Sustainable soil stabilisation with ground granulated blast-furnace slag activated by olivine and sodium hydroxide

Mohammad Hamed Fasihnikoutalab, Shahram Pourakbar, Richard Ball, Cise Unuler, Nuno Cristelo

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Ground granulated blast-furnace slag (GGBS), activated with olivine (Mg2SiO4) and sodium hydroxide (NaOH), was used to stabilise a clayey soil. Mechanical and microstructural properties of the stabilised soil were assessed through uniaxial compression strength (UCS) tests, X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDS), after curing periods of 7, 18 and 90 days. The UCS of the GGBS-treated soil (without activation with NaOH), even at the highest slag dosage (G20S), after 90 days, showed only a slight increase (142 kPa) relatively to the original soil. When olivine was added to the GGBS-treated mixture (O20G20S), the UCS increased to 444 kPa, after 90 days. However, when NaOH was used as an activator, the UCS of the olivine–GGBS-treated soil (NO20G20S) increased to more than 6000 kPa, after 90 days. This significant strength increase was attributed to the higher reaction degree provided by the NaOH, which enabled a more effective exploitation (dissolution) of the Ca and Mg present in the slag and olivine, respectively, forming a mixture of C–S–H and M–S–H gels.
Original languageEnglish
Pages (from-to)1981-1991
Number of pages11
JournalActa Geotechnica
Early online date30 Nov 2019
Publication statusPublished - 31 Jul 2020


  • Alkaline activation
  • Ground granulated blast-furnace slag
  • Olivine
  • Soil stabilisation

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