Experimental evaluation of natural material mixtures for soil resistivity reduction

Soil electrical resistivity is influenced by multiple factors, including temperature, geography, soil chemical composition, precipitation, and particularly moisture content, which exerts the most significant influence. Nevertheless, combining natural materials in varying proportions can produce distinctive physicochemical and electrical properties, relevant for the development of low-resistivity materials in engineering applications that require soil resistivity reduction. In this study, 15 mixtures were formulated using four natural materials with contrasting physicochemical characteristics. Experimental evaluations included electrical resistivity as a function of moisture content (10%-100%), pH, and electrochemical activity (ORP), the latter assessed through cyclic voltammetry. Principal Component Analysis (PCA) was also applied to identify patterns among the measured variables. The results show a progressive decrease in resistivity as moisture content increases. Likewise, the relationship between pH and conductivity displayed a non-linear behavior, with the lowest resistivity occurring within the pH range of 8.50-9.50. Mixtures exhibiting higher electrochemical activity were also the most conductive. Furthermore, PCA enabled the classification of mixtures according to their electrical behavior. These findings demonstrate that an integrated approach-combining physicochemical, electrical, and electrochemical analyses-is essential for the rational design of functional natural materials intended to serve as soil resistivity reducers.