| Summary: | As the population in Singapore rises, there was a strong need to utilise unused land consisting of weak soft marine clay by incorporating soil improvement techniques like Deep Soil Mixing (DSM) and dynamic compaction for top layer soils. The utilisation of Portland Cement (PC) have been known throughout the world for soil improvement. However, with the environmental impact that is brought along with the production of PC, various authors and researchers from different backgrounds have set their course on looking for other environmentally friendly materials as a substitute for PC. Ground Granulated Blastfurnace Slag (GGBS) has been a prominent material that could potentially eliminate the usage of PC in terms of soil stabilisation. In order to strengthen and reach its full activation, an alkali known as Reactive Magnesia (MgO) is needed together with GGBS. In this paper the utilisation of GGBS and MgO on Kaolin is investigated and its effect on soil is gauged through the stiffness. Adding on, a new compaction method known as “two step compaction with reversal of loading face” was implemented to allow the compaction to be more efficient. Various graphs and results with different parameters like curing days, binder content shows clearly, that there is a significant improvement in stiffness with increased usage of GGBS and MgO. The study also seeks to find out the most optimum ratio of MgO/Binder content to benefit the use of this novel activator with GGBS on actual sites. Through a comparative analysis of the range of curing periods, there was a significant improvement on the stiffness of soil. The highest stiffness value (5220 MPa) came from a 28 days old specimen of 10% MgO content with a binder composition of 30%.
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