Aghileh Khajeh

Clay soils in cold regions are highly vulnerable to repeated freeze-thaw cycles (FTCs), yet sustainable and effective stabilization methods that simultaneously enhance mechanical performance, frost durability, and environmental footprint remain underexplored. This study addresses this gap by investigating the synergistic stabilization of frost-susceptible clay using waste marble (WM) powder, nanozeolite (NZ), and polyvinyl alcohol fibers (PVAFs). A comprehensive experimental program evaluated unconfined compressive strength (UCS), indirect tensile strength (ITS), California bearing ratio (CBR), and durability index (DI), of untreated and treated soils (10% WM, up to 2% NZ, and up to 2% PVAF) subjected to up to 10 FTCs, complemented by microstructural analyses using X-ray diffraction (XRD) as well as scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). In addition, a comparative life cycle assessment (LCA) quantified environmental performance. The optimal mixture (10% WM, 1.5% NZ, 1.5% PVAF) achieved a UCS of 7.8 MPa (≈ 37 times that of untreated clay), an ITS of 654 kPa, and a soaked CBR of 108%. After 10 FTCs, more than 95% of compressive strength and over 80% of bearing capacity were retained. Multi-scale microstructural analyses confirmed the formation of cementitious hydration products and a cohesive fiber-reinforced matrix. An apparent linear correlation between UCS and CBR supports practical strength estimation. The LCA showed reductions of approximately 59% in global warming potential and over 89% in mineral resource scarcity compared to conventional cement-based stabilization. These findings demonstrate that WM-NZ-PVAF stabilization offers a sustainable, frost-resilient solution for cold-region geotechnical applications, though field validation remains necessary.

This article reviews geotechnical risk management theories applied to flood scenarios, focusing on the flooding of Rio Grande do Sul in 2024. The research addresses the definition of geotechnical risk, including the concepts of danger, vulnerability, exposure, and consequences. Qualitative and quantitative risk analysis methodologies are explored, such as Failure Mode and Effect Analysis, Fault Tree Analysis, and probabilistic methods, with an emphasis on application in flood situations. Probabilistic modeling, using stochastic models and Monte Carlo simulation, is discussed to predict the behavior of soils and structures, in addition to sensitivity analyses of geotechnical variables. The geotechnical impact of failures during floods, such as landslides and foundation collapses, is assessed, considering the quantification of material and economic damages. Mitigation strategies are presented, including preventive planning, strengthening infrastructure, and increasing the resilience of structures. This research advances geotechnical risk management by establishing an integrated probability-consequence framework that synthesizes qualitative, quantitative, and socioeconomic assessment methodologies. Validated through the 2024 Rio Grande do Sul floods, this approach offers actionable protocols for enhancing infrastructure resilience in flood-prone regions, particularly under climate change intensification.

Dry stacking of iron ore tailings (IOTs) with cementitious materials is a viable disposal option, but its large scale implementation faces challenges. Therefore, this study investigates the key factors influencing compaction in real field conditions, including moisture content (optimum moisture content and less than optimum moisture content), vibration frequency (0 Hz and 35 Hz), and number of roller passes (4P and 6P). To achieve this objective, an experimental IOT stack was constructed in five different layers using a specific amount of Portland cement as a cementing agent (2.5% by dry solid weight). Then, laboratory tests, such as unconfined compression, splitting tensile, and ultrasonic pulse velocity (UPV), were conducted on undisturbed samples to evaluate the unconfined compressive strength (qu), splitting tensile strength (qt), and initial shear modulus (G0). Based on the laboratorytests conducted on the field-collected specimens, it was concluded that samples with moisture contents closer to the optimum moisture content (OMC), exposed to vibration, and subjected to six-roller passes exhibited superior mechanical performance. This study provides insights into optimizing the compaction process for large-scale IOT stack structures.