Anti-rutting-anti-displacement layered composite asphalt material for level crossing road and gradient construction method thereof

Abstract

The invention relates to the technical field of road engineering, in particular to an anti-rutting-anti-displacement layered composite asphalt material for a level crossing road and a gradient construction method of the anti-rutting-anti-displacement layered composite asphalt material. The layered composite asphalt material for the level crossing road sequentially comprises an upper surface layer, a middle surface layer, a lower surface layer and an asphalt bonding layer arranged between every two adjacent layers from top to bottom, the upper surface layer is an anti-shearing asphalt concrete layer, the middle surface layer is an anti-rutting asphalt concrete layer, the lower surface layer is an anti-fatigue asphalt concrete layer, and the upper surface layer, the middle surface layer and the lower surface layer all contain stress self-adaptive modifiers. Functional layers are customized according to mechanical responses of different conflict areas of the level crossing, the upper layer is resistant to braking shear and sliding, the middle layer and the lower layer are resistant to rutting, fatigue and water, interlayer bonding is resistant to horizontal displacement and cracking, stress self-adaptive modifiers are added into the upper layer, the middle layer and the lower layer, deformation can be intelligently adjusted along with the load frequency, and damage self-sensing and self-repairing are achieved. A rigid-flexible gradient structure is formed, and a full-life-cycle solution is provided for urban intersections.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of road engineering, in particular to a flat crossing road anti-rutting-anti-slippage layered composite asphalt material and a gradient construction method thereof. BACKGROUND

[0002] The flat crossing road (flat intersection) refers to a traffic node formed by two or more roads intersecting at the same plane, and common forms include cross shape, T shape, ring shape, etc. Traffic flow is complex, and the pavement needs to bear more special damage than ordinary roads, such as the braking area, which will cause a high temperature shear of more than 60℃ due to frequent vehicle start-stop, and the traditional modified asphalt flow deformation is usually more than 15mm, so rutting is prone to occur; in the acceleration area, the asphalt layer slips due to the need to bear a large horizontal shear force, and interlayer slippage occurs; in the marking area, cracks are easily induced due to repeated wheel load extrusion, leading to water seepage. Therefore, the flat crossing road has more stringent requirements on pavement performance than ordinary road sections, but the existing material performance is single, and a single material cannot meet the multi-dimensional mechanical requirements of the conflict area, such as high modulus asphalt which cannot guarantee low temperature performance with a high temperature crack rate of up to 40%. Therefore, it is still necessary to improve the existing pavement materials and construction methods of flat crossing roads.

[0003] Chinese patent CN 113215907 A discloses a city road flat crossing old concrete pavement asphalt overlay structure and a construction method thereof. The method includes spreading an asphalt synchronous gravel functional layer on the old cement concrete panel treatment layer, leveling the surface of the old cement concrete panel treatment layer, then laying a durable asphalt concrete lower layer, then laying a high-performance reinforced mesh premixed gravel interlayer, then laying an anti-rutting asphalt concrete middle layer, then spreading an asphalt tack coat on the anti-rutting asphalt concrete middle layer, and then laying a wear-resistant asphalt concrete upper layer on the asphalt tack coat to complete the asphalt overlay construction. The construction method is for the overlay of old concrete pavement, and a wear-resistant layer needs to be laid after laying the anti-rutting layer. In addition, the interlayers between the layers are different, and the construction is complex. SUMMARY

[0004] The present application aims to improve the service life of flat crossing roads while reducing costs.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] The application provides a flat-crossing road layered composite asphalt material, which comprises, from top to bottom, an upper layer, a middle layer and a lower layer, and an asphalt bonding layer arranged between the two adjacent layers; the upper layer is a shear-resistant asphalt concrete layer; the middle layer is a rut-resistant asphalt concrete layer; the lower layer is a fatigue-resistant asphalt concrete layer; the upper layer, the middle layer and the lower layer all contain a stress self-adapting modifier, and the stress self-adapting modifier comprises core-shell polymer microparticles, carbon nanotube aerogel and activated rubber powder.

[0007] The upper layer is a shear-resistant asphalt concrete layer, mainly resisting braking shear and sliding; the middle layer is a rut-resistant asphalt concrete layer; the lower layer is a fatigue-resistant asphalt concrete layer; the middle and lower layers mainly realize rut resistance, fatigue resistance and water resistance; the asphalt bonding layer is added between the layers, which can enhance the interface bonding, resist horizontal displacement and cracking, and also absorb the interlayer stress; in addition, the stress self-adapting modifier is added in the upper, middle and lower layers, under low-frequency load (braking), the core-shell polymer microparticles can trigger viscoelastic conversion by shell rupture to enhance elastic recovery; under high-frequency load (acceleration), the carbon nanotube aerogel can compress energy storage to reduce shear wave propagation; and the activated rubber powder particles play a coordinating role, so that the rheological properties of each layer can be intelligently adjusted with the load frequency, damage self-sensing and self-repairing are realized, and the service life is improved.

[0008] Preferably, the shear strength of the upper layer is greater than or equal to 0.9 MPa; the dynamic stability of the middle layer at 60 DEG C is greater than or equal to 8000 times / mm; the bending strain energy of the middle layer and the lower layer is greater than or equal to 0.8 J / cm 3 The interface bonding strength between the adjacent layers at 25 DEG C is greater than or equal to 1.2 MPa, and the service life is better, which can be more than 8 years.

[0009] For the conventional anti-shear type, high modulus asphalt and aggregate are usually selected to mix. But in the anti-shear type asphalt concrete layer of the top layer of the asphalt material of the present application, the stress self-adapting modifier is also contained. In some preferred embodiments, in the top layer, in addition to the stress self-adapting modifier, the composite modified asphalt, basalt aggregate and basalt fiber material are also included. As in some embodiments, the SMA asphalt mixture added with the stress self-adapting modifier is used as the anti-shear type asphalt concrete layer, wherein the weight fractions of the components of the SMA asphalt mixture are: composite modified asphalt 5-6 parts; basalt aggregate 95-100 parts; basalt fiber 0.1-0.3 parts; in some embodiments, the AC asphalt mixture added with the stress self-adapting modifier is used as the anti-shear type asphalt concrete layer, wherein the weight fractions of the components of the AC asphalt mixture are: composite modified asphalt 4-5 parts; basalt aggregate 92-100 parts; basalt fiber 0.1-0.2 parts; the composite modified asphalt used in the above embodiments needs to have a PG grade of above PG82, which can be SBS modified asphalt, etc. Preferably, the amount of the stress self-adapting modifier added in the above embodiments is 7-9wt%. In this way, the thickness of 2-4cm can achieve a shear strength of ≥0.9MPa.

[0010] For the conventional anti-rutting type asphalt concrete layer, hard asphalt and aggregate are usually selected to mix. But in the anti-rutting type asphalt concrete layer of the top layer of the asphalt material of the present application, the stress self-adapting modifier is also contained. In some preferred embodiments, in the top layer, in addition to the stress self-adapting modifier, the hard asphalt, basalt aggregate and basalt fiber are also included. As in some embodiments, the SMA asphalt mixture added with the stress self-adapting modifier is used as the anti-rutting type asphalt concrete layer, wherein the weight fractions of the components of the SMA asphalt mixture are: hard asphalt 5-6 parts; basalt aggregate 95-100 parts; basalt fiber 0.1-0.3 parts; in some embodiments, the AC asphalt mixture added with the stress self-adapting modifier is used as the anti-rutting type asphalt concrete layer, wherein the weight fractions of the components of the AC asphalt mixture are: hard asphalt 4-5 parts; basalt aggregate 92-100 parts; basalt fiber 0.1-0.2 parts; in the above embodiments, the key parameters of the hard asphalt: penetration 45-55 (25℃, 0.1mm), which can be No.50 hard asphalt, etc. Preferably, the amount of the stress self-adapting modifier added in the above embodiments is 5-7wt%, which can achieve a dynamic stability of ≥8000 times / mm at 60℃, a bending strain energy of ≥0.8J / cm 3 .

[0011] For conventional fatigue-resistant asphalt concrete layers, high modulus and high strength are required, along with good toughness and ductility, and excellent durability. High modulus asphalt or modified asphalt is usually selected as the binder, and aggregates and modifiers are added to obtain the desired result. However, the fatigue-resistant asphalt concrete layer under the asphalt material of this invention also includes a stress-adaptive modifier. In some preferred embodiments, the lower layer, in addition to the stress-adaptive modifier, also includes heavy-duty road asphalt, limestone aggregate, and lignin fiber. For example, in some embodiments, SMA asphalt mixture with added stress-adaptive modifier is used as the fatigue-resistant asphalt concrete layer, wherein the weight parts of each component of the SMA asphalt mixture are: 5-6 parts heavy-duty road asphalt; 95-100 parts limestone aggregate; and 0.1-0.3 parts lignin fiber. In some embodiments, AC asphalt mixture with added stress-adaptive modifier is used as the fatigue-resistant asphalt concrete layer, wherein the weight parts of each component of the AC asphalt mixture are: 4-5 parts heavy-duty road asphalt; 92-100 parts basalt aggregate; and 0.1-0.2 parts lignin fiber. In the above embodiments, the key parameter of heavy-duty asphalt is: penetration 60-80 (25℃, 0.1mm), wherein the amount of stress-adaptive modifier added is 3-5wt%, which can achieve a bending strain energy ≥0.8J / cm. 3

[0012] The asphalt binder layer in the asphalt material of this invention mainly serves to bond, resist shoving, resist cracking, and absorb stress. In some preferred embodiments, the asphalt binder layer includes rubberized asphalt and crushed stone. The rubberized asphalt is asphalt with added rubber powder, and the dosage can be 10%-30%. The rubberized asphalt application rate is 2.0-2.5 kg / m³. 2 The full coverage rate of crushed stone should be 60-80%; the key parameters of rubber asphalt should meet the following requirements: viscosity at 180℃ 2-4 Pa. With a penetration of 30–60 (25℃, 0.1 mm) and a softening point ≥70℃, an interfacial bond strength ≥1.2 MPa can be achieved by adjusting the amounts of asphalt and rubber.

[0013] In some preferred embodiments, the stress-adaptive modifier in the asphalt material of the present invention is composed of 4-6 parts by weight of core-shell polymer microparticles, 2-4 parts by weight of carbon nanotube aerogel, and 1-3 parts by weight of activated rubber powder.

[0014] Preferably, the core-shell polymer microparticles have SBR as the core and epoxy resin as the shell, and their loss factor tanδ can be dynamically adjusted within a range of 0.2-0.8, resulting in better adjustment effect.

[0015] Preferably, the carbon nanotube aerogel has a porosity of ≥90%, such as 93%, 95%, etc.

[0016] The activated rubber powder in the stress self-adapting modifier is rubber powder obtained by crushing and desulfurization treatment of automobile waste tires and having a certain fineness specification.

[0017] The application also provides a gradient construction method of the layered composite asphalt material for flat intersection roads.

[0018] In some preferred embodiments, the middle layer is constructed and compacted by using an oscillation road roller, the exciting force is greater than or equal to 100 kN, and the vibration frequency is 30-40 Hz.

[0019] In some preferred embodiments, the upper layer is initially pressed by using a high-frequency double-steel-wheel roller and then transversely kneaded and compacted.

[0020] In some preferred embodiments, the lower layer is used to close pores by using a rubber-tired road roller.

[0021] In some preferred embodiments, the asphalt binder layer is constructed by spraying rubber asphalt and spreading gravel.

[0022] The application has the following beneficial effects:

[0023] The application customizes functional layers according to the mechanical responses of different conflict zones of flat intersections, designs a three-layer composite structure, the upper layer is resistant to braking shear and skidding, the middle and lower layers are resistant to rutting, fatigue and water, the interlayer bonding is resistant to horizontal displacement and cracking, and the stress self-adapting modifier is added to each layer to intelligently adjust the rheological properties with the load frequency, realize damage self-sensing and self-repairing, the asphalt material forms a "stiff-soft-tough" gradient structure, accurately matches the mechanical properties of the material with the stress field of the conflict zone, prolongs the service life of the flat intersection, reduces the cost, and provides a whole life cycle solution for urban intersections. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 FIG. 1 is a structural schematic diagram of the layered composite asphalt material for flat intersection roads. DETAILED DESCRIPTION

[0025] To make the purpose, technical scheme and advantages of the application clearer, the application is further described in detail below.

[0026] In the embodiments of the application, the proportions of the raw material components are generally weight proportions unless otherwise specified.

[0027] REFERENCE Figure 1The present application provides a layered composite asphalt material for crossing road, which comprises from top to bottom: upper layer 1, middle layer 2 and lower layer 3, and asphalt bonding layer 4 between the adjacent two layers.

[0028] The upper layer 1 is a shear-resistant asphalt concrete layer, which is preferably obtained by mixing high modulus asphalt and aggregate, but in the embodiment of the present application, a stress adaptive modifier is further added to further improve the performance of asphalt mixture rheology adjustment with load and improve the shear resistance effect. In the preferred embodiment, the upper layer of the present application comprises composite modified asphalt, basalt aggregate and basalt fiber and stress adaptive modifier.

[0029] The middle layer 2 is a rut-resistant asphalt concrete layer, which is usually obtained by mixing hard asphalt and aggregate, but in the embodiment of the present application, a stress adaptive modifier is further added to further improve the performance of asphalt mixture rheology adjustment with load and improve the bending strain energy. In the preferred embodiment, the middle layer of the asphalt material of the present application comprises hard asphalt, basalt aggregate, basalt fiber and stress adaptive modifier, and the asphalt can be 50# hard asphalt.

[0030] The lower layer 3 is a fatigue-resistant asphalt concrete layer, which is usually obtained by mixing high modulus asphalt or modified asphalt as binder, adding aggregate and modifier, but in the embodiment of the present application, a stress adaptive modifier is further added to further improve the performance of asphalt mixture rheology adjustment with load and improve the bending strain energy. In the preferred embodiment, the lower layer of the asphalt material of the present application comprises heavy traffic road asphalt, limestone aggregate, lignin fiber and stress adaptive modifier. The heavy traffic road asphalt can be 70# A-grade asphalt or modified asphalt (such as SBS modified asphalt, rubber powder modified asphalt, etc.).

[0031] The upper layer, the middle layer and the lower layer can be paved with SMA asphalt mixture or AC asphalt mixture.

[0032] As in some embodiments, each layer is SMA asphalt mixture. The upper layer 1 comprises composite modified asphalt 5-6 parts; basalt aggregate 95-100 parts; basalt fiber 0.1-0.3 parts, the composite modified asphalt needs PG grade above PG82, which can be SBS modified asphalt, etc., and the stress adaptive modifier is added in an amount of 7-9wt%. The middle layer 2 comprises hard asphalt 5-6 parts; basalt aggregate 95-100 parts, basalt fiber 0.1-0.3 parts; the key parameters of hard asphalt: penetration 45-55 (25℃, 0.1mm), which can be 50# hard asphalt, etc., and the stress adaptive modifier is added in an amount of 5-7wt%. The lower layer 3 comprises: heavy traffic road asphalt 5-6 parts; limestone aggregate 95-100 parts; lignin fiber 0.1-0.3 parts; and the stress adaptive modifier is added in an amount of 3-5wt%.

[0033] As in some embodiments, each layer is AC asphalt mixture. The upper layer 1 includes: composite modified asphalt 4-5 parts; basalt aggregate 92-100 parts, basalt fiber 0.1-0.2 parts; composite modified asphalt needs PG grade above PG82, which can be SBS modified asphalt, etc., and the stress self-adaptive modifier is added in an amount of 7-9wt%. The middle layer 2 includes: hard asphalt 4-5 parts; basalt aggregate 92-100 parts, basalt fiber 0.1-0.2 parts; the key parameters of hard asphalt: penetration 45-55 (25℃, 0.1mm), which can be No.50 hard asphalt, etc., and the stress self-adaptive modifier is added in an amount of 5-7wt%. The lower layer 3 includes: heavy traffic road asphalt 4-5 parts; basalt aggregate 92-100 parts; lignin fiber 0.1-0.2 parts; the key parameters of heavy traffic road asphalt: penetration 60-80 (25℃, 0.1mm), and the stress self-adaptive modifier is added in an amount of 3-5wt%.

[0034] The stress self-adaptive modifier described above includes core-shell polymer microparticles, carbon nanotube aerogel, and activated rubber powder. The core-shell polymer microparticles, which have a core-shell structure, can trigger viscoelastic conversion by shell rupture under low-frequency load (braking) to enhance elastic recovery. Preferably, the core-shell polymer microparticles have SBR as the core and epoxy resin as the shell, and the dynamic adjustment range of the loss factor tan δ can reach 0.2-0.8, achieving better adjustment effect. The carbon nanotube aerogel can compress energy storage under high-frequency load (acceleration), reduce shear wave propagation, and release activated rubber powder or core-shell polymer microparticles under pressure to repair microcracks. Preferably, the porosity of the carbon nanotube aerogel is ≥90%, such as 95%, 93%, etc. The activated rubber powder, which is obtained by crushing and devulcanization treatment of automobile waste tires, has a certain fineness specification and good elasticity, and can repair cracks. Preferably, the particle size of the activated rubber powder is 0.2-0.4mm.

[0035] In a preferred embodiment, the stress self-adaptive modifier in the asphalt material of the present application is compounded by 4-6 parts by weight of core-shell polymer microparticles, 2-4 parts by weight of carbon nanotube aerogel, and 1-3 parts by weight of activated rubber powder. The addition amount of the stress self-adaptive modifier in the upper, middle and lower layers is generally 7-9wt% for the upper layer, 5-7wt% for the middle layer, and 3-5wt% for the lower layer, and the addition amount gradually decreases from the upper layer to the lower layer.

[0036] The asphalt binder layer 4 in the asphalt material of the present application mainly plays the role of binding, anti-advance, anti-cracking and stress absorption. In some preferred embodiments, the asphalt binder layer comprises rubber asphalt and gravel, wherein the rubber asphalt is asphalt added with rubber powder, and the content of the rubber powder can be 10%-30%. The spraying amount of the rubber asphalt is 2.0-2.5 kg / m 2 ; the full paving rate of the gravel is 60-80%; the key parameters of the rubber asphalt should meet the following requirements: the viscosity at 180℃ is 2-4 Pa s, the penetration is 30-60 (25℃, 0.1mm), the softening point is ≥70℃, and by adjusting the amount of the asphalt and the rubber, the interface bonding strength can be ≥1.2 MPa,

[0037] In the asphalt material of the present application, the upper layer mainly plays the role of anti-braking shear and anti-skid, the middle and lower layers mainly play the role of anti-rutting, anti-fatigue and water resistance, and the asphalt binder layer is added between the layers, which can play the role of anti-horizontal advance and anti-cracking by enhancing the interface bonding, and can also absorb the interlayer stress. Preferably, the shear strength of the upper layer is ≥0.9 MPa; the dynamic stability at 60℃ of the middle layer is ≥8000 times / mm, the bending strain energy of the middle and lower layers is ≥0.8 J / cm 3 , the interface bonding strength between adjacent layers is ≥1.2 MPa, and the service life is better, which can reach 8 years.

[0038] The construction method of the layered composite asphalt material of the present application can use step temperature for paving, wherein the paving temperature of the lower layer is 150-160℃, the paving temperature of the middle layer is 155-165℃, and the paving temperature of the upper layer is 160-170℃. After each layer is paved, a certain interval is set for compaction, which can be 10 minutes. In some embodiments, the middle layer is compacted by using an oscillation road roller, and the exciting force is ≥100 kN and the vibration frequency is 30-40 Hz. In some embodiments, the lower layer is closed by using a rubber-tired road roller. In some embodiments, the upper layer is compacted by using a high-frequency double-steel roller to initially press and then transversely knead.

[0039] The asphalt binder layer between the layers is sprayed with rubber asphalt and combined with gravel for paving.

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with specific embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0041] Embodiment 1

[0042] Reference Figure 1The embodiment provides a flat crossing road layered composite asphalt material, which comprises, from top to bottom, an upper layer 1, a middle layer 2 and a lower layer 3, and an asphalt bonding layer 4 arranged between the adjacent two layers.

[0043] The upper layer 1 is a shear-resistant type asphalt concrete layer, which is prepared by using SMA asphalt mixture and comprises 5.5 parts of SBS modified asphalt, 96 parts of basalt aggregate and 0.2 part of basalt fiber, wherein the SBS modified asphalt is PG grade 82, and the stress self-adaptive modifier is added in an amount of 8 wt%.

[0044] The middle layer 2 is a rut-resistant type asphalt concrete layer, which is prepared by using SMA asphalt mixture and comprises 5.5 parts of No. 50 hard asphalt, 96 parts of basalt aggregate and 0.2 part of basalt fiber, wherein the hard asphalt has a penetration of 50 (25 DEG C, 0.1 mm), and the stress self-adaptive modifier is added in an amount of 6 wt%.

[0045] The lower layer 3 is a fatigue-resistant type asphalt concrete layer, which is prepared by using SMA asphalt mixture and comprises 5.5 parts of No. 70 A-grade asphalt, 96 parts of limestone aggregate and 0.2 part of lignin fiber, wherein the stress self-adaptive modifier is added in an amount of 4 wt%.

[0046] The asphalt bonding layer 4 comprises rubber asphalt and gravel. The rubber asphalt has a viscosity of 3 Pa s at 180 DEG C, a penetration of 45 (25 DEG C, 0.1 mm) and a softening point of 75 DEG C.

[0047] The stress self-adaptive modifier is prepared by compounding 5 parts of SBR / epoxy resin core-shell polymer microparticles, 3 parts of carbon nanotube aerogel with a porosity of 95% and 2 parts of activated rubber powder with a particle size of 0.2-0.4 mm.

[0048] The specific construction method is as follows:

[0049] 1. Material preparation

[0050] (1) The stress self-adaptive modifier is prepared by mixing the raw materials according to the above formula and uniformly mixing to obtain the stress self-adaptive modifier for standby.

[0051] (2) The SBS modified asphalt, basalt aggregate and basalt fiber are prepared according to the conventional design standard of the shear-resistant type asphalt concrete, and 8 wt% of the stress self-adaptive modifier is added and uniformly mixed for standby.

[0052] (3) The No. 50 hard asphalt, basalt aggregate and basalt fiber are prepared according to the conventional design standard of the rut-resistant type asphalt concrete layer, and 6 wt% of the stress self-adaptive modifier is added and uniformly mixed for standby.

[0053] (4) According to the conventional design standard of anti-displacement asphalt concrete layer, prepare No. 70 A-grade asphalt, limestone aggregate, lignin fiber, and add 4wt% stress self-adapting modifier, and mix uniformly for use.

[0054] (5) Prepare rubber asphalt with activated powder and crushed stone for use.

[0055] 2. Layered paving and compaction

[0056] Three-machine group paving is adopted, in turn:

[0057] Paving the lower layer: paving temperature 155°C; compaction after 10 minutes interval, using ground pressure 400kPa rubber-tired roller to close pores and compact;

[0058] Spraying rubber asphalt, and at the same time, construction of asphalt binder layer by spreading crushed stone; rubber asphalt spreading amount is 2.5kg / m 2 ; full paving rate of crushed stone is 70%;

[0059] Paving the middle layer: paving temperature 160°C; compaction after 10 minutes interval, using oscillation compactor with exciting force 120kN and vibration frequency 35Hz to vertically vibrate and prevent displacement compaction;

[0060] Spraying rubber asphalt, and at the same time, construction of asphalt binder layer by spreading crushed stone; rubber asphalt spreading amount is 2.5kg / m 2 ; full paving rate of crushed stone is 70%;

[0061] Paving the upper layer: paving temperature 165°C, compaction after 10 minutes interval, first using high-frequency double-steel-wheel initial compaction with amplitude 1mm and frequency 55Hz, and then transversely kneading and compacting.

[0062] Example 2

[0063] The difference between this example and Example 1 is that AC asphalt mixture is used for the upper, middle and lower layers, specifically,

[0064] The upper layer 1 is a shear-resistant asphalt concrete layer, including SBS modified asphalt 4.5 parts; basalt aggregate 93 parts; basalt fiber 0.15 parts, SBS modified asphalt PG grade 82, and stress self-adapting modifier addition amount is 8wt%.

[0065] The middle layer 2 is a rut-resistant asphalt concrete layer, including No. 50 hard asphalt 4.5 parts; basalt aggregate 93 parts, basalt fiber 0.15 parts; hard asphalt penetration 50 (25°C, 0.1mm), and stress self-adapting modifier addition amount is 6wt%.

[0066] The lower layer 3 is a fatigue-resistant asphalt concrete layer, which comprises 70# grade A asphalt 4.5 parts; limestone aggregate 93 parts; lignin fiber 0.15 parts; and stress self-adapting modifier in an amount of 4 wt%.

[0067] The components of the remaining layers and the specific construction method can refer to Example 1.

[0068] Comparative Example 1

[0069] The difference from Example 1 is that the upper layer, the middle layer, and the lower layer all do not contain stress self-adapting modifier.

[0070] During construction, the layers are laid and compacted at 175°C, and the thickness of each layer after compaction is the same as that in Example 1. Specifically:

[0071] 2. Laying and compacting layers

[0072] Three machines are used for joint paving, in the order of:

[0073] Paving the lower layer: laying temperature 175°C; compaction after laying for 10 minutes, using a ground pressure of 400 kPa rubber-tired road roller to close the pores and compact;

[0074] Spraying rubber asphalt, and simultaneously paving the asphalt binder layer by paving gravel; the rubber asphalt paving amount is 2.5 kg / m 2 ; the full paving rate of gravel is 70%;

[0075] Paving the middle layer: laying temperature 175°C; compaction after laying for 10 minutes, using a high-frequency double steel wheel with an amplitude of 1 mm and a frequency of 55 Hz for vibration compaction;

[0076] Spraying rubber asphalt, and simultaneously paving the asphalt binder layer by paving gravel; the rubber asphalt paving amount is 2.5 kg / m 2 ; the full paving rate of gravel is 70%;

[0077] Paving the upper layer: laying temperature 175°C, compaction after laying for 10 minutes, first using a high-frequency double steel wheel with an amplitude of 1 mm and a frequency of 55 Hz for initial compaction, and then transversely kneading and compacting.

[0078] Comparative Example 2

[0079] The difference from Example 2 is that the upper layer, the middle layer, and the lower layer all do not contain stress self-adapting modifier.

[0080] During construction, the layers are laid and compacted at 175°C, and the thickness of each layer after compaction is the same as that in Example 2. Specifically:

[0081] 2. Laying and compacting layers

[0082] Three machines are used for joint paving, in the order of:

[0083] Laying the lower layer: paving temperature 175℃; compaction after 10 minutes interval, using grounding pressure 400kPa rubber-tired roller to close the pores and compact;

[0084] Spraying rubber asphalt, and getting asphalt bound layer by simultaneously paving gravel; rubber asphalt paving amount is 2.5kg / m 2 ; the full paving rate of gravel is 70%;

[0085] Laying the middle layer: paving temperature 175℃; compaction after 10 minutes interval, using high frequency double steel wheel with amplitude 1mm and frequency 55Hz to vibrate and compact;

[0086] Spraying rubber asphalt, and getting asphalt bound layer by simultaneously paving gravel; rubber asphalt paving amount is 2.5kg / m 2 ; the full paving rate of gravel is 70%;

[0087] Laying the upper layer: paving temperature 175℃, compaction after 10 minutes interval, first using high frequency double steel wheel with amplitude 1mm and frequency 55Hz to primary compact, and then transversely kneading and compacting.

[0088] Comparative Example 3

[0089] The difference from Example 1 is that the stress self-adapting modifier is not contained in the upper, middle and lower layers, and the construction method is the same.

[0090] Comparative Example 4

[0091] The difference from Example 1 is that the paving temperature of the upper, middle and lower layers is 160℃ during construction, and others are the same.

[0092] Test results

[0093] The asphalt materials obtained from the above examples and comparative examples are tested for performance according to JTGE20-2011 “Highway Engineering Asphalt and Asphalt Mixture Test Procedures”, and the test results are shown in Table 1.

[0094] Table 1 Performance test results of each example and comparative example

[0095]

[0096] It can be seen from the comparison that the flat intersection road anti-rutting and anti-displacement layered composite asphalt material of the example can significantly improve the rutting dynamic stability, improve the interlayer front force, improve the bending strain performance, and has good waterproof property by optimizing the function design of each layer and adding the stress self-adapting modifier, and the material performance can be further improved by combining with the gradient temperature paving process.

[0097] The embodiment of the application sets material layer structures for different conflict zones of the intersection, designs an upper-middle-lower three-layer composite structure, the upper layer resists braking shear and sliding, the middle and lower layers resist rutting, fatigue and water resistance, the interlayer bonding resists horizontal displacement and cracking, and stress self-adapting modifiers are added to each layer to intelligently adjust the rheological properties with load frequency, realize damage self-sensing and self-repairing, form a "stiff-soft-tough" gradient structure, and through component optimization of each layer and construction process, the material mechanical properties can be accurately matched with the stress field of the conflict zone. Specifically, the shear strength of the upper layer is ≥0.9MPa; the dynamic stability of the middle layer at 60°C is ≥8000 times / mm; the bending strain energy of the middle and lower layers is ≥0.8J / cm 3 The interface bonding strength between adjacent layers is ≥1.2MPa, thereby prolonging the service life of the intersection, the service life of the intersection can be prolonged from 3 years to more than 8 years, and because up to 30% RAP and waste tire rubber powder (activated rubber powder) can be used, the cost can be reduced by up to 22%, providing a full life cycle solution for urban intersections.

[0098] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, however, as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present disclosure. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these are within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. A layered composite asphalt material for at-grade roads, characterized in that, The structure, from top to bottom, comprises: a top layer, a middle layer, and a bottom layer, and an asphalt bonding layer between adjacent layers; the top layer is a shear-resistant asphalt concrete layer; the middle layer is a rutting-resistant asphalt concrete layer; and the bottom layer is a fatigue-resistant asphalt concrete layer. Each of the top, middle, and bottom layers contains a stress-adaptive modifier, which includes: core-shell polymer microparticles, carbon nanotube aerogel, and activated adhesive powder.

2. The layered composite asphalt material for at-grade roads according to claim 1, characterized in that, The upper layer has a shear strength ≥ 0.9 MPa; the middle layer has a rutting dynamic stability at 60℃ ≥ 8000 cycles / mm; and the lower layer has a bending strain energy ≥ 0.8 J / cm. 3 The bonding strength at 25℃ between adjacent layers is ≥1.2MPa.

3. The layered composite asphalt material for at-grade roads according to claim 1 or 2, characterized in that, The upper layer also includes composite modified bitumen, basalt aggregate and basalt fiber material, wherein the stress adaptive modifier is added at an amount of 7-9 wt%.

4. The layered composite asphalt material for at-grade roads according to claim 1 or 2, characterized in that, The intermediate layer also includes hard asphalt, basalt aggregate and basalt fiber, wherein the stress adaptive modifier is added at an amount of 5-7 wt%.

5. The layered composite asphalt material for at-grade roads according to claim 1, characterized in that, The lower layer also includes heavy traffic road asphalt, limestone aggregate, and lignin fiber, wherein the stress adaptive modifier is added at an amount of 3-5 wt%.

6. The layered composite asphalt material for at-grade roads according to claim 1 or 2, characterized in that, The asphalt bonding layer comprises rubber asphalt and crushed stone.

7. The layered composite asphalt material for grade-separated roads as described in any one of claims 1-6, characterized in that, The stress-adaptive modifier is composed of 4-6 parts by weight of core-shell polymer microparticles, 2-4 parts by weight of carbon nanotube aerogel, and 1-3 parts by weight of activated adhesive powder.

8. The layered composite asphalt material for at-grade roads according to claim 7, characterized in that, The core-shell polymer microparticles have SBR as the core and epoxy resin as the shell, the carbon nanotube aerogel has a porosity of ≥90%, and the activated adhesive powder has a particle size of 0.2-0.4 mm.

9. The gradient construction method for layered composite asphalt materials for at-grade intersections as described in any one of claims 1-8, characterized in that, The paving temperature of the lower layer is 150-160℃, the paving temperature of the middle layer is 155-165℃, and the paving temperature of the upper layer is 160-170℃.

10. The gradient construction method according to claim 9, characterized in that, The intermediate layer is compacted using a vibratory roller with an excitation force ≥100kN and a vibration frequency of 30-40Hz.

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