What makes a good concrete slab
Set-out, steel, mix design and the finish — what separates a slab that lasts thirty years from one that cracks in five.
Concrete is forgiving up to a point. A good slab starts long before the truck arrives — with set-out, sub-base preparation and steel placement.
It starts in the dirt
A bad sub-base will crack any slab, no matter the mix. We strip topsoil, lay road-base in lifts and compact to 95% modified — same standard as a residential road. Then a layer of plastic vapour barrier so the slab isn't drinking moisture from the ground.
Steel does the heavy lifting
Mesh sits in the upper third of the slab — not on the dirt. Bar chairs every 700mm, tied at the laps. Extra trim bars around penetrations and re-entrant corners. This is invisible work. It's also the difference between a slab that ages and one that fails.
Mix design isn't a single number
32MPa is a strength rating — it tells you almost nothing about how the slab will finish. Slump, aggregate size, water-cement ratio and admixtures all matter. We spec mixes with our supplier based on the weather, the placement method and the finish — not a number off a clipboard.
The finish is the last 5%
Floats, trowels, brooms, washes — all matter, all are skill-based. But by the time you're finishing, 95% of slab longevity is already decided by what's underneath.