TITLE:
Structural and Mineralogical Characterization of the Clayey Deposits of Gbédji-Kotovi in Lama Depression, Bénin
AUTHORS:
Kassa Issifou Mounou Sambieni, François De Paule Codo, Christophe Kaki, Daouda Mama, Guy Apollinaire Mensah, Mina Amharref
KEYWORDS:
Lama Depression, Clays of Gbédji-Kotovi, Structure of Clays, Mineralogy of Clays, Scanning Electron Microscopy
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.13 No.1,
January
10,
2023
ABSTRACT: The objective of the study was to characterize the
clays of the Lama depression in Benin. Macroscopic examination of hand
soundings, dynamic penetration test and stratigraphic correlation of water
borehole logs, as well as scanning electron microscopy (SEM) combined with
energy-dispersive X-ray microanalysis (EDX) method were made on compact or
stratified clays. The large grains are embedded in a sintered matrix. The
texture is heterogeneous and open, including quartz, carbonates and organic
matter. The fine fraction is dominated by mineral paragenesis characterizing
Kaolinite-Quartz-Calcite-Gypsum dioctahedral smectites composed of: Oxygen,
Silica, Carbon, Aluminum, Iron, Zinc, Titanium and Magnesium. This smectic and
regular structure includes coarse grains of the order of 800 μm. The pore
diameters vary from 130 μm to 1.14 μm. The inter-particle porosity is poorly
developed unlike the inter-aggregate pores larger than 0.05 μm. The texture is
laminar and shows elongated turbo static particles with more or less rounded
edges and honeycomb particles. Quartz and carbonates induce an increase in
heterogeneities which develop mechanical sensitivity and hydraulic
conductivity. High contents of silica, iron or aluminum and low contents of
calcium and magnesium, as well as the presence of other trace elements suggest
an alumino-ferriferous clay resulting from the hydrothermal alteration of the acid
granite massif. These heterogeneities promote less tortuous pores or paths,
making these clays more permeable. Finally, other stabilization studies and
improvements to hydraulic products and binders should favor the use of the
studied clay as improved backfill or drilling muds.