Use of Polypropylene Fibres for Cohesive Soil Stabilization

Rapidly increasing infrastructure demands more ground availability to transfer the stresses safely. Scarcity of good bearing soil at infrastructure site requires improvement/modification in the soil properties to allow further construction activity mainly in fine-grained soils. This paper presents application of polypropylene fibres (PPF) for stabilization of expansive soil procured from Bhestan near Surat, South Gujarat. During the study, PPF in proportion of 0.75, 1.5, 2.0, 2.25 and 2.5% have been mixed randomly with soil. Various tests were performed to study compaction characteristics, soaked California bearing ratio (CBR) and unconfined compression of virgin soil samples and soil samples with above-mentioned PPF contents. Results showed that addition of PPF reduced maximum dry density in the range of 3–6.5% and increased optimum moisture content in the range of 2.3–5.25%. Also, mixing of PPF (10 mm fibre length) up to 2.25% increased soil CBR from 1.54 to 5.75%, which decreased on further addition of PPF. Increase in PPF fibre length from 10 to 30 mm further increased CBR from 5.75 to 7.06% for same PPF content. In addition, the unconfined compressive strength of the soil was observed to increase by 56.9% at 2.25% PPF. Results highlighted that soil stabilization using PPF is quite useful for modifying properties of cohesive soil.