# Comparison of Field and Laboratory Tests for Soil Suitability Assessment in Raw Earth Construction
## 4 Conclusions and Perspectives  
This comprehensive study characterized 39 soils from potential deposits for raw earth construction, employing both field and laboratory testing methods. The findings of this study contribute to bridging the gap between practical field experience and scientific understanding of earth construction. While this research provides valuable tools for preliminary soil assessment, it also emphasizes the complexity of earth material selection and the need for continued development of assessment methodologies that link soil properties to final construction performance. The research findings advance our understanding through several key methodological contributions. A strong correlation between the average cigar length and plasticity index and MBV validates this field test as a reliable indicator of soil plasticity. This correlation is particularly robust, with R\({}^{2}\) = 0.8863, providing scientific validation for this simple field-testing method. Consistent relationships have also been obtained between ring test results and clay-sized particle content percentages. The study reveals important insights about resource characterization, with clay-sized particle content ranging from 5% to 75% and plasticity indices varying from 0% to 50%. These correlationsdemonstrate the potential validity of field tests as preliminary screening tools, though laboratory testing remains essential for final material validation. The OM content frequently exceeded recommended limits (2-4%), indicating the need for careful material selection or treatment. These diverse material properties present both challenges and opportunities for innovative mixing and modification strategies. The traditional Guide des Terrassements Routiers classification system proved inadequate for predicting soil suitability for earth construction, highlighting the need for specialized classification systems. This limitation extends to conventional particle size distribution envelopes, as the research demonstrates successful earth construction possibilities outside these traditional boundaries. The study demonstrates the complementary nature of mason and laboratory approaches, emphasizing the importance of collaboration between practitioners, designers, implementers, and researchers in developing this sector. Future work should focus on the standardization of soil modification techniques, particularly developing protocols for treating soils with high organic content and establishing optimal soil mixing ratios. Additionally, comprehensive field guidelines should be developed to address soil selection and modification, including decision-making frameworks based on local resource availability and construction technique requirements. The adequacy of the tests selected for this protocol with the requirements of raw earth construction must be continued to define classification systems that allow for a reliable and statistically representative decision on the suitability of the soil. Further investigations using multivariate statistical analysis will enhance our understanding of the correlations between geotechnical and field tests, ultimately supporting more informed decision-making in earth construction practices. Conceptualization, J.S. ; Methodology, M.D. and J.S. ; Validation, J.S. and W.A.-S.; Formal analysis, M.D. ; Investigation, M.D. ; Data curation, M.D. ; Writing--original draft, J.S. and M.D. ; Writing--review & editing, W.A.-S.; Supervision, J.S. ; Project administration, J.S. ; Funding acquisition, J.S. All authors have read and agreed to the published version of the manuscript. This study was carried out as part of the [des terres] project, funded by Nouvelle-Aquitaine region, Gironde department, and Bordeaux metropolis through a call for projects. This research was funded by [des terres] project grant number N\({}^{2}\)2021-452. Not applicable. The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.