Assessment of bauxite residue stabilized with lime and graphene oxide as a geomaterial for road applications

Abstract

Negative traits of bauxite residue (BR) include low shear strength, inconsistent compaction characteristics and dispersion, render it unsuited geomaterial for engineering applications. The present study aims at stabilizing BR with the combination of lime (L) and graphene oxide (GO) in suitable proportions and investigating their impact on improvement in engineering properties (viz., density, unconfined compressive strength (UCS), dispersion, and durability). Lime of 2-10% and GO of 0.05-0.1% dosages (% weight of BR) are selected for experimentation purpose. Results demonstrate that L and GO together, not the individual additive, is effective to stabilize BR. A substantial improvement in UCS from 710 kPa of raw BR to 3890 kPa after treating with 10% L and 0.1% GO with 60 days curing period has been observed. 6% L and 0.05% GO for strength only in the short-term, and 10% L and 0.05% GO in durability aspect in the long-term are found as optimum dosages. Drastic decline in turbidity from 453 to 83 NTU establishes that L (6%) and GO (0.05%) addition completely alleviates dispersion behavior in BR. Though GO addition is trivial, its effect on strength and durability enhancement of BR is significant. Cementitious gel formations and bonding mechanism leading to particle aggregations are evidenced as the reason behind the improvement in strength and durability of BR. To verify the applicability of amended BR, the obtained findings are compared vis-à-vis with standards, which illustrated that the amended BR could be an excellent resource material in road construction, especially in base or sub-base courses.