Mineralogical and Geotechnical Characteristics of the Loose Weathered Trachytes of Fongo-Tongo (West-Cameroon)
Armand Sylvain Ludovic Wouatong, William Hyoumbi Tchungouelieu, François Ngapgue, Valentine Katte, Véronique Kamgang Kabeyene Beyala

Abstract
The loose materials of lower and median assemblages of soil profile developed on the Fongo-Tongotrachytes (West-Cameroon) have been the subject of mineralogical andgeotechnical characterization. Mineralogical analysis reveals the presence of quartz, kaolinite, gibbsite, hematite, goethite, illite and alkali feldspar. The proportion of kaolinite decreases from the bottom to the top of the profile; while the gibbsite concentration evolves in the opposite direction. Illite and alkali feldspar coexist at the bottom of the profile.Geotechnical characterization shows that the loose material of eluvial median horizon corresponds to loamy soils of the A-(6)7 class with 16 as group index; while the loose materials of illuvial median horizon and lower assemblages are clayed soils of the A-7-5 (17) and A-7-5 (18) classes respectively, according to Highways Research Board. Meanwhile, according to the Laboratoire Central des PontsetChaussées(LCPC), they are known as highly plastic silt (Lt).According to the Guide de TerrassementRoutier (GTR), they beyong to classA.

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