An enhanced approach to red mud (RM) sustainable management and utilization for marl stabilization considering the dynamic response and durability analysis

Marl soil, known for its high calcite content, presents significant challenges in construction projects due to its low strength and poor durability, especially under varying moisture conditions. In wet environments, marl often exhibits rapid disintegration, compromising stability and limiting its use in geotechnical applications. On the other hand, the worldwide disposal of red mud (RM) waste, an industrial by-product of alumina processing, has resulted in significant environmental concerns and substantial financial burdens. This study investigates the potential of RM for enhancing the mechanical, dynamic, and durability characteristics of marl soil under both dry and wet conditions. The experiments included the unconfined compressive strength test (UCS), Brazilian tensile strength test (BTS), bender element test (BET), long-time soaking test, as well as a set of microstructural analyses. The findings indicated that the UCS of the samples containing 30 % RM increased by 3.6 and 6.83 times after curing periods of 7 and 28, respectively, reaching an acceptable strength level even under wet conditions. Furthermore, RM was found capable of postponing the development of cracks and sustaining the integrity of the sample over the long term. RM treatment also improved the dynamic properties, increasing shear wave velocity by 127.9 % and reclassifying the soil from Class F (very weak) to Class D (very stiff) under seismic loading criteria. However, RM introduced brittle behavior to the treated samples, resulting in reduced axial strain and a 60–70 % drop in strength under wet conditions. Future research should focus on addressing these limitations by incorporating additional stabilizing agents. This study highlights the potential of RM for sustainable soil stabilization, offering an effective approach to managing industrial waste while enhancing marl’s performance in geotechnical applications. • Red mud enhances the UCS of marl up to 6.83 times after 28 days. • RM-treated marl shifts soil class from very weak to very stiff under seismic load. • 30 % RM delays cracks in marl in long-term soaking, preserving structural integrity. • RM improves marl's dynamic response, raising shear wave velocity by up to 127.9 %. • A sustainable solution for managing the by-product of aluminum production.