Laboratory experimental study on red mud geopolymer used as road subgrade materials Lusheng Qin, Qingke Nie, Haiqing Zhang, Xiangxin Jia and Chuanchuan Zhang E3S Web Conf., 261 (2021) 02043 Published online: 21 May 2021 DOI: 10.1051/e3sconf/202126102043