Concrete – Reinforcement Mesh
Purpose of Steel Mesh Reinforcement
A lot of people believe that the steel mesh adds substantially to the strength of concrete paving.
This is a myth!
The truth is large areas of concrete paving will crack.
What well thought out reinforcement steel does is:
- Limits cracking where you don’t want it (in the middle of slabs)
- If some cracking does occur it holds the cracks tightly closed.
- A reduced amount of steel across joints helps to make sure that cracks do occur at the joints (where you want it to crack).
Sizes and Types of Mesh Reinforcement
A single full sheet of mesh is 6m by 2.4m.
Many local suppliers will sell you half a sheet, or less, for small jobs if you plan on doing it yourself.
These are the common types of mesh that you can buy in Australia for paving work, with my opinions on what mesh to choose.
|
Type |
Description |
Comment |
|
SL52 |
5mm dia bars @ 200mm spacing |
For garden paths (max joint spacing 2m) |
|
SL62 |
6mm dia bars @ 200mm spacing |
For plain paths or patios (max joint spacing 3m) |
|
SL72 |
6.75mm dia bars @ 200mm spacing |
Caravan or Boat parking areas |
|
SL82 |
7.6mm dia bars @ 200mm spacing |
Front Driveway minimum for plain concrete |
|
SL92 |
8.6mm dia bars @ 200mm spacing |
Front Driveway best for patterned concrete |
|
RL81 |
7.6mm dia bars @ 100mm spacing |
Polished concrete floors |
There are many more types of mesh but they are more specialised, the above will be fine for typical concrete slabs around your home.
Depth of Cover
The minimum cover from the top and bottom surfaces of the slab should be 30mm.
This will prevent the steel rusting once the concrete is placed.
To make sure you get this cover see this link: ‘Bar Chairs‘.
Overlap
When you need to join two pieces of mesh the overlap should be 2 squares.
Do Not overlap mesh across the site where a joint is going to be. That will stop the crack forming at the joint.
Rust
Don’t worry about a bit of surface rust on the mesh, although you should remove any rust flakes. The roughness of the corroded area help the concrete grip the reinforcement.
The alkali nature of the concrete will stop any further rust, as long as the 30mm cover is maintained.
See this link for advice on the thickness of concrete slabs: Concrete Thickness
For more posts on on getting your paths and driveways correct see Concreting