Influence of mineralogical and geochemical multi-parameters on the geotechnical properties of gneiss-derived lateritic gravels from an equatorial zone, center Cameroon

Lateritic gravels are extensively used in road construction and other civil engineering structures. Depending on various parameters, genetic characteristics vary from one locality to another. Geological analyses were conducted to investigate their influence on the geotechnical properties of lateritic gravels developed on gneiss for their better use in road construction. Petrographical, mineralogical, and geochemical results show the existence of two types of lateritic gravels in the study area: yellowish to brownish lateritic gravels of humid savannah (LGHS) and reddish lateritic gravels of dry savannah (LGDS). These materials mostly content quartz, kaolinite, hematite, goethite, muscovite, gibbsite, anatase, Fe₂O₃, Al₂O₃, and SiO₂. The hematite, goethite, Fe₂O₃, and Al₂O₃ content has a positive influence on the geotechnical behavior of the studied lateritic gravels, while the content of quartz, muscovite, and SiO₂ has the opposite effect. The evaluation of alterologic parameters show that the degree of lateritization has a positive influence on CBR, maximum dry density, and the specific gravity. Three CBR models with determination coefficients R² = 0.85, 0.87, and 0.88 were established by associating the genetic characteristics of the materials with geotechnical parameters. The outcomes of the present study show that geotechnical properties of lateritic gravels are significatively influenced by their genetic characteristics. Is therefore important to performed geological studies for a better use of lateritic gravels in road construction.