Sustainable cementitious blends for strength enhancement of dredged mud in Queensland, Australia

Yaxu Liu,Zhuang Liu,Erwin Oh,Ross Hughes,Dominic E L Ong

doi:10.1680/jgere.21.00046

Abstract

Cement is commonly used as a stabilisation material in soft soil stabilisation. However, the use of cement can cause environmental issues, as the production of cement results in high emission of carbon dioxide (CO2). Hence, it is essential to develop other suitable stabilisation materials to reduce the amount of cement used in the stabilisation of soft soil. Fly ash and DuraCrete (blended cement) were investigated in this study to be used as partial replacements for traditional cement-only mixes. The behaviour of specimens stabilised using cement, fly ash and DuraCrete under both unconfined compressive and consolidated isotropic undrained conditions was investigated in this study. The experimental results proved that both fly ash and DuraCrete can be used as partial replacements for cement. Fly ash can provide the highest reduction in terms of percentage of cement. Meanwhile, DuraCrete is more cost effective, as a relatively smaller quantity of DuraCrete can replace a correspondingly larger amount of cement for a similar strength gain. The contribution of this research can provide engineers with alternative, more sustainable design mixes for soft soil stabilisation that can readily satisfy design strength requirements while emitting relatively less carbon dioxide.

Highlights

Soft soil deposits such as mine tailings, hydraulic fills, soft estuarine or marine clays commonly exist across the planet
This study investigated the mechanical, physical and microstructural properties of Port of Brisbane (PoB) soft soils that are stabilised by three different cement-based binders cement, fly-ash-blended cement and DuraCrete-blended cement
A further series of tests was conducted to investigate the use of fly ash and DuraCrete as partial replacement of cement

Summary

Introduction

Soft soil deposits such as mine tailings, hydraulic fills, soft estuarine or marine clays commonly exist across the planet. In a study conducted by Cheng et al (2018), regarding the mechanical behaviour of soft soil stabilised by fly-ash-blended cement, an empirical relationship between peak strength and confining pressure was proposed based on the triaxial compressive tests. The total mixture contents (cement + DuraCrete) range from 10 to 30%, which is consistent with the specimens stabilised by cement only or fly-ash-blended cement.

Results

Conclusion