Spongey sub base

[mathyou78]

Hi

Thank you for the excellent site, its been a great help so far.

This is my first block paving project and i'm after some advice or reassusrance regarding my soft sub base.

The project is a 32m sq. driveway which tapers along the side of the house. I have fitted a linear drain at the bottom but until i complete the drive this obviously won't drain the drive!

My problem is with the 'crusher run'. I was advised by my local aggregate supplier that '20mm down' limestone was what i needed. Whilst laying out the crusher run the heavens opened and soaked my drive to the point where the sub base came over the top of my shoe when i stepped in it. After 2 days of average weather (no rain) and 1 scorcher (today) it is dry to the point where the wacker now drives itself over it and doesn't get stuck and tries to dig itself a rut. but the base is still very slightly spongey (you can still tell who has walked on it by the imprint their shoe leaves, say 1 - 2 mm impression depth).

I have since bought a large impermiable plastic sheet to cover the drive when i'm not working on it, once bitten and all that.

I used terram 1000 underneath the sub base.

Am i ok to continue adding the 20mm down on top of this or do i need to wait until the surface is hard as nails? The surface now has a floated/ skimmed appearance in places due to the water comming to the top and the action of the wacker.

Should i keep wacking it or just let nature do its thing till it dries out?

Thanks again for the great website and apologies for the long question.

Cheers

Matt

[Tony McC]

20mm down is not the best choice of material for a sub-base, and the knobheads at the agg company should not have told you that it was suitable for this project. 40mm down is more or less identical to DTp1; 50mm down is tolerable, but 20mm is too dusty, with insufficient larger particles to effectively distribute the loadings.

However, digging it out at this stage is totally impractical, unless the agg supplier is prepared to cover your costs, so it'll have to stay put. The geo-textile will help with stability, eventually, so, all I can suggest at tghis stage is that you either get some genuine DTp1 to complete the sub-base, or carry on using the 20mm to dust that you have and then go in to your agg supplier and tell them that Tony McCormack says they're a bunch of effing useless winkers! :p