Macro-micro investigation on magnesium slag-aeolian sand blends as subgrade filler

To alleviate the scarcity of road construction materials, this study investigates the feasibility of utilizing magnesium slag-aeolian sand (MSAS) mixtures for road construction. Initially, nine groups of MSAS mixtures were designed using the method of equal proportion substitution of fine aggregates, based on a comprehensive analysis of the stability of magnesium slag (MS) and the physical properties of both MS and aeolian sand (AS). Subsequently, compaction and California Bearing Ratio (CBR) tests were conducted to evaluate the compaction characteristics and strength properties of the MSAS binary particle mixtures, considering variations in gradation types, blending proportions, and compaction degrees. Moreover, the strength formation mechanism of MS mixed with AS was elucidated based on the changing law of mechanical properties of the mixture. Finally, the economic benefits of MSAS as subgrade material were analyzed. The results show that MS material has good volume stability and environmental stability, its immersion expansion rate is less than 2 %, and it does not have heavy metals leaching toxicity. The addition of AS to the MS can greatly enhance the maximum dry density of the resulting mixture, and effectively mitigate the crushability within the mixture. The CBR value of Z-35 is 43.5 %, demonstrating excellent bearing capacity and strength performance and meets the technical specifications for road subgrade filling. The strength of the MSAS mixture is primarily provided by the filling effect of AS, the skeleton effect of MS, and the pozzolanic effect of MSAS. Overall, MSAS exhibits exceptional performance and achieves a 6 % reduction in materials and transportation costs. This study provides an important reference for the synergistic resource utilization of MS and AS materials. • The feasibility of MSAS as subgrade filler was investigated. • The stability and application potential of MS was evaluated. • The strength properties and optimum gradation composition of MSAS were investigated. • The strength formation mechanism of MSAS mixture was revealed.