International Journal of Civil and Structural Engineering Research ISSN 2348-7607 (Online) Vol. 6, Issue 2, pp: (58-64), Month: October 2018 - March 2019, Available at: www.researchpublish.com
Stabilization of Deltaic Soft Clay Soils using Irvinga Gabonesis Fiber Ash as Stabilizer Charles Kennedy1, Akpan Paul Paulinus2, Letam Leelee Prince3 1
Faculty of Engineering, Department of Civil Engineering, Rivers State University, Nkpolu, Port Harcourt, Nigeria
2,3
School of Engineering, Department of Civil Engineering, Kenule Beeson Saro-Wiwa Polytechnic, Bori, Rivers State, Nigeria. Authors E-mail: 1ken_charl@yahoo.co.uk, 2paulyncia07@gmail.com, 3leeprices076@yahoo.com
Abstract: The study examined the functional use of fiber ash of irvinga gabonesis to improve the geotechnical characteristics of weak and unstable subgrade pavement of Iwofe, Chokocho, Ndoni, and Ogbele roads characterized with differential settlement, degradation and cracks that resulted from swelling and shrinkage due to seasonal variation of wet and dry. Preliminary investigation revealed the soils are dark grey in color (from wet to dry states), plasticity index of 31.10%, 24.55%, 31.05%, and 32.17%. The soils has unsoaked CBR values of 7.35%, 7.75%, 8.15%, and 7.85% and soaked CBR values of 6.35%, 6.23%, 7.05% and 5.55%, unconfined compressive strength (UCS) values of 87.85kPa , 78.75kPa, 105.75kPa , and 85.35kPa and has classified the soils as poor and unfit for its applications for road constructional materials except modified. Results of stabilized state obtained signified decreased values of MDD and increased values of OMC, this implies the increased in fibre ash content decreases MDD and increases OMC compaction parameters of stabilized clay. Comparably, results indicated increased in CBR of altered soils with optimum mixed percentage ratios of 7.5% to soils. Results also indicated that at percentage ratio of 10% to soils and above, decreased in values were noticed as well as cracked presence. Comparative results of unconfined compressive strength showed increased values corresponding to percentage ratio of stabilizer inclusion. Results, when compared to unstabilized soils decreased in plastic index with fibre inclusion. Entire results showed potential use of fiber ash of irvinga gabones is as stabilizer. Keywords: Clay soils, Irvinga Gabonesis Fibre, CBR, UCS, Consistency, Compaction.
1. INTRODUCTION The desired properties of improved soil are to increased strength, reduced compressibility, appropriate permeability to solve stability and settlement problems. Soft clay formations, especially those with high in situ water contents, are susceptible to large settlements and possess low shear strength unless they are naturally cemented. For soil to meet the desirable standard recommended by Federal Ministry of Works (FMW [1]) for subgrade pavement, stabilization is needed to improve the soil to minimum requirements for soils or soil-based materials usable in road pavement structures. Studies have shown the effect of reinforcement on swelling behavior of clays (Puppala and Musenda, [2]); reduction of soil swell potential with fibre reinforcement (Loher et al. [3], and effect of fibres on swelling characteristics of bentonite (Banu et al., [4]). Charles et al. [5] evaluated the engineering properties of soil with the inclusion of costus afer (Bush sugarcane bagasse fiber ash (BSBFA) at varying percentages. Results of compaction of soil between the relationship of optimum moisture content (OMC) and maximum dry density (MDD) of soil and bagasse ash inclusion increased with increase in BSBFA percentages of 7.5% and decreased at 2.5% to 10% bagasse ash inclusion. Stabilization was found to satisfy subgrade requirements. Their results showed the potential of using BSBFA as admixture in soils of clay and laterite. Swelling of treated soil decreased with the inclusion of bagasse fibre ash up to 7.5% for both soils. Sabat [6] studied the effects of polypropylene fiber on engineering properties of RHA-lime stabilized expansive soil. Polypropylene fiber added were 0.5 % to 2 % at an increment of 0.5 %.The properties determined were compaction, UCS, soaked CBR, hydraulic conductivity and P effect of 0 day, 7 days and 28 days of curing ware also studied on UCS, soaked
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