The leaching of excessive heavy metals (HMs) from lithium slag (LS) presents a significant challenge for its use in road engineering, necessitating the development of safe treatment methods. This study employed solidification/ stabilization (S/S) technology to develop a magnesium slag-lithium slag composite solidified material (MS-LS). The deformation and displacement characteristics of MS-LS during destruction were analyzed using digital image correlation (DIC). Various microscopic analytical techniques were used to analyze the stabilization mechanisms of MS-LS towards HMs. Results indicated that adding MS significantly improved the compressive strength and resistance to cracking of MS-LS. The minimum strength of the 8 %-MS group reached 2.7 MPa, meeting the strength requirements for subgrade stabilized soil in a first-class highway under heavy traffic load conditions. The development of strength is attributed to improved structural compactness from particle micro-gradation effects and the cementitious hardening action of C-S-H gel. HMs immobilization was achieved through directional adsorption at active sites within the calcium-rich mineral phase and interlayer adsorption within the C-S-H gel, complemented by a physical encapsulation mechanism that reduces HMs leaching. The immobilization rates of Be(II) and Pb(II) in the 8 %-MS group exceeded 95 %, demonstrating the effectiveness of MS in stabilizing these HMs in LS.

In this study, geopolymer was adopted as an eco-friendly binding material to solidify waste drilling mud to fabricate geopolymer solidified waste drilling mud (GSWDM) as a pavement material in the subbase. Using precursor dosage, Na2SiO3 solution dosage, and slag powder (SP) dosage as parameters of mix proportion, the optimal mix proportions of GSWDM were determined through compressive strength tests. Based on a series of tests of unconfined compressive strength, splitting tensile strength, elastic modulus, and compressive resilient modulus, the effects of the SP percentage in the precursor and curing age on the mechanical properties of GSWDM were analyzed. The results indicated that all the mechanical properties of GSWDM were improved with the increasing SP percentage in the precursor. The 28-day unconfined compressive strength, splitting tensile strength, elastic modulus, and compressive resilient modulus of GSWDM were improved by 80.8%, 56.3%, 65.3%, and 76.72%, respectively, when the SP percentage in the precursor increased from 60% to 100%. A nonlinear increase in the mechanical properties of GSWDM was observed as the curing age increased, with a significant increase in the curing age from 7 days to 14 days and a slight increase in the curing age from 14 days to 28 days. Moreover, the microstructure of GSWDM was denser as the curing age and the SP percentage in the precursor grew. The results of this study verified that GSWDM can be used as construction material for road subbase.

The scarcity of natural resources, and energy demand/carbon footprints related to their processing and transportation, has led to the quest for alternate materials for road/pavement construction and other infrastructure development. On the other side, landfill mined soil like fraction (LMSF) forms significant proportion of mined legacy landfill waste that exists at different locations around the world; however, it has found limited applications. The present study explores the utilization of LMSF in development of novel asphalt road subbase layers for resilient road infrastructure. 30-60% of LMSF replacement has been studied, and findings based on gradation analysis, compaction tests and California bearing ratio (CBR) tests are quite encouraging. Most combinations of subbase layers studied exceed the design requirements for low volume roads in Indian scenario (rural and outer urban roads); while 30% LMSF in wet mix macadam satisfies the requirements of Indian and other international codes. The cost-benefit analysis shows significant saving in material cost due to utilization of LMSF in road subbase layer. The potential utilization of low cost and sustainable LMSF in asphalt road subbase layer would allow design of superior roads with CBR exceeding design values, resulting in better life cycle performance of road infrastructure with high resilience to fatigue effects, water inundation and overloading conditions.