

[0072] Fiber incorporation: Add pretreated fibers and stir for 15-30 seconds to initially disperse the fibers on the surface of the aggregate;

[0073] Wet mixing: Add modified asphalt at 160-180℃ and wet mix for 45-90 seconds until the mixture is uniform in color and free of fiber clumps (the dispersibility is verified by visual inspection and sieving, and the fiber clump rate is ≤5%).

[0074] 4. Spreading and compaction

[0075] Paving control: Asphalt pavers are used for uniform paving at a speed of 2-4 m / min (to avoid uneven thickness caused by speed fluctuations), and the paving temperature is 155-170℃ (below this temperature will easily lead to compaction difficulties); during the paving process, a non-contact balance beam is used to control the flatness to ensure that the surface flatness after paving is ≤3mm / 3m.

[0076] Layered compaction:

[0077] Initial compaction: Use a 10-12t steel wheel roller for static compaction 1-2 times at a temperature of 150-160℃ (static compaction at high temperature can initially fix the skeleton and avoid aggregate displacement caused by vibration);

[0078] Secondary compaction: Use an 18-20t vibratory roller with high frequency and low amplitude (frequency 30-50Hz, amplitude 0.3-0.5mm) to compact 2-3 times at a temperature of 140-150℃ (vibration can enhance density, and high frequency and low amplitude avoid damage to the frame).

[0079] Final compaction: Use a 10-12t steel wheel roller for static compaction 1-2 times at a temperature of 130-140℃ (to eliminate traces of repeated compaction and ensure a smooth surface).

[0080] Post-compaction testing: density ≥96% (Marshall standard density), porosity 3-5% (balancing impermeability and fatigue resistance).

[0081] To make the technical solution of this application clearer and easier to understand, the preparation method of high-temperature resistant asphalt concrete of this application will be described in detail below with reference to specific embodiments.

[0082] Example 1

[0083] Raw material selection:

[0084] Modified asphalt: SBS modified asphalt (penetration 70 (0.1 mm) at 25℃, softening point 62℃);

[0085] Aggregates: basalt coarse aggregate (4.75-9.5mm, 30%; 9.5-13.2mm, 25%), limestone fine aggregate (0.3-2.36mm, 20%; 2.36-4.75mm, 18%), limestone mineral powder (5%).

[0086] Fiber: Basalt fiber (5mm in length, 0.5% in content, based on the total mass of the mixture).

[0087] Preparation process:

[0088] Fiber pretreatment: Dry in an oven at 80℃ for 3 hours, moisture content 0.8%;

[0089] Mixing: Heat aggregate to 180℃, dry mix for 45 seconds, add fiber and mix for 20 seconds, add 170℃ asphalt and wet mix for 70 seconds;

[0090] Paving and compaction: Paving temperature 165℃, initial compaction 155℃ static compaction once, secondary compaction 145℃ vibration twice, final compaction 135℃ static compaction once.

[0091] Performance test results:

[0092] Dynamic stability at 60℃: 3450 cycles / mm;

[0093] Bending strain at -10℃: 3100με;

[0094] 48h residual stability: 88%;

[0095] Permeability coefficient: 85 mL / min.

[0096] Example 2

[0097] Raw material selection:

[0098] Modified asphalt: SBS-rubber composite modified asphalt (mass ratio 8:2, penetration at 25℃ 65 (0.1mm), softening point 65℃);

[0099] Aggregates: coarse granite aggregate (4.75-9.5mm, 28%; 9.5-13.2mm, 27%), fine limestone aggregate (0.3-2.36mm, 19%; 2.36-4.75mm, 16%), limestone mineral powder (6%).

[0100] Fiber: Basalt-polyester composite fiber (mass ratio 7:3, length 4mm, content 0.45%).

[0101] Preparation process:

[0102] Fiber pretreatment: Drying in an oven at 70℃ for 2.5 hours, moisture content 0.6%;

[0103] Mixing: Heat aggregate to 175℃, dry mix for 40 seconds, add fiber and mix for 25 seconds, add 165℃ asphalt and wet mix for 80 seconds;

[0104] Paving and compaction: Paving temperature 160℃, initial compaction 150℃ static compaction 2 times, secondary compaction 140℃ vibration 3 times, final compaction 130℃ static compaction 2 times.

[0105] Performance test results:

[0106] Dynamic stability at 60℃: 3620 cycles / mm;

[0107] Bending strain at -10℃: 3250με;

[0108] 48h residual stability: 90%;

[0109] Permeability coefficient: 78 mL / min.

[0110] Comparative Example (Traditional Method)

[0111] Raw material selection: ordinary road petroleum asphalt (25℃ penetration 80 (0.1mm), softening point 45℃), ordinary limestone aggregate (gradation is AC-13C standard gradation), lignin fiber (admixture 0.3%).

[0112] Preparation process: conventional mixing (aggregate heated to 160℃, asphalt heated to 150℃, dry mixing for 30s, wet mixing for 60s), conventional compaction (initial compaction at 140℃ static pressure, secondary compaction at 130℃ vibration).

[0113] Performance test results:

[0114] Dynamic stability at 60℃: 2100 / mm;

[0115] Bending strain at -10℃: 2200με;

[0116] 48-hour residual stability: 75%;

[0117] Permeability coefficient: 150 mL / min.

[0118] As can be seen from the comparison of Examples 1 and 2 with the comparative examples, the preparation method of this application significantly improves the high-temperature stability, low-temperature crack resistance and water stability of asphalt concrete, and fully meets the road performance requirements under high-temperature and heavy-load environments.

[0119] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing high-temperature resistant asphalt concrete, characterized in that, Includes the following steps: (1) Raw material selection: Modified asphalt was selected as the binder, high-strength coarse aggregate, wear-resistant fine aggregate and active mineral powder were selected as the aggregate system, and high-temperature resistant fiber was selected as the reinforcing agent. (2) Aggregate gradation optimization: Adjust the mass ratio of coarse aggregate, fine aggregate and mineral powder in the aggregate system to construct a skeleton-dense gradation structure; (3) Fiber pretreatment and mixing: After drying and pretreating the high-temperature resistant fiber, the pretreated high-temperature resistant fiber is mixed with the heated aggregate and modified asphalt in sequence, and the mixing temperature and mixing time are controlled to obtain asphalt mixture; (4) Paving and compaction: The asphalt mixture is paved at a preset temperature and compacted using a layered compaction process to obtain high-temperature resistant asphalt concrete.

2. The method for preparing high-temperature resistant asphalt concrete according to claim 1, characterized in that: The high-temperature resistant fiber mentioned in step (1) is at least one of basalt fiber, polyester fiber, and glass fiber.

3. The method for preparing high-temperature resistant asphalt concrete according to claim 2, characterized in that: Based on the total mass of the asphalt mixture, the content of the high-temperature resistant fiber is 0.3-0.6%; wherein, the content of basalt fiber is 0.4-0.6%, the content of polyester fiber is 0.3-0.5%, and the content of glass fiber is 0.35-0.55%.

4. The method for preparing high-temperature resistant asphalt concrete according to claim 1, characterized in that: The mass ratio of the skeleton-dense gradation structure in step (2) is as follows: 50-55% of coarse aggregate with a particle size of 4.75-13.2mm, 39-46% of fine aggregate with a particle size of 0.3-4.75mm, and 4-6% of mineral powder with a particle size of ≤0.075mm; and the fine aggregate with a particle size of ≤0.3mm accounts for 17-26% of the total mass of the fine aggregate.

5. The method for preparing high-temperature resistant asphalt concrete according to claim 1, characterized in that: The high-strength coarse aggregate mentioned in step (1) is basalt aggregate or granite aggregate, with a crushing value ≤18% and Los Angeles abrasion loss ≤20%; the wear-resistant fine aggregate is limestone aggregate, with an angularity ≥30s; the active mineral powder is limestone ground mineral powder, with a specific surface area ≥350m² / kg and a hydrophilicity coefficient ≤1.

0.

6. The method for preparing high-temperature resistant asphalt concrete according to claim 1, characterized in that: The mixing process parameters in step (3) are as follows: the heating temperature of modified asphalt is 160-180℃, and the heating temperature of aggregate is 170-190℃; the aggregate is first dry-mixed for 30-60s, then the pretreated high-temperature resistant fiber is added and stirred for 15-30s, and finally the modified asphalt is added and wet-mixed for 45-90s until the mixture is uniform in color and free of fiber clumps.

7. The method for preparing high-temperature resistant asphalt concrete according to claim 1, characterized in that: The paving and compaction process parameters in step (4) are as follows: paving temperature 155-170℃, paving speed 2-4m / min; compaction is divided into three steps: initial compaction, intermediate compaction and final compaction. The initial compaction temperature is 150-160℃, and a steel wheel roller is used for static compaction 1-2 times; the intermediate compaction temperature is 140-150℃, and a vibratory roller is used for high-frequency low-amplitude vibration compaction 2-3 times; the final compaction temperature is 130-140℃, and a steel wheel roller is used for static compaction 1-2 times, with a final compaction degree ≥96%.

8. The method for preparing high-temperature resistant asphalt concrete according to claim 1, characterized in that: The modified asphalt mentioned in step (1) is at least one of SBS modified asphalt or rubber modified asphalt, with a penetration of 60-80 at 25°C and a kinematic viscosity of 135°C. Softening point ≥60℃.

9. The method for preparing high-temperature resistant asphalt concrete according to claim 1, characterized in that: The fiber pretreatment process in step (3) is as follows: the high temperature resistant fiber is placed in an oven at 60-80℃ and dried for 2-4 hours to make the fiber moisture content ≤1%; and the length of the high temperature resistant fiber is 3-6mm and the diameter of the single filament is 10-20μm.

10. The method for preparing high-temperature resistant asphalt concrete according to claim 1, characterized in that: The performance indicators of the high-temperature resistant asphalt concrete meet the following requirements: dynamic stability at 60℃ ≥3000 cycles / mm, bending strain at -10℃ ≥2800με, Marshall residual stability after 48h immersion in water ≥85%, and water permeability coefficient ≤100mL / min.

Images