For 20 years, Expanded Polystyrene (EPS), known in civil applications as Geofoam, has been used in New South Wales, Australia as a lightweight fill material for various applications. Pioneered in Norway in the 1970s as a lightweight construction material to minimise settlement, Geofoam was first utilised in NSW for a highway widening on steep ground in 2002. Since then, Geofoam has been used as a lightweight fill to minimise vertical loads on soft ground where excessive settlement was predicted, for emergency and planned slope rehabilitation, as a way of reducing horizontal loading on bridge abutments, and for various other applications. There are several advantages to using Geofoam in construction. It can be more cost-effective than traditional ground improvement techniques; its use can lead to reduced construction time where earthworks’ compaction is needed and can reduce the vertical impact on services. Geofoam can be installed by smaller work crews utilising lighter plant and can minimise the excavation footprints for slope remediations. These examples are just some of the demonstrated advantages showcased as part of the case studies explored. Case study examples will illustrate where and in what capacity Geofoam has been utilised in NSW, practical experiences on how and why they have implemented at each location, observations on performance over time, and the process for wider acceptance in road construction projects.