## 2 State of the Art  
With industrialization, the increased production and disposal of industrial waste have resulted in significant soil pollution, primarily driven by industrial, agricultural, and urban activities [18], as illustrated in Figure 1.  
Major sources of contamination include industrial emissions into the atmosphere, effluents from industrial, urban, and agricultural sectors that pollute rivers and seas, landfills for both hazardous and non-hazardous waste, and insufficient treatment of industrial sludge [19; 20]. Abandoned mines also play a significant role, causing persistent environmental damage [21]. Notably, areas of high environmental risk due to contaminated sites are often located near urban centers [22]. Since its inception, the stabilization and solidification (S/S) process has relied heavily on Portland cement as its primary material [6]. Over the years, numerous studies have highlighted the benefits of OPC, including its low cost, non-toxicity of chemical ingredients, long-term chemical and physical stability, high compressive and impact strength, resistance to biodegradation, low water permeability, and ease of processing [23]. Cement-based stabilization/solidification has been widely applied to treat various types of waste containing hazardous components, including inorganic, organic, or mixed contaminants, yielding excellent results [7; 24]. This technique has also been successfully used for the treatment of marine sediments [25; 26]. The use of mixed cement significantly reduces the leaching of contaminants into the soil by enhancing the properties of the granular material. This process improves soil  
Figure 1: Causes of soil pollution (authors’ elaboration). compactness and decreases its water content, making it less permeable. Furthermore, the technique has proven particularly effective in reducing toxicity, demonstrating that contaminant immobilization can substantially mitigate environmental risks. However, the production of Portland cement is an energy-intensive process that generates substantial greenhouse gas emissions, contributing approximately 8% of global anthropogenic CO\({}_{2}\) emissions [27, 28]. In this context, minimizing carbon emissions has become a critical priority [29]. This underscores the need to explore alternative materials for the S/S process, such as cement kiln dust (CKD), lime, lime kiln dust (LKD), limestone, fly ash (FA), bentonite [30], ground granulated blast furnace slag (GGBFS), gypsum, phosphate, and other industrial waste materials. Numerous studies have demonstrated the effectiveness of pozzolan-based stabilization/solidification in immobilizing heavy metals in contaminated soils and sludges [31]. One study compared the compressive, thermal, and morphological properties of cement mortar and mortar reinforced with BFS and fly ash, revealing that pozzolan-enhanced mortar exhibits lower thermal conductivity, higher porosity, and acceptable compressive strength [32]. These findings suggest that incorporating pozzolanic materials can improve the physical properties of treated materials, thereby enhancing the stabilization process for contaminated soils. Furthermore, research has shown that adding quicklime and fly ash to contaminated soils effectively reduces the leachability of heavy metals to levels well below regulatory limits. The addition of fly ash also broadens the pH range for heavy metal immobilization and significantly improves the stress-strain properties of treated solids [31]. However, a potential drawback of this treatment is the excessive formation of pozzolanic ettringite in the presence of sulfates. The use of ground granulated blast furnace slag has proven effective in immobilizing heavy metals such as Pb\({}^{2+}\) and Cd\({}^{2+}\).