THE PERFORMANCE OF COAL GANGUE SUBGRADE FILLER MODIFIED BY CEMENT-FLY ASH SYNERGY
Keywords:
Coal gangue, Cement, Fly ash, Subgrade filler, Solid waste utilizationAbstract
To address the problems of performance discreteness, low strength, and insufficient water stability encountered in the resource utilization of coal gangue for road embankment filling, this study selected coal gangue samples from Meihuajing and Yangchangwan Mines in Lingwu City, Yinchuan, Ningxia. The coal gangue was compounded with typical fine-grained soil (Group C filler) at different proportions, and additives such as cement, fly ash, and lime were incorporated to systematically investigate the engineering properties of the mixtures. Through a series of laboratory tests, including particle size analysis, heavy compaction test, California Bearing Ratio (CBR) test, expansion ratio test, and resilient modulus test, the gradation characteristics, compaction behavior, strength, water stability, and deformation performance of the mixtures were comprehensively evaluated. The results show that blending coal gangue with Group C filler can significantly optimize the gradation, with the coefficient of uniformity (Cu) being greatly improved. The mixture with 3% cement and 8% fly ash exhibits the optimal performance: its maximum dry density reaches 2.16 g/cm³, the peak CBR value is 171.49%, and the resilient modulus exceeds 60 MPa. All these indices are far higher than the requirements specified in current specifications for subgrade filler used in the lower embankment of high-grade highways. In addition, the incorporation of cement and lime effectively inhibits the expansibility of the mixtures. This study verifies the feasibility of using coal gangue mixtures as subgrade filler and provides a theoretical basis and data support for the optimization of its engineering mix ratio.References
[1] Jia P. Application of coal gangue mixture in road subbase construction. Development Guide to Building Materials, 2025, 23(17): 58-60. DOI: 10.16673/j.cnki.jcfzdx.2025.0742.
[2] Cui X R, Huo X P, Zhou B J, et al. Spatial distribution characteristics and graded quality utilization pathways of coal gangue in China. Environmental Science, 2025, 46(4): 2281-2291. DOI: 10.13227/j.hjkx.202401269.
[3] Chen Y Y. Research on the application of cement-stabilized washed coal gangue in pavement base. Auto Time, 2025(19): 168-170.
[4] Xie X H. Pavement performance and dynamic response of coal gangue powder modified rubber asphalt mixture. Guangdong Highway Communications, 2025, 51(5): 7-12. DOI: 10.19776/j.gdgljt.2025-05-0007-06.
[5] Wang D C, Wei J W, Hu L, et al. Experimental study on mixing method and durability of coal gangue in pavement base mixture. Materials Reports, 2025, 39(11): 171-180.
[6] Xue X Y, Zhao M Z, Zhang J, et al. Effect of composite curing agent on pavement performance of fly ash-coal gangue mixture. Hebei Journal of Industrial Science and Technology, 2025, 42(1): 62-69.
[7] Song Q, Yang Y, Xu S, et al. Mechanical properties, durability, and carbon emissions of concrete with coal gangue coarse aggregate, fine aggregate and mineral admixtures in coal mining environment. Case Studies in Construction Materials, 2025, 23: e05187. DOI: 10.1016/J.CSCM.2025.E05187.
[8] Liu Y K, Luo Q, Jin F L, et al. Experimental study on influence of fines content on compaction characteristics of fine sandy soil. Railway Engineering, 2018, 58(12): 87-91.
[9] Mei H H. Experiment on permanent deformation characteristics of silt under cyclic-intermittent loading. Journal of Civil Engineering and Management, 2021, 38(2): 160-167. DOI: 10.13579/j.cnki.2095-0985.2021.02.023.
[10] Xie C H, Liu Y. Exploration on rapid determination method of CBR index for expansive soil filler. Chinese & Overseas Architecture, 2018(8): 249-251. DOI: 10.19940/j.cnki.1008-0422.2018.08.077.
[11] Liang C X. Experimental study on engineering characteristics of limestone rock mixture and gravel mixture. Chengdu University of Technology, 2018. DOI: 10.26986/d.cnki.gcdlc.2018.000058.
[12] Chen Y Y, Gao L. Laboratory model test study on reinforced fly ash embankment. Fly Ash Comprehensive Utilization, 2017(4): 40-42.
[13] Zhang T L. Analysis of pavement performance of cement stabilized coal gangue mixture. Western China Communications Science & Technology, 2023(11): 27-29. DOI: 10.13282/j.cnki.wccst.2023.11.009.
[14] Han J, Wang L H, Ma L, et al. Influence of cement and lime content on shear strength of improved expansive soil. Yellow River, 2025, 37(4): 137-139.
[15] Bai Y P, Xia Y, Ma L, et al. Performance study on fly ash-based geopolymer stabilized loess. Fly Ash Comprehensive Utilization, 2025, 39(5): 8-13. DOI: 10.19860/j.cnki.issn1005-8249.2025.05.002.