Effects of Cement and Lime Stabilization on Geotechnical Properties of Petroleum Contaminated Soils from Kolo-Creek, Niger Delta, Nigeria

Abstract Petroleum-contaminated soils, coupled with geohazards such as flooding, pose significant challenges to the development of climate-resilient infrastructure, especially in oil-rich regions like the Niger Delta, Nigeria. This study examines the geotechnical properties and remediation potential of petroleum-contaminated soils in the Kolo Creek area. The site lies within the central Niger Delta basin, geologically underlain by Recent Alluvium comprising soft clays, silts, and organic-rich sediments, characteristic of flood-prone environments. Ten (10) surface soil samples were analyzed for Total Petroleum Hydrocarbons (TPH), Polycyclic Aromatic Hydrocarbons (PAHs), and BTEX compounds. The results revealed high moisture content (12.0–25.5%, avg. 18.7%) and poor engineering performance, with clayey classifications (CL/CH), low Unconfined Compressive Strength (UCS 85 kPa), and elevated TPH (43.27–160.67 mg/kg; avg. 122.29 mg/kg), rendering the soils unsuitable for subgrade applications. Stabilization trials using Ordinary Portland Cement (OPC), lime, and blended additives at dosages of 5%, 8%, and 10% substantially improved geotechnical performance. improvements. At 10% OPC and 28 days of curing, UCS increased to 270 kPa, PI reduced to 5, and California Bearing Ratio (CBR) improved from 3–11%. For lime: UCS reached 245 kPa, PI dropped to 4, and CBR to 9%. The additive blend yielded UCS = 260 kPa, PI = 6, and CBR = 10%. Among all, cement stabilization was most effective, yielding the highest strength and lowest plasticity. These results confirm that in-situ stabilization can effectively rehabilitate petroleum-impacted soils for use in low-volume roadbeds, embankment fills, and non-structural backfills. Post-treatment, the soils are deemed suitable for subgrade layers in low-volume roads, embankment fills, and non-structural backfills. The findings support incorporating soil remediation into infrastructure planning to improve durability, climate resilience, and geohazard mitigation across vulnerable regions like the Niger Delta.