An integrated recycling strategy of utilising excavation waste soil in marine clay improvement

This study explored an integrated recycling strategy of utilising a typical excavation waste soil, completely decomposed granite (CDG), in geopolymer production as a sustainable alternative of cement for marine clay improvement. Experimental campaign was conducted to evaluate the effects of composite alkali content and sodium silicate modulus on the mechanical performance of CDG-based geopolymer paste. Test results identified an optimal sodium silicate modulus, while it was also found that the incorporation of magnesium oxide (MgO) in alkali activator could improve the general workability. Moreover, regarding the unconfined compressive strength of marine clay improved, it was demonstrated that the combination of calcined CDG and ground granulated blast furnace slag (GGBS) considerably outperformed cement at the same level of dosage. Finally, multi-criteria assessment based on life cycle analysis (LCA) demonstrated the advantage of CDG-based geopolymer compared to conventional binders, in terms of mechanical properties, environmental benefits, and economic cost.