Casting paving slabs

[Feralbilly]

Hi all,
I am thinking of casting my own paving slabs about 400mm square using a home made angle iron frame mould. Anybody got any tips on a good concrete mix for this sort of job. I am thinking of 65mm thick for a vehicle standing area. Any advice or tips would be much appreciated.

Billy

[Kev Y.]

Feralbilly First off welcome to the nut house..

I can not give you any advice on the concrete mix, but dont forget to add some reo in there, just incase the slabs crack after awhile

[Harry72]

Your mould sides may need a slight angle and be oiled to facilitate removal of the paver, and you will need to vibrate them somewhat once poured to form a nice durable surface finish.
You could add a pattern to the bottom of your moulds to make them look fancy and give them some grip when they are wet...
I dont think you will need any real special mix, I wouldnt go too heavy on the cement powder as it'll make then brittle and chip easy, just a standard 3:2:1 mix will do. Make a few with varying mixes and test them out(run them over with cars, drop sharp objects on them... hit them with high pressure water etc etc).
Also if your going to colour them, you must measure mix amounts exactly as possible!

[Clinton1]

I'll watch with interest, and if you would let us know how you got on and the cost I'd appreciate it.
Would have thought a normal slab mix be sufficient, along with some mesh.

[ozwinner]

I can not give you any advice on the concrete mix, but dont forget to add some reo in there, just incase the slabs crack after awhile

Commercial pavers dont have any reo in them.
The reo will rust and crack/spall the paver.

Welcome BTW too.

Al

[bitingmidge]

400 square paving slabs are buggers to keep level in use. You'll need a REALLY decent sub base (100-150mm or more depending on your soil conditions of compacted decomposed granite (deco) or crusher dust, if you are going to use it for vehicles.

A domestic driveway slab is in the order of 100mm thick with reinforcing steel.

Depending on what your motivation is, (when I did the following there were no financial options!) may I suggest the following

Pour a slab in sections, boxed into 400 squares, use about 38mm square boxing so the reinforcing can run continuously under the boxing.

It doesn't matter if the concrete flows under the boxing a bit, you'll cover it with concrete next.

You can either do it in two or three pours, removing the boxing between pours to give just a hairline between "tiles" or do it in one, and remove the boxing to reveal a gap (say 38mm) which you can fill with gravel.

400 squares are manageable and easy to get a nice steel finish, even for me, I can't remember the mix 2:3:5??? But you might find that if you set it up to do half the slab at a time, a mini-mix load will be not too much extra.


Try the Cement and Concrete Association Website for more info.
Cheers,

P

[Feralbilly]

Thanks Guys,
It will be some time before I go into production as there is a bit of hold up on getting the house finished.
I am thinking of 65mm thick pavers laid on sand on a 150mm bed of compacted roadbase. I Know the commercial pavers don't have reinforcing, but I believe that they are cast under pressure; I could well be wrong on that but that is what I have read somewhere.
I will keep posting as to how I get on once I get started.

Billy

[Pulpo]

Be careful with the sand that its wash sand, as the salt content could come through the pavers.

I did a post on this a while ago.

Also a standard mix as per a cement bag 4:2.5:1, higher cement content will have higher strength but will be harder to work.

Personally I would try the option of doing artificial boxes with strips of steel or aluminium as dividers with the bottom section all connected.

You should do a few box samples to test the strength.

Colour content should be measured very accurately, even then expect some variations, should add to the character.

Good luck

Pulpo

[Harry72]

cast under pressure

Most pavers are extruded and cut to thickness, did a tour of PGH(i think) when I was a kid!