Construction process of road asphalt lower surface layer

Abstract

The invention relates to the technical field of road construction, in particular to a construction process of a road asphalt lower surface layer, which comprises the following steps: S1, mixture mixing, S2, mixture index inspection, S3, mixture heat preservation transportation, S4, paving by a paver, S5, mixture compaction, S6, jointing, S7, self-inspection of various technical indexes and S8, acceptance check. The mixture is divided into a three-layer structure and loaded into a carriage of the transport vehicle, the single-layer structure of the mixture comprises a bottom layer, a middle layer and a top layer, the temperature of the bottom layer is higher than that of the middle layer, and the temperature of the top layer is higher than that of the bottom layer; after loading is completed, the top of the carriage is provided with double-layer heat preservation tarpaulin; in the step S4, when the paver is used for paving the mixture, the mixture in the carriage is taken out from top to bottom to enter the paver, and it is ensured that when the mixture reaches the construction area, the temperature difference between all layers of the mixture in the carriage is small.

Description

Technical Field

[0001] The present invention relates to the technical field of road construction, and in particular to a construction process for the lower asphalt layer of a road. Background Art

[0002] The lower asphalt layer refers to the bottom part of the asphalt pavement structure, usually located above the base course and below the upper layer. The lower asphalt layer can disperse the vehicle load, reduce the pressure on the base course, provide a flat foundation for the upper layer, ensure the uniformity of the road surface, and prevent water penetration to protect the base course and subgrade.

[0003] In the prior art, the construction process of the lower asphalt layer generally includes steps such as mixture mixing, mixture index inspection, mixture heat preservation transportation, paver paving, mixture compaction, jointing, self-inspection of various technical indicators, and acceptance.

[0004] Currently, during the mixture heat preservation transportation in the prior art, the mixture is usually loaded into the carriage of the transport vehicle according to the same standard for transportation, and then heat preservation measures are used to transport the mixture in the carriage. However, due to the heat dissipation difference at different positions in the carriage, there will be a large temperature difference in the mixture in different areas of the carriage after being transported to the construction site, resulting in poor consistency between the mixtures. Eventually, the consistency of the lower asphalt layer of the road after paving and compaction is insufficient, reducing the road standard. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present application provides a construction process for the lower asphalt layer of a road.

[0006] The construction process for the lower asphalt layer of a road provided by the present invention adopts the following technical solutions:

[0007] A construction process for the lower asphalt layer of a road includes the following steps: S1 mixture mixing, S2 mixture index inspection, S3 mixture heat preservation transportation, S4 paver paving, S5 mixture compaction, S6 jointing, S7 self-inspection of various technical indicators, and S8 acceptance;

[0008] In S3, the mixture is loaded into the carriage of the transport vehicle in a three-layer structure. The single-layer structure of the mixture includes a bottom layer, a middle layer, and a top layer. The temperature of the bottom layer is higher than that of the middle layer, and the temperature of the top layer is higher than that of the bottom layer; after loading, a double-layer heat preservation tarpaulin is used on the top of the carriage.

[0009] In S4, when using the paver to pave the mixture, the mixture in the carriage is taken out from top to bottom into the paver.

[0010] Preferably, in S3, the mixture materials at different temperatures are first separately loaded into a plurality of sub-packaging boxes, and then the plurality of sub-packaging boxes are stacked on the carriage in a three-layer stacking structure.

[0011] Preferably, in S3, the top of the sub-packaging box is open, the sub-packaging box is injection-molded from high-density polyethylene, and the inner side wall of the sub-packaging box is provided with a honeycomb structure.

[0012] Preferably, in S3, when the mixture material is loaded into the sub-packaging box, it does not need to be filled, and a 5-cm air layer is reserved between the upper and lower sub-packaging boxes.

[0013] Preferably, in S3, a contact temperature sensor is provided on the inner side wall of each sub-packaging box, and the contact temperature sensor in the sub-packaging box is used to monitor the temperature change of the mixture material during transportation.

[0014] Preferably, in S3, at least two lifting rings are provided on the top of each sub-packaging box, and a groove is also provided at the bottom of the sub-packaging box. When the sub-packaging boxes are stacked, the lifting rings of the lower sub-packaging box are embedded into the grooves of the upper sub-packaging box.

[0015] Preferably, in S4, the paver uses the sub-packaging box as a storage bin, and a quick-release structure is provided between the paver and the storage bin. When the mixture material in the storage bin is used up and needs to be replenished, the empty sub-packaging box is first removed, and then a new sub-packaging box is loaded, and the replenishment is quickly realized.

[0016] Preferably, in S5, the roller is used to perform three stages of initial compaction, re-compaction and final compaction on the paved mixture material. Both the initial compaction and the final compaction use a double-drum roller, and the re-compaction uses a rubber-tired roller. The roller is installed with a Beidou positioning module to record the compaction track, and the compaction situation is displayed through a color heat map. Blue indicates compaction 0 to 1 time, yellow indicates compaction 2 times, and red indicates compaction 3 times and more.

[0017] Preferably, in S3, a mechanical rolling curtain device is installed on the top of the carriage, and the double-layer heat-insulating tarpaulin is connected to the mechanical rolling curtain device.

[0018] Preferably, the double-layer heat-insulating tarpaulin includes an inner tarpaulin and an outer tarpaulin. The inner tarpaulin is an aluminum foil composite glass fiber, and the outer tarpaulin is a PVC-coated waterproof cloth. The mechanical rolling curtain device automatically adjusts the covering layers according to the ambient temperature. When the ambient temperature < 10°C, the top of the carport is covered with both the inner tarpaulin and the outer tarpaulin; when the ambient temperature ≥ 10°C, the top of the carport is only covered with the outer tarpaulin.

[0019] The beneficial effects of the present invention are as follows:

[0020] 1. Since in the carriage, the temperature loss at the top layer is faster than that at the bottom layer, and the temperature loss at the bottom layer is faster than that at the middle layer, loading materials according to the above temperature difference can better ensure that when the mixture reaches the construction area, the temperature difference between the layers of the mixture in the carriage is small, and the discharge temperature of the mixture is closer to the expected temperature.

[0021] 2. Multiple sub-packaging boxes are stacked on the carriage in a three-layer stacking structure, which can further improve the heat preservation effect of the mixture during transportation and improve the position stability of the mixture in each interval of the carriage.

[0022] 3. Since a 5-cm air layer is reserved between the sub-packaging boxes of the upper and lower layers, it can not only improve the heat insulation effect between the upper and lower sub-packaging boxes, but also prevent the mixture in the lower sealed packaging box from being compacted by the upper sub-packaging box, ensuring that the density of the mixture in each area of the carriage is relatively consistent when it reaches the construction site.

[0023] 4. After using the sub-packaging box as the storage bin of the paver, when the mixture in the storage bin is used up and replenishment is required, the empty sub-packaging box is removed, and a new sub-packaging box is directly loaded by hoisting, then the replenishment can be quickly realized, reducing the construction suspension time caused by replenishment and effectively ensuring that the construction period is completed within the expected time. Description of the Drawings

[0024] Figure 1 is the flow chart of the construction process of the lower layer of road asphalt in the embodiment of the present application;

[0025] Figure 2 is the cross-sectional view of the carriage and the sub-packaging box in the embodiment of the present application.

[0026] Description of the Reference Numerals: 1. Mixture; 2. Carriage; 31. Inner tarpaulin; 32. Outer tarpaulin; 4. Sub-packaging box. Detailed Embodiment

[0027] The following will be combined with Figure 1 - Figure 2 and the embodiments to further illustrate the present invention.

[0028] Embodiment 1

[0029] This embodiment discloses a construction process of the lower layer of road asphalt.

[0030] Referring to Figure 1 and Figure 2 , the construction process of the lower layer of road asphalt includes the following steps:

[0031] S1: Mixing the mixture 1;

[0032] Mixture 1 includes asphalt, aggregates, fillers, and additives. Among them, asphalt, as a binder, binds the aggregates together. Ordinary road petroleum asphalt or modified asphalt can be selected as the asphalt. The aggregates include coarse aggregates and fine aggregates. The coarse aggregates are gravel with larger particle sizes, providing strength and stability, and the fine aggregates are sand with smaller particle sizes, filling the voids between the coarse aggregates. Fillers are used to further fill the spaces between the aggregates, increasing the density of Mixture 1, and mineral powders such as limestone powder or cement can be selected as the fillers. Additives are used to improve the performance of Mixture 1, such as anti-aging and water damage resistance, and anti-stripping agents, fibers, and rubber powder can be selected as the additives.

[0033] S2: Inspection of the indicators of Mixture 1;

[0034] Mixture 1 needs to be subjected to gradation inspection, asphalt content inspection, temperature control inspection, volume parameter inspection, mechanical property inspection, and water stability inspection. In the gradation test, a shaking sieve machine and a standard square-hole sieve are used to test the passing rate of Mixture 1, so as to obtain the compliance between the actual gradation and the designed gradation. In the asphalt content test, a centrifugal asphalt extractor and the solvent method are used to detect the deviation between the actual asphalt content and the designed value. In the temperature control inspection, an insertion digital display thermometer is used to measure the mixing temperature. In the volume parameter inspection, a Marshall compactor is used to detect the void ratio of Mixture 1, and the deviation between the actual void ratio and the designed value is measured. In the mechanical property inspection, a rutting tester is used to detect the dynamic stability of Mixture 1. In the water stability inspection, an immersion Marshall test is used to detect the residual stability of Mixture 1.

[0035] S3: Heat preservation transportation of Mixture 1;

[0036] When loading in the carriage 2, a layered temperature management system and a dynamic covering system are adopted. Specifically, Mixture 1 is divided into a bottom layer, a middle layer, and a top layer with the same thickness. The temperatures of the bottom layer and the top layer are both higher than that of the middle layer, and the temperature of the top layer is higher than that of the bottom layer. In this embodiment, the temperature of the bottom layer is 2°C higher than that of the middle layer, and the temperature of the top layer is 3°C higher than that of the middle layer. The purpose is that in the carriage 2, the temperature loss at the top layer position is faster than that at the bottom layer, and the temperature loss at the bottom layer position is faster than that at the middle layer. Therefore, by loading with the above temperature difference, it can better ensure that when Mixture 1 reaches the construction area, the temperature difference between the layers of Mixture 1 in the carriage 2 is smaller, and the discharge temperature of Mixture 1 is closer to the expected temperature.

[0037] A mechanical rolling curtain device is installed on the top of the carriage 2. The mechanical rolling curtain device uses a double-layer thermal insulation tarpaulin, including an inner tarpaulin 31 and an outer tarpaulin 32. The inner tarpaulin 31 is an aluminum foil composite fiberglass, and the outer tarpaulin 32 is a PVC-coated waterproof cloth. The mechanical rolling curtain device automatically adjusts the covering layers according to the ambient temperature. When the ambient temperature < 10°C, both the inner tarpaulin 31 and the outer tarpaulin 32 are covered. When the ambient temperature ≥ 10°C, only the outer tarpaulin 32 is covered. On the one hand, it ensures that the mixture 1 in the carriage 2 can obtain a better temperature retention effect when the ambient temperature is low. On the other hand, it ensures that the waterproof outer tarpaulin 32 is always covered, reducing the situation of rainwater entering the carriage 2.

[0038] Finally, by combining the layered temperature management system and the dynamic covering system, not only can the temperature difference between the mixtures 1 be reduced to ensure the consistent performance of the mixture 1 when it reaches the construction site, but also the mixture 1 can have a better temperature retention effect during transportation, avoiding the temperature of the mixture 1 dropping too quickly to a temperature unsuitable for construction, and extending the effective construction time of the mixture 1 at the construction site.

[0039] In addition, it is necessary to regularly detect the temperature of each layer, collect the temperature change data during transportation, and continuously analyze the influence of factors such as transportation distance and ambient temperature on the temperature of the mixture 1 in the carriage 2, so as to adjust the loading temperature between the bottom layer, middle layer and top layer in the carriage 2 during subsequent transportation, and further improve the temperature difference of the mixture 1 after it reaches the construction site.

[0040] S4: Paving of the mixture 1;

[0041] After the mixture 1 is transported to the construction site, it is transferred into the paver. During the transfer process, the mixture 1 in the carriage 2 is transferred from top to bottom. The paver is used to pave the mixture 1. Before paving, the screed should be preheated to above 100°C. During the paving process, the paving speed is maintained at 2 - 4 m / min.

[0042] S5: Compaction of the mixture 1;

[0043] The roller is used to carry out three stages of initial compaction, double compaction and final compaction on the paved mixture 1. The initial compaction uses a double steel-wheel roller, with 1-2 static compaction passes and 2-3 vibratory compaction passes. The temperature is controlled above 130°C and the speed is 2-4 km / h. This can effectively improve the initial density of the asphalt mixture 1, reduce the void ratio, and ensure the stability of the road surface structure. Because in the static compaction stage, the loose state after paving is mainly eliminated, and the mixture 1 is initially stabilized; in the vibratory compaction stage, the mixture 1 is further compacted through high-frequency vibration, and the density is increased to more than 85%, while reducing wheel marks and surface unevenness. High-temperature rolling helps the particles of the mixture 1 to rearrange, enhancing the bonding force, laying a good foundation for the subsequent double compaction and final compaction, and ultimately ensuring the durability and rutting resistance of the road surface. The double compaction is carried out with a rubber-wheel roller for 4-6 passes, and the temperature is 100-120°C. The rubber-wheel roller can perform flexible compaction, and its kneading effect can further compact the mixture 1, filling the tiny voids remaining after the initial compaction, and improving the density and uniformity of the road surface. The final compaction is carried out with a double steel-wheel roller for 2-3 static compaction passes, and the temperature is ≥90°C.

[0044] Correspondingly, contact temperature sensors are installed on both sides of the double steel wheels or rubber wheels of the roller, and LED indicator lights are installed in the cab. When the temperature sensor of the roller is greater than the required temperature, the LED indicator light turns green, and normal rolling can be carried out at this time. When the temperature of the roller is slightly lower than the required temperature (such as when it is lower than the required temperature but the deviation temperature does not exceed 5°C), the LED lights yellow, and normal rolling can still be carried out at this time, but attention needs to be paid to the subsequent rolling temperature. When the temperature of the roller is much lower than the required temperature, the LED indicator light turns red, and rolling needs to be stopped at this time until the temperature of the double drum wheels or rubber wheels of the roller is adjusted to the required temperature.

[0045] In addition, the roller is installed with a Beidou positioning module to record the rolling track, and finally the rolling situation is displayed through a color heat map. For example, blue indicates 0 to 1 pass of rolling, yellow indicates 2 passes of rolling, and red indicates 3 passes and more of rolling, which is convenient for construction personnel to accurately obtain the compaction situation. Through the above design, the qualified rate of compaction can be effectively improved, and the over-compacted area can be effectively reduced.

[0046] S6: Joints;

[0047] The longitudinal joints adopt the hot joint method, with an overlap of 10-15 cm during paving to ensure that the temperature of the mixture 1 at the joint is the same. During rolling, first roll across the joint for 20-30 cm, and then compact along the joint direction to avoid obvious marks. The transverse joints are treated with a flat joint. Use a cutting machine to cut the end neatly, apply emulsified asphalt to enhance the bonding, and preheat the joint before paving the new material to ensure the tight combination of the new and old mixtures 1. During rolling, first transverse and then longitudinal, and focus on compacting the joint area to ensure that the density is the same as that of the adjacent area. The joint treatment needs to strictly control the temperature and flatness to avoid vehicle jumping or cracking, and ultimately ensure the continuity of the road surface and the driving comfort.

[0048] S7: Self-inspection of all technical indicators;

[0049] Use a laser profiler or a 3m straightedge to detect the flatness, with the requirement that the gap ≤ 3mm and IRI ≤ 2.0 m / km. Secondly, use a nuclear density gauge or the core sampling method to detect the compactness, with the requirement that it reaches over 96% of the Marshall standard density. Then, use an infrared thermal imager to check the temperature uniformity to ensure there is no low-temperature area or segregation phenomenon. Finally, use a friction coefficient tester and a water permeability tester to detect the skid resistance (BPN ≥ 45) and waterproof performance (water permeability coefficient ≤ 120 mL / min) respectively. During the self-inspection process, data should be recorded, and problems should be rectified in a timely manner to ensure that all indicators meet the design and specification requirements before acceptance.

[0050] S8: Acceptance;

[0051] Sign the acceptance report, transfer it to the maintenance unit, and enter the quality warranty period.

[0052] Example 2

[0053] This example also discloses a construction process for the lower asphalt layer of a road.

[0054] Refer to Figure 1 and Figure 2 , the difference from Example 1 is that:

[0055] During the loading process of the heat-insulated transportation of mixture 1 in S3, mixtures 1 at different temperatures are first respectively loaded into multiple sub-packaging boxes 4. The top of the sub-packaging box 4 is open, which is convenient for loading and taking materials during the subsequent paving process. The sub-packaging box 4 is injection-molded from high-density polyethylene, and a honeycomb structure is provided on the inner sidewall to achieve temperature convection inhibition, reduce heat dissipation, and improve the heat-insulating and heat-preserving ability. Then, multiple sub-packaging boxes 4 are stacked on the carriage 2 in a three-layer stacking structure. Loading the mixture 1 in this way can further improve the heat-preserving effect of the mixture 1 during transportation and improve the position stability of the mixture 1 in each interval in the carriage 2.

[0056] When the mixture 1 is loaded into the sub-packaging box 4, it is not necessary to fill it up, and a 5-cm air layer is reserved between the upper and lower sub-packaging boxes 4. On the one hand, the 5-cm air layer can improve the heat-insulating effect between the upper and lower sub-packaging boxes 4 through air insulation. On the other hand, it can prevent the mixture 1 in the lower sub-packaging box from being compacted by the upper sub-packaging box, ensuring that the compactness of the mixture 1 in each area of the carriage 2 is relatively consistent when it reaches the construction site, and avoiding the mixture 1 in the lower layer from being overly compacted, which may affect the subsequent normal paving or require re-stirring and dispersing.

[0057] Since the mixture 1 in the carriage 2 is loaded in separate boxes, the difficulty of temperature monitoring of the mixture 1 during transportation is greatly reduced. Specifically, contact temperature sensors are provided on the inner side walls of each separate loading box 4. During the transportation of the mixture 1, the contact temperature sensors in the separate loading box 4 are used to monitor the temperature change of the mixture 1 during transportation, so as to facilitate subsequent analysis and adjustment.

[0058] To facilitate the picking up and placing of the separate loading box 4 at the carriage 2, at least two lifting rings are provided on the top of each separate loading box 4, so as to facilitate the use of a construction crane to lift the separate loading box 4, achieving the effect of convenient picking up and placing of the separate loading box 4. Further, to prevent the lifting rings from blocking the stacking of the separate loading boxes 4, grooves are provided at the bottom of the separate loading box 4. When the separate loading boxes 4 are stacked, the lifting rings of the lower separate loading box 4 are embedded into the grooves of the upper separate loading box 4 to achieve avoidance. At the same time, the lifting rings and the grooves limit the positions of the upper and lower separate loading boxes 4, improving the position stability of the stacked separate loading boxes 4.

[0059] The difference from the first embodiment is also that:

[0060] During the paving process of the mixture 1 in S4, the paver uses the separate loading box 4 as a storage bin, and the storage bin of the paver is detachably installed. For example, it can be installed using a quick hydraulic locking device, installed using a modular flange connection structure, or installed using a self-locking dovetail groove guide structure. Compared with the method of the transport vehicle and the paver running in parallel and continuously feeding the paver through a conveyor belt, in the method of the present invention, the paver uses the storage bin for storage, without the need for the transport vehicle to follow, reducing the requirements for the construction space, and thus being more suitable for narrow road construction. In addition, after using the separate loading box 4 as the storage bin of the paver, when the mixture 1 in the storage bin is used up and needs to be replenished, the empty separate loading box 4 is removed, and a new separate loading box 4 is directly loaded by means of lifting, and then the replenishment can be quickly realized, reducing the construction suspension time caused by replenishment and effectively ensuring that the construction period is completed within the expected time. Similarly, during the paving process of this embodiment, the separate loading boxes 4 in the carriage 2 are lifted off the carriage 2 from top to bottom. The above are all preferred embodiments of the present invention, and the protection scope of this application is not limited accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A construction process for a road asphalt lower layer, comprising the following steps: S1: mixing the mixture (1); S2: testing the index of the mixture (1); S3: transporting the mixture (1) under heat preservation; S4: paving by a paver; S5: compacting the mixture (1); S6: jointing; S7: self-checking various technical indexes; and S8: acceptance, characterized in that: In S3, the mixture (1) is divided into a three-layer structure and loaded into a carriage (2) of a transport vehicle, wherein the single-layer structure of the mixture (1) includes a bottom layer, a middle layer and a top layer, wherein the temperature of the bottom layer is higher than the temperature of the middle layer, and the temperature of the top layer is higher than the temperature of the bottom layer; after the loading is completed, a double-layer thermal insulation tarpaulin is used on the top of the carriage (2); In S4, when the mixture (1) is spread by the spreading machine, the mixture (1) in the carriage (2) is taken out from top to bottom into the spreading machine.

2. A construction process for a road asphalt lower layer according to claim 1, characterized in that: In S3, the mixed materials (1) at different temperatures are first loaded into a plurality of sub-packaging boxes (4) respectively, and then the plurality of sub-packaging boxes (4) are stacked on the carriage (2) in a three-layer stacking structure.

3. A construction process for a road asphalt lower layer according to claim 2, characterized in that: In S3, the top of the packaging box (4) is open, the packaging box (4) is injection-molded with high-density polyethylene, and the inner wall of the packaging box (4) is provided with a honeycomb structure.

4. A construction process for a road asphalt lower layer according to claim 3, characterized in that: In S3, the mixed material (1) does not need to be filled completely in the sub-packaging box (4), so that a 5 cm air layer is retained in the sub-packaging box (4) between the upper and lower layers.

5. The construction process of the road asphalt lower layer according to claim 4 is characterized by: In S3, the inner wall of each of the packaging boxes (4) is provided with a contact temperature sensor, and the contact temperature sensor in the packaging box (4) is used to monitor the temperature change of the mixed material (1) during transportation.

6. A construction process for a road asphalt lower layer according to claim 5, characterized in that: In S3, at least two lifting rings are arranged on the top of each of the packaging boxes (4), and a groove is also arranged on the bottom of the packaging boxes (4). When the packaging boxes (4) are stacked, the lifting rings of the lower packaging boxes (4) are embedded in the grooves of the upper packaging boxes (4).

7. A construction process for a road asphalt lower layer according to claim 6, characterized in that: In S4, the paver uses a packing box (4) as a material storage box, and a quick-release structure is provided between the paver and the material storage box. When the mixed material (1) in the material storage box is used up and needs to be refilled, the empty packing box (4) is first removed, and then a new packing box (4) is loaded, so that the refilling can be quickly achieved.

8. The construction process of the road asphalt lower layer according to claim 1, characterized in that: In S5, the paved mixture (1) is subjected to initial compaction, secondary compaction and final compaction by a roller. Both the initial compaction and the final compaction are performed by a double steel wheel roller, and the secondary compaction is performed by a rubber wheel roller. The roller is equipped with a Beidou positioning module to record the compaction trajectory and display the compaction situation through a color heat map. Blue represents 0 to 1 times of compaction, yellow represents 2 times of compaction, and red represents 3 times of compaction or more.

9. The construction process of the road asphalt lower layer according to claim 1, characterized in that: In S3, a mechanical rolling curtain device is installed on the top of the carriage (2), and the double-layer thermal insulation tarpaulin is connected to the mechanical rolling curtain device.

10. A construction process for a road asphalt lower layer according to claim 9, characterized in that: The double-layer heat-insulating tarpaulin comprises an inner tarpaulin (31) and an outer tarpaulin (32), wherein the inner tarpaulin (31) is aluminum foil composite glass fiber, and the outer tarpaulin (32) is PVC coated waterproof cloth. The mechanical rolling curtain device automatically adjusts the number of covering layers according to the ambient temperature. When the ambient temperature is less than 10°C, the top of the carport is covered with both the inner tarpaulin (31) and the outer tarpaulin (32); when the ambient temperature is greater than or equal to 10°C, the top of the carport is only covered with the outer tarpaulin (32).

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