Foamed glass - an alternative lightweight and insulating material

The Norwegian Public Roads Administration has initiated a programme to promote the use of recycled material in road structures. Granulated foamed glass, produced by recirculating waste glass, is being investigated as a material for road construction applications. The production process involves mixing finely ground glass powder from different glass sources with an activator such as silica carbide. During grinding, heavy metals are separated and recycled to metal melting plants. The powder is spread on a steel belt conveyor running through high temperature ovens where the powder expands to form a foam. When it leaves the oven it cracks into smaller fragments. The material is characterised by favourable drainage and insulating properties and light weight. It can be used as a lightweight filling material and/or frost insulating layer. The results of a monitoring programme of field tests conducted by the Public Roads Administration are presented. Use of foamed glass on road E6 at Eggemarka to reduce the weight on a culvert, improve stability and reduce settlement problems is described.