Underestimated Chemical Risks in West African Soils: The Role of Baumann-Gully Acidity in Concrete Durability

The premature deterioration of concrete infrastructures in West Africa is frequently attributed to mechanical and environmental factors, while the role of chemical soil aggressiveness remains largely underestimated and insufficiently investigated. In many developing countries, geotechnical studies rarely include comprehensive chemical characterization of soils, despite its critical importance for long-term infrastructure durability. This study evaluates the relevance of Baumann-Gully acidity as a low-cost, reliable, and accessible indicator of soil aggressiveness toward concrete. A total of nine soil samples collected from various locations in Benin were analyzed using the standardized method EN 16502. The results revealed acidity values ranging from 165 to 257 mL/kg, indicating predominantly moderate to high aggressiveness levels. Notably, several samples exceeded the commonly accepted threshold associated with severe chemical attack risks. Graphical analysis further highlights the significance of these findings. The distribution of acidity values across sampling sites shows a consistent prevalence of aggressive conditions, while the histogram confirms a concentration of results within the upper range of aggressiveness. The boxplot analysis reveals a relatively high variability, with extreme values indicating localized zones of particularly high chemical risk. In addition, the relationship between depth and acidity suggests that aggressive conditions are not limited to surface soils but may persist across deeper layers, which has important implications for foundation design. These findings emphasize the critical need to systematically integrate chemical soil analysis into geotechnical investigations in developing countries. The study demonstrates that Baumann-Gully acidity is not only a practical and cost-effective tool, but also a scientifically relevant parameter for predicting soil-induced degradation of concrete. Its adoption could significantly improve infrastructure durability and reduce maintenance costs in resource-limited settings.