Geotechnical and geochemical assessment of Ahoko clay of the Patti formation for use as compacted landfill liner

Abstract

Geotechnical and geochemical characteristics of clay within the Patti Formation, which is widespread around Ahoko in the Southern Bida Basin, were assessed to determine their suitability as landfill liners. The methods employed included field operation and laboratory analyses. The samples collected were subjected to grain size analysis, Atterberg limits, geochemical and cation exchange capacity determination. The chemical tests include determination of the percentage of oxides including SiO₂, Al2O3, Fe₂O₃, CaO, MgO, K₂O, Na2O and TiO₂. The results of the analyses revealed that the percentage of fines in the sample is >50%, the plasticity index is >10%, the activity ranges from 0.34 to 0.56 and the compressibility of the compacted clay was low which implies that kaolinite (a low activity clay mineral) is the dominant mineral in the samples that were analyzed. The samples have cation exchange capacity values ranging from 8.9mEq/100g to 12.4mEql/100g which indicate a low negative charge of the clay fraction and hence, a low heavy metal sorption capacity. The results also indicate that SiO2 content is high, ranging from 54.5% to 81.6%, which is in support of the high clay content of the samples. These characteristics indicate that Ahoko clay satisfies the property of a good clay liner.

Keywords: Ahoko clay, landfill liner, geotechnical and geochemical analyses.