What is the Classification of Asphalt Pavement Recycling Methods?


What is the Classification of Asphalt Pavement Recycling Methods?

The main recycling methods for old asphalt pavements are in-place recycling and mixing recycling at a factory. The former can be further divided into two types: in-place hot recycling and in-place cold recycling.

In-place hot recycling construction uses a comprehensive regenerating and re-paving unit to continuously realize processes such as heating, raking, adding recycled material, heating and mixing, and paving. This method requires relatively minor damage to the road surface layer, and the bonding layer and base layer are intact. The thickness of the old pavement layer is greater than 50mm, and the depth of various diseases and damages to the old asphalt is less than 50mm. The penetration of the old asphalt exceeds 20 (1/10mm), and the area of cracks is less than 40%. The characteristics of in-place hot recycling are a short construction cycle, small interference with traffic, small transportation volume, good environmental friendliness, complex equipment systems, high technical requirements, and a large investment. The technological flexibility is poor, and existing paving equipment and technologies cannot be utilized.

In-place cold recycling construction technology can be used for re-paving damaged road surfaces and roadbeds ranging from 100mm to 500mm. The old asphalt pavement materials are first milling, crushed, and collected, and a certain amount of lime, cement, emulsified asphalt, or foam asphalt is added as an additive. After mixing, it is used as a base mixture for regeneration. On this base, a wearing course and suitable surface treatment are applied as the surface layer and formed into a new road for use.

Mixing recycling at a factory refers to transporting milling old asphalt road materials to a mixing plant (station), crushing, screening, and processing them according to the requirements of different old materials and the requirements of recycling roads. Part or all of the old materials are used, and asphalt or regenerate is added, heated and mixed, and transported to the construction site for paving and rolling. Mixing recycling at a factory can be divided into continuous and batch types.

Mixing recycling at a factory is easy to control the process and quality, and can be used for recycling different old materials. It is suitable for producing a variety of materials for recycling. The construction period is long, the interference with traffic is large, the transportation costs are also large, but it can utilize existing construction equipment. The investment is small, and it is easy to start a project.