Amount of water in 4 to 1 concrete mix

[davphi338]

Hi,

If I add 4 buckets of ballast and 1 bucket of cement into a concrete mixer how many buckets of water do I need to add to get the correct mix.

The mix is to fill 400mmx400mm x 400mm deep holes to support anchours of a decking.

thanks

 

[noseall]

add enough water to facilitate the mixing process and still allow the concrete to be workable i.e. not too runny.

if you are shovelling the mix into the holes then it wants to be stiff enough to stay on the shovel.

if you are doing a direct pour out of the barrow then a little bit runnier won't hurt.

but don't mix it like p*ss.

 

[davphi338]

Thanks for the reply, but I was hoping there was a proportion of water so I could get the mix right everytime.

I found an online calulator for C20 general mix and it states for a 400mmx400mm by 400m deep hole I need 20Kg of cemet, 100kg of ballast and 19 litres of water. I just wondering if someone knew a good way of getting the proportions right if using a bucket so I could fill the same size bucket with cemet, then 4 ballast and them a similar size bucket for the water.

 

[wanabechippie]

Fill the bucket with a known volume of water. Mix the sand and cement and add enough water from the bucket to make the mix just right. Check how much water's left in the bucket at the end of the mix and subtract that from the volume you started with. The figure you're left with is how much water you need for the subsequent mixes.

All you need to do then is to fill the same bucket with the pre-determined amount of water and Robert's your mothers brother.

 

[^woody^]

You can't guage the water, as it depends on how wet the ballast and sand is in the first place. It's different every time

And you don't worry about c20 mixes for garden posts/anchors

Use the hole as a guide. If the hole is a big as a bag of ballast, then a bag of ballast it is.
For a 25kg bag, you are looking at 1 one flat (not heaped) builders shovel of cement.

Don't worry about strength and ratios. It's not important for this situation.

All you need to do is make sure its mixed to a uniform colour, and it workable.

 

[Nige F]

some water in the mixer first...........keeps the mix from sticking to the drum.........and clean out thoro`ly after use

 

[JoshRogan]

Nice tip about the water in drum first, thanks!

C

 

[Nige F]

no probs..... it`s simple but makes so much difference.....like labourer`s shovels USED to be polished @ the end of each day........because it makes graft easier NOW they just use mechanical Paddy`s .......mini JCB`s