Ordinary Portland Cement Stabilization of Engineering Soil using Coconut Shell and Husk Ash as Admixture (original) (raw)

For many developing countries, failure of roads has been a worrisome situation and this more common in southeastern Nigeria. Over time, the basic preliminary phase of civil engineering project like proper soil investigation is ignored leaving completed civil engineering project at the mercy of the effects of such negligence. In most cases, weak engineering soil is used to foundations without proper studies and investigation to determine the geotechnical engineering properties of a material in use. One of the contributing factors of the use of poor or weak engineering soil is the high cost of stabilizing or binding agents used for construction eg cement, quick lime, etc. The present research was carried out to provide cheaper, safer and better materials to improve engineering soil for civil engineering works. The stabilization of laterite for improved engineering properties was investigated, and the geotechnical, chemical, and phase analytic method was used to characterize both the raw and treated laterite. Coconut Shell-Husk Ash (CSHA) was used as admixture for the stabilization in varying percentage at a constant percentage of Ordinary Portland Cement (OPC). The engineering soil used for this investigation was collected from Amizi, Olokoro in Umuahia South LGA, Abia State, Nigeria and preliminary tests carried out on the sample show that it is too brittle and thus not suitable as sub-base materials. The result of the sieve analysis and Atterberg limits tests graded the soil as Reddish Sandy Silt soil with a little high plasticity and it falls in the A-2-7 AASHTO classification system. It failed some of the standard requirement specified by the Ministry of Works and Housing in Nigeria. For instance, for the standard required 80% CBR, the sample had a value of 28% which is relatively low. The CBR test shows that the addition of cement at 5% by mass improves the soil, and further addition of varying percentages of CSHA in the order; 2%, 4%, 6%, 8% and 10% increased it relatively and it reached its peak of 82% at 8%CSHA and 5%OPC which is which is considerably satisfactory. The triaxial test result showed an improvement from Cu=23 KN/m2 and Ǿ=200 at its natural state to Cu=25 KN/m2 and Ǿ=290 thereby making the soil satisfactory for sub-base material in road pavement construction.