Lime stabilisation of the chicoco mud of the Niger Delta

Abstract

Chicoco mud is a very soft and extremely compressible organic marine mud found extensively and to considerable depths within the saline tidal flat or mangrove swamp of the Niger delta region in southern Nigeria. Natural chicoco mud is highly compressible barely able to support an average human weight but air-dried chicoco has been used successfully by the natives for shore protection, etc. especially if placed above water. In this study, varying percentages (ranging from 1% to 9%) of industrial and locally produced (from periwinkle shells) slaked-lime were used to stabilise chicoco. It was observed that neutralisation of acidic “air-dried” chicoco by basic lime inhibited the expected ion-exchange reaction and its attendant improvement in mechanical properties. As a result and as lime (industrial or locally-produced) content increases, maximum dry density (MDD) decreases, optimum moisture content (OMC) decreases while unsoaked CBR maximises within low lime content of about 4%. Also, significant improvement in all three parameters (MDD, OMC and CBR) was recorded with saltwater addition. However and with maximum unsoaked CBR of only 12.5%, lime-stabilised chicoco can only produce subgrade materials in roadworks, i.e. not unsuitable for sub-base and base-course materials.

Keywords: chicoco mud, Niger delta, lime, periwinkle, stabilisation

Global Journal of Engineering Research Vol.4 (1&2) 2005: 69-73