New-Generation Biochar-Modified Permeable Pavement Materials
Compared with impermeable pavements, permeable or porous pavements facilitate stormwater percolation and infiltration, which are especially suitable for Hong Kong and the cities in Germany, where life and property are from time to time under the threat of flooding and stormwater. This project aims to develop the new-generation permeable pavement material (PPM) by using biochar as a modifier. Biochar, a carbon-dense solid residue produced from biomass pyrolysis has been widely investigated and recognized as a sorbent to remove organic and inorganic pollutants from stormwater. By using different physical and chemical treatment methods to change the surface area and the abundance of oxygenated functional groups, modified biochar can show varying performances in removing heavy metals and other pollutants. In the field of pavement engineering, some recent studies have shown that biochar can be applied in asphalt pavement as a green additive to improve the rheological properties of asphalt binder. In addition, some exploratory studies also showed that the pollutant emissions such as volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) generated during asphalt mixture production can be effectively absorbed by the biochar added in the asphalt mixture.
Because of the unique chemical composition and porous structure, biochar may help enhance the mechanical performance of PPM, provide PPM the filtering function to remove both organic and inorganic pollutants from stormwater, and absorb pollutant emissions during PPM construction. The optimum composition of the biochar modified permeable pavement material (BMPPM) will be identified through comprehensive laboratory tests on the mechanical performance, hydraulic performance (including leaching and other pollutants related test) and emission absorption performance of the BMPPM mixture. Upon the completion of the project, the filtration and absorption mechanism of the BMPPM will be revealed and the prototype durable BMPPM with the filtration function and low construction emission will be developed. The success of this project will not only enhance the sustainability of the roadway system, but also contribute to a more sustainable stormwater management system.