The Brew Cabin

Tony, I would appreciate your advice on the provision of a suitable base capable of bearing 20 tonne wagons five or six times a year. Here is the difficult bit though: in one area (100sq m) near the entrance to my home I wish to lay Indian stone flags which are only 30mm thick but the larger area (300 sq m), may be covered in 65mm (flexible) pavors.
The whole area has been dug off already down to firm clay. I have laid terram over the whole area and covered the terram with re-claimed crushed brick and stone (max. particle size 30mm) with 'dust' as a binding medium. It varies in thickness from 200mm - 400mm.

The Indian stone is iffy when used for any driveway. There are some better 'grades' on the market, but even if you got hold of one of the top flagstones, it would need to be laid on 150mm of C20 equivalent (ST4) concrete. It could, in theory, be directly bedded, but, in practice, it's probably easier for a contractor to create the 150mm concrete slab, using appropriate reinforcement, and then lay the flagstones on a 20-30mm bed of Class II mortar, with Ronafix or another strengthening agent used to ensure good adhesion and full, strong support.

The clay pavers are a lot easier. 150mm sub-base of DTp1, using a membrane if necessary, then 35mm of bedding and the pavers. I'm not so sure about this crushed brick you've been using - it may well be absolutely fine and dandy, but I can't be sure. Do you know whether it was DTp1 or DTp2 grade, or was it just 'crushed brick'?

Thanks for your reply.The crushed brick is reclaimed machine-crushed material from S&B Tippers from Great Harwood. (The aim is to reduce unnecessary landfill)
It is a variety of aggregates but mainly concrete, brick and natural stone mixed with dust. It is starting to lock together more as we drive over it with a transit van & trailer and other smaller vehicles, but not as solid as MOT.
How would you consider testing it? I was advised by the firm who produce it that it is fine for my purposes.
Great site Tony, it has renewed my confidence in the internet!

Kev

I know the stuff you mean - Maher's in Manchester have been supplying it all over the North-West of Eng-er-land for the last few years, and it sets like bloody rock once it's been wetted and Wacked.

However, it can be a bit claggy when first wetted, so we found it was best to use it as a fill material, and then dress the top surface with 40-60mm of DTp1, just to keep it clean until the laying course sand was put in place.

On a job in dead-posh Hale Barns some years back, we were instructed by the developer to use it without the DTp1 blinding, and we found it mixed with the laying course sand when we came to prepare the screed. This was probably because the job was done in high summer and the surface was as dry as a bone and very dusty, so the vibration of the plate compactor seemed to churn the dust and the sands together, somehow.

I've no evidence that this was detrimental to the pavement - we were never called back to deal with any ponding or settlement, but I did make a mental note that, if we used it again, we'd spray the surface with a hose before placing the laying course sand, to try and eliminate the mixing problem.

So, in summary, I'd say you'll be fine, but keep your eye on any dust problem, and make sure you get a nice tight finish to the sub-base layer before carrying on with the block laying.

Thanks Tony