Experimental evaluation of kaolin stabilised with class F fly ash

Pratistha Tamang,Susana Lopez-Querol,Arathany Sriskantharajah,Pedro Ferreira

doi:10.1007/s10064-021-02373-5

Pratistha Tamang, Susana Lopez-Querol + Show 2 more

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https://doi.org/10.1007/s10064-021-02373-5

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Abstract

This study aims to investigate the effectiveness of fly ash (FA) in stabilising a kaolin soil through laboratory tests. Kaolin is an example of moderate plasticity clays that require stabilisation methods for construction purposes. The influence of FA on the improvement of kaolin is studied by varying its dosages in the mixtures (0%, 10% to 20%) as well as the cement content, used as an activator in different percentages (5 and 7%). The influence of the dry unit weight and the curing time of the soil mixture is also analysed through unconfined compressive strength and indirect tensile strength tests. The experimental results show that the strength increases linearly with both FA and cement contents. Moreover, higher initial dry unit weights also yield higher final strengths. To further assess the improvement, the application of the porosity over the volumetric cement content ratio, as the main variable, succeeded in attaining a relationship with the strength and the stiffness of the studied soil. Results for the combined effect of the porosity and the volumetric cement on the secant modulus were also determined. Furthermore, a unique relationship was obtained combining porosity, volumetric cement and FA content.

Highlights

Introduction and literature reviewSoil stabilisation is a method of improving the performance of a soil to suit the geotechnical requirements of a project, commonly used in soft soils such as clays, silts and organic soils
It was found that unconfined compressive strength (UCS) test (Cristelo et al 2012b; Mehdi et al 2014; Kolias et al 2005) and indirect tensile strength (ITS) test (Kolias et al 2005; Baykal et al 2004) have been commonly used by previous researchers to examine the performance of soil stabilisation
The experimental study of kaolin improved with class F fly ash (FA), activated with cement, was carried out to investigate the effectiveness of reutilising this waste material (FA), as a soil stabiliser in the construction industry

Summary

Introduction

Soil stabilisation is a method of improving the performance of a soil to suit the geotechnical requirements of a project, commonly used in soft soils such as clays, silts and organic soils. The use of fly ash (FA) for stabilisation of soils has received much attention as an alternative to conventional chemical additives; using FA has a carbon emission factor (i.e. the rate of pollutant released to produce a kg of material) of about 0.027 k gCO2_equivalent/kg, while more conventional methods using Portland cement have values of 0.92 kgCO2_equivalent/kg (Liu et al 2015). As soil stabilisation in ground improvement projects requires a large volume of raw materials, utilisation of FA in soil stabilisation has a significant potential to minimise the amount of disposed waste material (Cristelo et al 2013)

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