Browsing by Author "Henry, Rachel"

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    Suitability of shredded waste rubber tires for improvement of geotechnical properties of laterite soil
    (University of Dar es Salaam, 2014) Henry, Rachel
    Most of the soils and gravels available in Tanzania do not have adequate engineering properties to sufficiently bear the expected wheel load. Laterite soils are the most common soils and gravels found in Tanzania. They can be used as road sub-grades, sub-base and base course materials in natural form or after being stabilized. Cement and lime are the most common materials used for soil stabilization in Tanzania. However the cost of cement and lime is constantly increasing and their production contributes to environmental pollution. Therefore, there is a need of studying alternative materials, including waste rubber tyres, to asses or examine if they have positive effects on geotechnical properties of laterite soils for road construction. A study has been carried out to investigate the suitability of shredded waste rubber tyres for improvement of geotechnical properties of laterite soils. Samples of laterite soil mixed with varying amounts of shredded rubber were subjected to various laboratory tests including particle size distribution, specific gravity, modified proctor compaction, CBR, permeability, 1-D consolidation and CU-triaxial tests. Results show that addition of 4% chip rubber improved the CBR of laterite soil from 8% to 21% in soaked condition. The cohesion also increased from 65 kN/m2 to 73 kN/m2 and the permeability increased from 3x10-8 cm/s to 4x10-6 cm/s. Addition of shredded waste rubber tyres to laterite reduced the MDD of the materials from 2020 kg/m3 to 1490 kg/m3. This may qualify laterite-shredded rubber tyre mixture to be used as a lightweight fill material for embankments, retaining wall back fill or lightweight subgrade material.