Sub-base: Granite or Limestone?

Patio flagstones (slabs), concrete flags, stone flags including yorkstone and imported flagstones.
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abancroft
Posts: 8
Joined: Mon May 05, 2003 7:43 pm

Post: # 1984Post abancroft

I'm putting a patio in my back garden ('yard' in American English ;-) and plan to lay a sub-base over the sub-grade.

After phoning round a few places here in Texas, it seems the material choice is crushed concrete, crushed granite or 3/8" limestone (funnily enough, no-one mentioned DTp1!)

The crushed concrete supplier won't deliver less than 15 tons which is a tad more than I require (by about 300%!). Which leaves either crushed granite or 3/8" limestone.

Is the granite worth the extra &#36 over limestone?

Thx

84-1093879891

Post: # 1993Post 84-1093879891

For a typical residential patio, even one in Texas-shire, any of those fill materials will be fine for a sub-base. I reckon it would be difficult to source DTp1 around your neck of the woods because there is no DTp (English English for Department of Transport) :)

We get both crushed granite and crushed limestone in this part of the world, and there's nowt to choose between them. Granite is hard and inert while limestone has a tendency to self-bind, making it a popular choice for northern road builders. For a patio, it really doesn't make that much difference - it's the 'grading envelope' ie, the distribution of lumps and fines, that is more important than the type of rock. As long as there's a good distribution of the lumps and fines, then it should be "reet gradely" as they say in Lancastrian English. :)

So - how much does a ton(ne) of crushed rock cost in Texas-shire? British buyers have to pay around 25 quid (40 dollars) for a single tonne.

abancroft
Posts: 8
Joined: Mon May 05, 2003 7:43 pm

Post: # 2003Post abancroft

Sounds like I can make my decision based on cost & availability, thx.

The limestone is going for &#3640 yd3 & the cheapest granite I could get is &#3646 yd3.

Exactly what the density of the rock is, I have no idea. But this web page (http://www.natural-stone.com/limestone.html) reckons limestone varies from 110 to 160lb/ft3. So 1 cubic yard will be between 2970 & 4320 lbs. i.e between 1.3 & 1.9 metric tons.

84-1093879891

Post: # 2005Post 84-1093879891

I can't work in cubic yards, pounds, cubits and all those other ancient measures; they make me brain hurt, but we reckon limestone has a density of around 2.2-2.4 tonnes per m³ and granite 2.4-2.9 T/m³ (these being the new-fangled metric tonnes, which are 1,000 kg, not 2,240 (??) pounds)

I know you chaps over there in US are way behind the rest of the world and have a penchant for all thing antique, but the old imperial measures are so bloody difficult to work with and non-logical I have to wonder why you persist with them. It's like the carrier bags you seem to use for bringing home the shopping - we have handles on ours, which make them so much easier to carry, but yours seem to be handle-less for some perverse reason!

Anyway, back to business - &#3640 for a cubic yard is around &#3648 per cubic metre, or &#3620-24 per tonne, which is around 15-18 quid per tonne, a good bit cheaper than we can get it in the UK in small quantities.

abancroft
Posts: 8
Joined: Mon May 05, 2003 7:43 pm

Post: # 2145Post abancroft

I'm a Brit (Scot actually) so the units of measure are a bit weird for me as well. Of course, we have no-one to blame for the widespread use of Imperial units but ourselves... ;-)

Carrier bags: for some reason, a minority of Americans do insist on using paper bags with no handles to carry their shopping (aka groceries). However, despite the stereotypes in older movies most of them are sensible (in this respect at least...) & use plastic bags with handles just like the ones in the UK.

Antque - here that's anything over 50 years old. I am not kidding - they won't knock down buildings over that age without a discussion on whether or not it should be preserved!

I finally managed to get crushed limestone for &#3630/yd, or ~&#3619/ton ~ 12 pounds.

Of course, I screwed up the estimate and am slightly short of material. :-( So I can look forward to another weekend of moving tons of rock using a shovel & wheelbarrow in 100°F & 100% humidity, when all sensible people are at the pool drinking beer. :-(

84-1093879891

Post: # 2148Post 84-1093879891

It could be worse - they could be drinking proper British Ale instead of that fizzy gut rot that they laughingly refer to as 'beer'! ;)

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