Quantity of sharp sand required

[JohnC]

Hi,

I am in the planning stage for laying approx 11.25 sqm of riven paving, a mixture of 600 x 600, 600 x 300 and 300 x 300 riven slabs. I intend to lay a foundation base of 40 - 50 mm of sharp sand but I have no idea how much sand I will require. Can you help? Is there a simple way of converting a surface area to to the weight required for the sub base?

Many Thanks in advance.

[Mark B]

You will need 1 ton of sharp sand for 11.25m2 at 50mm depth for your job.

[JohnC]

Mark,

Thanks for your prompt reply. BTW can you tell me how you calculated the amount of sand required?

Cheers :;):

[Mark B]

This web site has calculators on it for workin out various quantities of different materials. just use the calculator for working out sharp sand amounts. see the link for the full list which can be found on the site. http://www.pavingexpert.com/calcall.htm

[clintpm]

I am laying a patio of 35m2 and need to put down a semi-dry bedding foundation to a depth of 75mm.

The mix is 6 parts sharp sand to 1 part cement.

I have tried using the calculators on your site but am not confident in what I am doing.

Please can you tell me quantities and the best way to buy them.

Cheers
Clint

[Nigel Walker]

First of all , you shouldnt be laying your flags on a bedding depth of 75mm

The maximum depth of bedding I use on my flagging is 40mm.
You should make the rest up with some Hardcore Sub-Base and compact

I use my own calculations for working out quantities of tons etc.
For a semi dry sand cement bedding mix for flags - I work out the m3 ie square metres multiply by depth and multiply by 1.5. This gives you the tonnage required.

So 35m2 at 40mm depth = 1.4m3 Multiply this by 1.5 = 2.1 Tons of Sand required

Other calculations I use are
Sub Base - m3 multiply by 1.8
Grit Sand - m3 multiply by 1.9
Loose Gravel - m3 multiply by 1.3

These quantities have worked for me for years. I very rarely run short or have too much left over

Of course it all depends on the type of aggregate you are using - how dense it is, how large the stone is in the Sub Base, how different aggregates compact. A lot of variables, but you get to know eventually.
Everyone has their own way of working out - even Tony !!

Nigel

[Nigel Walker]

Sorry I forgot the second part of your question

The best way to buy 2 ton of sand would be to buy the Bulk Bags from your local Builders Merchants (BM)

The bulk bags are approx. 900kgs in weight

If you buy 2 of these you will probably need 12 bags of 25kg size to make up. The problem with this is that 12 bags of 25kg sand would cost about £22 (inc vat), but a Bulk Bag would cost you £27 (there are approx. 36 bags of 25kg in a bulk bag). Best to buy 3 of the Bulk Bags and shovel the remaining sand into small bags yourself for future use.

We have a few local Sand Quarries that you can collect Sharp Sand for around £12 per ton (inc vat), which makes it cheaper, but then you need transport.

Probably the BM is the best bet + they will deliver your flags and cement at the same time


Nigel

[clintpm]

Thanks Nigel.

I also was thinking I should put down a compacted hardcore sub base and then the sand / cement dry mix, but then I read the recomendations from Bradstone about laying their Carpet stones (Cover the entire area with a semi-dry foundation mix of 6 parts sharp sand to 1 part cement to a depth of 75mm. Compact and level).

What problems could occur if I follow their instructions?

[clintpm]

I've found the calculator for working out quantities of sharp sand and another for a semi dry mix of sand and cement, but I need to work out quantities for a semi dry mix of sharp sand and cement.

How do I work out quantity 6 parts sharp sand to 1 part cement to cover 30m2 at 50mm deep?


???

[Stuarty]

At a rough estimation you needed around 2.5 tons of sharp sand, and 17 bags of cement.

Work out the tonnage of sand to be used for the paving, like the calculator on the site, make it in kilos then divide by 6 giving you the 1/6th you want for the cement.

IE - 2500 / 6 = 416.66 / 25 = 16.66 ( round up ) = 17.

[lutonlagerlout]

i defer stuarty, i reckon 2.5 tonnes needs 12 bags of dust for the mix he suggested
it doesnt actually work out kilo for kilo as the cement is much heavier than sand per volume
the way i work it is half a bag of dust per mix which works out at 5 bags per bulk bag
always comes about right
cheers tony

[Stuarty]

i did think 17 sounded a bit much tbh, always good to have others views / comments. Makes this place what it is.

[lutonlagerlout]

i have done exactly the same as you stuarty before but sand and cement have different densitys etc
on bwk 5 bags to the bulk bag works out bang on,lean mix 2 bags to the bulk,and concrete 5 bags to the bulk
also remember different cements look stronger
blue circle comes out very dark grey ,whereas castle always comes out yellow no matter how much you put in
maybe one of the manafacturers can explain this??
cheers
tony

[Nigel Walker]

I have always worked on 5 bags of cement per ton of sand (bulk bag) for a 6 : 1 mix of semi dry bedding

As I have said earlier, everyone has different ways of doing things and working things out.
Nobody is wrong, and nobody is exclusively rightYou find out what works for you through trial and error.


Nigel

[clintpm]

Thanks guys.