Tyre bale foundations for roads on soft ground

Road construction over soft ground presents considerable technical challenges. Such roads often serve relatively remote communities and traffic levels are often low, meaning that construction and maintenance must be achieved within very limited budgets. There are two broad approaches to such construction: above ground (floating) construction and below ground (buried) construction. Historically floating construction has often employed bundles of twigs, called fascines, to provide a degree of resistance to differential settlement; the modern equivalent is the geosynthetic separation layer. This approach generally works best where a relatively stiff material, such as fibrous peat, overlies a less competent material, such as amorphous peat. Buried construction is generally preferable in more competent materials, or in poor materials of shallower depth such that removal is a viable option. In either case lightweight construction materials are highly desirable but can be costly. This study introduces a relatively new lightweight construction material in the form of tyre bales. Issues in relation to the use of tyre bales such as sustainability, waste management, costs and end of life are addressed in addition to describing their application to the construction of road foundations over soft ground.