Sub base query - Drive project

[bradley756]

hi, I have searched the archive and I am unable to find the answer so I thought i would post it for ideas.

I am constructing a new drive which is 87 metres in length we have dug out to the appropriate depth and are now at the stage of filling in. We have placed a geo-textile membrane, followed by a 225mm capping layer, my query is firstly is it a good or bad idea to use recycled hardcore for the sub-base level or is best to go for DPT1. I would normally use use dpt1 but we have on site approx 900 tonne of crushed hardcore which would be great if we could use it. The drive is residential but will have the occasional 7.5 tonne lorry for fuel delivery etc. Would it also be best to go for a highway construction or will a normal flexible drive be adequate (going to be block paved by the way).

Hope all this makes sense ?

[lutonlagerlout]

crushed concret is ok as long as it meets the criteria for type 1
I.E. 35mm down to fines
and contains no crap
i take it you will be rolling the subbase with a sit on roller?
LLL

[bradley756]

just measured the hardcore and some of it is 80mm down could I not double the depth due to the 2x rule of thumb. Yes will be using a sit on. imagine using a whacker plate blimey I would be bored ! (LOL)

[GB_Groundworks]

crushed concrete is ok, but brick is a poor substitute for virgin aggregate. this was debated on another thread a while back and i found a study that showed crush brick had a abrasion resistance of about 500 comapred to virgin quarried limestone aggregate of 4000 what ever the units were.

but if you ve got it for free and a large roller like a 1200 wide etc should be fine

if you double the depth remember to compact in layers

[bradley756]

thanks for your reply not sure if to just use it for capping layers and use roadstone for subbase and do away with my highway construction idea. Decisions, decisions.

[Bob_A]

Could you hire a crusher to break down the hardcore a bit more?

[bradley756]

This has already gone through a huge 23 t crusher and to crush it more would turn most of it to fines and make it unuseable we did try passing it through the crusher twice and the results were not to good

[seanandruby]

It's a no brainer really if you have 900 ton of crush available on site ???

[bradley756]

I know and I agree all I was concerned about was the structural; integrity of it I don't want to take the time to put it down and then take it up again at a later date.