A high-speed pavement containing an environmentally friendly high-content RAP recycled cement stabilized mixture base layer and a construction process thereof

Abstract

The application belongs to the technical field of cement stabilized macadam mixture preparation and application, and particularly relates to a high-speed pavement containing an environmentally-friendly high-mixing-amount RAP recycled cement stabilized mixture base and a construction process thereof, wherein the high-speed pavement comprises, from top to bottom, a surface layer, a base layer and a roadbed, the base layer comprises an upper base layer, a lower base layer and a bottom base layer; the laying materials of the upper base layer and the lower base layer are environmentally-friendly high-mixing-amount RAP recycled cement stabilized mixture, and the laying material of the bottom base layer is lime-fly ash macadam mixture. Through the structure combination of double base layers, compared with the construction project of the ordinary cement stabilized base, the construction period can be shortened by 85%, and the early asphalt pavement diseases such as local segregation, looseness and rutting are not prone to occur on the pavement, so the application has a strong practical use value.

Description

Technical Field

[0001] This invention belongs to the field of cement stabilized mixture preparation and application, specifically relating to a rapid pavement base course containing environmentally friendly high-content RAP recycled cement stabilized mixture and its construction process. Background Technology

[0002] With the rapid development of my country's highway transportation, national and provincial trunk highway networks have gradually taken shape. The proportion of newly built highways is decreasing year by year, while the proportion of reconstruction and major repair projects is constantly expanding. If traditional methods are continued to be used for asphalt pavement reconstruction, a large amount of asphalt mixture from excavation and milling will be discarded, increasing the amount of asphalt and gravel needed for road reconstruction, which pollutes the environment and wastes resources.

[0003] To address the issues of resource waste and environmental pollution associated with asphalt milling, recycled asphalt mixture (RAP) technology has been widely applied in road surface layers. With the increasing number of reconstruction and expansion projects, the total amount of RAP is constantly increasing. Its application solely in surface layers can no longer meet the demand for recycled asphalt mixture processing. Applying RAP to cement-stabilized crushed stone by adding an appropriate amount of waste asphalt mixture can not only significantly improve the various road performance characteristics of the pavement base layer but also enhance its fatigue performance, frost resistance, and erosion resistance.

[0004] In the prior art, Chinese Patent No. CN106320127B provides a recycled asphalt pavement, which adopts a design of subbase, base course, seal course and surface course, and uses 70% to 90% recycled asphalt pavement material, 1% to 3% modified asphalt material, 1% to 3% first admixture, and the remainder is modified aggregate. It effectively solves the technical problems of recycling and road performance of recycled pavement materials, thereby achieving a recycled pavement material blending ratio of more than 60% and a recycling rate of 100% in a certain area.

[0005] However, the existing technologies mentioned above still have the following problems: 1. When modified RAP is used to manufacture water-stabilized base courses, it is the same as ordinary water-stabilized base courses, requiring a curing period of about 7 days before it can form strength and then carry out asphalt surface course construction; 2. Due to drying shrinkage and thermal shrinkage, recycled base courses are prone to cracking, and under traffic loads, the base course cracks are easy to extend and reflect to the surface course, forming early cracking defects; 3. When using RAP to manufacture water-stabilized base courses, due to its relatively weak strength performance, it is mainly used in the subbase course, and its application in the upper base course is relatively limited, which restricts the application research of RAP. Summary of the Invention

[0006] To address the aforementioned issues of long curing times and concentrated application in the subbase layer of current RAP recycled cement stabilized base courses, this invention provides a rapid pavement with a base course containing environmentally friendly, high-dosage RAP recycled cement stabilized mixture and its construction process. Using this environmentally friendly, high-dosage RAP recycled cement stabilized mixture as the base course material and employing a double-base course continuous paving structure, compared to ordinary water-stabilized base course construction projects, the construction period can be shortened by up to 85%, and the pavement is less prone to early asphalt pavement defects such as local segregation, loosening, and rutting. The specific technical solution is as follows: First, the present invention provides a rapid road surface with an environmentally friendly high-content RAP recycled cement stabilized mixture base course, comprising a surface layer, a base course, and a subgrade arranged sequentially from top to bottom. The base course comprises an upper base course, a lower base course, and a subbase course; the paving material of the upper base course and the lower base course is an environmentally friendly high-content RAP recycled cement stabilized mixture, and the paving material of the subbase course is a lime-stabilized crushed stone mixture.

[0007] Furthermore, the environmentally friendly high-content RAP recycled cement stabilized mixture comprises graded crushed stone, cement, and a curing agent-free agent; the graded crushed stone is composed of the following parts by weight: 12%–20% RAP1 # Material, 18%~20%RAP2 # Material, 10%RAP3 # The mixture consists of 32%–42% coarse aggregate and 18% fine aggregate; the RAP1... # Particle size is 10mm~20mm, RAP2 # Particle size is 5mm-10mm, RAP3 # The aggregate particle size is greater than 0 mm and less than 5 mm, the coarse aggregate particle size is 16 mm to 31.5 mm, and the fine aggregate particle size is greater than 0 mm and less than 2.36 mm; the cement added accounts for 2.5% to 4% of the total weight of the environmentally friendly high-content RAP recycled cement stabilized mixture; the amount of the curing agent added is 6% to 8% of the cement weight.

[0008] Furthermore, the RAP1 # Material, RAP2 # Material and RAP3 # The coefficient of variation for the asphalt content is 4.5%–5.5%; the coefficient of variation for penetration is 6.5%–7.5%; the coefficient of variation for softening point is 5%–5.5%; the coefficient of variation for ductility at 10℃ is 6%–9.5%; the aforementioned RAP1 # Material, RAP2 # Material and RAP3 # The coefficient of variation for the passing rate of the material through sieves with apertures smaller than 9.5 mm is 4%–14%; the coefficient of variation for the passing rate through sieves with apertures larger than 9.5 mm is 2%–7%. The curing-free agent comprises anionic surfactants and expanding agents. The anionic surfactants include any one or more of anionic polyacrylamide and fatty alcohol polyoxyethylene ether phosphate. The expanding agents are any one or more of calcium magnesium oxide expanding agents and calcium sulfoaluminate expanding agents. The curing-free agent meets the following technical indicators: pH value 7-9; alkali content ≤0.75%; specific surface area ≥200m2 / kg; initial setting time ≥3h, final setting time ≤10h; water reduction rate ≥25%.

[0009] Furthermore, the thickness of the upper base layer is 18cm to 20cm, the thickness of the lower base layer is 18cm to 20cm, and the thickness of the bottom base layer is 20cm.

[0010] Furthermore, the surface layer includes a top layer, a middle layer, and a bottom layer; the thickness of the top layer is 4cm to 5cm, the thickness of the middle layer is 6cm to 8cm, and the thickness of the bottom layer is 8cm to 10cm; the material used for laying the top layer is SBS modified SMA-13; the material used for laying the middle layer is SBS modified Sup-20; and the material used for laying the bottom layer is Sup-25.

[0011] This invention also provides a construction process for a rapid pavement base course containing an environmentally friendly high-dosage RAP recycled cement stabilized mixture, comprising the following steps: Step 1. Lay the base layer; Step 2. Subbase and subgrade preparation: Inspect the quality of the subbase and subgrade, and conduct trial paving, measurement, and layout work; Step 3. Mixing the mixture: Calculate the mix proportion of the mixture for the day based on the construction site, and mix the graded crushed stone, cement and curing agent according to the mix proportion; Step 4. Transport of the mixture; Step 5. Mixture paving: First, moisten the subbase with water, then install steel formwork on the shoulder side and adjust the angle of the sensors and guide control lines. Use the paver to maintain continuous paving. Step 6. Compaction of the mixture: Use a road roller to compact the mixture in the following steps: static compaction, weak vibration, strong vibration and rubber-tired static compaction, and check the degree of compaction; Step 7. Base layer curing: After the compaction degree test is qualified, cover with geotextile and add water for curing.

[0012] Furthermore, the quality inspection of the subbase and roadbed in step two includes compaction, deflection, elevation, centerline deviation, width, cross slope and smoothness; the trial paving measurement and layout work includes road edge lines, elevation and width.

[0013] Furthermore, in step five, the paving speed is 1.5m / min to 2m / min, and the tamping hammer vibration level is 4.0; the steel mold has a height of 18cm and a thickness of 4mm. Furthermore, in step six, the static compaction number is 1-2 times and the compaction speed is 1.5-1.7 km / h; the weak vibration number is 3-4 times and the compaction speed is 1.8-2.2 km / h; the rubber-tired static compaction number is 3-4 times and the compaction speed is 1.8-2.2 km / h; the compaction length per pass is 50m-80m; and the roller compaction overlap is ≥30cm.

[0014] Furthermore, the health maintenance period in step seven is 1 day.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1) This invention addresses the problem that existing RAP materials undergoing recycling are uneven in quality and have large performance fluctuations due to differences in the initial gradation of different pavement structure layers, asphalt content and properties, and inconsistent external environments during use. This makes the design and use of RAP materials difficult. By limiting the variability of RAP materials, the mixture can achieve the gradation range for use, which can further save cement usage and improve the comprehensive mechanical properties of the base course prepared with the water-stabilized mixture of this invention, making it applicable to both upper and lower base courses, thus broadening the research and application scenarios of RAP materials.

[0016] 2) This invention, through a rational structural design, applies environmentally friendly, high-dosage RAP recycled cement-stabilized mixture to both the upper and lower base courses. In practical road applications, this rapid pavement exhibits extremely high strength and toughness. Compared to ordinary water-stabilized pavements without RAP and environmentally friendly, high-dosage RAP recycled cement-stabilized mixture pavements without curing agents, it leads in splitting tensile strength, compressive rebound, fatigue resistance, and erosion resistance. In actual road tests, all indicators meet practical usage standards, and the pavement is less prone to early asphalt pavement defects such as local segregation, loosening, and rutting, demonstrating strong practical value.

[0017] 3) This invention adds a curing-free agent to the expressway. The curing-free agent contains anionic surfactants. After the curing-free agent is added to the cement-stabilized crushed stone mixture, it is adsorbed on the surface of the cement particles. The particles will carry the same charge and be evenly dispersed, improving the workability of the mixture. At the same time, due to the formation of an adsorption film on the particle surface, the cement crystals grow more completely and the network structure is more compact, which improves the strength and density of the matrix. It can achieve rapid increase in the strength of the cement-stabilized crushed stone mixture in a short period of time. In addition, the curing-free agent contains micro-expansion components to resist matrix shrinkage and reduce construction time. Attached Figure Description

[0018] Figure 1This is a schematic diagram of the overlay structure of a rapid road surface with an environmentally friendly high-content RAP recycled cement stabilized mixture base course, as shown in Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of the overlay structure of the expressway in Comparative Example 1 of the present invention; Figure 3 This is a schematic diagram of the overlay structure of the expressway in Comparative Example 2 of the present invention; Figure 4 This is a bar chart showing the experimental results of erosion resistance in Experiment Example 1 of the present invention.

[0019] Attached diagram descriptions: 1. Upper layer, 2. Middle layer, 3. Lower layer, 4. Upper base course, 5. Lower base course, 6. Subbase course, 7. Roadbed. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with embodiments.

[0021] Example 1 This embodiment provides a construction process for a rapid pavement base course containing an environmentally friendly high-dosage RAP recycled cement stabilized mixture, specifically including the following steps: Step 1. Lay the base layer (6); Specifically, in this embodiment, the base course (6) is a lime-fly ash crushed stone base course. The construction method and mix ratio of the lime-fly ash crushed stone base course can be any one of the existing technologies, which will not be elaborated here.

[0022] Step 2. Preparation of subbase (6) and roadbed (7): Check the quality of subbase (6) and roadbed (7) and carry out trial paving, measurement and layout work; Specifically, the first step is to conduct surveying and layout work the day before the trial paving, including the road edge lines, elevation, and width. Based on the design drawings, the layout width is carried out according to the design to ensure the compaction of the base layer edges. Every 10 meters, a boundary line is marked with lime, and simultaneously, a 18cm high, 4mm thick channel steel template is erected on the outer side to control the boundary. The template installation should be straight and have a neat line shape; deformed steel templates must not be used. Marks are made according to the paver width and sensor spacing, and guide control line supports are installed. The guide control line height is determined based on the loose paving thickness (the loose paving coefficient is 1.31, and the loose paving thickness of a 2cm compacted layer is 26.2cm). The guide control line is then hung, with the wire rope tension not less than 800N.

[0023] The loose paving coefficient was determined using a relative coordinate measurement method. The instrument was set up stationary, and measurement sections were pre-arranged to measure the relative elevations of the original ground surface, before compaction, and after compaction. The average loose paving coefficient of the effective compaction thickness was taken as the loose paving coefficient. One section was set up every 10 meters, for a total of 10 sections. Five control points were set up at each section, positioned at distances of 2m, 4m, 6m, 8m, and 10m from the edge stakes. The distances of the control points from the edge stakes at each stage of measurement were considered before and after.

[0024] On the day of construction, the compaction, deflection, elevation, centerline deviation, width, cross slope, and flatness of the roadbed were tested according to the acceptance standards for the top surface of the roadbed provided in the design drawings. This ensured that all test indicators met the requirements of the design documents and complied with the requirements of the "Highway Engineering Quality Inspection and Evaluation Standard" (JTG F80 / 1-2017).

[0025] Step 3. Mixing the mixture: Calculate the mix proportion of the mixture for the day based on the construction site, and mix the graded crushed stone, cement and curing agent according to the mix proportion; Specifically, the required raw materials are prepared according to the calculated proportions. In this embodiment, the cement addition is 4% of the total weight of the mixture, the curing agent addition is 6% of the cement addition, and the remainder is graded crushed stone. The graded crushed stone includes 20% RAP1. # Material, 20%RAP2 # Material, 10%RAP3 # material, 32% coarse aggregate, 18% fine aggregate. RAP1 # Particle size is 10mm~20mm, RAP2 # Particle size is 5mm-10mm, RAP3 # The particle size of the aggregate is 0mm to 5mm, the coarse aggregate particle size is 16mm to 31.5mm, and the fine aggregate particle size is 0mm to 2.36mm. In this embodiment, RAP1... # The coefficients of variation for the passing rates of materials through 19mm and 9.5mm sieves were 2.10% and 6.03%, respectively; the coefficient of variation for the passing rate through a 4.75mm sieve was 11.10%. RAP2 # The coefficient of variation for the passing rate through a 9.5mm sieve was 3.45%; the coefficients of variation for the passing rates through 4.75mm and 2.36mm sieves were 11.52% and 13.24%, respectively. RAP3 # The coefficients of variation for the passing rates of the material through 4.75mm and 0.075mm sieves were 4.55% and 9.93%, respectively.

[0026] The coefficient of variation of recycled asphalt in RAP in this embodiment is shown in Table 1: In this embodiment, the gradation range of the crushed stone after mixing meets the requirements of Table 2: In this embodiment, the preservative-free agent includes anionic surfactants and expanding agents. The anionic surfactant includes any one or more of anionic polyacrylamide and fatty alcohol polyoxyethylene ether phosphate, preferably anionic polyacrylamide. The expanding agent includes any one or more of calcium magnesium oxide expanding agents and calcium sulfoaluminate expanding agents, preferably calcium sulfoaluminate expanding agents, such as U-shaped expanding agents. Both the anionic surfactant and the expanding agent in this invention are commercially available products.

[0027] The technical specifications of the preservative-free product meet the requirements of Table 3. It should be dissolved in water before use.

[0028] After preparing the aggregates according to the above components, check the moisture content of the aggregates at various locations on site. Add water as needed according to the mix proportions for the day to ensure that the moisture content of the mixture is within 5.1% and the maximum dry density is not greater than 2.254 g / cm³. 3 It should be noted that, taking into account losses during actual transportation and mixing, the actual cement dosage can be approximately 0.5% greater than the cement dosage determined during the mixture composition design.

[0029] After mixing begins, samples must be taken at discharge to check if the mix proportions conform to the design. The mixer discharge must not be collected by free-fall piles or by loading with a loader. A hopper with a valve must be provided for direct loading and transportation of the mixture onto trucks. During loading, the vehicle should move back and forth, and the mixture should be loaded in three stages to prevent segregation.

[0030] Step 4. Mixed Material Transportation: Specifically, after the mixture is mixed, it is transported to the paving site using a truck equipped with mixing and discharging functions. It is important to note that the time from initial setting to final compaction of the mixture in the truck must not exceed 3 hours. Any material exceeding this timeframe due to transportation malfunctions or other reasons must be discarded.

[0031] Step 5. Mixture paving: First, moisten the subbase with water, then install steel formwork on the shoulder side and adjust the angle of the sensors and guide control lines. Use the paver to maintain continuous paving. Specifically, before paving, a uniform layer of cement slurry is evenly sprayed to moisten the subbase, with the spraying length not exceeding 30m to 40m of the paver's paving length. Simultaneously, steel formwork is installed on the shoulder side before paving, with a height of 18cm and a thickness of 4mm. The angle between the sensor arm and the guide control line is adjusted and checked, and the thickness and elevation of the subbase are strictly controlled to ensure that the road camber meets design requirements.

[0032] During paving, a single paver is used to pave the entire width, maintaining continuous paving throughout the process. The paver speed is controlled at 1.5 m / min to 2 m / min, and the tamping hammer vibration level is set to 4.0. The condition of the mixture behind the paver is checked continuously during paving to prevent segregation. Layers with excessive coarse aggregate are promptly removed and filled with freshly mixed asphalt.

[0033] Step 6. Compaction of the mixture: Use a road roller to compact the mixture in the following steps: static compaction, weak vibration, strong vibration and rubber-tired static compaction, and check the degree of compaction; Specifically, the compaction scheme is shown in Table 4: Each compaction cycle is 50m to 80m long, following a defined procedure and process. Compaction is carried out in the order of static compaction, weak vibration, strong vibration, and final compaction until no wheel tracks remain on the surface. During compaction, the degree of compaction is checked regularly using the sand cone method to ensure that the degree of compaction is greater than 98%. It is also important to note that when using a road roller, the wheel overlap should be no less than 1 / 2 of the wheel width, and the overlap width should be more than 30cm.

[0034] Step 7. Base layer curing: After the compaction degree test is qualified, cover with geotextile and add water for curing.

[0035] Specifically, after each section of the water-stabilized test section is compacted and passes the compaction test, it should be cured immediately and traffic should be closed. Curing should be carried out by covering with geotextile and supplementing with water trucks as needed. The curing period for environmentally friendly high-content RAP recycled cement stabilized base course is 1 day. During the curing process, the moisture loss inside the geotextile should be monitored frequently. If water shortage is found, water should be added in time to achieve the best curing effect. Curing is determined by the presence of water droplets when the geotextile is lifted.

[0036] Step 8. Surface layer construction.

[0037] Specifically, the surface layer includes a top layer (1), a middle layer (2), and a bottom layer (3). The laying materials are SBS modified SMA-13, SBS modified Sup-20, and Sup-25, respectively. The construction technology is existing technology and will not be elaborated here.

[0038] A schematic diagram of a rapid pavement structure consisting of an environmentally friendly, high-content RAP recycled cement stabilized mixture base course, formed after construction, is attached. Figure 1 As shown, from top to bottom, it includes a 4cm top layer (1), a 6cm middle layer (2), an 8cm bottom layer (3), an 18cm upper base layer (4), a 20cm lower base layer (5), a 20cm subbase layer (6), and a roadbed (7).

[0039] Comparative Example 1 The difference between this comparative example and Example 1 lies in the design and construction of the expressway overlay. A detailed overlay diagram is attached. Figure 2 As shown, the base course in this comparative example is a 38cm ordinary water-stabilized base course combined with a 20cm lime-stabilized crushed stone base course (i.e., the subbase course in Example 1). The ordinary water-stabilized base course includes new aggregates and cement, with the cement content being 3% of the weight of the new aggregates. The proportion of new aggregates and the sieve aperture size passing rate under the synthetic gradation are shown in Tables 5 and 6 below: In this comparative example, the construction method and mix proportion of the lime-stabilized crushed stone base course are any of the existing technologies, and will not be elaborated further here.

[0040] The specific construction method in this comparative example can be found in Example 1.

[0041] Comparative Example 2 The difference between this comparative example and Example 1 lies in the design and construction of the expressway overlay. A detailed overlay diagram is attached. Figure 3 As shown, in this comparative example, the upper base layer (4) is an 18cm high-mixture recycled water-stabilized crushed stone base layer without added curing agent. The high-mixture recycled water-stabilized crushed stone base layer includes graded crushed stone and cement, wherein the graded crushed stone is composed of the following raw materials: 20% RAP1 # Material, 20%RAP2 # Material, 10%RAP3 # 32% coarse aggregate, 18% fine aggregate; RAP1 # Particle size is 10mm~20mm, RAP2 # Particle size is 5mm-10mm, RAP3 # The aggregate particle size is 0mm–5mm, the coarse aggregate particle size is 16mm–31.5mm, and the fine aggregate particle size is 0mm–2.36mm. The cement addition is 4% of the environmentally friendly high-dosage RAP recycled cement stabilized mixture, and the moisture content is 4.5%. The blending ratio of new aggregate for high-dosage recycled water-stabilized crushed stone base course and the percentage of passing through each sieve size after synthesis are shown in Tables 7 and 8 below: The specific construction method in this comparative example can be found in Example 1.

[0042] Comparative Example 3 The difference between this comparative example and Example 1 is that the RAP1 used is different. # Material, RAP2 # material, RAP3 # The coefficient of variation of the material sieve aperture throughput is shown in Table 9: The coefficient of variation of recycled bitumen in RAP in this comparative example is shown in Table 10: The specific construction method in this comparative example can be found in Example 1.

[0043] Experiment Example 1: Road Performance Test Experiment Experimental methods: The road performance test items include splitting strength test, compressive resilient modulus test, fatigue resistance test and erosion resistance test. The experimental methods are carried out in accordance with the standards T0806-2009, T0806-2009, T0856-2009 and T0860-2009 respectively. The performance of the upper base course (3) mixture in Example 1 and Comparative Examples 1 to 3 was tested.

[0044] The results of the splitting strength test are shown in Table 11: Experimental Results Analysis: The table above shows that the splitting strength of the embodiment of the present invention was the highest at 1 day of age, followed by Comparative Example 3, while Comparative Example 2 had the lowest. Even at 7 days of age, the splitting strength of the embodiment of the present invention remained the highest. After 90 days, the splitting strength of the embodiment of the present invention was also the highest. This indicates that the pre-curing agent has a significant effect on the splitting strength of the water-stabilized curing material in the early stages. Specifically, comparing the splitting strength of Comparative Examples 1 and 2 with Example 1, it can be seen that the use of the pre-curing agent and the RAP material in combination has a significant synergistic effect, with a 1+1 greater than 2 effect. In Comparative Example 3, the RAP material, due to the lack of sieving and crushing, had a larger coefficient of variation for the passing rate of each sieve and the coefficient of variation for the old asphalt. The splitting strength of the mixture prepared from this RAP material decreased compared to Example 1.

[0045] The experimental results of compressive resilience modulus are shown in Table 12: Experimental Results Analysis: The table above shows that the compressive resilient modulus of the embodiment of the present invention is the highest at 1 day of curing, followed by Comparative Example 1, while Comparative Example 2 has the lowest. Furthermore, the compressive resilient modulus of the embodiment of the present invention remains the highest at 7 days of curing. This indicates that the no-curing agent has a significant effect on the compressive resilient modulus of the water-stabilized curing material in the early stages. Specifically, comparing the compressive resilient modulus of Comparative Examples 1 and 2 with that of Example 1, it is evident that the use of a mixture of no-curing agent and RAP material has a significant synergistic effect, resulting in a synergistic effect greater than the sum of its parts. However, after the coefficient of variation of the RAP material used in Comparative Example 3 increased, its compressive resilient modulus also decreased compared to Example 1.

[0046] The results of the fatigue resistance test are shown in Table 13: Analysis of Experimental Results: The table above shows that the fatigue life of Comparative Example 1 under different stress ratios was significantly lower than that of the other two specimens, indicating that milled material has a certain effect on improving the fatigue life of the mixture. This is because the asphalt film coating in the recycled water-stabilized mixture can reduce stress concentration at the interface between coarse aggregate and cement mortar, reducing the interface's weakness and the possibility of crack initiation, thereby improving fatigue resistance. Furthermore, the high toughness and deformation resistance of the asphalt material will prevent further crack propagation, which is beneficial for improving fatigue life. The fatigue lives of Comparative Example 2 and Example 1 are similar. Considering the discrete nature of the experimental data, their fatigue lives can be considered approximately equal, indicating that the absence of a curing agent has no significant effect on the fatigue life of the mixture. However, Comparative Example 3, after using RAP material with low performance and dimensional uniformity, showed lower fatigue resistance than Comparative Example 2 under multiple stress ratios, indicating that the performance and dimensional uniformity of RAP material have a significant impact on the fatigue resistance of the water-stabilized mixture.

[0047] The test results for erosion resistance are attached. Figure 4 As shown: Analysis of experimental results: The erosion resistance in this experiment was tested at 28 days of age. The results show that the erosion resistance of the water-stabilized mixture prepared in this embodiment is better than that of the water-stabilized mixtures in Comparative Examples 1, 2 and 3.

[0048] Experimental Example 2: Nanjing-Ma'anshan National Expressway Reconstruction and Expansion Project, Liucun Interchange to Tongjing Section Experimental Methods: To further investigate and verify the performance of high-dosage recycled water-stabilized base course and environmentally friendly high-dosage RAP recycled cement-stabilized base course technologies, this project applied the technology to the Liucun Interchange to Tongjing section of the Nanjing-Ma'anshan National Expressway Reconstruction and Expansion Project. Two sections of the main line were selected for trial paving of Comparative Example 2 and Example 1, respectively, and the actual application data were tested after 7 days. The test results are shown in Table 14, where the designed thickness is 180mm. Experimental results analysis: The expressway of the present invention meets the actual use standards in all indicators in practical applications, and has obvious advantages in all indicators compared with the expressway of Comparative Example 2.

[0049] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and not restrictive in all respects. Furthermore, it should be understood that although this specification describes embodiments, it does not encompass only one technical solution. This descriptive method is merely for clarity, and those skilled in the art should consider the specification as a whole. The technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A rapid pavement with a base course containing environmentally friendly high-dosage RAP recycled cement stabilized mixture, characterized in that: It includes a surface layer, a base layer and a roadbed (7) arranged sequentially from top to bottom, characterized in that: the base layer includes an upper base layer (4), a lower base layer (5) and a subbase layer (6); The upper base layer (4) and lower base layer (5) are laid with environmentally friendly high-content RAP recycled cement stabilized mixture, and the lower base layer (6) is laid with lime-stabilized crushed stone mixture. The environmentally friendly high-content RAP recycled cement stabilized mixture includes graded crushed stone, cement, and a curing-free agent. The graded crushed stone is composed of the following materials by mass percentage: 12%–20% RAP1 # Material, 18%~20%RAP2 # Material, 10%RAP3 # 32%–42% coarse aggregate, 18% fine aggregate; RAP1 # Particle size is 10mm~20mm, RAP2 # Particle size is 5mm-10mm, RAP3 # The particle size of the aggregate is greater than 0 mm and less than 5 mm, the particle size of coarse aggregate is 16 mm to 31.5 mm, and the particle size of fine aggregate is greater than 0 mm and less than 2.36 mm. The cement addition amount accounts for 2.5% to 4% of the total weight of the environmentally friendly high-content RAP recycled cement stabilized mixture; The amount of the curing agent added is 6% to 8% of the cement weight; RAP1 # Material, RAP2 # Material and RAP3 # The coefficient of variation for asphalt content in the asphalt mix is ​​4.5%–5.5%; the coefficient of variation for penetration is 6.5%–7.5%; the coefficient of variation for softening point is 5%–5.5%; and the coefficient of variation for ductility at 10℃ is 6%–9.5%. RAP1 # Material, RAP2 # Material and RAP3 # The coefficient of variation for the passing rate of sieves with apertures smaller than 9.5 mm is 4%–14%; the coefficient of variation for the passing rate of sieves with apertures larger than 9.5 mm is 2%–7%.

2. The rapid road surface with a base course containing environmentally friendly high-dosage RAP recycled cement stabilized mixture according to claim 1, characterized in that: The preservative-free agent includes anionic surfactants and swelling agents. The anionic surfactants include any one or more of anionic polyacrylamide and fatty alcohol polyoxyethylene ether phosphate. The swelling agents include any one or more of calcium magnesium oxide swelling agents and calcium sulfoaluminate swelling agents. The aforementioned growth regulator meets the following technical specifications: pH value 7-9; alkali content ≤0.75%; specific surface area ≥200m². 2 / kg; initial setting time ≥3h, final setting time ≤10h; water reduction rate ≥25%.

3. The rapid road surface with a base course containing environmentally friendly high-dosage RAP recycled cement stabilized mixture according to claim 1, characterized in that: The thickness of the upper base layer (4) is 18cm to 20cm, the thickness of the lower base layer (5) is 18cm to 20cm, and the thickness of the bottom base layer (6) is 20cm.

4. A rapid pavement with a base course containing environmentally friendly high-dosage RAP recycled cement stabilized mixture as described in claim 1, characterized in that: The surface layer includes a top layer (1), a middle layer (2), and a bottom layer (3); The thickness of the top layer (1) is 4cm to 5cm, the thickness of the middle layer (2) is 6cm to 8cm, and the thickness of the bottom layer (3) is 8cm to 10cm. The material used for laying the upper layer (1) is SBS modified SMA-13; The intermediate layer (2) is made of SBS modified Sup-20. The material used for laying the lower layer (3) is Sup-25.

5. A construction process for a rapid pavement base course containing an environmentally friendly high-dosage RAP recycled cement stabilized mixture, as described in any one of claims 1-4, characterized in that, Includes the following steps: Step 1. Lay the base layer (6); Step 2. Preparation of subbase (6) and roadbed (7): Check the quality of subbase (6) and roadbed (7) and carry out trial paving, measurement and layout work; Step 3. Mixing the mixture: Calculate the mix proportion of the mixture for the day based on the construction site, and mix the graded crushed stone, cement and curing agent according to the mix proportion; Step 4. Mixed Material Transportation: Step 5. Mixture paving: First, moisten the subbase with water, then install steel formwork on the shoulder side and adjust the angle of the sensors and guide control lines. Use the paver to maintain continuous paving. Step 6. Compaction of the mixture: Use a road roller to compact the mixture in the following steps: static compaction, weak vibration, strong vibration and rubber-tired static compaction, and check the degree of compaction; Step 7. Base layer curing: After the compaction degree test is qualified, cover with geotextile and add water for curing; Step 8. Surface layer construction.

6. The construction process for a rapid pavement base course containing environmentally friendly high-dosage RAP recycled cement stabilized mixture as described in claim 5, characterized in that: The quality inspection of the subbase (6) and roadbed (7) in step two includes compaction, deflection, elevation, centerline deviation, width, cross slope and flatness; the trial paving measurement and layout work includes road edge line, elevation and width.

7. The construction process for a rapid pavement base course containing environmentally friendly high-dosage RAP recycled cement stabilized mixture as described in claim 5, characterized in that: In step five, the paving speed is 1.5m / min to 2m / min, and the tamping hammer vibration level is 4.

0. The steel mold has a height of 18cm and a thickness of 4mm.

8. The construction process for a rapid pavement base course containing environmentally friendly high-dosage RAP recycled cement stabilized mixture as described in claim 5, characterized in that: In step six, the static compaction is performed 1 to 2 times, and the compaction speed is 1.5 to 1.7 km / h. The weak vibration frequency is 3 to 4 times, and the rolling speed is 1.8 to 2.2 km / h; The number of strong vibrations is 2 to 3 times, and the rolling speed is 1.8 to 2.2 km / h; The number of static compaction cycles of the rubber-tired rollers is 3 to 4, and the compaction speed is 1.8 to 2.2 km / h; The length of each compaction pass is 50m to 80m; the compaction overlap of the road roller is ≥30cm.

9. The construction process for a rapid pavement base course containing environmentally friendly high-dosage RAP recycled cement stabilized mixture as described in claim 5, characterized in that: The health maintenance period in step seven is 1 day.

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