I. Introduction
With the acceleration of urbanization, the scale of urban road construction projects is constantly expanding. During road construction, a large amount of old asphalt pavement construction waste is generated every year. If not treated in a timely manner, it not only wastes resources but also seriously occupies land and causes irreversible environmental damage. Therefore, recycling old asphalt pavements has become an urgent and important task.
II. Hot Recycling Method
Hot recycling is a commonly used recycling method. It involves multiple steps such as crushing, heating, screening, and mixing old pavement materials to reduce them into new asphalt mixtures for reuse in road construction. This method is widely applicable to the recycling of shale asphalt and petroleum asphalt in asphalt concrete pavements and can effectively reduce costs and improve resource utilization. However, it is not suitable for curved or steeply sloping pavements and has high requirements for furnace temperature and mixing time.
III. Cold Recycling Method
Cold recycling refers to the method of generating recycled asphalt mixtures by crushing, screening, and mixing old pavement materials at room temperature. This method is suitable for road sections with high hardness and a pavement thickness of 10cm or less. Compared to hot recycling, cold recycling requires less equipment and energy and is simpler to operate. However, because it involves restoration at room temperature, its product performance is relatively lower.
IV. Mechanical Recycling
Mechanical recycling involves removing, crushing, sorting, and screening the old pavement, then mixing it with raw materials to obtain recycled asphalt mixture. This method requires no heat treatment, produces no pollutants, and the finished product has high applicability and reliability, making it a low-cost and high-efficiency recycling method. However, it has high requirements for the old pavement, requiring multiple steps such as screening, and cannot be applied to multi-layer composite roads.
V. In-situ Recycling
In-situ recycling involves converting the old pavement into recycled asphalt mixture while maintaining the original pavement structure, using processes such as heating, crushing, and mixing. This method is suitable for roads that occupy large amounts of land and require both pavement structure preservation and recycling. In-situ recycling is environmentally friendly, but it is sensitive to the condition of the old pavement and requires precise construction techniques.
VI. Concrete Recycling Method
Concrete recycling refers to the process of crushing, processing, and sorting old concrete pavement to obtain recycled concrete materials for reuse in road construction. This method is simple and easy to implement, and holds promise for large-scale production of recycled concrete pavement. However, this method has strict requirements regarding the quality, particle size, moisture content, and impurity content of the original concrete pavement, and the types of materials that can be recycled are relatively limited.
VII. Conclusion
In summary, the recycling of old asphalt pavement has become an important measure for environmental protection and resource conservation. Currently, the application of asphalt pavement recycling methods in my country is not widespread, and further exploration and promotion in equipment, technology, and markets are needed.