Cheaper hardcore - Is it any good

[pecka]

Hi, been reading this excellent site for over two yrs now,and decided to have a go block paving our drive recently.

Anyway, yesterday we had 10 tonne of recycled hardcore dropped off. Is this stuff any good? The bloke I got it from assured us that a lot of pavers use nothing but this on domestic jobs. On close inspection I dont know how much of the grit is sand or soil!(Mebbe its just my eyes) The rest is a mix of dolomite, broken an crushed bricks/ concrete and the occasional twig,wooden pegs an bits of dust sheet!(which I have been removing)

Will 100mm of this stuff properly compacted succesfully hold a car?

[Dave_L]

Twigs, wooden pegs, membrane.......the alarm bells are ringing Pecker!

What is the sub-grade like? Firm?

Have you a photo of the hardcore, it might help.

btw, mind if I ask how much you paid for the 10t?

[pecka]

I havent wacked it yet, still on laying it. I have seen similiar stuff used in various places, some other driveways and they are using it at Newcastle university when we passed there last week (they are also using green sand !). Will try and get a photo but basically its pretty firm and heavy to shovel.

I paid £10 a tn plus vat. These are Newcastle prices mind!

[bobbi o]

we're paying £12 a tonne for mot type 1 delivered. so you've been robbed.

[Dave_L]

That has to be 20ton loads Bobbi?

Still, that's cheap in todays marketplace with sky-high fuel costs etc.

[dig dug dan]

we're paying £12 a tonne for mot type 1 delivered. so you've been robbed.

those days will soon be gone with the cost of mot going through the roof. Apparantly its an "environmental tax", as its not good on the environment to keep blasting away hillsides and hauling the stuff all over the place

[pecka]

Oh well, if my drive sinks, at least I can sleep at night knowing Ive done my bit for the enviroment

Ps. it should okay shouldnt it? Im looking for reassurance from the experts here. Surely SOMEONE here has used recycled stuff before?

thanks

[Mikey_C]

in my humble diy'ers opinion it will probably be alright, what depth are you putting down? compact it well (i.e. till refusal) ideally with a heavy plate if you can put a structural non woven geo textile underneath it would possibly benefit. it probably looks a bit like soil because its wet. is it fairly narrow drive, where all the weight (car) is going to always go in the same place therefore increasing your risk of rutting. your alternatives are slightly limited as you are either going to have to digging it out now or later and would always take the chance of it working.

[Tony McC]

The reason no-one can give a valid opinion on your material is because none of us are really sure of just what you've got. It is possible to get a Type 1 recycled aggregate, and these have been used on numerous projects for several years without any problems. However, with the price of aggs continually rising, some suppliers are now offering "recycled", but recycled what? Recycled crap, by the sound of what you have. If there are bits of wood, twig, dust sheet, etc., than it is NOT a quality agg.

There need be no qualitative difference between primary (newly quarried) aggs and recycled: It's the classification of the agg that really matters. A recycled Type 1 or Type 2 is just as good (structurally) as a primary agg, and better from an environmental point of view. However, just because an agg is said to be recycled or reclaimed does not mean it is fit for purpose.

I return to my carpet underlay analogy: we all know we can get crappy underlay for 99p per metre at Karpet-Klownz but we know it's only really fit for the spare bedroom. If we're carpeting the living room, it's worth spending a few bob more to ensure we get an underlay that won't turn to foamy-dust in a few months.

[pecka]

Not a very clear pic but this is it not compacted


When I say pegs and sheet, I dont mean its riddled with the stuff, just a few bits here and there. Inspecting it again it seems to be a good mix of sand, gravel and aggregate
(ie broken bricks,dolly and concrete) its just some bits are a bit chunky.

[Dave_L]

Personally I think you'll be OK.

It's not ideal, but it will do.

Properly compacted, I think this will give a firm enough base. Just make sure you whack it down as hard as you can.

[Rich H]

I'm now buying crushed Type 1. £15/tonne. You do get the odd bit of twig or rag but I think it's from the yard where the bucket picks up the material. It's no bother to fish out the few bits from my supplier, but it's bound to vary from place to place. It does look suspicious at first as the dust is a browny sort of colour. I guess it's the mix of concrete, brick and mortar dust that's doing it.

[pecka]

Thanks for the replies. Rich, yeh thats exactly what I thought at first when it was tipped.

Its all down now, can I ask, roughly what height should it be uncompacted, its about 5 inches loose, will that wack down to 4? Or is it a case of trial and error. I have read thru the guides, but couldnt see an answer relating to sub base uncompacted height.

[Rich H]

Well, it varies a lot but I lay it just a few mm above my finished height (certainly no more than 10mm per 100mm) then one pass with the plate, then check it and make good any high or low points before doing the full compaction.

With block paving, it's important to take time over this and get it nice and even. Unlike paving with mortar, you want to ensure that the bedding course is of a consistent depth so that when you compact the blocks you don't end up with small undulations which could become exaggerated with time.

[Slabba.]

Blue elvin type1 hardcore. cant beat it. its all about quality and if its got any pegs, twigs ect it aint quality. If the base is bad quality you`ll get one of those sinkin feelins!!!