Influence of compaction energy and iron ore tailings on properties of tropical black clay using statistical approach

Abstract The study assessed the suitability of iron ore tailings (IOT) as a stabilizing additive for selected tropical black clay (TBC) also called black cotton soil, BCS compacted at varying energy levels (ELs). The soil was treated with 0, 2, 4, 6, 8, 10, 12, 14 and16% IOT and compacted with British Standard Light (BL), West African Standard (WS), and British Standard Heavy (BH). Tests conducted include index tests, compaction, strength tests and durability assessment. Results show that both liquid limit and plasticity index decreased with increase in IOT content, maximum dry density (MDD) generally increased, while optimum moisture content (OMC) decreased with increase in IOT content. Unconfined compressive strength (UCS) values at 7, 14, and 28 days increased with both higher IOT content and energy levels. The unsoaked California Bearing Ratio (CBR) increased from 7.89, 9.82 and 15.03% to peak values of 16.24, 19.64, and 21.15% at 14% IOT for BL, WS, and BH energies, respectively. Resistance to loss in strength (RLS) increased with increase in energy levels and IOT content. Statistical findings using analysis of variance (ANOVA) and correlation analysis confirmed that IOT significantly enhanced the engineering properties of the soil. Regression coefficients of 96.4, 85.9, 87.3 and 70.7% were recorded from regression analysis using UCS, Unsoaked CBR, soaked CBR and RLS respectively, as dependent parameters. Based on the results, an optimal 10–12% IOT significantly improve the soil properties and can be used as sub-based materials for lightly trafficked or rural roads.