Hydraulic Conductivity of Compacted Laterite Treated with Iron Ore Tailings

Umar Sa’Eed Yusuf,Matawal Danladi Slim,Elinwa Augustine Uchechukwu

doi:10.1155/2016/4275736

Umar Sa’Eed Yusuf, Matawal Danladi Slim + Show 1 more

Open Access

https://doi.org/10.1155/2016/4275736

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Abstract

The objective of this study was to investigate the effect of iron ore tailings (IOT) on hydraulic conductivity of compacted laterite. The IOT conforms to ASTM C 618-15 Type F designations. In the present study, soil was admixed with 0–20% IOT and compacted at moulding water content ranging from 10 to 25% using four types of compactive efforts. Hydraulic conductivities of the compacted soil-IOT mixtures were determined using deionized water and municipal solid waste leachate as the permeant fluids, respectively. Deionized water was the reference permeant fluid. Results of this study showed that hydraulic conductivity decreased with increase in IOT content as a result of improvement in mechanical properties of the soil. Permeation of the soil-IOT mixtures with leachate caused the hydraulic conductivity to drop to less than 1 × 10−9 m/s especially at higher compactive efforts. Also, bioclogging of the soil pores due to accumulation of biomass from bacteria and yeast present in the leachate tends to significantly reduce the hydraulic conductivity. From an economic point of view, it has been found from the results of this study that soil specimens treated with up to 20% IOT and compacted at the British Standard Light (BSL) compactive effort met the maximum regulatory hydraulic conductivity of less than or equal to 1 × 10−9 m/s for hydraulic barrier system.

Highlights

Guidelines have been compiled for selecting appropriate soil properties and compaction methods that are likely to result in low hydraulic conductivity of liners and covers [1, 2]
Three samples were prepared for each percentage addition of iron ore tailings (IOT) and the average optimum moisture contents (OMCs) and maximum dry densities (MDDs) taken
The MDD falls within a narrow range for each compactive effort: 1.75 to 1.82 Mg/m3 for Reduced British Standard Light (RBSL), 1.77 to 1.83 Mg/m3 for British Standard Light (BSL), 1.80 to 1.86 Mg/m3 for West African Standard (WAS), and 1.83 to 1.91 Mg/m3 for British Standard Heavy (BSH)

Summary

Introduction

Guidelines have been compiled for selecting appropriate soil properties and compaction methods that are likely to result in low hydraulic conductivity of liners and covers [1, 2]. These guidelines are based on experience and generally include minimum values or acceptable ranges for properties that describe composition of soil (e.g., Atterberg limits, particle size distribution) [3]. Soil barriers containing appreciable clay minerals are materials used extensively in constructing liners and covers for waste containment units due to their low hydraulic conductivity. Large cracks can occur in wet, compacted clays that are allowed to dry [7] For this reason, it is necessary to investigate the engineering properties of compacted lateriteIOT mixtures for liner in hydraulic barrier system. Compacted laterite soil has been shown to possess good hydraulic conductivity and low shrinkage [8]

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