Heavy traffic integrity anti-rutting pavement structure and its paving method

Abstract

The application belongs to the technical field of road pavement, and particularly relates to a heavy-load traffic integrity anti-rutting pavement structure and a pavement method thereof. The pavement structure is arranged on a top surface of a roadbed. The pavement structure is sequentially composed of a semi-rigid lower base layer, a synchronous gravel seal coat, a rich-asphalt seal bottom protective layer, a combined semi-flexible anti-rutting layer and a surface wearing layer from bottom to top. The integrity anti-rutting pavement structure not only improves the bearing capacity of the pavement, but also strengthens the ability of the pavement to resist reflection cracks. The anti-rutting performance of the pavement structure is better, the integrity is better, the bearing capacity is stronger, and the pavement diseases such as rutting and cracks in a short period of time are effectively avoided, so that the service life of the pavement is greatly prolonged.

Description

Technical Field

[0001] This invention belongs to the technical field of road paving, specifically relating to a heavy-duty traffic integral anti-rutting pavement structure and its paving method. Background Technology

[0002] The existing highway and urban road pavements in my country are basically divided into two categories: asphalt concrete pavement, which is a flexible pavement, and cement concrete pavement, which is a rigid pavement. Under repeated traffic loads, the thickness of the asphalt layer at wheel tracks thins, and the accumulation of permanent deformation leads to rutting on the road surface, weakening the overall strength of the surface layer and pavement structure, and easily inducing other diseases. In particular, when asphalt concrete pavement is under high temperature conditions, the deformation resistance of the asphalt mixture decreases, and under repeated loads, it is very easy for the asphalt pavement to exhibit shear deformation such as rutting, undulation, and bulging, especially at highway toll gates, docks, freight stations, and steep slopes. At road intersections and long longitudinal slopes, ports and container terminals, near bus stops on municipal roads, and in urban BRT and FRT lanes, the pavement surface material is subjected to not only high compressive stress but also high shear stress due to the frequent braking and acceleration of heavy-duty vehicles at relatively low speeds. This combined stress state and temperature effect is the most fundamental reason why rutting is particularly prominent in the asphalt surface layer in these sections.

[0003] Due to the presence of joints, cement concrete pavements suffer from poor driving comfort, and are prone to defects such as edge chipping, misalignment, and mud pumping at the joints. Moreover, once cement concrete pavements are damaged, repairs are difficult, time-consuming, and disrupt traffic.

[0004] To address the aforementioned issues of rutting, insufficient overall strength of the pavement structure, and poor smoothness, current technologies explore the use of a combination of asphalt and cement pavement in asphalt pavements, resulting in a semi-flexible pavement structure. Semi-flexible pavements combine the advantages of both asphalt and cement concrete pavements, possessing both flexibility and rigidity, thus overcoming the respective shortcomings of each. This makes them suitable for projects with high requirements for rutting resistance, such as heavy-duty highways, underpasses, bridge paving, military bases, airport runways, toll booths, and gas stations.

[0005] CN215518214 discloses a pavement structure resistant to heavy-load rutting, comprising, from top to bottom: a zero-rutting asphalt pavement surface layer, an interlayer waterproof bonding layer, and an infilled semi-flexible composite pavement bottom layer. This pavement structure has the following problems: the semi-flexible composite pavement bottom layer is formed by filling and hardening with special cement grout. Due to its high rigidity, it is prone to cracking under traffic loads. Furthermore, there is no buffer layer between the infilled semi-flexible composite pavement bottom layer and the zero-rutting asphalt pavement surface layer, meaning cracks in the bottom layer are directly reflected to the surface layer, severely affecting the road's service life and hindering its large-scale promotion and use.

[0006] Huang Lei et al.'s publicly available mix design and implementation of C-ETM semi-flexible base asphalt pavement presents a pavement structure for semi-flexible base asphalt pavement. This structure, from bottom to top, consists of an emulsified asphalt tack coat, a semi-rigid base coat, an emulsified asphalt prime coat, a C-ETM semi-flexible base coat, another emulsified asphalt prime coat, and an AC-13 asphalt surface layer. This pavement structure has the following problems: Directly placing a 20cm semi-rigid base coat on the existing asphalt pavement results in poor pavement integrity, dispersed stress, and a high susceptibility to defects; the placement of the C-ETM semi-flexible base coat on top of the semi-rigid base coat causes a concentration of stiffness in the pavement structure, neglecting the impact of different layer combinations on the propagation of reflective cracks in the base coat, making the pavement highly prone to cracking.

[0007] In addition, the existing grouting semi-flexible pavement has many limiting factors. On the one hand, the grouting material used is cement mortar, which has performance defects such as slow strength development, long curing time, large shrinkage and easy cracking. It cannot meet the requirements of rapid traffic opening and high durability after the reconstruction of municipal roads.

[0008] On the other hand, existing grouting-type semi-flexible pavement construction technologies have many drawbacks. The existing construction methods for grouting-type semi-flexible pavements are mainly divided into two types: The first type involves first laying a layer of large-void asphalt mixture with a certain thickness and a porosity of 15% to 25%. After appropriate cooling, cement mortar is typically prepared during operation using small-scale grouting equipment and then injected. Simultaneously, a plate vibrator is used for compaction. A retarder is sprayed first, and before the internal cement grout sets, the surface cement grout is washed away, forming a "suspension stone" surface. A vibratory plate roller is then used to allow the cement grout to penetrate into the voids of the base asphalt mixture.

[0009] The second method involves first spraying emulsified asphalt, and then laying a large-void matrix asphalt mixture after the emulsified asphalt has broken down. The mixture is then prepared using cement grout mixing equipment. After the matrix mixture cools down, grouting is started. No vibration equipment is needed during the grouting process. The mixture is self-leveling and permeable. After grouting, the road surface is scraped to remove the grout. Once the cement has quickly solidified, a composite anti-rutting road structure is formed.

[0010] However, the two existing construction methods mentioned above have the following drawbacks: The first method increases the number of construction steps, making the process more complex and increasing construction costs; it is also unsuitable for multi-lane road construction, affecting the construction efficiency and quality of semi-flexible pavements, and generating a large amount of wastewater containing cement slurry during construction, causing "pollution" to surrounding lanes. The second method uses emulsified asphalt as a bonding layer, resulting in poor adhesion to the underlying layer, which is not conducive to improving the overall performance of the pavement. Cement mortar, through self-leveling and penetration, has high requirements for its fluidity and self-penetration properties, making production difficult, costly, and unstable. Summary of the Invention

[0011] The purpose of this invention is to provide a heavy-duty traffic integral anti-rutting pavement structure to address the aforementioned deficiencies. This anti-rutting pavement structure combines flexibility and rigidity, avoiding rutting problems caused by insufficient bearing capacity of the pavement structure and poor deformation resistance of the pavement material.

[0012] The specific technical solution is as follows:

[0013] A heavy-duty traffic integral anti-rutting pavement structure is laid on the top surface of the roadbed. The pavement structure consists of a semi-rigid subbase, a synchronous chip seal, an asphalt-rich bottom seal, a combined semi-flexible anti-rutting layer, and a surface wear layer from bottom to top.

[0014] The composite semi-flexible anti-rutting layer is constructed by paving the matrix with open-graded large-particle-size asphalt mixture and sand-free large-pore cement concrete. Modified emulsified asphalt grout is injected into the matrix to form the composite semi-flexible anti-rutting layer. The modified emulsified asphalt grout is composed of mineral powder, lignin fiber and high-viscosity modified emulsified asphalt with a Seybert viscosity of 20-100s at 25°C.

[0015] In this invention, the semi-rigid subbase of the heavy-duty traffic integral anti-rutting pavement structure is constructed by a single layer of cement-stabilized crushed stone mixture; the thickness of the semi-rigid subbase is 22-28cm, and the compaction degree of the semi-rigid subbase is 97%-100%.

[0016] Using cement-stabilized crushed stone mixture as a semi-rigid subbase can give the pavement structure a higher ability to resist plastic deformation. Compared with the thickness of ordinary semi-rigid base, it is 4-10cm thicker, which makes the strength and stiffness of the semi-rigid subbase greater, the pavement slab structure better, and the bearing capacity and rutting resistance stronger.

[0017] In this invention, the synchronous chip seal in the heavy-duty traffic integral anti-rutting pavement structure is composed of SBS modified asphalt and limestone chips with a single particle size of 5-10mm. The function of the synchronous chip seal is to enhance the bonding strength between the asphalt-rich underlayer and the semi-rigid subbase, resulting in a stronger overall pavement structure.

[0018] Preferably, the SBS application rate in the synchronized chip seal layer is 1.8 g / m³. 2 The amount of gravel spread is 7m³ 3 / 1000m 2 It accounts for 65% of the total paved area.

[0019] In this invention, the asphalt-rich bottom sealing protective layer in the heavy-duty traffic integral anti-rutting pavement structure is laid in a single layer using continuously graded asphalt mixture; the compacted thickness of the asphalt-rich bottom sealing protective layer is 4-6 cm; wherein the void ratio of the asphalt mixture is 2%-3%, the void ratio of the aggregate is 12%-14%, and the saturation is 80-100%.

[0020] The functions of the rich asphalt sealing and protective layer are threefold: first, it serves as a stiffness coordination layer between the asphalt layer and the inorganic binder layer, enhancing the fatigue resistance of the asphalt mixture layer; second, it acts as a stress absorption layer for the inorganic binder layer, preventing local stress concentration in the inorganic binder layer from causing damage to the asphalt layer and preventing cracks in the base layer from reflecting upwards, thus preventing road surface defects such as cracks and potholes; and third, it provides sealing and protection, ensuring that grouting materials do not penetrate into the bottom layer.

[0021] In this invention, the thickness of the combined semi-flexible anti-rutting layer in the heavy-duty traffic integral anti-rutting pavement structure is 28-32cm;

[0022] Preferably, the open-graded large-particle-size asphalt mixture has a porosity of 15%-20%, an asphalt film thickness greater than 12μm, a compaction thickness of 8-12cm, and a compaction degree of 96%-100%.

[0023] Preferably, the compacted thickness of the no-fines concrete is 18-22 cm; the porosity is 20%-30%.

[0024] Compared with conventional semi-flexible asphalt mixtures, the composite semi-flexible pavement matrix of the present invention is composed of open-graded large-particle-size asphalt mixture and no-fines concrete, which combines rigidity and flexibility. It avoids the cracking phenomenon caused by excessively low rigidity of existing asphalt pavements due to excessive load-bearing capacity, and also avoids the cracking phenomenon caused by excessively high rigidity of existing cement concrete pavements due to easy shrinkage.

[0025] In this invention, the surface wear layer thickness in the heavy-duty traffic integral anti-rutting pavement structure is 4-6cm; SMA-13 ​​asphalt mixture is used.

[0026] Another objective of this invention is to provide a method for paving the aforementioned heavy-duty traffic integral rutting-resistant pavement. This paving method solves the problems of easy cracking and complex construction of conventional semi-flexible pavements.

[0027] The specific technical solution is as follows:

[0028] A method for paving the aforementioned heavy-duty traffic integral rutting-resistant pavement structure involves laying a semi-rigid subbase, a synchronous chip seal, an asphalt-rich undercoat, a combined semi-flexible rutting-resistant layer, and a surface wear-resistant layer sequentially from bottom to top on the top surface of the roadbed. The specific steps for laying the combined semi-flexible rutting-resistant layer are as follows:

[0029] (3) The base layer of open-graded large-particle-size asphalt mixture for laying the composite semi-flexible anti-rutting layer:

[0030] ① Before laying the open-graded, large-particle-size asphalt mixture layer, apply SBS modified emulsified asphalt tack coat at a rate of 0.4-0.6 kg / m³. 2 .

[0031] ② Using the volumetric method for gradation design, the gradation range of open-graded large-particle-size asphalt mixtures is:

[0032] The passing rate is 100% for a standard sieve aperture of 31.5mm; 95%-70% for a standard sieve aperture of 26.5mm; 76%-40% for a standard sieve aperture of 19mm; 58%-28% for a standard sieve aperture of 13.2mm; 39%-19% for a standard sieve aperture of 9.5mm; 29%-6% for a standard sieve aperture of 4.75mm; 15%-3% for a standard sieve aperture of 1.18mm; 7%-1% for a standard sieve aperture of 0.3mm; and 4%-1% for a standard sieve aperture of 0.075mm.

[0033] The above-mentioned open-graded large-particle-size asphalt mixture ensures that the mixture can form a skeleton and has a sufficiently large porosity; at the same time, it reduces segregation of the asphalt mixture during mixing and paving.

[0034] The asphalt content of the open-graded large-particle-size asphalt mixture is 2.8-3.1 wt%.

[0035] ③ Rolling open-graded large-particle-size asphalt mixture: The initial compaction temperature is controlled at 165℃-175℃; after static compaction 1-2 times with a 12t double-drum roller, vibratory compaction begins, with a compaction speed of 1.5-2km / h, and vibratory compaction is performed 2-3 times to achieve a compaction degree of over 95%.

[0036] (4) The upper substrate of the composite semi-flexible anti-rutting layer is a sand-free, large-pore cement concrete layer:

[0037] ① When the temperature of the asphalt mixture in the ungraded large-particle-size layer drops below 50℃, the construction of the sand-free large-pore cement concrete layer shall be carried out; 2-6 hours before construction, high-viscosity emulsified asphalt shall be sprayed. The Seybert viscosity of this high-viscosity emulsified asphalt at 25℃ is 20-100s, and the spraying rate is 0.4-0.6kg / m³. 2 .

[0038] ② The volumetric method was used for gradation design. The gradation range of the sand-free large-pore cement concrete was as follows: 100% passing through a 37.5mm sieve, 100%-90% passing through a 26.5mm sieve, 60%-25% passing through a 13.5mm sieve, 10%-0% passing through a 4.75mm sieve, 5%-0% passing through a 2.36mm sieve, and 2%-0% passing through a standard sieve with a 0.075mm diameter.

[0039] ③ After the sand-free, large-pore cement concrete is mixed according to the mix proportion, it is spread on site by a slipform synchronous paver and compacted by roller or vibration. After the construction is completed, it is covered with a curing film for 3-7 days.

[0040] (3) Grouting construction of modified emulsified asphalt mortar:

[0041] The high-viscosity emulsified asphalt is sprayed onto the substrate and penetrated through self-leveling. The spraying rate is 1.0-1.2 kg / m³. 2 This allows air to escape from the pores inside the matrix.

[0042] Preparation of modified emulsified asphalt mortar: High-viscosity modified emulsified asphalt, mineral powder, and lignin fiber are compounded and mixed in a weight ratio of (100-120):(80-100):(0.1-0.2);

[0043] Determine the grouting volume: The weight ratio of the total weight of open-graded large-particle-size asphalt mixture and sand-free large-pore cement concrete to the grouting volume is (90-100):(12-18);

[0044] One to two hours after spraying high-viscosity emulsified asphalt, the modified emulsified asphalt grout is injected into the substrate through a pressure grouting device. The pressure grouting device can be any one of the following: F-512 high-pressure grouting machine, HJB-2 extrusion hose grouting machine, or HJB-3 piston rod grouting machine.

[0045] After grouting is completed, a leveling machine is used to level the surface. No water curing is required. The next layer can be constructed after 2-2.5 hours.

[0046] In this invention, the specific paving operation of the semi-rigid subbase in the paving method of the heavy-duty traffic integral anti-rutting pavement structure is as follows: the material of the semi-rigid subbase is cement-stabilized crushed stone mixture; it is paved in a single layer at one time, the 7-day strength of the cement-stabilized crushed stone mixture is not less than 4.5 MPa, and the cement dosage is ≤5%.

[0047] In this invention, the specific paving operation of the synchronous chip seal layer in the paving method of the heavy-duty traffic integral anti-rutting pavement structure is as follows: After the semi-rigid subbase is constructed, a slow-cracking anionic emulsified asphalt tack coat is sprayed at a rate of 1.2 kg / m²-1.5 kg / m². 2 The emulsified asphalt penetration depth is 5-8mm; the asphalt synchronous chip seal layer is spread one day before the construction of the rich asphalt base protective layer.

[0048] In this invention, the specific operation of the rich asphalt sealing and protective layer in the heavy-duty traffic integral anti-rutting pavement paving method is as follows: The rich asphalt sealing and protective layer is paved with continuously graded asphalt mixture A, with a paving thickness of 4-6 cm; the gradation range of asphalt mixture A is as follows: 100% passing rate for a standard sieve with a 16mm aperture, 100%-90% passing rate for a standard sieve with a 13.2mm aperture, 50%-24% passing rate for a standard sieve with a 9.5mm aperture, 38%-15% passing rate for a standard sieve with a 1.18mm aperture, 28%-10% passing rate for a standard sieve with a 0.6mm aperture, 20%-7% passing rate for a standard sieve with a 0.3mm aperture, 15%-5% passing rate for a standard sieve with a 0.15mm aperture, and 8%-4% passing rate for a standard sieve with a 0.075mm aperture.

[0049] Asphalt mixture A uses SBS modified asphalt, with an asphalt content of 5.0%-5.3%.

[0050] The porosity of asphalt mixture A is 2-3%, the aggregate porosity is 12-14%, the saturation is 80-100%, and the Marshall stability is not less than 8 kN.

[0051] In this invention, the specific operation of the surface wearing layer in the heavy-duty traffic integral anti-rutting pavement paving method is as follows: the surface wearing layer uses asphalt mixture with a maximum nominal particle size of 13.2mm, such as AC-13 asphalt mixture or SMA-13 ​​asphalt mixture, and its gradation range, asphalt content, volume index and construction method are all implemented in accordance with the current specifications.

[0052] The beneficial effects of the present invention are as follows: The heavy-duty traffic integral anti-rutting pavement structure of the present invention, through the setting of pavement structure layers such as the combined semi-flexible anti-rutting layer and the rich asphalt sealing protective layer, not only improves the bearing capacity of the pavement, but also strengthens the pavement's ability to resist reflective cracking. The pavement structure has better anti-rutting performance, better integrity, and stronger bearing capacity, effectively avoiding the occurrence of rutting, cracks and other diseases in the pavement in a short period of time, and greatly extending the service life of the pavement.

[0053] The specific advantages are as follows:

[0054] (1) The heavy-duty traffic integral anti-rutting pavement structure combines flexibility and rigidity, reducing the problem of rutting due to insufficient bearing capacity of the pavement structure and poor deformation resistance of the pavement material. The composite semi-flexible anti-rutting layer in the structure is composed of open-graded large-particle-size asphalt mixture and sand-free large-pore cement concrete. The load-bearing capacity of sand-free large-pore cement concrete is much greater than that of asphalt mixture, but it is prone to stress concentration and cracking. Therefore, the lower matrix uses open-graded large-particle-size asphalt mixture to release stress and reduce the risk of cracking. At the same time, modified emulsified asphalt grout is used for injection, and the upper and lower matrices are injected at the same time to form an integral whole, further preventing stress concentration and cracking, and compensating for the lack of flexibility of rigid pavement.

[0055] Conventional semi-flexible pavement requires a stability of >15kN, while the stability requirement of this invention is >25kN. Conventional semi-flexible pavement requires a deflection of less than 15-25 (0.1mm), while the deflection requirement of this invention is less than 10 (0.1mm).

[0056] (2) By verifying the anti-rutting performance of conventional semi-flexible pavement structure and pavement structure of the present invention under the same design years and traffic load parameters, the rutting depth of asphalt layer was reduced by more than 40% within 15 years.

[0057] The stability of conventional semi-flexible pavement layers is generally greater than 15kN, while the stability of the semi-flexible anti-rutting layers of this invention is greater than 25kN.

[0058] (3) It solves the problem of easy cracking of conventional semi-flexible pavement. Compared with conventional semi-flexible pavement, the composite semi-flexible pavement matrix of the present invention is composed of open-graded large-particle-size asphalt mixture and sand-free concrete, which combines rigidity and flexibility. It avoids the phenomenon of cracking caused by low stiffness and excessive load of asphalt pavement, and also avoids the phenomenon of cracking caused by excessive stiffness and easy shrinkage of cement concrete pavement.

[0059] Setting a rich asphalt sealing layer on top of a semi-rigid subbase reduces the rate of performance degradation of the semi-rigid subbase and slows the propagation of reflective cracks to the road surface, thereby improving the pavement structure's resistance to reflective cracks and greatly extending the service life of the pavement.

[0060] The paving method described in this invention uses high-viscosity emulsified asphalt grout as the grouting material. Compared with cement-based grouting materials, which require more than 3 days of water curing before they can be used, the curing period of this invention is shorter. After paving is completed and cooled to 50°C, traffic can be opened.

[0061] Compared to the complex procedures involved in cement grouting (edge ​​sealing, preparation of cement grout, grout transportation, simultaneous grouting and compaction with a plate vibrator, surface treatment, and road surface water curing), this invention uses high-viscosity emulsified asphalt grout for grouting. After edge sealing, asphalt spreader or pressure grouting device is used to grout the substrate, followed by leveling. The next layer can be applied after 2 hours, making the construction process simple. Attached Figure Description

[0062] Figure 1 This is a schematic diagram of a road surface paving structure resistant to heavy-load rutting in an embodiment of the present invention.

[0063] Figure 2 This is a schematic diagram of the pavement structure of SBS modified emulsified asphalt-based mortar mixture in Comparative Example 1.

[0064] Figure 3 This is a schematic diagram of the cement-emulsified asphalt mortar mixture pavement structure for Comparative Example 2.

[0065] Figure 4 This is a construction flowchart of the integral anti-rutting pavement structure of the present invention.

[0066] Among them, 1 is the roadbed, 2 is the semi-rigid subbase, 3 is the synchronous chip seal, 4 is the rich asphalt bottom protective layer, 5 is the combined semi-flexible anti-rutting layer, 6 is the surface abrasion layer, 7 is the cement-stabilized crushed stone subbase I, 8 is the cement-stabilized crushed stone subbase II, 9 is the cement-stabilized crushed stone base, 10 is the SBS modified emulsified asphalt-based mortar mixture, 11 is the densely mixed asphalt concrete, 12 is the cement-stabilized crushed stone subbase a, 13 is the cement-stabilized crushed stone subbase b, 14 is the cement-stabilized crushed stone base c, and 15 is the cement-emulsified asphalt mortar mixture. Detailed Implementation

[0067] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0068] Example 1

[0069] The integral rutting-resistant pavement structure and paving method of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0070] like Figure 1As shown, the integral anti-rutting pavement structure in this embodiment is directly laid on the roadbed 1 from bottom to top, consisting of a 25cm semi-rigid subbase 2, a synchronous chip seal 3, a 5cm asphalt-rich bottom protective layer 4, a 30cm combined semi-flexible anti-rutting layer 5, and a 4cm surface abrasion layer 6. The total thickness of the integral anti-rutting pavement structure is 64cm.

[0071] I. Semi-rigid subgrade

[0072] 1. Raw materials

[0073] In this embodiment, the semi-rigid subbase 2 is a cement-stabilized crushed stone mixture laid on the roadbed 1. The technical specifications of the aggregate used in the cement-stabilized crushed stone mixture must meet the requirements in Table 1.

[0074] Table 1. Technical Requirements for Aggregates

[0075]

[0076] The cement used should be grade 42.5, and its technical specifications should meet the requirements in Table 2.

[0077] Table 2 Cement Technical Requirements

[0078]

[0079]

[0080] 2. Control parameters for cement-stabilized crushed stone mixture

[0081] The cement dosage of cement-stabilized crushed stone mixture is 4.5%.

[0082] The synthetic gradation is as follows: 100% passing rate for a standard sieve aperture of 31.5mm; 100%-90% passing rate for a standard sieve aperture of 26.5mm; 86%-76% passing rate for a standard sieve aperture of 19mm; 55%-43% passing rate for a standard sieve aperture of 9.5mm; 36%-26% passing rate for a standard sieve aperture of 4.75mm; 26%-16% passing rate for a standard sieve aperture of 2.36mm; 16%-8% passing rate for a standard sieve aperture of 0.6mm; and 5%-2% passing rate for a standard sieve aperture of 0.075mm.

[0083] The representative 7-day strength of cement-stabilized crushed stone mixture shall not be less than 4.5 MPa.

[0084] 3. Construction Requirements

[0085] The compaction thickness of the semi-rigid subbase 2 is controlled at 25cm, and it is laid in one layer at a time.

[0086] Before paving, the surface of the underlying layer should be appropriately moistened with water. Two pavers should be used in a team, one in front and one behind, to ensure consistent speed, paving thickness, loose paving coefficient, road camber slope, paving smoothness, and vibration frequency. The joint between the two pavers should be smooth. A combination of single-drum roller, double-drum roller, and rubber-tired roller should be used for compaction. Compaction should be carried out when the moisture content of the mixture is at or slightly above the optimum moisture content, and the compaction degree should be controlled at 97%-100%. After compaction, the compaction degree, thickness, smoothness, width, and elevation should be tested. After the test is passed and the surface is slightly dry, the prime coat emulsified asphalt should be spread. Any areas that are not spread properly should be manually patched.

[0087] II. Transdermal Layer

[0088] Within 6 hours of the completion of the semi-rigid base course 2 construction in this embodiment, a high-penetration, slow-cracking anionic emulsified asphalt tack coat is applied using the following method.

[0089] 1. Raw materials

[0090] The tack coat uses PC-2 emulsified bitumen, and its main technical indicators should meet the requirements of Table 3.

[0091] Table 3 Technical Requirements for the Quality of PC-2 Tack Coat Emulsified Asphalt

[0092]

[0093]

[0094] 2. Requirements for permeable layer

[0095] The dosage was determined to be 1.3 L / m³ through trial spraying. 2 The emulsified asphalt penetrates to a depth of approximately 5 mm.

[0096] 3. Construction Method

[0097] Before applying the tack coat, the road surface should be thoroughly cleaned. The tack coat should ideally be applied immediately after the underlying layer has been completed and the surface is slightly dry or has finished curing. The tack coat asphalt must be sprayed evenly in one pass using an asphalt distributor. The penetration depth and viscosity of the tack coat asphalt should be confirmed through test spraying, and during construction, boreholes should be dug at a frequency of 5 locations per 10,000 square meters for testing. The tack coat oil must penetrate to a depth of at least 5 mm into the base layer and bond seamlessly with the underlying layer.

[0098] 4. Health preservation

[0099] After the tack coat is applied, vehicles and pedestrians are strictly prohibited from passing through. The construction unit should ensure that the base layer after the tack coat is applied remains in good condition to facilitate subsequent work. Traffic should be closed in principle; construction vehicles that must travel on the road may only do so after 12 hours, maintaining a speed of 3-5 km / h and refraining from braking or turning around. Any sticky or discolored patches should be promptly repaired. The modified asphalt synchronous chip seal layer can be applied 48 hours after the tack coat is applied.

[0100] III. Synchronous Crushed Stone Seal

[0101] In this embodiment, after the semi-rigid base layer 2 is constructed and before the asphalt-rich bottom protective layer 4 is constructed, a hot asphalt seal layer is sprayed.

[0102] 1. Raw materials

[0103] The technical specifications of SBS modified asphalt must meet the requirements of the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40-2004). The aggregate should be limestone crushed stone, clean, dry, unweathered, free of impurities, and have good particle shape with a nominal particle size of 4.75mm-9.5mm. The technical requirements should meet the requirements for coarse aggregate in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40-2004).

[0104] 2. Sealing layer design requirements

[0105] The SBS topcoat application rate is 1.8 g / m². 2 The amount of gravel spread is 7m³ 3 / 1000m 2 It covers approximately 65% ​​of the total paved area.

[0106] 3. Construction Requirements

[0107] SBS modified asphalt must be sprayed using a synchronized chip seal vehicle. The asphalt should be applied evenly in one application according to the designed dosage. Immediately after applying the hot asphalt, stone chips should be spread; the temperature of the hot asphalt must not be lower than 80℃. Once the seal layer is laid, only asphalt pavers and material transport vehicles are permitted to pass.

[0108] IV. Rich Asphalt Sealing and Protective Layer

[0109] In this embodiment, the asphalt-rich bottom sealing protective layer 3 uses continuously graded FAC-13 asphalt mixture, and the specific technical requirements are as follows:

[0110] 1. Raw materials

[0111] Coarse aggregate should be clean, dry, unweathered, and free of impurities, and have sufficient strength and wear resistance. Fine aggregate should be clean and dry, with a focus on controlling the 0.075mm passing rate. Angularity, sand equivalent, or methylene blue index must meet the requirements. All index requirements should meet the requirements for coarse and fine aggregates in the "Technical Specification for Construction of Asphalt Pavement of Highway" (JTG F40-2004).

[0112] SBS modified asphalt is used, with an asphalt content of 5.2%, and the index requirements must meet the requirements in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40-2004).

[0113] 2. Asphalt mixture control parameters

[0114] The synthetic gradation is as follows: 100% passing rate for a standard sieve aperture of 16mm; 100%-90% passing rate for a standard sieve aperture of 13.2mm; 50%-24% passing rate for a standard sieve aperture of 9.5mm; 38%-15% passing rate for a standard sieve aperture of 1.18mm; 28%-10% passing rate for a standard sieve aperture of 0.6mm; 20%-7% passing rate for a standard sieve aperture of 0.3mm; 15%-5% passing rate for a standard sieve aperture of 0.15mm; and 8%-4% passing rate for a standard sieve aperture of 0.075mm.

[0115] Porosity: 2%-3%;

[0116] The aggregate interstitial ratio is 12-14%;

[0117] Saturation level is 80-100%;

[0118] The Marshall stability is not less than 8 kN.

[0119] 3. Construction requirements:

[0120] The compacted thickness of the asphalt-rich bottom protective layer 3 is controlled at 5cm.

[0121] Before construction, the underlying layer should be kept clean, and the asphalt mixture should be mixed evenly. The pure mixing time should not be less than 40 seconds, and the mixing temperature should be 170-180℃. The paver must pave slowly, evenly, and continuously without interruption. The paving speed should be controlled within the range of 1-3 m / min. For compaction, a reasonable combination of rollers and compaction steps should be selected. The initial compaction should use a double-drum roller with a compaction temperature of 140-160℃, the secondary compaction should use a rubber-tired roller with a compaction temperature of 110-140℃, and the final compaction should use a double-drum roller with a compaction temperature of 80-110℃.

[0122] V. Composite Semi-Flexible Anti-Rutting Layer

[0123] In this embodiment, the combined semi-flexible anti-rutting layer 5 is laid on the asphalt-rich sealing and protective layer 4.

[0124] 1. Raw materials

[0125] Coarse aggregates should be clean, dry, unweathered, and free of impurities, and have sufficient strength and wear resistance. Fine aggregates should be clean and dry, and all indicators should meet the requirements for aggregates in the "Technical Specification for Construction of Asphalt Pavement of Highway" (JTG F40-2004).

[0126] LSPM asphalt mixture uses SBS modified asphalt with an asphalt content of 3.1%, and the index requirements must meet the requirements in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40-2004).

[0127] The cement used in the sand-free macroporous cement concrete is grade 42.5 cement, with a cement dosage of 10% and a water-cement ratio of 0.41. Its technical indicators must meet the requirements in Table 2.

[0128] The grouting material uses high-viscosity modified emulsified asphalt, mineral powder, and lignin fiber in a weight ratio of 120:90:0.15. The technical requirements for high-viscosity modified emulsified asphalt should meet the requirements of Table 4, and the mineral powder and lignin fiber should meet the requirements of the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40-2004).

[0129] Table 4 Technical Requirements for High-Viscosity Modified Emulsified Asphalt

[0130]

[0131] The ratio of the grouting material's grouting weight to the total weight of LSPM asphalt mixture and sand-free macroporous cement concrete is 15:95.

[0132] 2. Mixture control parameters

[0133] The preferred gradation range for LSPM asphalt mixtures is:

[0134] The passing rate is 100% for a standard sieve aperture of 31.5mm; 95%-70% for a standard sieve aperture of 26.5mm; 76%-40% for a standard sieve aperture of 19mm; 58%-28% for a standard sieve aperture of 13.2mm; 39%-19% for a standard sieve aperture of 9.5mm; 29%-6% for a standard sieve aperture of 4.75mm; 15%-3% for a standard sieve aperture of 1.18mm; 7%-1% for a standard sieve aperture of 0.3mm; and 4%-1% for a standard sieve aperture of 0.075mm.

[0135] The control parameters for LSPM asphalt mixtures include:

[0136] The porosity is 15%-20%;

[0137] The asphalt film thickness is greater than 12 μm;

[0138] The binder loss in the Schellenberg bitumen leakage test is not less than 0.2%;

[0139] The mixture loss in the Kentaburg scattering test was no less than 20%.

[0140] The preferred gradation range for sand-free, large-pore cement concrete is:

[0141] The passing rate of a 37.5mm sieve is 100%, the passing rate of a 26.5mm sieve ranges from 100% to 90%, the passing rate of a 13.5mm sieve ranges from 60% to 25%, the passing rate of a 4.75mm sieve ranges from 10% to 0%, the passing rate of a 2.36mm sieve ranges from 5% to 0%, and the passing rate of a standard sieve with a 0.075mm aperture ranges from 2% to 0%.

[0142] The control parameters for sand-free, large-pore cement concrete include:

[0143] The preferred porosity is 20%-30%.

[0144] The 7-day compressive strength is not less than 8 MPa;

[0145] The permeability coefficient is not less than 2 cm / s.

[0146] 3. Construction requirements:

[0147] The overall compacted thickness of the combined semi-flexible anti-rutting layer is 30cm.

[0148] 2-6 hours before LSPM layer construction, the underlying layer should be cleaned, and high-viscosity emulsified asphalt should be applied using an intelligent asphalt distributor at a rate of 0.4 kg / m³. 2 The LSPM layer thickness is controlled at 10cm. The mixture's factory temperature is 175℃-185℃, and the initial compaction temperature is controlled between 165℃-175℃. On-site compaction is performed using a double-drum vibratory roller and a rubber-tired roller. The roller uses high frequency and high amplitude compaction, with adjacent roller tracks overlapping by approximately 20-30cm. The mixture porosity is controlled between 15% and 20%.

[0149] Once the temperature of the mixture within the LSPM layer drops below 50℃, the no-fines, large-pore cement concrete layer can be constructed. Two to six hours before construction, high-viscosity emulsified asphalt is sprayed at a rate of 0.4 kg / m³. 2 The compacted thickness of each layer of sand-free, large-pore cement concrete is controlled at 20cm. After mixing according to the mix proportion, the sand-free, large-pore cement concrete is directly unloaded by tanker truck or transported by wheelbarrow, spread, and compacted by roller (which can be done by covering with a curing film) or by slight vibration on a mat. After construction, it is covered with a curing film for 3-7 days for curing.

[0150] After the sand-free, large-pore cement concrete layer has been cured for 3 days, grouting is carried out. A grouting material is prepared using a weight ratio of high-viscosity modified emulsified asphalt, mineral powder, and lignin fiber of 120:90:0.15. The prepared grouting material is pumped onto the sand-free, large-pore cement concrete pavement. Under gravity, the grout self-levels and penetrates. After the grout is pumped onto the asphalt mixture surface, it needs to maintain self-leveling and penetration for at least 15 seconds, until the grout stops seeping and bubbling, before proceeding with subsequent grouting operations. When the pavement has a longitudinal slope, the grout should be spread from the lower slope to the higher slope to prevent poor penetration due to rapid grout flow. The specific construction process is as follows: Figure 4 As shown.

[0151] VI. Surface Wear Layer

[0152] In this embodiment, the surface wear layer 6 is laid on the combined semi-flexible anti-rutting layer 5. The surface wear layer 6 is a 4cm SMA-13 ​​surface layer, and its technical requirements should meet the requirements for SMA-13 ​​asphalt mixture in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40-2004).

[0153] Comparative Example 1

[0154] The comparative example uses SBS modified emulsified asphalt-based mortar mixture pavement structure.

[0155] The pavement structure, from bottom to top, consists of a double-layer cement-stabilized crushed stone subbase, a single-layer cement-stabilized crushed stone base, SBS-modified emulsified asphalt-based mortar mixture, and dense-graded asphalt concrete. For example... Figure 2 As shown.

[0156] Comparative Example 2

[0157] The comparative example uses a cement-emulsified asphalt mortar mixture pavement structure.

[0158] The pavement structure consists of, from bottom to top, a double-layer cement-stabilized crushed stone subbase, a single-layer cement-stabilized crushed stone base, and cement-emulsified asphalt mortar concrete. For example... Figure 3 As shown.

[0159] The following uses the current asphalt pavement design specifications to perform layering of the three pavement structures in Example 1, Comparative Example 1, and Comparative Example 2 according to the following requirements, and calculates the permanent deformation of each layer.

[0160] 1. Surface layer, using 10mm as a single layer.

[0161] 2. The second layer is divided into 30mm sections.

[0162] 3. The third layer is divided into two equal layers if the thickness is no more than 100mm or less.

[0163] 4. The fourth layer and all layers below it are considered as a single layer.

[0164] Each type of mixture undergoes a rutting test under standard conditions to obtain the corresponding rutting (permanent deformation) amount. After calculating the permanent deformation amount of each layer according to formula (1-1), the total permanent deformation amount of the asphalt layer is obtained.

[0165]

[0166] Where: Ra - permanent deformation of the asphalt layer (mm);

[0167] Rai - Permanent deformation of layered i (mm);

[0168] n — number of layers;

[0169] The equivalent temperature of permanent deformation of the T-asphalt layer is determined according to Appendix B of this specification (°C).

[0170] Vertical compressive stress (MPa) on the top surface of the pi-asphalt layer i;

[0171] Ne4 - The cumulative number of times the design axle load on the design lane is applied during the design period of permanent deformation of the asphalt layer, according to this...

[0172] Calculation (axle number) is specified in Appendix A of the standard.

[0173] Initial porosity (%) after V-asphalt layer construction;

[0174] V0-Loop test specimen porosity (%);

[0175] hi-i layer thickness (mm);

[0176] h0 - Thickness (mm) of the wheel rut test specimen;

[0177] The permanent deformation (mm) of R0i-i layered asphalt mixture under wheel rutting test at a test temperature of 60℃, a pressure of 0.7MPa, and a loading cycle of 2520 times;

[0178] Ki - the comprehensive correction coefficient, is calculated according to formulas (1-2) to (1-4).

[0179]

[0180]

[0181]

[0182] Where: zi - the depth of asphalt layer i (mm), the first layer is taken as 10mm, and the other layers are the depth of the road surface from the midpoint of the asphalt layer;

[0183] ha - thickness of asphalt layer (mm). When ha is greater than 200mm, take 200mm.

[0184] Using measured structural and material parameters, calculations were performed on the asphalt layer rutting within the design life of three pavement structure forms: Example 1, Comparative Example 2, and Comparative Example 3. The indices are shown in Table 5.

[0185] Table 5 Fatigue Cracking Calculation Indicators for Semi-rigid Substrates

[0186] Verification indicators Example of road surface structure Comparative Example 1: Road Surface Structure Comparative Example 2: Road Surface Structure Rutting of asphalt layer within 15 years 8.36 15.22 17.28

[0187] The "Daokedaowang" online pavement design system was used to calculate the rutting resistance of two pavement structures under the same design life and traffic load parameters.

[0188] As shown in Table 5, within the design life (15 years), the results show that: the road structure of Comparative Example 1 has a rutting thickness of 15.22 mm during its service life; the road structure of Comparative Example 2 has a rutting thickness of 17.28 mm during its design life; and the structure of the present invention has a rutting thickness of 8.36 mm during its service life.

[0189] It is evident that the road structure provided by this invention has excellent rutting resistance, can withstand more vehicle loads, and has a longer service life.

Claims

1. A heavy-duty traffic integral rutting-resistant pavement structure, characterized in that, The pavement structure is laid on the top surface of the roadbed; the pavement structure, from bottom to top, consists of a semi-rigid subbase, a synchronous chip seal, an asphalt-rich bottom protective layer, a combined semi-flexible anti-rutting layer, and a surface abrasion layer; The composite semi-flexible anti-rutting layer is constructed by pavement of open-graded large-particle-size asphalt mixture and sand-free large-pore cement concrete. Modified emulsified asphalt grout is injected into the substrate to form the composite semi-flexible anti-rutting layer. The modified emulsified asphalt grout is composed of mineral powder, lignin fiber and high-viscosity modified emulsified asphalt with a Seybert viscosity of 20-100s at 25°C. The combined semi-flexible anti-rutting layer is laid through the following specific steps: (1) The subbase of the composite semi-flexible anti-rutting layer is an open-graded large-particle-size asphalt mixture layer: ① Before laying the open-graded, large-particle-size asphalt mixture layer, apply SBS modified emulsified asphalt tack coat at a rate of 0.4-0.6 kg / m³. 2 ; ② Using the volumetric method for gradation design, the gradation range of open-graded large-particle-size asphalt mixtures is: The passing rate of a standard sieve with a sieve aperture of 31.5mm is 100%; the passing rate of a standard sieve aperture of 26.5mm ranges from 70% to 95%; the passing rate of a standard sieve aperture of 19mm ranges from 40% to 76%; the passing rate of a standard sieve aperture of 13.2mm ranges from 28% to 58%; the passing rate of a standard sieve aperture of 9.5mm is 19% to 39%; the passing rate of a standard sieve aperture of 4.75mm ranges from 6% to 29%; the passing rate of a standard sieve aperture of 1.18mm ranges from 3% to 15%; the passing rate of a standard sieve aperture of 0.3mm ranges from 1% to 7%; and the passing rate of a standard sieve aperture of 0.075mm ranges from 1% to 4%. The asphalt content of the open-graded, large-particle-size asphalt mixture is 2.8-3.1 wt%. ③ Rolling open-graded large-particle-size asphalt mixture: The initial compaction temperature is controlled at 165℃-175℃; after static compaction 1-2 times with a 12t double-drum roller, start vibratory compaction at a speed of 1.5~2km / h, and vibrate for 2-3 times to achieve a compaction degree of over 95%. (2) The upper substrate of the composite semi-flexible anti-rutting layer is a sand-free, large-pore cement concrete layer: ① When the temperature of the asphalt mixture in the ungraded large-particle-size layer drops below 50℃, the construction of the sand-free large-pore cement concrete layer shall be carried out; 2-6 hours before construction, high-viscosity emulsified asphalt shall be sprayed. The Seybert viscosity of this high-viscosity emulsified asphalt at 25℃ is 20-100s, and the spraying rate is 0.4-0.6kg / m³. 2 ; ② The volumetric method was used for gradation design. The gradation range of the no-fines large-pore cement concrete was as follows: 100% passing through a 37.5mm sieve, 100%-90% passing through a 26.5mm sieve, 60%-25% passing through a 13.5mm sieve, 10%-0% passing through a 4.75mm sieve, 5%-0% passing through a 2.36mm sieve, and 2%-0% passing through a standard sieve with a 0.075mm diameter. ③ After the sand-free, large-pore cement concrete is mixed according to the mix proportion, it is spread on site by a slipform synchronous paver and compacted by roller or vibration. After construction, it is covered with a curing film for 3-7 days. (3) Grouting construction of modified emulsified asphalt mortar: The high-viscosity emulsified asphalt is sprayed onto the substrate and penetrated through self-leveling. The spraying rate is 1.0-1.2 kg / m³. 2 This allows air to escape from the pores inside the matrix. Preparation of modified emulsified asphalt mortar: High-viscosity modified emulsified asphalt, mineral powder, and lignin fiber are compounded and mixed in a weight ratio of (100-120):(80-100):(0.1-0.2); Determine the grouting volume: The weight ratio of the total weight of open-graded large-particle-size asphalt mixture and sand-free large-pore cement concrete to the grouting volume is (90-100):(12-18); One to two hours after spraying the high-viscosity emulsified asphalt, the modified emulsified asphalt grout is injected into the substrate using a pressure grouting device. After grouting, a leveling machine is used to level the substrate, and the next layer can be constructed after 2 to 2.5 hours.

2. The heavy-duty traffic integral anti-rutting pavement structure according to claim 1, characterized in that, The semi-rigid subbase is constructed by a single layer of cement-stabilized crushed stone mixture; the thickness of the semi-rigid subbase is 22-28cm, and the compaction degree of the semi-rigid subbase is 97%-100%.

3. The heavy-duty traffic integral anti-rutting pavement structure according to claim 1, characterized in that, The synchronous chip seal layer is composed of SBS modified bitumen and limestone chips with a single particle size of 5-10mm; The SBS application rate in the synchronous chip seal layer is 1.8 g / m³. 2 The amount of gravel spread is 7m³. 3 / 1000m 2 It occupies 65% of the total floor area.

4. The heavy-duty traffic integral anti-rutting pavement structure according to claim 1, characterized in that, The rich asphalt bottom sealing protective layer is paved with a single layer of continuously graded asphalt mixture; the compacted thickness of the rich asphalt bottom sealing protective layer is 4-6cm; the void ratio of the asphalt mixture is 2%-3%, the void ratio of the aggregate is 12%-14%, and the saturation is 80-100%.

5. The heavy-duty traffic integral rutting-resistant pavement structure according to claim 1, characterized in that, The thickness of the combined semi-flexible anti-rutting layer is 28-32cm; The open-graded, large-particle-size asphalt mixture has a porosity of 15%-20%; an asphalt film thickness greater than 12μm; a compaction thickness of 8-12cm; and a compaction degree of 96%-100%. The compacted thickness of the sand-free, large-pore cement concrete is 18-22 cm; the porosity is 20%-30%.

6. The heavy-duty traffic integral rutting-resistant pavement structure according to claim 1, characterized in that, The surface wear layer has a thickness of 4-6 cm; it uses SMA-13 ​​asphalt mixture.

7. A method for paving a heavy-duty traffic integral rutting-resistant pavement structure as described in any one of claims 1-6, characterized in that, From bottom to top, a semi-rigid subbase, synchronous chip seal, rich asphalt bottom protective layer, combined semi-flexible anti-rutting layer and surface abrasion layer are laid on the top surface of the roadbed. The specific paving operation of the semi-rigid subbase is as follows: the material of the semi-rigid subbase is cement-stabilized crushed stone mixture; it is paved in a single layer at one time, the 7-day strength of the cement-stabilized crushed stone mixture is not less than 4.5 MPa, and the cement dosage is ≤5%.

8. The paving method for a heavy-duty traffic integral anti-rutting pavement structure according to claim 7, characterized in that, The specific paving operation of the synchronous chip seal is as follows: After the semi-rigid subbase is constructed, a slow-cracking anionic emulsified asphalt tack coat is sprayed at a rate of 1.2 kg / m². 2 -1.5kg / m 2 The emulsified asphalt penetration depth is 5-8mm; the asphalt synchronous chip seal layer is spread one day before the construction of the rich asphalt base protective layer.

9. The paving method for a heavy-duty traffic integral anti-rutting pavement structure according to claim 7, characterized in that, The specific operation of the rich asphalt sealing and protective layer is as follows: The rich asphalt sealing and protective layer is paved with continuous graded asphalt mixture A, and the paving thickness is 4-6cm. The gradation range of asphalt mixture A is as follows: 100% passing rate for a standard sieve with a 16mm aperture; 100%-90% passing rate for a standard sieve with a 13.2mm aperture; 50%-24% passing rate for a standard sieve with a 9.5mm aperture; 38%-15% passing rate for a standard sieve with a 1.18mm aperture; 28%-10% passing rate for a standard sieve with a 0.6mm aperture; 20%-7% passing rate for a standard sieve with a 0.3mm aperture; 15%-5% passing rate for a standard sieve with a 0.15mm aperture; and 8%-4% passing rate for a standard sieve with a 0.075mm aperture. Asphalt mixture A uses SBS modified asphalt, with an asphalt content of 5.0%-5.3%; The porosity of asphalt mixture A is 2-3%, the aggregate porosity is 12-14%, the saturation is 80-100%, and the Marshall stability is not less than 8 kN.

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