STABILIZATION OF CRUDE OIL CONTAMINATED LATERITIC SOIL USING COMPOSITE MIXTURE OF BIOCHAR AND CEMENT

Abstract

This work studied the effects of composite mixture of cement and biochar in the stabilization of crude oil contaminated lateritic soil to ascertain its suitability as earthwork construction material. Disturbed lateritic soil sample was artificially contaminated with 10% crude oil obtained from Olomoro-Oleh Oil and Gas Field, Isoko South Local Government Area, Delta State, Nigeria. The natural and contaminated soil specimens were subjected to geotechnical tests to determine the Specific gravity (SG), Plasticity Index (PI), Percentage Passing Sieve No 200, Maximum Dry Density (MDD), Optimum Moisture Content (OMC), unsoaked and soaked California Bearing Ratio (CBR). Results indicated that the contamination of the soil with 10% crude oil increased its plasticity and generally reduced its workability and strength. Stabilization of the crude oil contaminated soil with biochar increased the plasticity index of the soil. However, addition of cement decreased the PI of the crude oil contaminated soil. The percentage passing sieve No 200 increased with increasing contents of cement and biochar. The addition of cement improved the MDD and CBR, but there was reduction MDD and CBR with the addition of biochar. Two-way Analysis of Variance (ANOVA) performed on the results showed that cement and biochar had statistically significant effects on all the parameters. Based on this research, the use of 15% cement with 4% biochar improved the strength of crude oil contaminated lateritic soil and is therefore recommended for the use of crude oil contaminated soil as subgrade material in earthworks construction.