Strength and Workability Improvement Potential of Admixture of Corn Cob Ash and Cement for Stabilizing Lateritic Soil

O M Osuolale ,J R Oluremi ,Solomon Adedokun

doi:10.7176/jiea/9-7-06

Abstract

A natural lateritic soil classified as A-7-5 (10) and CL based on AASHTO and USCS classification systems, was stabilized with up to 5% cement admixed with up to 12% CCA to assess their effect on its basic geotechnical properties such as particle size distribution, Atterberg limits, compaction, unconfined compressive strength and California bearing ratio. The liquid limit decreased and plastic limit increased while there is a reduction in corresponding plasticity index of the clay soil. There was an increase in Maximum Dry Density (MDD) and Optimum Moisture Content (OMC) of the stabilized soil sample, which increased with the increasing content of CCA and cement. Both the Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) of the soil increased with increasing percentage of cement and CCA. Based on the results of this study, corn cob ash (CCA) cannot be used as a stand-alone stabilizer for this lateritic soil but with a more potent stabilizer for clay soil such as lime. It is therefore recommended that the mixture of 12% CCA and 2.5% cement could be used to stabilize A-7-5 (10) lateritic soil for use as subbase material and 12% CCA and 5.0% cement could be used to stabilize A-7-5 (10) lateritic soil for use as base material for improving pavement structure in terms of strength, stability and workability. Keywords: Lateritic soil, Corn cob ash, Cement, Stabilization, Strength and Workability DOI : 10.7176/JIEA/9-7-06 Publication date: December 31 st 2019

Highlights

There are several highway pavement failures in Nigeria and these failures had been attributed to inadequate strength of the foundation materials, properties of construction materials, subgrade conditions, environmental conditions, traffic loading, lack of drainage and poor workmanship (Osuolale, et al, 2012)
Since the percentage passing sieve No 200 is greater than 35%, and the plasticity index is greater than 12%, the soil is described as poor subgrade material according to Nigerian Highway Specification for Road and Bridges, (1997)
From this study, the following conclusions were deduced: 1. The stabilization of the lateritic soil, classified as A-7-5 (10) and CL based on Association of State Highway and Transportation Officials (AASHTO) and USCS

Summary

Introduction

There are several highway pavement failures in Nigeria and these failures had been attributed to inadequate strength of the foundation materials, properties of construction materials, subgrade conditions, environmental conditions, traffic loading, lack of drainage and poor workmanship (Osuolale, et al, 2012). Laterite soil is a common construction material available in almost all the countries of the humid tropics of the world (Akinrinlola 1991). This available soil does not have adequate engineering properties to really carry the expected wheel load, especially high traffic density. The need for improvement of the engineering properties of laterite soil has been a paramount concern to the highway engineers especially in Nigeria where the cost of locating, burrowing and hauling of alternative suitable soil may be too expensive. Soil improvement is achieved through either the stabilization or modification of the unsuitable or unstable soil

Methods

Results

Conclusion