Background
In China, more than 80% of highways and urban roads are asphalt pavements, among which 96% are paved by hot-mix asphalt mixture. The construction temperature of hot-mix asphalt mixture is generally controlled between 160℃ and 180℃, which could consume large amounts of fuel for heating, causing large quantities of greenhouse gases, asphalt fumes and other harmful emissions. Thus, foaming warm mix asphalt technology originated in Europe was extensively promoted worldwide. This technology, performing exceptionally in the reduction of both temperature and emissions though, hardly meets the requirements in terms of low-temperature crack resistance and water damage resistance. With the mechanical foaming warm mix asphalt technology developed, this project demonstration could not only lower the construction temperature but improve low-temperature crack resistance, water damage resistance and the property of road compaction at the same time.
Demonstration
The Project team proposed the optimal foaming parameters of petroleum asphalt, according to the environment and construction regulations in Xin Jiang. On-site discharge temperature of mechanical foaming warm mix asphalt was 15℃ lower than that of the hot-mix asphalt mixture under the condition of 1.5% water content. The construction and workability of the paving asphalt mixture on site were improved, making it easy to roll and form. There is no obvious gas emission such as asphalt smoke during paving. The results of core drilling compactness test showed that the minimum compactness of mechanical foaming warm mix asphalt mixture is 93.2%, which is equivalent to that of hot-mix asphalt mixture. Under the design requirement, a pavement with a thickness of 6cm and a length of 5km has been paved successfully.
Benefits Expected
During the mixing and paving process of warm mix asphalt, the emission of harmful gases is significantly reduced, among which the emission of toxic gases such as asphalt fume, and Benzene-Soluble Organics has dropped by more than 80%, and greenhouse gas emissions have been reduced by more than 50%. On the premise of ensuring the road performance of the asphalt mixture, the use of warm mix technology can significantly reduce the production temperature of the asphalt mixture and achieve a significant reduction in harmful gas emissions.