# A Practical Group Symbol and Group Name Approach (PSNA) according to EN ISO 14688-2:2018
## 3 Practical Group Symbol and Group Name Approach (PSNA)  
Identifying and classifying soil is the first step in designing engineering projects. In this study, a soil marking method called the Practical Group Symbol and Group Name Approach (PSNA) was proposed along the lines of EN ISO 14688-2:2018 [21]. Not only did this method consider EN ISO 14688-2:2018, it was supported with ASTM D2487-17e1 [25] for the logical principles of classification and symbolization. The idea of assigning names and symbols to soil particles based on two standards emerged due to the limitations of EN ISO 14688-2:2018, which provides a general classification of soil grains but lacks detailed group names and numbers. EN ISO 14688-2:2018 does not provide specific ratios and explanations to determine precise classifications in practical applications. Therefore, to overcome these obstacles, a novel, comprehensive, and practical group symbol and group name marking method was proposed in this study. A practical and effective naming and symbolizing method should provide the boundaries of the particles clearly by assessing the soil mass precisely. The EN ISO 14688-2:2018 standard offers a comprehensive overview of soil principles, focusing on the general characteristics of soils rather than providing specific group symbols and names for classification. In other words, it does not provide an exhaustive and detailed classification. To fill this technical and practical gap in the  
Figure 3: Cumulative Particle-Size Plot of ASTM D2487-17e1 [25]. Figure 2: Plasticity chart of ASTM D2487-17e1 [25]. literature, PSNA was proposed. However, PSNA is not a classification system or a standard. Therefore, in order to accurately apply EN ISO 14688-2:2018, it is necessary to obtain precise percentages of grain size boundaries and identify soil particles. In this regard, the utilization of ASTM D2487-17e1 proved beneficial. After EN ISO 14688-2:2018 came into force, national classification systems were withdrawn in CEN countries and EN ISO 14688-2:2018 became practically unusable in countries without a national standard compatible with EN ISO 14688-2:2018. The absence of national standards in numerous European countries rendered of EN ISO 14688-2:2018 inadequate to the task of providing a comprehensive classification of soil in geotechnical applications. The lack of a detailed definition and classification of soils presents a significant obstacle in accurately identifying and resolving soil-related issues in geotechnical applications. This situation places experts in a difficult position as they are unable to effectively and thoroughly address these problems. The more detailed the classification is, the more precise the data a project generates. In this study, C\({}_{\text{u}}\) and C\({}_{\text{c}}\) were used to describe coarse particles for five subgroups, and plasticity was employed to describe fine particles for four subgroups according to EN ISO 14688-2:2018. However, ASTM D2487-17e1 is based on only two subgroups such as \"well and poorly graded\" and \"low and high\". If the detail for the classification increases, the geotechnical behavior of the material can be caught with greater ease. Soils are divided into two main categories, namely, cohesionless and cohesive. The behavior of cohesionless soils is different from that of cohesive soils and the distinction between these soils is not the same as that between fine-grained and coarse-grained soil made in the standards. For example, some coarse-grained soils according to ASTM D2487-17e1 such as SC (clayey sand) behave as cohesive soils because of their fine content, especially if the fine quality is derived from clay [28; 29; 30; 31]. A similar assessment is valid for the liquefaction phenomenon. Sand-type soils are susceptible to liquefaction [32]. However, parameters such as fine-grained percentages, the plasticity behavior of fines, and the grading shape of coarse material affect liquefaction potential [33; 34; 35; 36; 37]. Therefore, each type of sand does not liquefy.