PAS 108 vs Australian Standards: Tyre Bale Compliance for Construction

By:     Kieran Donnelly

The Standards Gap: Why PAS 108 Matters in an Australian Context

When a UK civil engineer specifies tyre bales for a road embankment or coastal protection project, they reference PAS 108, the BSI Publicly Available Specification that defines exactly what a compliant tyre bale must contain, how dense it must be, what dimensions it must meet, and how it must be wrapped. The standard provides a clear, shared language between tyre bale producers and civil engineering buyers, enabling procurement, design, and construction to proceed with confidence that the product meets a defined specification.

Australia does not have an equivalent national standard. There is no Australian Standard (AS) or Australian/New Zealand Standard (AS/NZS) that specifies tyre bale requirements for civil engineering in the same way PAS 108 does for the UK. This absence creates both opportunity and complexity for Australian tyre recyclers producing bales for civil engineering use and for Australian civil engineers wanting to specify tyre bales in their projects.

The opportunity: Australian engineers who want to use tyre bales have access to a growing body of international research, including PAS 108 and the engineering literature underpinning it, that they can reference in project-specific specifications. They are not constrained by a conservative national standard; they can specify to the level of technical rigour appropriate for each project.

The complexity: without a national standard, every civil engineering project using tyre bales in Australia requires project-specific engineering assessment and specification rather than reference to an off-the-shelf standard. This increases the design cost and engineering effort for each tyre bale application, and may deter engineers less familiar with tyre bale technology from specifying it where it would otherwise be appropriate.

Gradeall International produces the MKII tyre baler that makes PAS 108-compliant bales in the UK and that produces bales to the same specification for Australian operators. With nearly 40 years of manufacturing experience and equipment in over 100 countries, Gradeall’s perspective on the PAS 108 vs. Australian standards question is grounded in practical experience of both the UK standard and the Australian regulatory environment.

What PAS 108 Specifies: The Technical Requirements

Understanding what PAS 108 actually requires is the starting point for assessing how it applies or could be applied in an Australian context.

Bale composition. PAS 108 specifies that bales should consist of used passenger car and light van tyres. The tyres must have rim wires intact (rims not cut), no significant contaminants, and the tyres must be whole. Mixed tyre types (including truck tyres) are not standard PAS 108 bale composition.

Bale dimensions. PAS 108 specifies bale dimensions of approximately 1.55 to 1.65 metres long, 1.1 to 1.25 metres wide, and 0.7 to 0.8 metres high. These dimensions are what the MKII tyre baler’s chamber geometry is designed to produce.

Bale mass. The minimum mass per bale is specified at approximately 1,000 to 1,100 kg. This mass requirement is the combined effect of the number of tyres per bale and the tyre composition; a bale of the specified dimensions containing approximately 100 standard car tyres achieves this mass range.

Density. PAS 108 specifies a minimum bale density of approximately 580 to 620 kg/m³. This density requirement ensures that the bale has adequate structural stiffness for civil engineering use; bales that are too loosely compressed deform more readily under load.

Geotextile wrapping. Completed bales must be wrapped in geotextile fabric meeting specified permeability and weight requirements before use in civil engineering applications. The geotextile wrap prevents direct tyre-soil contact that could mobilise rubber leachates into surrounding ground.

Wire ties. The compressed bale is held by a minimum number of steel wire ties of specified tensile strength.

Australian Civil Engineering Standards Framework

Australian civil engineering operates within the framework of Australian Standards (AS) developed by Standards Australia, and for some applications, joint Australian/New Zealand Standards (AS/NZS). The National Construction Code (NCC) references Australian Standards for construction compliance, and government infrastructure procurement typically references Australian Standards in contract specifications.

For geotechnical and earthworks applications where tyre bales might be used, the relevant standards framework includes:

AS 4678-2002: Earth-retaining structures standard. Relevant for retaining wall applications where tyre bales provide the retaining structure.

AS 3798-2007: Guidelines on earthworks for commercial and residential developments. Relevant for embankment fill applications.

State road agency specifications. Each state road agency (Transport for NSW, VicRoads/MTIA, TMR Queensland, Main Roads WA, etc.) maintains its own specifications for road construction materials and methods. These state specifications are the practical procurement documents for road projects in each state; they don’t reference tyre bales in the way that Highways England’s Specification for Highway Works references tyre bales in the UK.

The absence of tyre bales from standard Australian road agency specifications means that using tyre bales on a road project in Australia requires the road agency’s approval of a project-specific technical submission, rather than straightforward reference to an approved specification. This is achievable but requires more engineering effort than the UK approach.

How Australian Engineers Can Reference PAS 108

For Australian civil engineers wanting to specify tyre bales in their projects, PAS 108 is available as a reference document and can be cited directly in project-specific specifications. The standard is a BSI publication accessible through Standards Australia’s subscription services and directly from BSI.

Specifying to PAS 108 in an Australian project. A project-specific specification for tyre bales on an Australian civil engineering project can adopt PAS 108’s technical requirements directly, either by reference (“tyre bales shall comply with BS PAS 108”) or by reproducing the relevant technical criteria (bale dimensions, mass, density, geotextile wrap specification) as project requirements. This approach gives the tyre bale supplier (the tyre recycler) clear compliance criteria and gives the design engineer a defensible technical basis for the specification.

Engineering design with PAS 108 data. The design of tyre bale structures in civil engineering relies on material property data for the bales. PAS 108 and the research literature underpinning it provide compressibility, stiffness, and drainage characteristics for PAS 108-compliant bales. Australian geotechnical engineers designing tyre bale structures can use these published property data in their designs, provided they specify that the bales supplied meet PAS 108’s manufacturing requirements that the property data relates to.

Independent testing. For projects requiring Australian regulatory approval of a non-standard construction method, independent testing of bales from the proposed supplier may be required to confirm that the property data used in design is representative of actual supplied bales. This testing is more likely to be required for novel or high-risk applications than for straightforward fill applications.

Research Supporting Tyre Bale Use in Australia

Several Australian universities and research institutions have published research on tyre bale use in geotechnical applications, drawing on both UK experience under PAS 108 and Australian-specific investigations. The University of Queensland, the University of Sydney, and RMIT University have all contributed to the literature on tyre bale mechanical and environmental properties relevant to Australian applications.

The Transport Research Laboratory (TRL) in the UK published significant research supporting the development of PAS 108 and subsequent revisions; this research is cited internationally including in Australian engineering assessments of tyre bale applications.

For Australian civil engineers undertaking novel tyre bale applications, the combination of PAS 108’s specification framework and the broader academic literature on tyre bale behaviour provides an adequate technical basis for engineering design, comparable to what is available for other non-standard fill materials used in Australian geotechnical practice.

The Gradeall MKII in an Australian PAS 108 Context

The MKII tyre baler produces bales to PAS 108 dimensional and density specifications. An Australian tyre recycler using the MKII baler and following the PAS 108 baling procedure (correct tyre loading, geotextile wrapping, wire tying) produces bales that comply with PAS 108 even though the standard is a UK document.

For Australian tyre recyclers seeking to supply civil engineering projects, the ability to state that bales are produced to PAS 108 specification provides a credible technical reference that Australian engineers can assess and accept. Until Australia develops its own national standard for tyre bales, PAS 108 is the most rigorous internationally recognised specification available for civil engineering tyre bale procurement.

“We see increasing interest in tyre baling for civil engineering applications in Australia,” says Conor Murphy, Director of Gradeall International. “The technical case is sound, the research supports it, and PAS 108 provides the specification framework that Australian engineers can reference. The MKII produces compliant bales whether it’s installed in Northern Ireland, New South Wales, or Western Australia. What’s needed in Australia is the market development work to connect tyre recyclers producing bales to civil engineering projects that can use them.”

Contact Gradeall International for MKII tyre baler information and to discuss the civil engineering bale market for Australian tyre recycling operations.

Frequently Asked Questions

← Back to news