Date of Publication :7th November 2016

Abstract: The work presents the impact of Mango Nut Ash on expansive or Black cotton soil, the work was conducted with the bias of investigating the how suitable Mango Nut Ash (MNA) would have on expansive soils when used as subgrade material in Highway Engineering. Series of laboratory tests were conducted on soil that was fetched few meters away from the major mess of Career Point University Kota, the soil was obtained at about one-meterdepth. The laboratory tests conducted in the course of this research includes; Specific gravity, liquid limit, California Bearing Ratio (CBR), unconfined Compression strength (UCS), free swell index, compaction by proctor method, Insitu- dry density by Core- cutter method. Tests were conducted in the 3% increment at each stage, 3%, 6%,9%,12% and 15% of Mango Nut Ash (MNA) were blended with the soil. It was observed that the CBR value of the soil on addition of CBR increased by 85% with the Optimum CBR value at 15% addition of MNA, Unconfined compression test improved with about 61.50% with optimum value at 15% as it increased from 3% to 15% in geometric progression. Maximum Dry Density (MDD) improved by 50% at Optimum value of 15% blending of MNA with soil. Optimum Moisture Content reduced by 56% at 9% of MNA, free swell index fell by 22.22 % and specific gravity increased by 62. %, plastic Limit decreased significantly, the plasticity index decreased. The experimental results showed that Mango Nut Ash (MNA) has the ability to improve geotechnical characteristics of expansive soils for use as sub-grade material. Design of pavement was done for CBR of 2%(Natural soil) and 12% (optimum) and the differences in thickness and economic advantage was compared.

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