Ian Pearson
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| posted on 14/4/07 at 11:32 AM |
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Cement Mix Ratio
I'm building a "SHED" and am about to start mixing concrete for the base. I've put down about 6" of hardcore and
scalpings, and have about 5" for the concrete. I will be storing the Locost in it when finished, along with my lathe. I'm trying to find
out the best ratio to use but am getting conflicting advice.
So far it's:
Cement : 1
Sand : 2
Gravel : 4
or:
Cement : 1
Sand : 1
Gravel : 2
Any advice would be great.
Regards, Ian.
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martin1973
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| posted on 14/4/07 at 12:19 PM |
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5 ballast - 1 cement.
that what mine is.
martin
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Confused but excited.
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| posted on 14/4/07 at 12:29 PM |
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Mix A: 1 part cement, 2 and a half parts damp sand and 4 parts coarse aggregate.
Alternatively 1 part cement to 5 parts mixed aggregate ( half inch to dust).
This mix is suitable for thicknesses of 3" and over, ie; drives, floor slabs and foundations.
Mix B: 1:2:3, cement, sand, aggregate or 1 part cement to 3and a half parts mixed aggregate. This is a stronger mix and is used paths and small
sections or slabs less than 3" thick.
If dry sand is used ( it is normally supplied damp), reduce the amount for mix A by 20% and mix B by 25%.
[Edited on 14/4/07 by Confused but excited.]
Tell them about the bent treacle edges!
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Mal
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| posted on 14/4/07 at 12:29 PM |
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Damp Proofing
Don't forget to 'blind' the base hardcore with sand and put a layer of 250um polythene damp proofing membrane on top of the sand
before filling with concrete.
HTH
Mal
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ecosse
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| posted on 14/4/07 at 12:32 PM |
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5:1 (3+2 or ballast as stated)
Cheers
Alex
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907
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| posted on 14/4/07 at 01:05 PM |
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Hi
My brother does this for a living (ground worker)
He says,
When I order readymix it's 1/3/6 for drives, floors, & footings.
1/2/4 for anything that requires reinforcing.
That's Portland cement / sand / stone.
(not masonry cement from DIY stores)
The stone makes no difference to the strength of the mix, but too much stone makes it harder to get a finish.
Hth
Paul G
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mark chandler
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| posted on 14/4/07 at 06:17 PM |
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I would not worry about the science that much, a standard small mixer takes 1/2 bag of dust then fill with ballast, around 10 shovels from memory.
The bags are sized to make it easy.
Regards Mark
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Peteff
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| posted on 14/4/07 at 06:35 PM |
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You don't get as much cement on a shovel as you do ballast so it's all guesswork anyway unless you actually use buckets to load it in. I
use the plenty to one mix same as the builders round here 
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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bodger
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| posted on 14/4/07 at 06:48 PM |
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My Dad was a builder & he always told me 1:2:6. for drives, etc. Remember to use sharp sand for concrete.
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omega 24 v6
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| posted on 15/4/07 at 09:14 AM |
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As the mix ratio's are pretty much confirmed the best other bit of advice is here
quote:
You don't get as much cement on a shovel as you do ballast so it's all guesswork anyway unless you actually use buckets to load it in.
Use a bucket cause you'll get almost twice as much sand/gravel mix on a shovel than you will cement. Ending up with a 10/12 to 1 ratio is not
good.
If it looks wrong it probably is wrong.
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ukbaggio
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| posted on 15/4/07 at 09:58 AM |
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quote:
Originally posted by ecosse
5:1 (3+2 or ballast as stated)
Cheers
Alex
yep thats it
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Ian Pearson
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| posted on 15/4/07 at 10:23 AM |
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Thanks all.
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