Cement mixer

I've bought a 130L cement mixer for a project - in the first instance I need to pour the footings for a porch. Can anyone tell me what mix I should use (gravel-sand-cement) and how much of each I'll be using for each barrow load?

Cheers Richard

Reply to
geraldthehamster
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6 gravel, 3 sand, 1 cement is more than sufficient for a porch, provided the strips are going to be a decent thickness and they are on something solid like clay.

Don't forget, the 'large bags' of sand, gravel, ballast etc from b&q only contain about 20kg, while the cement contains 25kg.

tips on mixing: Water in first, every time, followed by half the stone, then half the sand, all the cement, more water and then the remainder of the sand and stone.

Don't throw cement to the back of the mixer as it will stick and not mix, pour it into the beak.

Don't let the mixer run dry, keep it wettish up to the point of the last bit of sand being added.

Don't spend too long on each mix - once the final ingredients are in, it should be tipped or bucketed out within about 5 minutes and fresh water allowed to run in prep for the next mix...don't try and tip it straight down a hole - I've seen mixers fall in lots of times, usually when the sides collapse under the weight.

Don't try and wheel a full mixer around - more of it will end up on the floor than in the mixer, and don't try and tip it while it's not turning as it doesn't come out.

Oh and the ratios quoted WRT mixing anything are a guide only, it's not imperative to keep everything exact - if it's too wet, add some dry sand if ther's room, if not, bung part of it in the hole and add more sand, stone and cement, likewise if the sand is soaking wet, keep the water to a minimum or it will get really messy, really quickly.

wear gloves.

Reply to
Phil L

Thanks both. I should have been clearer - I have all the materials, more than enough. As welI as the mix, I just need to know roughly how much of each I'll need to put in the mixer for each barrowload (ie each barrow load - it's a barrow mixer)

Cheers Richard

Reply to
geraldthehamster

IIRC a mixer is about 2 barrow loads

Reply to
The Natural Philosopher

No. Certainly not mine, anyway.

If you try to load more than will comfortably fit the barrow, it spews back over the barrel rim. If you tilt the barrel to get more in, it doesn't mix properly.

I think builders barrows and small mixers have been around long enough for this to be sorted:-)

regards

Reply to
Tim Lamb

It's a barrow mixer. One mix to the barrow, as you say.

All I am asking is how much of each I should expect to be putting in to make up one barrow mix.

Cheers Richard

Reply to
geraldthehamster

No one can answer that as apart from the nominal 130l size of the mxer we don't know how big you barrow is.

Seems pretty obvious to me that all you need to do is simply count shovel fulls of sand/gravel into the barrow until it is "a few shovels short of full" and start from there. Bear in mind that mixed concrete will flow a lot better than sand/gravel when you pick the barrow up to move it.

Reply to
Dave Liquorice

Why not just put some dry gravel in the barrow and see how measures[1] it holds. Then apportion that number between gravel, sand and cement in the appropriate ratios?

[1] Shovel, bucket - or whatever you're using to transfer the ingredients
Reply to
Roger Mills

Umm... I use *ballast* which nowadays seems to mean 20mm graded stone mixed with sharp sand. 12 loaded shovels brims my mixer and barrow.

The cement shouldn't take up space anyway. You could try a dry run with aggregate and sand in the ratios suggested and then add the appropriate amount of cement. If you overcook it slightly, put the barrow under the mixer outlet.

regards

Reply to
Tim Lamb

Lots of very good advice there. On this bit, I picked up from a brickie we recently used. When tipping, he would switch it off, tip it up, and then get the first two thirds or so or so out with a few on/ off jolts before leaving it on for the rest. It makes it much neater and easier to control rather than trying to lower the mixer gradually while it's kicking.

Reply to
Bolted

So about 12 then. Thank you. That's going to be 8 gravel, 4 sand, and about 1 1/4 cement then. Unless your barrow is vastly huger than mine. I'll test the water first with 6.3.1 as 6, 3 and 1 shovels full.

Cheers Richard

Reply to
geraldthehamster

Umm again... I think the way concrete works is for the different grit sizes to fully occupy the spaces. Your sand should fit in the spaces between chunks of aggregate... Try it and see:-)

regards

Reply to
Tim Lamb

6:3:1 and multiples therof until it's full
Reply to
Phil L

Thanks. Pretty much. I went with 6:3:1 as shovels full, which gave me a nearly full barrow that I could push and tip without losing any.

8:4:1 and a bit would have gone in. Job done anyway.

Cheers Richard

Reply to
geraldthehamster

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