Case evaluation of structural strength improvement of cement stabilized lateritic soil reinforced with sisal fibers and plastic waste strips

The progressive increase in the rate of production of plastic bottles by the beverage and food industries in Nigeria has increased considerably over time, constituting large volume of waste generations from plastic waste bottles. Also, increasing demand for eco-friendly soil improvement materials and the growing desire to minimize waste generated daily, prompted the need for this study to look into ways to use such wastes and other sustainable materials in soil improvement. This study investigated the potential use of sisal fiber and plastic waste strips as partial replacement for cement to enhance the geotechnical characteristics of lateritic soils. Various laboratory experiments were conducted, encompassing specific gravity determination, grain size distribution, compaction assessment, Atterberg limit, unconfined compressive strength (UCS), and microscopic analysis. Sisal fiber and plastic waste strips were each varied at 0, 0.5, 1.0, 1.5, 2.0 and 2.5% while maintaining a constant 5% cement added to all the mix proportions. Results of investigation revealed an enhancement in plasticity of the soils with both treatment methods. Liquid limit shows a steady drop from 43% in its natural state to 42% and 41% at 1% sisal fiber and 1% plastic strips content respectively, while plasticity index showed a decline from 14.8% in its natural form to 12.69% and 10.8% at 2% sisal fiber and 1% plastic waste strips content respectively. Strength properties of the treated soil increased with increase in admixtures content. Microanalysis of the natural and optimally modified soils showed alteration in the fabric arrangement of the particles of soils. Based on the results of the study, optimally 1–1.5% sisal fiber/5%cement and 1–1.5% plastic waste strips/5%cement meaningfully improved the soil strength and can both be used as sub-base materials for light trafficked roads.