1. Excavation of old asphalt roads
The old materials used for regeneration should not be mixed with too much non asphalt mixture materials, so debris should be removed as much as possible during excavation and transportation. The machinery used to excavate the surface layer generally includes planers, cold milling machines, air picks, and hydraulic pliers on excavators, as well as manual excavation. Asphalt pavement excavation is a labor-intensive, time-consuming, and essential process.
2. Crushing and screening of old asphalt materials
The particle size of the old material used for recycled asphalt mixture should not be too large, otherwise it will be difficult to incorporate the recycling agent into the old material, which will affect the regeneration effect of the mixture. Generally speaking, the particle size of crushed old materials is generally less than 25mm, and the maximum does not exceed 35mm. The crushing methods include manual crushing, mechanical crushing, and heating decomposition. The currently used crushing machinery includes impact crushers, jaw crushers, roller crushers, and secondary crushing screening machines. The methods of heating decomposition include indirect heating (i.e. placing the mixture on a steel plate and heating it under it), steam heating decomposition, and hot water decomposition. Some units also lay old materials on the ground, grind them with tracked tractors and three wheeled rollers, and then screen them for later use. Grid type rollers have been used abroad to crush old materials, and the surface of the roller's steel wheels is not smooth, but made into a grid type to help reduce the possibility of old materials being crushed.
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