Laboratory characterization of mixed waste materials from Semakau Landfill

Abstract

With a supposed life expectancy till 2045, Singapore’s only offshore landfill – Semakau Landfill, however, is expected to reach maximum capacity by 2035. The National Environment Agency of Singapore (NEA) had started to look into ways to reuse the mixed waste materials in Semakau in order to free up space. One of the possible reutilizations of mixed waste materials is reusing it as a fill material for land reclamation. The land-scarce Singapore has always been looking into land reclamation to tackle the challenges of growing population and strive for economic growth. With the growing bans of sand exports from other countries into Singapore, the country must look into alternatives for its current and future land reclamation projects. In this report, Mixed Materials (MM) came directly from Semakau Landfill are being studied. The mixture includes incineration bottom ash (IBA), incinerated fly ash (IFA) and non-incinerable wastes. MM is tested for its mechanical properties – specifically the shear strength. The 2 parameters of shear strength, cohesion and angle of internal friction, and the stress-strain behaviour of MM are determined using Direct Simple Shear Test method by going through both the consolidation process and the monotonic shear test. The angle of internal friction will then be used to compare with the current fill materials used for land reclamation to determine the feasibility of MM to be reused as a fill material for land reclamation.In general, the angle of internal friction calculated from the data collected shows that MM is a potential fill material for land reclamation as the friction angles are comparable to coarse-grained sand – the most used fill material for land reclamation. However, more tests will still need to be conducted under different conditions to fully determine if the reutilization of MM as fill material for land reclamation is feasible.