Tire Bales in US Civil Engineering: Specifications and Applications

By:     Conor Murphy

Tire bales have been used in civil engineering construction projects in the United States since the early 1990s. They are not experimental technology. The Federal Highway Administration (FHWA) published technical guidance on tire bale use in highway construction in 2008. The EPA has documented their use in embankment and retaining structure applications. ASTM D6270 provides the specification framework for engineers using them in geotechnical design. The body of US case study evidence is substantial enough that a civil engineer familiar with the technology has a reasonable basis for incorporating tire bales into appropriate applications.

The opportunity for US tire bale producers is that this established but underused technology represents a higher-value downstream market than TDF for the same bales. Civil engineering buyers who specify tire bales for construction projects typically pay more per bale than TDF buyers, because the bale’s structural properties are the value being purchased, not just its energy content. Building relationships with civil engineering contractors and state DOTs is a route to premium bale pricing for operations that can demonstrate consistent bale specification.

Physical Properties That Make Tire Bales Useful in Civil Engineering

Tire bales have a combination of physical properties that make them attractive for specific civil engineering applications. Their low density (approximately 30 to 40 lb per cubic foot compared to 90 to 110 lb per cubic foot for compacted fill soil) makes them valuable as lightweight fill in applications where reducing load on weak foundation soils is an objective. An embankment built with tire bales exerts significantly less load on the underlying soil than a conventional earth embankment of the same height.

Tire rubber has excellent elastic properties, giving tire bale structures vibration damping characteristics that are useful in noise barrier and rail vibration mitigation applications. The rubber also provides excellent drainage characteristics; tire bales do not retain water in the way that clay soils do, which is beneficial in applications where drainage through the structure is required.

Documented US Civil Engineering Applications

The FHWA’s 2008 guidance document on tire bales in highway construction (Report FHWA-HRT-08-002) catalogues US projects where tire bales have been used successfully. Embankment construction on soft ground is the most common application: the low unit weight of tire bales allows embankments to be built where the foundation soil cannot support the weight of conventional fill. Road approaches to bridges over soft soil have used tire bale fill to manage differential settlement between the bridge structure and the approach embankment.

Retaining wall construction using tire bales as structural fill is documented in multiple US highway projects. The bale’s structural integrity and free-draining properties make it suitable as retained fill behind retaining wall structures. Tire bale walls, where the bales themselves form the retaining structure in a stacked and interlocked arrangement, have been used in slope stabilization and erosion control applications.

Noise barriers along highway corridors represent another application where tire bales have been tested and used. The vibration-damping properties of tire rubber contribute to noise attenuation, and bale barriers can be constructed faster and at lower cost than conventional concrete barrier systems in some configurations. Landfill cap and closure applications have used tire bales as a drainage layer, leveraging the free-draining characteristic.

US operators building relationships with civil engineering buyers benefit from having PAS 108-compliant bale production documented. The Gradeall MKII Tire Baler is designed to produce bales to PAS 108 specification, the international reference standard for tire bales in civil engineering that US project engineers with international experience recognize as a credible quality standard.

Approaching Civil Engineering Buyers in the US Market

Selling tire bales to civil engineering buyers requires a different approach from selling to TDF buyers. TDF buyers purchase bales as fuel; the transaction is essentially a commodity purchase based on energy content and volume. Civil engineering buyers purchase bales as a construction material; they need to be confident in the consistent structural properties of the material for their design to perform as intended.

The pathway to civil engineering bale sales in the US runs through state Departments of Transportation (DOTs), county highway departments, and civil engineering consultants who specify geotechnical fill materials. State DOTs have approved material lists (approved products lists or qualified products lists) that specify what materials can be used in state highway projects. Getting tire bales listed on your state DOT’s approved materials list is a significant commercial milestone because it opens every state highway project to tire bale supply without individual project specification approvals.

“Civil engineering is a patient market to develop but a loyal one,” says Conor Murphy, Director of Gradeall International. “Once a DOT or consultant specifies tire bales in a project and the performance meets design expectations, they specify them again. The first project is the hardest; the subsequent ones come from documented performance.”

Bale Specification Requirements for Civil Engineering Supply

Civil engineering buyers have more exacting specification requirements than TDF buyers. Consistent bale dimensions are critical because engineers design structures around the bale dimensions in their as-designed drawings. A bale significantly outside the specified dimensions creates a field construction problem that reflects poorly on the supplier and may result in rejection. Bale weight consistency matters because it affects the structural load calculations. Wire tie integrity is critical because a bale that loses its ties during or after installation has compromised structural properties.

For operations supplying or planning to supply civil engineering markets, the Gradeall truck tire sidewall cutter is important context: civil engineering specifications for tire bales typically require whole tire construction (not mixed with cut tire sections), so producing civil engineering bales from car and light truck tires uses a different production stream from truck tire processing. Separating these streams operationally avoids specification contamination and gives you cleaner quality control documentation for your civil engineering bale buyers.

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