The Brew Cabin

Hi
I'm about to lay a small (3m x 4m) temporary (less than two years) flat area with home-made 600mm X 600mm concrete pavers. I live one street from the calm water beach so the soil here is actually a course sand.
My question is; as the paving will be temporary and the base is already sand do I really need to lay a seperate road base. It's called crusher dust here(Queensland-Australia) and is usually laid as a compacted base before the bedding sand then the pavers.
The area I have dug has some compacted and some loose sand.
Also the pavers will be laid about 70mm apart with white stone between.
I'm betting your answer is go with the compacted crusher dust!!!
thanks for any advise and great well organised site

Paul

Hi Paul,

I s'pose I could get all technical and tell you that the decision as to whether a sub-base is needed depends on the CBR of the undisturbed sand sub-grade, but it would only give you a nedache, so I won't bother.

If the sandy sub-grade is stable and firm, then you could omit the sub-base, and just lay a membrane over it before placing the bedding material. The advantage of using a membrane is that it will acommodate any short term deficiencies in the sandy sub-grade by helping to spread the load. So: how do you determine if the sandy sub-grade is "stable and firm"?

Well, how loose is it? Can you kick it up with your boots as though it were dust, or is it reasonably well bound together? A loose, dusty sand is more of a problem and, if you're planning on putting vehicles on the paving, then I would opt for a "proper" sub-base, but if it's a tight, well-bound sand, then go for the membrane.

Naturally, if this were a long-term pavement, it's much better to dig out the sand (not exactly a back-breaking job, compared to claggy clay!) and put in a genuine sub-base of your "crusher dust" or other suitable hardcore.

I'm intrigued with these home-made pavers. At 600x600mm, they're what we'd call 'flags' (or slabs if you're from south of Stoke), and the home-made types are usually exceptionally fragile. How do you make them strong enough to withstand traffic?

Thanks Tony
The size of the pavers 600mm X 600mm is the same as some seen at a paving display...they are 50mm thick
They are a bit of an experiment and I was unable to find out if the local manufactures use any type of bonding solution or wire reinforcement....
I have one made as a trial and will let you know if it works out.
For the design effect to work- stones between the slabs/pavers- the pavers need to be fairly large.
Only foot traffic is possible at their location
The sand varies between kickable and more firm.
A membrame is a good idea...they use a plastic semi porous weed mat here.

thanks again for the prompt reply and a very nice site.
Paul

There's two types of 600x600mm 'pavers' commonly used in Britain. The first is a wet cast unit, made by pouring wet concrete into a mould and vibrating it to settle into the mould simultaneously driving out any air bubbles. These are medium strength, suitable for patios and pathways.

The other type is a hydraulically pressed type, made by squeezing the living daylights out of a semi-dry concrete beneath a hydraulic ram. This gives high strength units that can be used for vehicle overrun (if laid on a suitable bed).

For home made flags, it's well worth adding the polyester fibre reinforcement as that gives a stronger product without all the faffing about required with steel reinforcement mesh.

Let me know how yours turn out. :)