Aluminium Crane Mats: The Alloy, the Interlock and What Actually Makes Them Work

"Aluminium" covers a wide family of alloys with very different mechanical properties, depending on what's added to the base metal and how it's processed. We make every ALIMATS module from 6005A — a certified recycled extruded aluminium alloy from the 6xxx series — because it extrudes cleanly into long structural profiles and heat-treats to a genuinely useful strength without the brittleness some higher-strength alloys bring.

The numbers behind that choice: 6005A gives a compressive strength of 280MPa, a tensile strength of 270MPa, a modulus of elasticity around 69,000MPa and a density of 2,700kg/m3. Those figures matter more as a ratio than in isolation — strength-to-weight is the number a specifier actually cares about, and it's that ratio that puts aluminium ahead of both mild steel and timber or plastic. Steel is denser, so a steel mat thick enough to match our stiffness comes out too heavy to handle; timber and plastic are light enough, but nowhere near stiff enough at a comparable thickness.

Extruding from recycled stock rather than virgin billet also keeps the alloy's properties consistent module to module — extrusion is a controlled process, so there's none of the variability you'd get from a casting. It's a practical sustainability point as well: aluminium recycles repeatedly without the base metal degrading the way some recycled materials do, which is why our recycled 6005A holds the same compressive and tensile figures as the numbers above.

The other half of what makes ALIMATS handleable — rather than just "made of a light metal" — is our patented interlocking design. Modules connect edge to edge with no bolts, no pins and no crew standing round with a torque wrench. The interlock is mechanical, built into the extrusion profile itself, so two modules lock together under load the same way whether it's a groundworker's first day on a project or their five-hundredth.

That matters on site because crane mat configurations rarely stay one shape for a whole contract — a run laid for a crawler's tracks on Monday might need reconfiguring for a mobile crane's outrigger footprint by Thursday, and the interlock is what lets a small team do that without lifting gear. Our modules combine into configurations from 1.34m2 up to 8.07m2, built from the range we set out below, so a specifier isn't stuck with whatever single mat size a supplier happens to hold in stock — the footprint gets assembled to match the actual load area, rather than the load being squeezed to match the mat.

Steel is stiffer than aluminium, and we won't pretend otherwise — it's a plain materials fact. The problem is handleability. Steel dense enough to be useful under crane loads, in a size a two-person team can lift without plant, doesn't really exist; you end up needing a machine to move your ground protection, which defeats the purpose of matting. Plastic goes the other way — UHMW-PE mats are genuinely light, but they flex far more than aluminium under load.

Independent bending tests put a number on that gap: at the same test loads, ALIMATS deflected in single millimetres where a competing UHMW-PE plastic mat deflected in tens of centimetres — the full rig, loads and figures are in our aluminium vs plastic bending test. That's the case for aluminium in one paragraph — stiff enough to keep a crane's outrigger pad level and the ground pressure genuinely spread, light enough that modules still move by hand. Deflection isn't just a comfort figure, either. A mat that flexes tens of millimetres under an outrigger is a mat letting the load point tilt, which is exactly the movement a crane's stability calculations assume isn't happening underneath it.

Ground mats live outside — in mud, standing water, de-icing salt residue and UV — for years on end, often stacked away wet straight off a site. That's a harder environment than it sounds, and it's where a lot of ground protection quietly gets worse without anyone noticing, until a mat is pulled out of storage for a job and doesn't behave the way it did when it went in.

Aluminium sidesteps most of that, and we don't have to do anything to make it happen: its corrosion resistance comes from the metal reacting with the air — a thin, stable oxide layer — not from anything sprayed or dipped on at the factory. Steel plate left in the same conditions builds up rust scale that changes its weight and surface texture over time; a steel mat that's spent a winter stacked wet doesn't handle the way it did new, and the fix is usually repainting or replacing it. Pull an ALIMATS module out of our yard after the same winter and it weighs, and behaves, much as it did going in — which matters far more for a product we expect people to move by hand than for something a machine shifts anyway.

ALIMATS come in five module sizes, combining into configurations from 1.34m2 to 8.07m2 depending on what a lift needs underneath it.

SWL across the range runs up to 80 tonnes, and our configurations sit comfortably under cranes up to 150 tonnes — covering everything from a compact mobile crane's outriggers to a large crawler's track mats. Every SWL figure across that range has been independently verified with a Fellow of the Institution of Structural Engineers, not taken on the extrusion supplier's word or modelled in-house alone. We'd say that's worth asking any supplier about specifically, because "SWL" printed on a spec sheet is only as good as whoever checked it.

ALIMATS are available on single day hire, weekly hire, long-term hire or outright purchase, and we'll paint them in a contractor's corporate colours for firms that want their own branding on site rather than ours. We deliver 24/7 across the UK on our own FORS Bronze-accredited fleet, with our own drivers — most of them CPCS certified — rather than a subcontracted haulier, which matters when a mat run has to be on site ahead of a crane turning up at an odd hour.

Between hires, we inspect, clean and quality-check every mat before it's redeployed, so what turns up on the next job hasn't quietly carried hairline damage off the last one. Our system has been specified on HS2, Hinkley Point C, Heathrow and Gatwick airports, Google's King's Cross HQ, Euston Station, Grangemouth Refinery, London Bridge, Manchester's Co-op Live Arena and Scottish wind farm developments, and it's now used by more than 80% of the UK's top twenty Tier 1 contractors. Which route makes sense — day rate, weekly, long-term or purchase — usually comes down to how often you need matting rather than the size of a single job: a contractor with mats on rotation across several sites a year tends to find long-term hire or purchase cheaper over time, while a one-off lift is usually a short hire and nothing more.

"Aluminium crane mat" isn't a single spec, and we'd treat the phrase as a starting point for questions rather than an answer in itself. Ask what alloy is actually used — 6005A behaves very differently under load to a softer alloy that extrudes just as easily but doesn't hold the same compressive strength. Ask whether the mat is extruded or cast, because extrusion gives the consistent, controlled grain structure that casting doesn't.

Ask how the modules connect — a genuine interlocking system, patented or not, behaves differently under lateral load than mats simply butted together or bolted with separate plates. Ask who verified the SWL figures, and how, because a number with no independent check behind it is a marketing claim, not an engineering one. And ask what happens to the mats between hires — a supplier who can't describe an inspection and refurbishment process is telling you, indirectly, that the mat you get might be the one that came off a job with damage nobody looked at. None of that shows up in a photo of a mat on a pallet, which is exactly why we'd ask before one ever ends up under a crane.