International Journal of Civil and Structural Engineering Research ISSN 2348-7607 (Online) Vol. 6, Issue 2, pp: (27-34), Month: October 2018 - March 2019, Available at: www.researchpublish.com
Improvement of Expansive Soils with Blended Composite Materials as Stabilizers Terence Temilade Tam Wokoma1, Charles Kennedy2, Tobi Derebebeapade Stanisslous3 1,2
School of Engineering, Department of Civil Engineering, Kenule Beeson Saro-Wiwa Polytechnic, Bori, Rivers State, Nigeria 3 Department of Architecture, School of Environmental Technology, Kenule Beeson Saro-Wiwa Polytechnic, Bori, Rivers State, Nigeria. Authors E-mail: 1terencett.wokoma@gmail.com, 2ken_charl@yahoo.co.uk, 3tedsasso@yahoo.com
Abstract: The study observed the application of waste extracted bagasse fibre ash of costaceae lacerus blended with lime to improve the engineering geotechnical properties of an expansive soil subgrade for road pavement materials. Preliminary investigations proved the sampled soils poor and fell below the minimum requirement for such application. The soils are classified as A-7-6 of American Association of State and Transport Officials (AASHTO) soil classification system with plastic index properties of 20.33%, 20.35%, 21.85%, 26.30%, and 21.35% respectively of sampled roads. Compaction test results obtained showed increased values in both maximum dry density and optimum moisture content relatively to ratio percentage additives. Comparatively, stabilized clay soils California bearing ratio increased with increase in additives inclusion with optimum mix proportion of 7.5% + 7.5%. Cracks occurred beyond optimum mixed level. Unconfined compressive strength test results increased with varying additive percentages. Costaceae lacerus bagasse fibre ash and lime proved to be good composite materials combination in soil stabilization. Keywords: Clay soils, costaceae lacerus bagasse ash, Lime CBR, UCS, Consistency, Compaction.
1. INTRODUCTION The desirable requirement of widely used soils (lateritic and clay) for materials for road earthworks can be achieved with the use of soil stabilizers of fibre , lime, cement, fly- ash and others, either in single or in combined actions. Except in very rare and exceptional cases, soils (including deltaic lateritic soils) in their natural states hardly possess characteristics suitable for desired engineering applications, particularly for road works. The minimum requirements for soils or soilbased materials usable in road pavement structures have been indicated by the FMW Specifications [1]. Soil Stabilization has proved to be very economical as it provides cheap materials for the construction of low cost roads. Numerous kinds of stabilizers were used as soil additives to improve its engineering properties. A number of stabilizers, such as lime, cement and fly ash, depend on their chemical reactions with the soil elements in the presence of water (Azadegan et al. [2]; Mallela et al. [3];). Other additives, such as geofiber and geogrid, depend on their physical effects to improve soil properties (Alawaji, [4]; Viswanadham et al. [5]). In addition, it can be combined both of chemical and physical stabilization, for example, by using lime and geofiber or geotextile together (Yang et al. [6]; Chong and Kassim, [7]). Lime is the oldest traditional chemical stabilizer used for soil stabilization (Mallela et al. [3]). Rao et al. [8] studied the effects of RHA, lime and gypsum on engineering properties of expansive soil and found that UCS increased by 548 % at 28 days of curing and CBR increased by 1350 % at 14 days curing at RHA- 20%, lime -5 % and gypsum -3%. Charles et al. [9] investigated and evaluated the engineering properties of an expansive lateritic soil with the inclusion of cement / lime and costus afer bagasse fibre ash ( locally known as bush sugarcane fibre ash(BSBFA ) with ratios of laterite to cement, lime and BSBFA of 2.5% 2.5%, 5.0% 5.0%, 7.5% 7.5% and 10% 10% to improve the values of CBR of less than 10% and termed poor on remarks required subgrade and strength fo constructional works. At 8% of both
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