Hot in-place recycling construction steps (part 2)

2023-09-11 11:33:13 ENUO

(4) The recycler works.

First, the first and second road heating machines are ignited on the construction section for heating. The heating time is generally 10 to 15 minutes. When the road surface temperature reaches about 190°C, the operator drives the first and second heating machines forward. Heating for another 5 to 10 minutes, then the operator returns the first and second heating machines to the starting position and continues heating. Repeat the heating several times (usually 3 times. The first static heating time is long, and the subsequent two static heating times are short , usually about 3 minutes), and finally the third heating machine starts to ignite and heat on the working surface. When the road surface temperature is about 210°C or the heating box temperature is about 480°C, the operator starts to drive the heating machine at a constant speed which no more than 2 meters/min. It should be noted that the heating machine is prohibited from heating at the same position for too long, which may cause the road surface temperature to be too high. The road surface temperature shall not be higher than 240°C. The measurement method is to use an infrared thermometer, and a dedicated measuring personnel will be assigned on site to control the temperature.

During the forward movement of the heating machine, the heating milling machine starts the front and rear milling preheating. When the three heating machines move forward 5m~6m as a whole, the heating milling machine enters the working surface, first drops the front milling machine, and the milling depth is 2.5cm, and then waits until all the heating boxes enter the milling surface and ignites the heating box. Then wait until the back milling machine enters the working surface, then drop the back milling machine to a depth of 1.5cm. There should be no obvious interlayers after milling. If the upper and lower layers of the original pavement are not well combined and are loose, all loose layers must be milled clean. At this time, the construction speed should be appropriately slowed down to ensure that there is enough space at the joint. The temperature (not lower than 60℃) ensures that the recycled pavement and the original pavement surface layer are well combined. The heated width is 10cm wider on both sides than the milling width to facilitate good longitudinal joints between the recycled pavement and the original pavement. During the milling process, arrange for full-time personnel to measure the milling width and depth and keep records. When there is a discrepancy between the milling width and the milling depth, timely feedback will be provided to the on-site management personnel, who will arrange for relevant personnel to make adjustments to achieve the specified width and depth.

According to the on-site investigation, during the construction of the fourth lane, the heating width is about 4m. From the outside of the solid line to the outside of the dotted line, during milling, the outside of the solid line is only about 25cm away from the edge of the road, and the narrow part is only 10cm. Considering the integrity of the road surface, milling starts from the middle of the solid line and clears the markings. During the construction of the third lane, the heating width is about 3.8m, and the fourth lane is heated by about 10cm at the same time, so that the longitudinal joints can be heated joints. When milling, it is also necessary to mill about 10cm more to ensure good longitudinal joints between the regenerated road surface and the fourth lane and the original road surface.

Before the remixer is run, the settings of 0.15% asphalt, 5% regenerant, and 15% new material addition are completed according to the mix ratio. When the milling machine begins to move forward, the mixer also begins to enter the working surface. The mixing method adopts intermittent mixing, and the mixing time is about 25 seconds, which fully ensures uniform mixing and no segregation. Hot air circulation heating is used in the material receiving port, conveyor belt, metering bin, and mixing pot of the compounding machine to ensure that the mixture can be heated in all aspects, increase the temperature of the compounding material, and ensure that the paving temperature must not be less than 120°C. For the detection of asphalt, regenerant, and new material addition amounts, total amount review is used.