Double asphalt paving, also known as "hot on hot" paving internationally, is referred to as "double integral paving" in China. This asphalt paving technology was patented by a German professor in 1993. What are the technical features of double paving? A comparison between traditional asphalt paving and the double integral asphalt paving structure reveals that the traditional method involves layered paving, sequential compaction, and the application of an adhesive layer between the layers. The drawbacks of this technique include: the wearing layer cools quickly, affecting compaction quality; the layers are susceptible to external environmental pollution; the application of adhesive oil increases costs; and the construction time is lengthy, with low equipment utilization. Compared to traditional asphalt paving methods, double integral paving boasts more advantages. The double paving technique, due to the hot-to-hot connection of the adhesive and wearing layers during paving, has no clear distinction between layers during rolling, resulting in better interlocking of the wearing layer and the adhesive layer. The two different asphalt mixtures with different blends integrate into one at the bonding surface, creating a more solid interlocking between layers.
The double-layer paving technology optimizes the road structure by reducing the thickness of the wear layer and increasing the thickness of asphalt mixture in the bonding layer (middle layer), enhancing the asphalt pavement's resistance to rutting and extending its service life accordingly. Due to the thermal bonding between the wear layer and the bonding layer, cooling is slower, improving the traditional asphalt paving's drawback of rapid cooling due to the thin wear layer. It also allows for the appropriate temperature and time for compacting the wear layer, enabling a more rational arrangement of the compaction process for better density.
The second phase of the highway features a test section with a double-layer asphalt paving technique. The wearing course of the test section is available in two thicknesses: 3cm and 2.5cm. Initial compaction after laying was achieved using the sand-bag method, followed by inspections behind the smoothing plate. The final compaction rates were as follows: flatness of 0.49~0.79mm, texture depth over 0.6mm, meeting the road acceptance standards.
The nation's highway construction is experiencing a leap in development. Understanding the technical features of double-layer paving, if one-tenth of the newly constructed and reconstructed national and provincial roads and expressways, which meet the conditions for asphalt double-layer paving, adopt this method each year, it would not only shorten the construction and maintenance cycles of highways but also save a significant amount of asphalt pavement materials.
