Journal of Yangtze River Scientific Research Institute ›› 2024, Vol. 41 ›› Issue (1): 114-120.DOI: 10.11988/ckyyb.20220847

• Rock-Soil Engineering • Previous Articles     Next Articles

Performance of Cement-Lime-Phosphogypsum Solidified Red Mud as Road Base Material

SHI Ming-lei1, TIAN Xin-tao1, WANG Hua-jin1, YU Chang-yun1, DU Xu-yang1, ZHANG Rui-kun2   

  1. 1. School of Transportation, Southeast University, Nanjing 210096, China;
    2. Jiangsu Huaning Engineering Consulting Company Ltd., Nanjing 210096,China
  • Received:2022-07-14 Revised:2022-10-18 Online:2024-01-01 Published:2024-01-15

Abstract: We conducted indoor experimental research to evaluate the unconfined compressive strength, splitting strength, resilient modulus, and dry-wet and freeze-thaw durability of phosphogypsum-activated cement-lime solidified red mud for road applications. The aim was to investigate the feasibility of using this solidified red mud as a road base material. The experimental results demonstrate that the best road base performance is achieved when the curing agent mixing ratio is mcement:mlime:mphosphogypsum=8:2:2. The 7-day unconfined compressive strength reaches 4.18 MPa, meeting the strength requirements of road base. The splitting strength and resilient modulus at 28-day age are 0.256 MPa and 1 020 MPa, respectively. After five cycles of dry-wet and freeze-thaw, the mass change rate is less than 2%, and the strength loss index (BDR) exceeds 80%. Microscopic analysis using a mercury intrusion test reveals that the AFt (ettringite) generated from the reaction of phosphogypsum could enhance the strength of red mud by filling pores (0.1~1 μm) in the solidified red mud. However, excessive AFt causes volumetric expansion and gives rise to micro-crack pores (1~10 μm), resulting in deteriorated strength performance. In conclusion, the performance test results indicate that the solidified red mud prepared with a ratio of mred mud:mcement:mlime:mphosphogypsum=100:8:2:2 can be effectively used as a substitute for traditional pavement base materials. This discovery provides a broader avenue for the comprehensive utilization of red mud.

Key words: red mud, road engineering, road base, unconfined compressive strength, road performance

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