Compaction Characteristics of Igumale Shale

Abstract

This paper reports the outcome of an investigation into the effect of different compactive energies on the compaction characteristics of Igumale shale, to ascertain its suitability as fill material in highway construction. Tests were conducted on specimen of Igumale shale, which included classification, compaction using three compactive energies in the laboratory (British standard light, West African standard and British standard heavy), and unsoaked and four-day soaked California bearing ratio (CBR) test. Results showed that Igumale shale was an A-7-6 soil. Maximum dry density (MDD) increased, while optimum moisture content (OMC) decreased with increase in compactive energy. The MDD of samples 1 and 2 increased from 1.53 Mg/m³ and 1.59 Mg/m³ to 1.90 Mg/m³ and 1.89 Mg/m³ while the OMC decreased from 19.1 % and 16.8 % to 14.3 % and 13.0 % respectively. The unsoaked CBR of samples 1 and 2 increased from 16.1 % and 10.1 % to 40 % and 37.5 % respectively. A similar trend was observed for the four-day soaked CBR values. The study showed that Igumale shale is not suitable for use as base, subbase and filling materials in road construction. However, chemical stabilization with higher compactive energy can be applied for better improvement.