Effects of CIV 001 on California Bearing Ratio of High Plastic Clay Subgrade

Abstract

This study investigated the effectiveness of Clay Improving Vanish 1 (CIV 001), derived from a white afara tree in Bayelsa State, Nigeria, in enhancing the California Bearing Ratio (CBR) of high plastic clay soils from Bayelsa State (Loc 1-B) and Delta State (Loc 2-D) in the Niger flood zone. These soils pose challenges for road construction due to their low CBR values. Various ratios (0, 1:250, 1:200, 1:150, 1:100, and 1:150) of CIV 001 to water by dry soil weight were assessed through laboratory tests, including compaction and CBR tests. Both soils were classified as A-7-6 and CH by AASHTO and USCS respectively. For Loc 1-B, the Optimum Moisture Content (OMC) and Maximum Dry Density (MDD) were 21.5% and 1.380 g/cc, while for Loc 2-D they were 16.01% and 1.803 g/cc. Adding CIV 001 increased the MDD values for Loc 1-B to 2.301 g/cc and decreased OMC to 10.02%. For Loc 2-D, MDD increased with CIV 001 addition except for the 1:50 mix, which remained constant, while OMC decreased. The CBR values increased significantly from 4% to 10% for Loc 1-B and from 5% to 11% for Loc 2-D with CIV 001 addition. A model equation was formed through analysis. The study concluded that a 1:50 mix of CIV 001 significantly enhanced the CBR value to meet Federal Ministry of Works (FMW) standards in Nigeria, suggesting further investigation beyond the 1:50 mix could continue to improve CBR values

Keywords — CIV 001, California bearing ratio, Mix ratio, Soil Stabilization, Terminalia Superba