Concrete – Ready Mix or DIY?
If you have got a concreting job to do there are a few different options for getting the mix:
Small Jobs
Up to about 0.1m3 buy premixed bags 20kg bags ( 0.01m3) from a DIY store.
Not cheap at a cost of around $7.50 a bag ($750/m3), but convenient.
For fence posts its probably better to use a rapid set premix at around $8 for a 20kg bag,
That means that the concrete sets in about 15mins.
If you want to save a few dollars you can always drop some half bricks into the hole, it will be fine as long as each stone/brick is surrounded by concrete.
I normally mix in a barrow as it keeps the area cleaner than mixing on the ground.
Medium Sized Jobs
0.1 to 0.4m3 it will be cheaper to buy aggregate, cement, and sand, then mix it yourself.
For mix design see Concrete What Is It
Expect it to cost around $150 per m3 if you can pick the gravel and sand up, more if you get it delivered.
Larger Jobs
More than 0.4m3 I would use a local ready mix supplier, due to the saving of time and effort.
Prices are around $180 for 0,5m3 ($360/m3) dropping to $250 for 1m3.
A couple of things to bear in mind:
- You need enough help to be able to place the concrete in 20-30 minutes otherwise you will have to pay extra.
- If you let a big mixer on your drive it could crack it, so if you are working in the back garden you could have a lot of barrowing. We have generally used at least barrows.