In-situ Road cold recycler of roads belongs to the scope of road maintenance and reconstruction. Road Road cold recycler technology refers to making full use of the existing asphalt pavement materials (surface course and base course), adding some new aggregates if necessary, and adding a certain proportion in proportion. Amount of additives (cement, foamed asphalt, emulsified asphalt, lime, fly ash, etc.) at the natural ambient temperature (without heating) to continuously complete the milling, crushing, mixing, paving and compacting of the material in situ, Thereby, a new basic operation process with the required performance quality is constructed. This construction technique mainly solves the problem of damage to the asphalt pavement base.
In-situ cold regeneration technology is not only suitable for the maintenance and reconstruction of high-grade highways, but also for the maintenance and reconstruction of general roads and rural roads. This technology began to be applied in Europe, America and other countries in the 1950s, and it has been widely used in developed countries, and it is often used as the first choice for road maintenance. Since our country introduced the first pavement Road cold recycler machine from abroad in 1998, in recent years, the in-situ Road cold recycler technology has received widespread attention and recognition in the industry in China, and has been popularized rapidly, such as Liaoning, Jilin and Hebei. Such areas have been widely used, and have achieved good social and economic results.
The main construction machinery of in-situ Road cold recycler technology is a pavement Road cold recycler machine that integrates crushing and mixing. At present, the domestic models are mainly Wirtgen WR2500 and BMW PH121, etc., and the number is only a hundred. There are no geographical restrictions on the construction process of the Road cold recycler machine, and this process can be used on Lezi roads throughout the country. According to estimates, if it is to be promoted, a prefecture-level city should be equipped with 3-5 units. As a model that has been maturely applied in developed areas in Europe and the United States, the domestic stock is so low. There are many reasons for this. The expensive price of imported models should be one of the main reasons. In response to domestic demand, in order to promote this advanced construction technology and reduce construction costs, our company has jointly developed WR2400 and WR2000 pavement Road cold recycler machines with universities. This series of pavement Road cold recycler machines use special milling rotors, double bridge drives, and four wheels. Steering, cross slope automatic adjustment, the water spray system controlled by the microcomputer can automatically adjust the water spray proportion according to the proportion, the technical performance is advanced, and it can replace the foreign cold recycle machine.
The working device of the Road cold recycler machine is a milling mixing rotor equipped with a large number of special milling cutters. The machine runs along the working surface on the old road, the rotor descends to the set depth, rotates at high speed, mills and crushes and mixes the original pavement materials (including the surface layer and the base layer), and the water spray system is based on the travel speed and the milling depth. Pump water from the waterwheel and spray a certain amount of water into the working device cover automatically. The water delivery volume is precisely controlled by a microprocessor-controlled pumping system. The milling rotor thoroughly mixes the water with the milling material. Liquid stabilizer, such as hot asphalt (optional emulsified asphalt spraying device for cold recycler), can spray emulsified asphalt into the working device housing through specially designed nozzles; powder stabilizer, such as cement, can be added in advance according to the design amount Spread on the working surface of the regenerator. The regenerator will crush and mix the powdery stabilizer with the road and water at one time.
In case of poor original grading of the pavement regeneration layer, the missing aggregate can be spread on the road before construction, and the grading of the original pavement material can be improved by adding old materials and mixing.
Compared with traditional construction methods, in-situ Road cold recycler technology has many advantages, which can be summarized as the following 4 points:
1.Low cost
The cold-in-place regeneration of roads uses all the old pavement pavement materials, which reduces the excavation, transportation, disposal, and purchase of new materials of old pavement materials during road maintenance or reconstruction, resulting in a significant cost reduction. Compared with the traditional method, in-situ cold regeneration on the road can reduce the cost by 20% -46% with the thickness of the regeneration layer. The thicker the thickness of the cold regeneration road, the more cost reduction. For example, after the construction of the rock segment reconstruction project of Jilin 202 line in 2005, after comparing the economic and technological mutually exclusive schemes, the cement Road cold recycler construction process was used to regenerate the road base, saving investment by nearly 43%. The regeneration thickness is 27cm, and the cost of the regeneration layer project is 42 yuan / m2. The traditional process requires two layers of water to reinforce it. In addition, the original pavement material needs to be broken. The cost is 73 yuan / m2. From this example, we can see the cold regeneration technology Can greatly reduce engineering costs. The reuse of raw materials in high-grade pavement bases can save a lot of investment. In low-grade pavements, the use of Road cold recycler technology can increase the level of pavement bases and reduce the investment in the surface layer. The existence of this objective practical advantage makes it Geothermal regeneration technology has been recognized and has been the source of rapid development.
2.High efficiency
The construction of road in-situ Road cold recycler machinery can complete milling, crushing, adding, mixing and paving at one time, thereby simplifying the construction process and shortening the construction period. Using in-situ cold-recycling machinery, daily work can complete 5000-8000 square meters of workload. For example, in the October 2005 Cangzhou Dongwaihuan cold regeneration reconstruction project, a cold regeneration machine completed the on-site cold regeneration construction task with a road width of 16.5m and a length of 1km in only 3 days. The asphalt pavement was paved. The total construction period of the project lasted only 10 days, creating a new milestone in road reconstruction and rapid construction. The impact on road traffic was minimized, and it was well received by the citizens and leaders of Cangzhou.
3. Little affected by weather conditions
The old ground Road cold recycler can be constructed under uncertain weather conditions. Except when the rainfall is heavy, the general cloudy weather, light rain, and Road cold recycler machines can be used for construction. Even after heavy rain, construction can be resumed immediately. .
4. Significantly reduced impact on public transportation
The characteristics of Road cold recycler process construction are simple Road cold recycler process, large machinery intensive construction, few construction facilities, and insensitivity to traffic interference. The entire Road cold recycler machinery combination can be located in the same lane, without affecting the traffic of another lane. It can be used for open construction, and is particularly suitable for road construction with heavy traffic or narrow road widths. When half of the road is under construction, the other half will be opened as usual, thereby greatly improving the traffic conditions during construction. Therefore, as an efficient, energy-saving and environmentally friendly road maintenance method and new process, pavement Road cold recycler machines have become one of the main methods of road reconstruction in the world.
5. Good construction quality
In-situ Road cold recycler can be designed according to the actual situation of different road old pavement materials. Different additives are selected and the proportion is accurate, which can ensure the excellent quality and construction quality of the recycled materials, and form a thick and uniform bonding layer for construction. Guaranteed road life after maintenance. For example, the 7-day unconfined compressive strength of the regeneration layer on all regeneration sections of the Qingxian No. 1 Machine Factory and Cangzhou East Outer Ring Road and Jilin 202 Line Project (mixed cement dosage is 6%) has reached above 3Mpa. In general, the aggregate of the Road cold recycler layer uses the milling material RAP from the original pavement structure. The evaluation of the Road cold recycler layer is mainly controlled by its strength. The strength is determined by the design department according to the different pavement grades. There is no side-limiting resistance for 7 days. The compressive strength should be above 2 MPa, but for Road cold recycler of cement, the amount of cement should generally not exceed 6%. If there are too few granules in the recycled layer, the RAP grading is unreasonable (the gradation control curve can refer to the cement stabilized crushed stone grading curve), but after the test, some specifications are added to adjust the grading to ensure the normal cement dosage. Under the premise of ensuring the quality of the regeneration layer.
6, with environmental advantages
Using traditional road maintenance methods, the waste volume of asphalt pavement is huge, causing pollution to the environment. The exploitation of a large number of new materials will also cause reduction of resources and environmental damage. When using traditional excavation construction techniques, both the construction department and the owner The "waste" treatment is a headache, storage requires a lot of space and causes secondary pollution. The Road cold recycler construction process is adopted without the need to dispose of waste materials, which can completely avoid the above problems. Not only can it save a lot of investment, but it is also conducive to environmental protection, so it is called "green" construction technology.
The superiority of the Road cold recycler construction process, as well as the huge social and economic benefits it generates, will surely make pavement Road cold recycler machines more and more widely used.
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