Geotechnical Behavior of Clays from Ngbo Area, Eze-Aku Formation, Southeastern Nigeria in Construction

Author(s): Mathias O. Nweke, Hilary N. Ezeh, Philip N. Obasi, Ikenna A. Obasi

Clays noted to be highly expansive belonging to Ezeaku Formation, southeastern Nigeria were characterized using the following geotechnical properties which included Grain size distribution, Atterberg limits, free swell, bulk density, specific gravity, cation exchange capacity (CEC), chemical composition. The chemical composition of the clays indicates low percentages of Na2O with fairly higher percentages of CaO and K2O. The clays are plastic with liquid limit (LL) of 58.8 to 72.8, plastic limit (PL) of 24.6 to 30.1 and plasticity index (PI) of 35.5 to 45.8. They classify as inorganic clays of high plasticity (CH) according to USCS and as A-7-6 according to AASHTO classification systems. Plots of LL against PI show that the study clays are predominately illite with low presence of montmorillonite. The clays showed high specific gravity, which may be a reflection of their high iron content. This is an indication that the clay material is unsuitable for use as highway such as sub-base, base course and sub-grade materials and airfield pavement bases unless improved. Adequate road design and heavy compaction with necessary stabilization material will boost strength and stability of the clays for all purposes, especially as a base course material.

Clay, Effium, Ezeaku Formation, Ngbo, Southeastern Nigeria

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