Mineralogy and microstructure effects on the stiffness of activated slag treated alluvium

Paul Sargent, Noor H. Jaber, Mohamed Rouainia

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Abstract

Alkali-activated alumino-silicate-based industrial waste products have recently proven to be beneficial as low-carbon alternatives to ordinary Portland cement binders for strengthening soft soils. This paper examines the small-strain stiffness behaviour of a UK silty alluvial soil in its natural state and
artificially cemented using sodium hydroxide-activated ground-granulated blast-furnace slag (GGBS). Undrained triaxial testing with bender element measurements revealed that the initial small strain shear stiffness (Gmax), shear strength and hydraulic conductivity of the alluvium were all significantly
enhanced after 28 d curing. Microstructural and mineralogical analyses were carried out on stabilised soil to understand the mechanisms better through which the enhanced engineering performances were achieved. Through hydration and pozzolanic reactions, a significant proportion of the clay
minerals within the original soil had been converted into new cementitious hydrates. These were observed to infill pore spaces, coating soil and GGBS particle surfaces and increased interparticle bonding throughout the matrix of the material. The outcomes from this study have the potential to contribute towards improving current practices for modelling cemented soils and ultimately making geotechnical designs involving deep soil mixing less conservative.
Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalGeotechnique Letters
Volume10
Issue number2
DOIs
Publication statusPublished - 30 Mar 2020

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