Road Performance Evaluation of Unburned Coal Gangue in Cold Regions

At present, the cumulative storage of coal gangue in China exceeds 7 billion tons, covering an area of approximately 70 km2. The engineering application of unburned coal gangue is mainly utilized as concrete aggregate or cement production after the overfire process. However, it is prone to environmental pollution and has limited consumption. Using unburned coal gangue as roadbed filling not only alleviates the difficulty of land acquisition and soil collection for road constructions in mining areas, but also consumes a large amount of accumulated unburned coal gangue. This study conducts research on the road performance of unburned coal gangue. A series of laboratory tests have been performed to determine the physical and chemical properties of the unburned coal gangue and its performance as a filling material in cold regions. The influence of compaction effort, clay content, and number of freezing–thawing cycles on the mechanical performance of the unburned coal gangue was investigated. The typical unburned coal gangue in the Heilongjiang region is mainly composed of SiO2, Al2O3, and Fe2O3, which accounts for approximately 91% of the total mass. The unburned coal gangue meets the minimum CBR requirement of 8% after 7 freezing–thawing cycles. This study helps fully and reasonably utilize typical unburned coal gangue in the local area, providing technical support for achieving the overall goal of “green development, conservation and intensification, and low-carbon environmental protection”.