Using recycled tyres for access road

Ecoflex Systems was commissioned by Energy Australia for a project which resulted in recycling 75,000 truck tyres. The Tomago all-weather access road project was required as part of a larger project to upgrade electricity supply from Tomago to the Tomaree Peninsula in New South Wales.

The project required the construction of a 16 km stretch of pavement which:

• required that there be no excavation, compaction or levelling of the ground, to avoid: exposure of acid sulfate soils; disturbance of heritage sites, flora and fauna; and impact on private land;
• created a load-bearing capacity of 60 tonnes for crane traffic during construction of an electricity transmission line;
• was permanent and required little maintenance;
• had a low profile to preserve visual amenity; and
• was water permeable horizontally and vertically, to minimise impact on the ecosystem.

The project used Ecoflex E-Pave units in a recycled-tyre reinforced payment design which is claimed to save 15% in costs over the conventional macadam design. The project also absorbed 6% of NSW's annual waste tyre stream which would otherwise have gone to landfill.

The tyre-reinforced permeable pavement was developed specifically for water saturated conditions, where the ground has low load bearing capability. The method used robust engineering systems to take advantage of the structural value of recycled tyres.

The recycled tyre consists of an approved tyre with the side-wall cut out at a precise location. An approved tyre is one that has a solid rubber tread with even thickness, passes strength and rigidity tests, has no exposed steel, and has not been stripped for re-treading.

The cost competitiveness of technology is underpinned by the adaptation of a machine that efficiently and effectively removes the sidewalls. The sidewall is then put inside the tyres on site to improve their tensile strength.

The tyres are placed on geofabric laid directly on the ground and arranged in a honeycomb pattern which helps minimise the gaps between the tyres, thus helping to maintain the pavement's structural integrity. Each tyre is butted up to adjoining tyres, again so that fill does not infiltrate gaps and weaken the pavement. A topping layer is then applied to interlock the fill material. When constructed according to quality control procedures, there is no need to fix adjoining tyres to maintain the pavement's trafficability over time.

The recycled tyre approach to this project required 60% less fill material than a conventional pavement. This meant a reduction in fuel consumption to mine and transport fill which could equate to saving 2110 tonnes of greenhouse gas emissions.