Hot mix asphalt pavement construction can be divided into two stages: mixing and transportation of asphalt mixture and on-site paving. After the hot-mix asphalt pavement is completed, wait for natural cooling and the surface temperature is lower than 50°C before opening to traffic.
Before mixing the asphalt mixture, the sample should be carried out according to the determined mixing ratio. During the trial mixing, the various mineral materials and asphalt used should be strictly measured. After the asphalt mixture of the sample is tested, the construction mix can be selected. Compare.
1) Mixing and transportation of hot mix asphalt mixture
(1) Asphalt mixture must be mixed with a mixer in an asphalt mixing plant (field, station).
(2) Asphalt concrete for urban trunk roads and expressways should be mixed with intermittent (separate mixing) mixers.
(3) The mixed asphalt mixture should be uniform, free from white material, agglomeration, or serious separation of coarse and fine materials.
(4) In order to cooperate with the mass production of the mixture, it is advisable to use a large-tonnage dump truck for transportation. During transportation, evenly spray a thin layer of oil and water on the bottom and side panels of the cargo compartment (1:3 mixture of diesel oil and water, and be careful not to accumulate oil at the bottom of the compartment.
(5) Asphalt mixture delivered from the factory shall be weighed on a vehicle-by-vehicle scale, the temperature shall be measured, and a triplicate bill of materials shall be issued.
(6) When unloading from the mixing pot to the car, unload the material evenly from front to back to prevent the separation of coarse and fine materials. The asphalt mixture should be covered during transportation.
2) Pavement of hot mix asphalt mixture
The base layer is prepared and set out. Before paving the asphalt mixture, the quality of the lower layer should be checked and confirmed. If the quality of the lower layer does not meet the requirements, or the permeable layer, sticky layer asphalt or thermal lower seal layer is not spread according to regulations, asphalt should not be paved. Surface layer. In order to control the paving thickness of the mixture, after the base layer is prepared, measurement and stakeout should be carried out, that is, sample piles are set along the centerline of the road surface and a quarter of the road surface width, and the loose paving thickness of the mixture is marked. When the automatic leveling paver is used, the control datum line guiding the running direction and elevation of the paver should be released.
For paving, the hot-mix asphalt mixture should be paved by machinery. For expressways and first-class roads, two or more pavers should be paved together to reduce the longitudinal cold joints. The vertical distance between two adjacent pavers is 10-30m, and there should be a 5 cm width of paving overlapping in the horizontal direction. During the paving process of the asphalt paver, the dump truck unloads the mixture into the hopper and then transfers the mixture to the spiral paver through the conveyor. As the paver advances, the spiral paver is The mixture is spread evenly across the width of the pavement belt, then compacted and leveled by spreading plates.
The transport capacity of the transport vehicle should be slightly larger than the working capacity of the leading machinery. When urban trunk roads and expressways start to be paved, the number of vehicles waiting for unloading should not be less than 5. It is advisable to adopt two (including two) or more paver machines to work in echelons for joint paving. The overlap between two adjacent panels should be 5-10cm, the distance between the front and rear paver should be 10-30m, and the qualified temperature of the mixture should be maintained. The paper should have an automatic leveling and thickness adjustment device, a receiving hopper with sufficient capacity and sufficient power to push the material truck, a preliminary vibrating and ironing device, and the paving width can be adjusted. It is not suitable for construction when the construction temperature of urban trunk roads and expressways is lower than 10°C, or when the construction temperature of other grades of roads is lower than 5°C. The asphalt mixture should be paved slowly, evenly, and continuously without interruption. The mixture paved by machinery shall not be trimmed manually.
Rolling, followed by the rolling process after paving, the compaction is divided into three stages: initial pressing, re-pressing, and final pressing (including forming). During normal construction, the rolling temperature is 110-140°C, and not lower than 110°C; for low-temperature construction, the rolling temperature is 120-150°C. The temperature at the end of rolling should not be lower than 65-80°C. The rolling speed should be slow and even. The temperature of the material is high during the initial pressure, and no shifting or cracking may occur. The road roller should roll from the outside to the center, and the adjacent rolling belts overlap by 1/3 to 1/2 of the wheel width. The drive wheels should face the paver when rolling. Heavy-duty tire rollers or vibratory rollers should be used for re-pressing, and it should not be less than 4-6 times to achieve the required compaction degree. The final pressure can be done with a heavy-duty tire roller or a vibratory roller with no vibration, and it should not be less than 2 times until there is no wheel mark. During rolling after continuous paving, the road roller shall not stop at will. In order to prevent the roller from sticking to asphalt, water mixed with washing powder can be sprayed on the roller, and diesel oil is strictly prohibited.
The road roller shall not turn, turn around or stop and wait on the unrolled and cooled road. It is also not allowed to park any mechanical equipment or vehicles on the formed road surface, and it is not allowed to scatter mineral materials, oil, and other sundries to strengthen the awareness of finished product protection. The ultimate goal of rolling is to ensure that the degree of compaction and flatness meets the specification requirements.
The compacted asphalt mixture should meet the requirements of flatness and compaction. Therefore, the thickness of each layer of asphalt mixture should not be greater than 10cm, otherwise, it should be paved and compacted in layers. It is divided into three stages: initial pressure, re-pressure, and final pressure. The initial compaction is carried out at a relatively high temperature after the mixture is paved. It is advisable to use a 60-80kN double-wheel roller to compact it evenly twice at a slow speed. The compaction temperature should meet the requirements of the construction temperature. After the initial compaction, check the flatness, and road The arch should be properly adjusted if necessary; re-pressing is to use heavy-duty wheeled road rollers or vibratory rollers to roll 4 to 6 times after the initial pressing. To achieve the required compaction degree, there is no obvious wheel track. Therefore, re-pressing Compaction is the main stage to achieve the required compactness; the final compaction is carried out immediately after recompression, and the final compaction should be done with a 60-80kN double-wheel roller for no less than 2 times, and the wheel tracks generated during the compaction process should be eliminated and ensured. Good smoothness of the road surface.