Evaluation of Compacted Laterite Soil Admixed with Cement and Hair Fibres as Road Construction Material

Abstract

A natural lateritic soil classified as A-5 (4) based on American Association of State Highway and Transportation Officials (AASHTO) soil classification system and ML-CL according to Unified Soil Classification System (USCS), was admixed with ordinary Portland cement and synthetic hair fibres (SHF) was evaluated as road construction material. Soil test specimens were made by admixing lateritic soil with up to 4% cement  in 1 % step concentration and up to 12% SHF in step concentration of 2 % by dry weight of the soil and were subjected to British Standard Light (BSL) or Standard Proctor method of compaction, unconfined compressive strength (UCS) and California bearing ratio (CBR) tests. Results indicated a decrease in the values of optimum moisture content (OMC) while no general trend was established for maximum dry density (MDD). The values of UCS and CBR increased as the content of both cement and SHF increased. Analysis of variance (ANOVA) of the results shows some level of statistical significance on some geotechnical properties considered. Regression analysis on the results using Minitab R15 software shows that MDD, OMC, cement and SHF significantly influenced the UCS and CBR values of the stabilized soil with correlation coefficient value (R2) of 82.9 and 83.3% respectively. Based on the results, an optimal blend of 3% cement 9% SHF significantly improved  the soil properties and is recommended  for improving the geotechnical properties of cement/synthetic hair fibre treated lateritic soil as road construction material.