The use of alkali activated waste binders in enhancing the mechanical properties and durability of soft alluvial soils

This paper presents recent work in utilising industrial by-products as sustainable binders for use in deep soil mixing, to enhance the geotechnical properties of soft soils. The study has used geotechnical and mineralogical tests to determine the performance of the binders when incorporated into an artificial silty sand soil. Comparisons with the strength and durability of untreated and stabilised soils have been made. The study indicates that from the by-products tested, soils stabilised with alkali activated blast furnace slag resulted in the greatest strength and durability improvements; with other materials tested showing smaller improvements. The addition of alkali activators has been observed to allow pozzolanic reactions to occur, which has led to improved mechanical properties; primarily strength, which increased with time. The durability of the soil was improved by the additions of by-products, though alkali activation did not cause significant additional increase in durability.

► IBP's have good potential as replacement binders for cement in soil stabilisation.
► Alkali activation proved successful in enhancing the performance of alluvial soils.
► The improved strengths of IBP-soil mixtures would suit construction specifications.
► IBP binders may be used for cases where strong brittle/plastic behaviour is needed.
► Using IBP binders over cement would be preferred financially and environmentally.