## 3 Materials and Methods  
The remediation of contaminated areas involves various technologies designed to contain pollutants and reduce their mobility within natural environments. Commonly employed techniques (see Table 1) for soil remediation include incineration, phytoremediation, biodification, solidification and stabilization processes, as well as soil washing [9; 39; 40]. Among these techniques, stabilization/solidification (S/S) is one of the most used methods, involving the use of reagents to immobilize contaminants [41]. Solidification and stabilization technologies are widely applied to reduce the mobility and leachability of contaminants in soils. Solidification physically encapsulates contaminants within a solid matrix using binders, thereby reducing soil permeability and limiting the spread of contaminants to the surrounding environment. Stabilization, in contrast, chemically interacts with contaminants to reduce their solubility and minimize their mobility, thus preventing water resource contamination [4] (see Figure 2). As illustrated in Figure 2, contaminated soils were treated using a combined solidification and stabilization process. This approach aimed to reduce both the permeability and solubility of contaminants by utilizing binding materials such as cement in combination  
Figure 2: Various techniques for soil contamination remediation (source: authors’ elaboration). with industrial waste. The process is shown in Figure 3 in schematic form. As seen in the image, there are phases for testing the raw materials, both the contaminated soil and the waste materials used. These are then mixed in the mixer to be processed together, ultimately resulting in non-contaminated and stabilized soil. This phase will be explained in detail in the following sections. The process involved the following main phases:  
* Collection and preparation of representative samples. * Chemical, physical, and geotechnical characterization of the samples. * Selection and preparation of green materials. * Characterization of green materials. * Mix design procedures and optimization of the mixtures. The S/S process begins with the collection of representative samples, which are then chemically, physically, and geotechnically characterized. This characterization provides information on the nature and extent of the contamination, as well as on the mechanical properties of the soil, such as permeability and strength [42]. Simultaneously, \"green\" materials derived from industrial waste, such as fly ash or blast furnace slag, are selected and prepared. These materials are chosen for their ability to bind with contaminants and are characterized to ensure their compatibility with the soil and their effectiveness in stabilizing the contaminants [43]. Since this study focuses on mix design, solidification/stabilization tests are not yet performed. After selecting the materials, tests are conducted to simulate their integration into the soil, assessing their ability to reduce the permeability and solubility of the contaminants. These tests ensure that the mixes improve environmental safety [44]. Subsequently, a mix design process is carried out to optimize the proportions of materials, with the aim of creating a stable and effective mixture. The resulting mix immobilizes contaminants over the long term and minimizes the risk of dispersion. The design aims to determine the optimal proportions of materials to achieve a stable mix that immobilizes contaminants in the long term and minimizes the risk of dispersion [16]. Figure 3: Schematic representation of the solidification/stabilization process for soils from industrial sites (source: authors’ elaboration). Each of these stages is crucial for developing a treatment that effectively remediates the contaminated site while ensuring the protection of the surrounding environment. A key factor driving the adoption of S/S is its proven effectiveness, which is largely due to the well-established chemistry for treating metal contaminants.