An ultra-thin pavement structure based on ultra-high toughness cement-based composite material and its implementation process

Abstract

The present invention relates to an ultra-thin pavement structure and implementation process based on ultra-high toughness cement-based composite materials, and belongs to the field of traffic engineering transportation technology. The structure includes a carriageway and a shoulder, and shoulders are arranged on both sides of the carriageway. The carriageway includes a wear layer, a load-bearing layer and a base layer arranged in sequence from top to bottom, wherein an adhesive layer is arranged between the wear layer and the load-bearing layer, and an isolation layer is arranged between the load-bearing layer and the base layer. The present invention adopts an engineering cement-based composite material with super strong bending and tensile deformation resistance and fine steady-state cracking performance as the main bearing layer of the pavement, greatly reducing the thickness of the pavement, improving the bending and tensile strength and deformation resistance of the pavement structure, effectively solving the problems of reflective cracks and early damage of asphalt pavements, reducing energy consumption, reducing economic costs, and realizing the symbiosis of ecology, resources and development.

Description

Technical Field

[0001] The invention relates to an ultra-thin pavement structure based on ultra-high toughness cement-based composite materials and an implementation process thereof, belonging to the technical field of traffic engineering transportation. Background Art

[0002] Asphalt pavement is a widely used pavement structure in my country's high-grade highways and urban roads, and semi-rigid base is the main base type of asphalt pavement. However, due to the low tensile strength of semi-rigid base materials and the large shrinkage characteristics of the material itself, it is easy to crack under the action of cyclic vehicle loads and complex service environments, resulting in reduced base bearing capacity and causing reflective cracks in the asphalt surface layer.

[0003] The appearance of cracks not only affects driving comfort, but also reduces the strength and durability of the pavement structure, greatly shortening the service life of the road. In order to improve the bearing capacity of the base layer, prevent fatigue cracking and damage to the pavement, and extend the service life of the pavement, the asphalt pavement structure layer continues to thicken. The thickness of the commonly used asphalt pavement structure is as high as 60cm to 80cm. Although the increase in the thickness of the pavement structure layer can improve the bearing capacity of the pavement and slow down fatigue cracking to a certain extent, due to the inherent shrinkage properties of semi-rigid materials, reflective cracks on the pavement are still difficult to avoid. In addition, the overly thick pavement structure increases the demand for asphalt and cement, especially greatly increases the amount of aggregates such as sand and gravel, which will not only significantly increase the cost of pavement construction, but also cause a large amount of resource and energy consumption, causing serious pollution to the environment, and the contradiction with my country's ecological environmental protection strategy is becoming increasingly prominent.

[0004] Chinese patent CN105926401A discloses a thin layer of asphalt concrete structure and paving method for suppressing reflective cracks on the road surface, which includes old cement concrete pavement, anti-cracking layer, rubber-modified asphalt fiber gravel seal layer and special graded modified asphalt mixture surface layer from bottom to top, the anti-cracking layer includes a number of anti-cracking stickers, the rubber-modified asphalt fiber gravel seal layer is made of a mixture of rubber-modified asphalt, aggregate and fiber, and covers the anti-cracking layer and the entire road surface, the special graded modified asphalt mixture surface layer is made of a high-viscosity modified asphalt, aggregate, filler and fiber stabilizer mixed into a high-viscosity asphalt mixture, and is covered on the rubber-modified asphalt fiber gravel seal layer. This structure suppresses the generation and extension of reflective cracks by adding an anti-cracking layer, and the main material is still asphalt, which will still increase the cost of pavement construction and cause resource and energy consumption.

[0005] Therefore, the present invention is proposed to solve the problems of excessive thickness of the semi-rigid base asphalt pavement structure layer and easy occurrence of reflective cracks. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides an ultra-thin pavement structure and implementation process based on ultra-high toughness cement-based composite materials, which adopts an engineering cement-based composite material with super strong resistance to flexural and tensile deformation and fine steady-state cracking performance as the main bearing layer of the pavement, greatly reducing the thickness of the pavement, improving the flexural and tensile strength and deformation resistance of the pavement structure, effectively solving problems such as reflective cracks and early damage of asphalt pavements, reducing energy consumption, reducing economic costs, and achieving symbiosis of ecology, resources and development.

[0007] The technical solution of the present invention is as follows:

[0008] An ultra-thin pavement structure based on ultra-high toughness cement-based composite materials includes a carriageway and shoulders, shoulders are arranged on both sides of the carriageway, and the carriageway includes a wearing layer, a load-bearing layer and a base layer arranged in sequence from top to bottom, wherein an adhesive layer is arranged between the wearing layer and the load-bearing layer, and an isolation layer is arranged between the load-bearing layer and the base layer.

[0009] Preferably, the thickness of the wear layer is 4 cm to 6 cm, and the wear layer is made of asphalt mixture, which has the advantages of anti-skid and wear-resistant, high temperature rutting resistance, and low temperature cracking resistance;

[0010] The load-bearing layer material is an ultra-high toughness cement-based composite material with a thickness of 9cm to 15cm. As the main load-bearing layer of the pavement structure, the elastic modulus is 18000-22000MPa, and it has super strong bending deformation ability and ultra-high toughness;

[0011] The base material is cement stabilized crushed stone with a thickness of 10cm to 20cm and an elastic modulus of 6000-8000MPa, which can give full play to the bearing capacity and anti-scouring performance of the base. At the same time, the mixture has good water filtration, which can reduce water accumulation in the roadbed and improve the bearing capacity of the roadbed.

[0012] Preferably, the adhesive layer is made of PA-3 emulsified asphalt, and the spreading amount is 0.3-0.6L / m 2 It is used to enhance the bonding force between the wearing layer and the load-bearing layer, thereby enhancing load transfer while avoiding harmful phenomena such as displacement and congestion of the wearing layer.

[0013] Preferably, the isolation layer is made of EVA geomembrane with a thickness of 1-3 mm. The EVA geomembrane is soft in texture, smooth in surface and strong in toughness, which can ensure the normal pouring of ultra-high toughness cement-based composite materials and prevent the slurry from seeping in when the load-bearing layer is poured, thereby eliminating the constraints of the base layer on the bottom of the load-bearing layer, allowing the load-bearing layer to bear the vehicle load and temperature load through its own deformation, giving full play to its stress characteristics and ensuring that the cracks in the load-bearing layer are better dispersed harmlessly.

[0014] Preferably, transverse construction joints are evenly arranged at intervals of 40-60m in the load-bearing layer, and the interval distance of the transverse construction joints is set according to the shrinkage characteristics of the ultra-high toughness cement-based composite material (800-1000μ strain in 28 days). The transverse construction joints include a ground beam and a polyurethane elastic adhesive coating. The ground beam is a spliced ​​component, and polyurethane elastic adhesive coatings are arranged on both sides of the ground beam. The ground beam runs through the carriageway area and is connected to the longitudinal joint between the shoulder and the carriageway. The polyurethane elastic adhesive coating provides deformation space for the expansion of the load-bearing layer to prevent the expansion of the load-bearing layer under the action of temperature load from causing arching or warping.

[0015] Further preferably, the thickness of the polyurethane elastic adhesive coating is 10-20 mm.

[0016] Preferably, the shoulder includes a wear layer, a tack layer, a load-bearing layer and a base layer arranged in sequence from top to bottom. The thickness of the wear layer, tack layer and base layer of the shoulder are the same as those of the carriageway. The shoulder load-bearing layer is paved with C15 cement concrete, and the thickness of the shoulder load-bearing layer is the same as that of the carriageway load-bearing layer.

[0017] Further preferably, a notch is provided at the longitudinal seam between the shoulder load-bearing layer and the carriageway load-bearing layer, the width of the notch is 3-8mm, the depth is 30mm-40mm, and the notch is filled with polyurethane sealant to prevent the infiltration of moisture and the embedding of impurities.

[0018] Preferably, a transverse tie rod is provided in the longitudinal joint between the shoulder load-bearing layer and the lane load-bearing layer. The transverse tie rod is made of B14 threaded steel bar with a length of 700mm and a laying spacing of 900mm. The spacing between the transverse tie rod and the transverse construction joint is greater than 100mm. The transverse tie rod enhances the load transfer capacity of the transverse construction joint, which is beneficial to the coordinated force of the lane and the shoulder, while reducing the displacement difference on both sides of the transverse construction joint to prevent the lane and the shoulder from being separated and damaged.

[0019] The implementation process of the ultra-thin pavement structure based on the ultra-high toughness cement-based composite material is as follows:

[0020] (1) Use a paver to lay the cement-stabilized gravel base, with the paving area covering the carriageway and shoulder. After compaction, sprinkle water and maintain for up to 7 days;

[0021] (2) Support the formwork at the inner and outer edges of the shoulder, insert the tie rod at the longitudinal connection joint with the roadway, pour the shoulder concrete bearing layer, and after sprinkling water for 2-3 days, use a road cutter to set a transverse contraction joint every 4m, with a depth of 1 / 3 of the thickness of the shoulder concrete bearing layer. Continue sprinkling water for seven days, and then lay the EVA geomembrane isolation layer in the roadway range;

[0022] (3) According to the designed plane position and elevation, the formwork is supported on the inner side of the lane, and the shoulder concrete is used as the outer side formwork. The ultra-high toughness cement-based composite material is spread by a three-roller leveler at a spreading speed of 1 to 2.5 m / min. The material is self-compacting and does not require vibration.

[0023] (4) After the cement-based composite material has been cured for 7 days, the adhesive layer is laid;

[0024] (5) After the moisture in the tack coat evaporates, lay the asphalt mixture wearing course on the carriageway and shoulder to complete the pavement construction.

[0025] Preferably, in step (3), a ground beam needs to be installed before paving the ultra-high toughness cement-based composite material, and the specific implementation steps are:

[0026] ① Prefabricated shear key structure type ground beam components, in which threaded steel bars are embedded in the components to cross the ground beam and connect the ultra-high toughness cement-based composite materials on both sides;

[0027] ②According to the designed expansion joint spacing requirements, dig transverse trenches according to the designed depth and width on the paved cement-stabilized gravel base;

[0028] ③Install the ground beam components in the trench, splice them into a whole along the road horizontally, and fill the seams with cement mortar;

[0029] ④ Pour a polyurethane elastic adhesive coating on both sides of the ground beam, and then lay the ultra-high toughness cement-based composite material until it is flush with the top surface of the ground beam.

[0030] Further preferably, in step (1), the length of a single ground beam is 1 m, and a threaded steel bar is arranged every 200 mm in the single ground beam, and the threaded steel bars are B14 steel bars.

[0031] The beneficial effects of the present invention are:

[0032] 1. The present invention provides a new type of ultra-thin composite pavement structure, which consists of a 4-6 cm wearing layer, a 9-15 cm bearing layer and a 10-20 cm base layer from top to bottom. Compared with traditional high-grade asphalt pavements with the same design life, the thickness is reduced by 30 cm to 50 cm, which greatly reduces resource and energy consumption and reduces economic costs.

[0033] 2. The wearing layer of the pavement structure of the present invention adopts asphalt mixture, which has the advantages of anti-skid and wear resistance, high temperature rutting resistance, low temperature cracking resistance, etc.; the load-bearing layer adopts ultra-high toughness cement-based composite material, which has ultra-high toughness and super strong bending, tensile and deformation resistance, which can improve the bearing capacity of the pavement structure and enhance the service level and service life of the highway; the base layer ensures that the modulus ratio between each structural layer is within a reasonable range, gives full play to the high toughness and high bearing capacity of the load-bearing layer, and can quickly discharge groundwater to improve the bearing capacity of the roadbed.

[0034] 3. The present invention provides an invisible transverse construction joint, which is composed of a prefabricated ground beam block with threaded steel bars, to ensure the normal transfer of load at the construction joint, so that the ultra-high toughness cement-based composite material load-bearing layer is smoothly connected, its shrinkage deformation is limited and its temperature warping is prevented, so that the surface of the asphalt mixture surface layer is smooth and free of reflective cracks.

[0035] 4. The present invention adopts prefabricated concrete ground beams and connects them by shear keys, which optimizes the construction process and effectively shortens the construction period; at the same time, it reduces the dead weight of a single prefabricated part and facilitates hoisting construction.

[0036] 5. The present invention provides a connection method between the pavement structure and the shoulder, using cement concrete as the shoulder load-bearing layer, providing a template for pouring the ultra-high toughness cement-based composite material of the driving lane, and using tie rods to connect the ultra-high toughness cement-based composite material with the shoulder concrete to ensure the flatness of the load-bearing layer. The shoulder base layer and the wear layer are paved simultaneously using the same material type as the driving lane. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the structure of the present invention;

[0038] Figure 2 Schematic diagram of the comparison between Example 1 and asphalt concrete pavement structure;

[0039] Figure 3 It is a schematic diagram of the transverse construction joint structure of the present invention;

[0040] Figure 4 It is a schematic diagram of the ground beam structure of the present invention;

[0041] Figure 5 It is a schematic diagram of the connection mode between the carriageway and the shoulder of the road according to the present invention.

[0042] Among them: 1. Wear layer; 2. Adhesive layer; 3. Load-bearing layer; 4. Isolation layer; 5. Base layer; 6. Asphalt concrete upper layer; 7. Asphalt concrete middle layer; 8. Asphalt concrete lower layer; 9. Cement-stabilized gravel base layer; 10. Ground beam; 11. Polyurethane elastic adhesive coating; 12. Threaded steel bars; 13. Transverse tie rods; 14. Notches. DETAILED DESCRIPTION

[0043] The present invention will be further described below by way of embodiments in conjunction with the accompanying drawings, but is not limited thereto.

[0044] Embodiment 1:

[0045] like Figure 1-5 As shown, this embodiment provides an ultra-thin pavement structure based on ultra-high toughness cement-based composite materials, including a carriageway and shoulders, shoulders are arranged on both sides of the carriageway, and the carriageway includes a wear layer 1, a load-bearing layer 3 and a base layer 5 arranged in sequence from top to bottom, wherein an adhesive layer 2 is arranged between the wear layer 1 and the load-bearing layer 3, and an isolation layer 4 is arranged between the load-bearing layer 3 and the base layer 5.

[0046] The thickness of the wear layer 1 is 4 cm, and the wear layer material is asphalt mixture, which has the advantages of anti-skid and wear resistance, high temperature rutting resistance, low temperature cracking resistance, etc.

[0047] The material of the load-bearing layer 3 is an ultra-high toughness cement-based composite material with a thickness of 10 cm. As the main load-bearing layer of the pavement structure, it has super strong bending deformation ability and ultra-high toughness;

[0048] The base layer 5 is made of cement-stabilized crushed stone with a thickness of 18 cm and an elastic modulus of 7000 MPa, which can give full play to the bearing capacity and anti-scouring performance of the base layer. At the same time, the mixture has good water permeability, which can reduce water accumulation in the roadbed and improve the bearing capacity of the roadbed.

[0049] The adhesive layer 2 is made of PA-3 emulsified asphalt, and the spreading amount is 0.3L / m 2 It is used to enhance the bonding force between the wearing layer and the load-bearing layer, thereby enhancing load transfer while avoiding harmful phenomena such as displacement and congestion of the wearing layer.

[0050] The isolation layer 4 is made of EVA geomembrane with a thickness of 1 mm. The EVA geomembrane is soft in texture, smooth in surface and strong in toughness, which can ensure the normal pouring of ultra-high toughness cement-based composite materials and prevent the slurry from seeping in when the load-bearing layer is poured, thereby eliminating the constraints of the base layer on the bottom of the load-bearing layer, allowing the load-bearing layer to bear the vehicle load and temperature load through its own deformation, giving full play to its stress characteristics and ensuring that the cracks in the load-bearing layer are better dispersed harmlessly.

[0051] Transverse construction joints are evenly arranged at intervals of 40m in the load-bearing layer. The intervals between the transverse construction joints are set according to the shrinkage characteristics of the ultra-high toughness cement-based composite material (800-1000μ strain in 28 days). The transverse construction joints include a ground beam 10 and a polyurethane elastic adhesive coating 11. The ground beam is a spliced ​​component. Polyurethane elastic adhesive coatings are arranged on both sides of the ground beam. The ground beam runs through the lane area and is connected to the longitudinal joint between the shoulder and the lane. The polyurethane elastic adhesive coating provides deformation space for the expansion of the load-bearing layer to prevent the expansion of the load-bearing layer under the action of temperature load from causing arching or warping.

[0052] The thickness of the polyurethane elastic adhesive coating 11 is 10-20 mm.

[0053] The shoulder includes a wearing layer, a tack layer, a load-bearing layer and a base layer from top to bottom. The thickness of the wearing layer, tack layer and base layer of the shoulder are the same as those of the carriageway. The shoulder load-bearing layer is paved with C15 cement concrete, and the thickness of the shoulder load-bearing layer is the same as that of the carriageway.

[0054] A transverse tie rod 13 is provided in the longitudinal joint between the shoulder load-bearing layer and the lane load-bearing layer. The tie rod 13 adopts B14 threaded steel bar with a length of 700mm and a spacing of 900mm. The spacing between the transverse tie rod and the transverse construction joint is greater than 100mm. The transverse tie rod enhances the load transfer capacity of the transverse construction joint, which is beneficial to the coordinated force of the lane and the shoulder, and at the same time reduces the displacement difference on both sides of the transverse construction joint to prevent the lane and the shoulder from being separated and damaged.

[0055] The implementation process of the ultra-thin pavement structure based on the ultra-high toughness cement-based composite material is as follows:

[0056] (1) Use a paver to lay the cement-stabilized gravel base, with the paving area covering the carriageway and shoulder, and sprinkle water for curing for up to 7 days;

[0057] (2) After compaction, support the formwork at the inner and outer edges of the shoulder, insert the tie rod at the longitudinal connection joint with the lane, pour the shoulder concrete bearing layer, and after sprinkling water for 2-3 days, use a road cutter to set a transverse contraction joint every 4m, with a depth of 1 / 3 of the thickness of the shoulder concrete bearing layer. Continue sprinkling water for seven days, and then lay the EVA geomembrane isolation layer in the lane range;

[0058] (3) According to the designed plane position and elevation, the formwork is supported on the inner side of the lane, and the shoulder concrete is used as the outer side formwork. The ultra-high toughness cement-based composite material is spread by a three-roller leveler at a spreading speed of 1 to 2.5 m / min. The material is self-compacting and does not require vibration.

[0059] (4) After the cement-based composite material has been cured for 7 days, the adhesive layer is laid;

[0060] (5) After the moisture in the tack coat evaporates, lay the asphalt mixture wearing course on the carriageway and shoulder to complete the pavement construction.

[0061] In step (3), a ground beam needs to be installed before paving the ultra-high toughness cement-based composite material. The specific implementation steps are as follows:

[0062] ① Prefabricated shear key structure type ground beam components, in which threaded steel bars are embedded in the components to cross the ground beam and connect the ultra-high toughness cement-based composite materials on both sides;

[0063] ②According to the designed expansion joint spacing requirements, dig transverse trenches according to the designed depth and width on the paved cement-stabilized gravel base;

[0064] ③Install the ground beam components in the trench, splice them into a whole along the road horizontally, and fill the seams with cement mortar;

[0065] ④ Pour a polyurethane elastic adhesive coating on both sides of the ground beam, and then lay the ultra-high toughness cement-based composite material until it is flush with the top surface of the ground beam.

[0066] In step (1), the length of a single ground beam 10 is 1 m, and a threaded steel bar 12 is arranged every 200 mm in the single ground beam, and the threaded steel bar adopts B14 steel bar.

[0067] This embodiment is applied to a newly built expressway in highway natural zone III. According to traffic survey and analysis, the design axle load is 100kN, the heaviest axle load is 220kN, and the traffic volume of large passenger cars and trucks is 12,358 vehicles / day. The vehicle types of the designed road and the proportion of non-full load and full load of each type of vehicle can be determined based on traffic history data.

[0068] (1) Traffic analysis

[0069] The pavement design reference period is set at 15 years. According to Table A.2.4 of the water-mixed concrete specification, the lateral distribution coefficient of the vehicle wheel track at the critical load position is taken as 0.22. The average annual growth rate of traffic volume is 4.2%, and the cumulative number of equivalent design axle load actions for the fatigue life of the asphalt layer and the fatigue life of the inorganic binder layer can be calculated respectively:

[0070]

[0071]

[0072] (2) Pavement structure parameters

[0073] The thickness of the asphalt mixture layer is 0.04m, the thickness of the ECC (cement-based composite material) layer is 0.10m, and the thickness of the base layer is 0.18m;

[0074] The elastic modulus of asphalt mixture layer is 7500MPa, Poisson's ratio is 0.25, and the thermal expansion coefficient is 2.1×10-5 / ℃; base elastic modulus 7000MPa, Poisson's ratio 0.2, thermal expansion coefficient 1×10 -5 / ℃. The flexural strength of ECC material is 13MPa, and the compressive strength is 40MPa; the elastic modulus of the ECC layer is 20000MPa, the Poisson's ratio is 0.27, and the thermal expansion coefficient is 1×10 -5 / ℃.

[0075] (3) Pavement structure verification

[0076] 1) Verification of ultra-thin pavement structure based on ultra-high toughness cement-based composite materials

[0077] A. ECC layer fatigue calculation

[0078] a) Load fatigue stress calculation

[0079] According to the calculation formula of ECC plate load fatigue stress obtained by the above analysis, the load stress σ generated by the design axial load at the critical load position is calculated using the ABAQUS finite element model. p And the load stress σ generated by the ultimate load at the critical load position pm , substituting into the fatigue stress calculation formula:

[0080] σ pr =k r k f k c σ ps =1.5799MPa

[0081] σ p,max =k r k c σ pm =1.3436MPa

[0082] where k r k is the stress reduction factor considering the load transfer capacity of the joint; c is the comprehensive coefficient; k f is the fatigue stress coefficient.

[0083] b) Temperature fatigue stress calculation

[0084] According to the calculation formula of ECC plate temperature fatigue stress obtained by the above analysis, the maximum temperature warping stress is calculated by ABAQUS finite element model, and the regression coefficient is determined according to the highway natural zoning III in the area. Substituting it into the fatigue stress calculation formula, it is obtained:

[0085] σ tr =k t σ t,max =0.1758MPa

[0086] where kt is the temperature fatigue stress coefficient.

[0087] c) ECC board limit state verification

[0088] Refer to the clause explanation table 3-1 in the "Highway Cement Concrete Pavement Design Specification" (JTG D40-2011), and check whether the pavement structure meets the requirements according to the comprehensive fatigue stress calculation formula:

[0089] γ r (σ pr +σ tr )=1.20×(1.5799+0.1758)=2.106MPa≤f r =13MPa

[0090] γ r (σ p,max +σ tm )=1.20×(1.3436+0.1758)=1.8233MPa≤f r =13MPa

[0091] Therefore, the pavement structure meets the design requirements and can not only withstand the combined fatigue effects of load stress and temperature stress within the design reference period, but also withstand the one-time effect of the heaviest axle load at the maximum temperature gradient.

[0092] B. Calculation of permanent deformation of asphalt mixture layer

[0093] According to B.3.1 of the "Asphalt Pavement Design Specification" (JTG D50-2017), the permanent deformation of each layer is calculated separately. First, the comprehensive correction coefficient k Ri Perform the calculation:

[0094]

[0095] Secondly, the permanent deformation of each layer of the asphalt mixture is calculated, and the permanent deformation of each layer of the asphalt mixture is obtained as follows:

[0096]

[0097] Calculate the permanent deformation of asphalt mixture layer:

[0098]

[0099] The calculated permanent deformation R of the asphalt mixture layer a =4.1509mm is smaller than the allowable permanent deformation of asphalt mixture layer of highways specified in the "Asphalt Pavement Design Specification" (JTG D50-2017) of 15mm, which meets the design requirements.

[0100] C. Fatigue cracking calculation of inorganic binder layer (base layer)

[0101] According to Table 3.0.1 and Table B.2.1-1 in the "Asphalt Pavement Design Code" (JTG D50-2017), the various parameters in the fatigue cracking life formula of the inorganic binder layer are selected. Substituting the above values ​​into the fatigue cracking formula of the inorganic binder layer, the following is obtained:

[0102]

[0103] Fatigue cracking life of inorganic binder layer N f2 =1.97×10 10 Axis number>N e2 =4.12×10 9 axle times, indicating that the pavement structure design scheme meets the requirement of a design service life of at least 15 years.

[0104] The existing asphalt concrete pavement structure is Figure 2 As shown in (b), it includes an asphalt concrete upper layer 6, an asphalt concrete middle layer 7, an asphalt concrete lower layer 8 and a cement stabilized crushed stone base layer 9 arranged from top to bottom. The existing asphalt concrete pavement structure is verified as follows:

[0105] Pavement structure parameters: The cumulative thickness of asphalt concrete upper layer, asphalt concrete middle layer and asphalt concrete lower layer is 0.18m, and the thickness of cement stabilized gravel base is 0.54m;

[0106] The elastic modulus of asphalt mixture layer is 7500MPa, Poisson's ratio is 0.25, and the thermal expansion coefficient is 2.1×10 -5 / ℃; base elastic modulus 7000MPa, Poisson's ratio 0.2, thermal expansion coefficient 1×10 -5 / ℃.

[0107] A. Calculation of permanent deformation of asphalt mixture layer

[0108] According to B.3.1 of the "Asphalt Pavement Design Specification" (JTG D50-2017), the asphalt mixture layer is divided into seven layers:

[0109] First, the comprehensive correction coefficient k Ri Perform the calculation:

[0110] Correction coefficient k for each layer Ri Calculation results

[0111] <![CDATA[k R1 ]]> <![CDATA[k R2 ]]> <![CDATA[k R3 ]]> <![CDATA[k R4 ]]> <![CDATA[k R5 ]]> <![CDATA[k R6 ]]> <![CDATA[k R7 ]]> 3.82 5.12 7.17 7.38 6.23 4.75 1.94

[0112] Secondly, the permanent deformation of each layer of the asphalt mixture is calculated. The parameters are taken according to the "Asphalt Pavement Design Specification" (JTG D50-2017). The parameters and the top compressive stress of each layer of the asphalt mixture are substituted into the formula to obtain the permanent deformation of each layer of the asphalt mixture as follows:

[0113]

[0114] The permanent deformation of the asphalt mixture layer can be obtained:

[0115]

[0116] The calculated permanent deformation R of the asphalt mixture layer a =6.99mm is smaller than the allowable permanent deformation of asphalt mixture layer of highways specified in the "Asphalt Pavement Design Code" (JTGD50-2017) of 15mm, which meets the design requirements.

[0117] B. Fatigue cracking calculation of inorganic binder layer (cement stabilized crushed stone base)

[0118] According to Table 3.0.1 and Table B.2.1-1 in the "Asphalt Pavement Design Code" (JTG D50-2017), the various parameters in the fatigue cracking life formula of the inorganic binder layer are selected and substituted into the fatigue cracking formula of the inorganic binder layer to obtain:

[0119]

[0120] Fatigue cracking life of inorganic binder layer N f2 =5.16×10 9 Axis number>N e1 =4.12×10 9 axle times, meeting the pavement performance design requirements, indicating that this pavement structure design scheme meets the requirement of a design service life of at least 15 years.

[0121] Compared with the above-mentioned asphalt concrete pavement structure, the ultra-thin pavement structure based on the ultra-high toughness cement-based composite material in this embodiment reduces the pavement thickness by 40 cm while meeting the same design life.

[0122] Embodiment 2:

[0123] An ultra-thin pavement structure based on ultra-high toughness cement-based composite material, the structure is as described in Example 1, except that the thickness of the wear layer is 6 cm, the thickness of the load-bearing layer is 9 cm, the thickness of the base layer is 10 cm, the elastic modulus is 6000 MPa, and the amount of the adhesive layer is 0.6 L / m 2 The thickness of the isolation layer is 3 mm, and transverse construction joints are evenly arranged at intervals of 60 m in the load-bearing layer.

[0124] Embodiment 3:

[0125] An ultra-thin pavement structure based on an ultra-high toughness cement-based composite material, the structure being as described in Example 1, the thickness of the load-bearing layer being 15 cm, the thickness of the base layer being 20 cm, and the elastic modulus being 8000 MPa;

[0126] A notch 14 is provided at the longitudinal joint between the shoulder load-bearing layer and the carriageway load-bearing layer. The width of the notch 14 is 3-8 mm and the depth is 30 mm to 40 mm. The notch is filled with polyurethane caulking glue to prevent water penetration and impurity embedding.

Claims

1. A process for implementing an ultra-thin pavement structure based on ultra-high toughness cement-based composite materials, characterized in that: The pavement structure includes a carriageway and shoulders. The carriageway is provided with shoulders on both sides. The carriageway includes a wearing layer, a bearing layer and a base layer arranged in sequence from top to bottom. An adhesive layer is arranged between the wearing layer and the bearing layer, and an isolation layer is arranged between the bearing layer and the base layer. The thickness of the wear layer is 4 cm to 6 cm, and the material of the wear layer is asphalt mixture; The load-bearing layer material is an ultra-high toughness cement-based composite material with a thickness of 9 cm to 15 cm and an elastic modulus of 18000-22000 MPa; The base material is cement-stabilized crushed stone with a thickness of 10 cm to 20 cm and an elastic modulus of 6000-8000 MPa; The load-bearing layer is evenly provided with transverse construction joints at intervals of 40-60m, the transverse construction joints comprising a ground beam and a polyurethane elastic adhesive coating, the ground beam is a spliced ​​component, and polyurethane elastic adhesive coatings are provided on both sides of the ground beam; A notch is set in the longitudinal seam between the shoulder load-bearing layer and the carriageway load-bearing layer. The width of the notch is 3-8mm and the depth is 30mm~40mm. The notch is filled with polyurethane sealant. A transverse tie rod is installed in the longitudinal joint between the shoulder bearing layer and the carriageway bearing layer. The transverse tie rod is made of B14 threaded steel bar with a length of 700mm and a laying spacing of 900mm. The spacing between the transverse tie rod and the transverse construction joint is greater than 100mm. The adhesive layer is made of PA-3 emulsified asphalt, and the spreading amount is 0.3-0.6L / m 2 ; The isolation layer is made of EVA geomembrane with a thickness of 1-3 mm; The thickness of the polyurethane elastic adhesive coating is 10-20mm; The shoulder includes a wearing layer, a tack layer, a load-bearing layer and a base layer from top to bottom. The thickness of the wearing layer, tack layer and base layer of the shoulder are the same as those of the carriageway. The shoulder load-bearing layer is paved with C15 cement concrete, and the thickness of the shoulder load-bearing layer is the same as that of the carriageway; The implementation process of the ultra-thin pavement structure based on the ultra-high toughness cement-based composite material is as follows: (1) Use a paver to lay the cement-stabilized gravel base, with the paving area covering the carriageway and shoulder, and sprinkle water for curing for up to 7 days; (2) After compaction, support the formwork at the inner and outer edges of the shoulder, insert the tie rod at the longitudinal connection joint with the lane, pour the shoulder concrete bearing layer, and after sprinkling water for 2-3 days, use a road cutter to set a transverse contraction joint every 4m, with a depth of 1 / 3 of the thickness of the shoulder concrete bearing layer. Continue sprinkling water for seven days, and then lay the EVA geomembrane isolation layer in the lane range; (3) According to the designed plane position and elevation, the formwork is supported on the inner side of the carriageway, and the shoulder concrete is used as the outer formwork. The ultra-high toughness cement-based composite material is spread by a three-roller leveler at a spreading speed of 1-2.5 m / min. The material is self-compacting and does not require vibration. Before paving the ultra-high toughness cement-based composite material, the ground beam needs to be installed. The specific implementation steps are as follows: ① Prefabricated shear key structure type ground beam components, the length of a single ground beam is 1m, and a threaded steel bar is set every 200mm in a single ground beam. The threaded steel bar adopts B14 steel bar. The threaded steel bar that crosses the ground beam is pre-embedded in the component to connect the ultra-high toughness cement-based composite materials on both sides; ②According to the designed expansion joint spacing requirements, dig transverse trenches according to the designed depth and width on the paved cement-stabilized gravel base; ③Install the ground beam components in the trench, splice them into a whole along the road horizontally, and fill the seams with cement mortar; ④ Pour a polyurethane elastic adhesive coating on both sides of the ground beam, and then lay the ultra-high toughness cement-based composite material until it is flush with the top surface of the ground beam; (4) After the cement-based composite material has been cured for 7 days, the adhesive layer is laid; (5) After the moisture in the tack coat has evaporated, lay the asphalt mixture wearing course on the carriageway and shoulder to complete the pavement construction.

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