Getting ready to mix and pour a foundation

[onionsa]

Hi all,

Is there a rough guide on how much water is required as a 'part' in the 1:2:4 mix that I plan on using for the foundations of my garage extension/workshop? I want to make sure I've got things right before I order and get started.

I think I'll be needing 2.3 cubic meters of mix for the foundation. An online calculator has given the following values:
736 Kg of cement
1449 Kg of sand
2691 Kg of gravel

I plan on hiring a mixer and then pour from a barrow into the trench.

Any tips, advice etc always welcomed.

Thanks
Anthony

 

[John D v2.0]

The water is very dependent on the sand condition, so you can't do it by volume, but anyway you usually want the minimum to avoid shrinkage and reduction in strength, and you only need the smallest amount to react. Having said that it needs to be workable and possible to level.

 

[SFK]

Onion
1) Why bother with Gravel + Sand when many just use Ballast (which is gravel mixed with sand) to make concrete?
ie 4,140kg of ballast and 736kg cement
ie You're mixing to a 5.6 to 1 ratio
Link to Ballast here: https://www.google.com/search?q=wickes+ballast&ie=utf-8&oe=utf-8&client=firefox-b-ab

2) Regarding water, I found a hose was not fast enough, and as I wanted to go fast I had a big builders bucket filled with water with a hose in slowly keeping it topped up. That way could use a small bucket to put water into mixer.

Then have a look here as at a previous similar topic: https://www.diynot.com/diy/threads/getting-ready-to-mix-and-pour-a-foundation.508356/#ixzz5Q3HC7KXU

From this link, here is my method, but note that others then had better/diffrent methods than mine.

>>>>>>>>>>>>>>>>>>>>>>
For me as a DIYer when I did this is for a 1:6 mix I did the following
-Get mixer running first.
-Put mixer in good position to pour/tip directly into hole or into wheel barrow.
-Put some water onto Mixer first (washes last mix off the sides and makes next stages quieter).
-Use a bucket (I am not good enough to use a shovel) and put in 1.5 buckets of Ballast and then half a bucket of Cement and then 1.5 buckets of Ballast to get 1:6 ratio.
let mix a bit.
-Then add more water until mix looks right (I used small bucket scooping water out of builders bucket so I could count number of small buckets and be faster adding water next time).
(Note that I found hose pipe was too slow, so I filled a larger builders bucket/dustbin full of water to act as reservoir to fill small bucket).
-Leave until mix is even (I used this time to prep by filling buckets) and then pour into hole/barrow.
-Put some water water into mixer now to stop leftover bit sticking to sides.

Note that I found with my hired mixer I could JUST get 2.5 bags of 25kg ballast and half a 25kg bag of cement in giving a 1:5 mix. Saved me time as no need for bucket as simply poured bags in. But a bit messy as some spillage from mixer.
Also if it is a hot day consider in advance if it is going to dry out too fast and make advance preparations to cover after you have finished pouring.

When I did this as a DIYer I think I got all this from:
http://www.diydoctor.org.uk/projects/mixing_concrete.htm
sfk

 

[Charlie George]

Is there a reason your'e mixing yourself, it would work out similar price to get barrowmix ready mixed right where you need it, would take all day doing it yourself and a lot of hard work.
Reckon on 40 mixes at least.
Jim

 

[onionsa]

Thanks for the replies all. Much appreciated. I’ll look at replacing the sand/gravel with ballast - seems a good idea and saves on one measurement at least.
The reason I’m wanting to mix and pour myself is purely financial. I’m doing this on a budget so saving £350 on pumped concrete and spending a a couple days doing 40 loads is something I’m willing to do to save that and additional costs.

 

[SFK]

Onion,
Sounds good.

Note that I was luck in that I got all the balast and cement delivered near to the hole.
So in my case (and I am sure it will be different for you) I put Cement Mixer next to hole, was able to move the dry items to the mixer, filled the mixer, rotated mixer it on its stand and poured straight into hole.

Good luck, SFK

 

[onionsa]

It should only be a short walk down the side of the house to haul the materials through so will probably mix on the drive and then wheel a barrow full through and pour.

I’ve just been doing some probing and looks like the existing foundations are only 150mm deep.

 

[Charlie George]

It should only be a short walk down the side of the house to haul the materials through so will probably mix on the drive and then wheel a barrow full through and pour.

Why the need for a pump, Barrowmix will put it in your foundation for similar cost to you for materials alone.

 

[onionsa]

It should only be a short walk down the side of the house to haul the materials through so will probably mix on the drive and then wheel a barrow full through and pour.

Why the need for a pump, Barrowmix will put it in your foundation for similar cost to you for materials alone.

Do you have a link for this barrowmix?

 

[Charlie George]

Where abouts are you ?

 

[pilsbury]

My exactamix truck either dumped muck down a 4m chute or the blokes helped barrow. Did it for £90 cube. So by my reconning for about £200 and 45 minutes work your foundations will be done.

Or you can do it your way, £90 for 30 bags cement, £120 for 4 bulk bags of ballast and break your back for a day pouring yourself a foundation where the start of it is going off before you finish the last part.....

 

[onionsa]

I'm in west sussex. Not found anything near that cheap round here, but happy to hear recommendations.

 

[pilsbury]

I’m in West Midlands. Just googled the hell out of it and phoned a load up. Saying that, the cheapest company I used for foundations were not the cheapest for floor slab. I bet if they’ve got jobs in your area that day they might go cheaper than if they had to make a special trip.

 

[onionsa]

Waiting on quotes from a couple of places locally, but if they're in the same ball park as the quote i got yesterday I'll be going back to my original plan. Will update this thread with the outcome.

 

[Notch7]

Waiting on quotes from a couple of places locally, but if they're in the same ball park as the quote i got yesterday I'll be going back to my original plan. Will update this thread with the outcome.

I reckon thats £350+vat for materials.

5 bags of ballast @ £40+vat ea

29 bags of cement @ £5+vat ea

ready mix is between £90 and £125 + vat per metre maybe plus delivery for a small load.

mixing 5 tonnes of concrete will be hard work

you would be best with a batch mix for a small load


Have you tried the concrete network?