Hardcore - can i use crushed glass?

[unclebob1]

I'm going to be undertaking a removal of the underfloor void of my suspended timber floor and replacing it with a solid floor with the following construction:
top to bottom:
10mm tile,
50mm screed
100mm insulation
100mm concrete
rest (approx 200-250mm) of hardcore.

Question is can i use crushed glass for hardcore? I have access to loads of the stuff from a local glass toughening company.

Alternatively, do i need hardcore at all, can i just chuck more concrete in and make that a 300-350 mm thick slab?

 

[wessex101]

I heard a lot of those glass bottles we put in the mixed colour bottle banks are now crushed and used as a special sub-base in road building. The only problem I can see is breaking it down into small enough pieces so it will compact down without leaving big voids and just the practicalities of moving and placing it.

In theory you could have a thick slab but that will just add to your work and cost so doesn't seem worth it.

 

[unclebob1]

Looking to get concrete pumped in as ready mix - prob looking at 30m(sq) with a thinkness of 100 or 200mm so more then i care to mix, will that still add more work for the thicker slab? just to note that the base under most of the area is already a concrete base that the house is built on.

The glass - it is shattered toughtened glass or left over bits from cutting down large sheets. most will be about 1cm cube sizing so should compact down well, just not sure on suitability! It will be bagged in rubble bags so moving around will be fiarly easy.

 

[tomfe]

I can't see why not, it's angular and is stronger than limestone.
Ask your BC.

 

[geraldthehamster]

There's at least one DPM missing from that list of layers.

Cheers
Richard

 

[unclebob1]

Geraldthehamster - apologies the DPM will be between hardcore and concrete - with some softer filling between hardcore and concrete to ensure no sharp edges and a fairly packed base.

tomgfe -
I'll ask him but he's a bit green - was arguing with my builder for another part of work - 100mm of celotex to be removed and replaced with 100mm of rockwool... took a while for builder to educate the BC guy re the u values of each, and eventually agreed the celotex could stay... then insisted it be tape sealed, instead of foam filled... a bit more arguing and he let the builder foam fill joints...

 

[geraldthehamster]

some softer filling between hardcore and concrete to ensure no sharp edges and a fairly packed base

That'll be sand then?

 

[unclebob1]

yup thats the one! just depends on what state hardcore is in as to how much!

 

[unclebob1]

Just to update, didnt use glass in the end, having removed the 4 inches of concrete from the old kitchen, followed by another 4 inches of compacted stones (possibly coal?) and some left over bricks from the original suspended floor support, the floor was more or less full.
About an inch of ballast was compacted down, and DPM on top. About 10cm of concrete went down on Saturday morning and so far all appears well. On to taking the rest of the plaster off the walls for eleci to wire new sockets.