Effect Lime and Recron Fibre on Geotechnical Properties of Black Cotton Soil

Abstract

Clayey soils are considered as the weakest subgrade soil from civil engineering point of view under moist condition. These soils attract and absorb water and loses their strength. Because of this reason certain inherent properties of these clayey soils need modification for their bulk use in construction of highways, embankments etc. Recently, many synthetic fibres have emerged to strengthen soft soils. Synthetic fibres are low-cost materials, hydrophobic and chemically inert in nature which does not allow the absorption or reaction with soil moisture. The inclusion of synthetic fibres provides reinforcement to the soil and use of lime as a soil stabilizer in BC soil cut down the plasticity index and also increase its strength. For this an extensive laboratory test program was conducted to analyse the variation geotechnical properties of soil by changing the percentage of recron fibre at an optimum dose of lime. The laboratory tests include Atterberg Limit Test, Modified Proctor Test, Unconfined Compressive Strength Test and California Bearing Ratio Test. To conduct different tests on soil sample the proportion of lime is kept fixed and proportion of polyester recron fibre is varied from 0% to 1% by dry weight of soil sample for different lengths of fibre(6 mm, 12 mm & 18 mm separately). Optimum dose of lime is find out by plasticity index of BC soil mixed with varying percentages of lime (4%, 6%, 8% and 10%). Results of the experiments shows that with the increase in the appropriate percentage in recron fibre the Unconfined Compressive Strength and California Bearing Ratio increases. On increasing the length of Recron Fibre, the Unconfined Compressive Strength and California Bearing Ratio also increases. Combination of lime and recron fibre in BC soil give higher CBR value. Therefore it can be used in the improvement of Clayey Soil Subgrade in pavement design and in the construction of embankements.