Concrete expansion cutting in Ballarat and Melbourne
Concrete Expansion Cutting
Expansion and control joints are shallow, deliberately placed cuts in a concrete structure, set at regular intervals so cracking happens where you want it to.
Control joints are planned cracks. They allow for the movement caused by temperature change and drying shrinkage. Put simply: concrete is going to crack, so you may as well have an active role in deciding where it cracks, and make sure it cracks in a straight line rather than randomly across the middle of a finished floor.
Depth and spacing matter
A joint that's too shallow won't control anything, and the slab will crack somewhere else anyway. As a general rule the cut needs to reach around a quarter of the slab depth to create a reliable plane of weakness, with spacing set to suit the slab thickness, the mix and the reinforcement.
Timing matters just as much. Cut too early and the edges ravel; leave it too long and the slab has already cracked on its own. We work with your concreter to get on the slab in the right window.
Where expansion joints are cut
- Driveways, footpaths and crossovers
- Warehouse and factory floors
- Carparks and hardstands
- Shed and garage slabs
- Around columns, pits and re-entrant corners where cracking wants to start
Joint cutting in existing slabs
Older slabs sometimes need joints cut in retrospectively, either to relieve movement that's already causing damage or to isolate a section being altered. It's the same process, just with more care taken to find and avoid whatever is already in the slab.
Frequently asked questions
How deep should a control joint be cut?
As a general rule, around a quarter of the slab depth. That's enough to create a reliable plane of weakness. Cut shallower than that and the slab is likely to crack somewhere else instead.
How soon after the pour should joints be cut?
There's a window: too early and the edges ravel, too late and the slab has already cracked on its own. It shifts with weather, mix and slab thickness, so we coordinate with your concreter to get on it at the right time.
How far apart should control joints be spaced?
Spacing is set to suit the slab thickness, the mix and the reinforcement. Re-entrant corners, columns and pits also need attention, because that's where cracking wants to start regardless of the grid.
Can you cut joints into an existing slab?
Yes. Older slabs sometimes need joints added to relieve movement that's already causing damage, or to isolate a section being altered. Same process, with more care taken to find what's already in the slab.
Working somewhere awkward? Send a photo and a rough measurement. We'll tell you which method suits, what access we need and what it'll cost, usually the same day.
Related concrete cutting services
Concrete Expansion Cutting is available throughout Ballarat, Ballan, Bacchus Marsh, Melton, Melbourne and right across Western Victoria. Request a quote or call 0432 089 194.
Let's cut through it.
Send through your drawings or a photo of the job and we'll come back with a fixed price and a date.