Quick fire concrete mixing questions:

[HugeWesty]

I’m a mixing newbie and doing a shed base (10x8) all by myself. I’m a fit and strong guy, but still know I’m in for some body aches after. I had some quick fire questions it would be good if someone could answer pls:


· For mixing order. I understand best solution is to add ½ water, ½ ballast, all cement, ¼ water, ½ ballast, ¼ of water. Please let me know if need correcting.

· I wanting to use a retarder to lengthen the workability time. Is this recommended? I intend to do the work when temp 10 degrees.

· Can I use concrete reinforcing fibres with a retarder? I’m not going to use rebar/grid etc.

· How best for one man band to mix? (1) Put current mix in wheelbarrow, lay down in base – and then load up the mixer again (leaving it to mix) before levelling shed base……… Or (2) do I finish the levelling process each time on the shed base before going and starting the mixing process again?

· When the day is finished, I need to clean the drum and understand I do this with water and say pebbles/gravel. What do I do with the finished slurry? Can’t put down the drain.

Thks

 

[Ian H]

I’d put 2 bags of ballast in a decent size wheelbarrow, 1/2 bag of cement, give that a mix, then add as much water as you want to get the consistency you want.

Actually I wouldn’t, I’d hire a mixer.

 

[^woody^]

For mixing order.
Throw most of the sand in first, it may be damp and you don't know how much water you will need. Then some cement, see how it goes, add water as necessary, then the rest of the sand and cement. Water to taste.

Second and subsequent mixes, tip the amount of water you used on the first mix in first, then 1/2 sand, all cement, rest of sand. Water to taste.

I wanting to use a retarder to lengthen the workability time.
Not needed unless the shed is in the middle east or thereabouts.

Can I use concrete reinforcing fibres with a retarder?
Waste of time and money, won't do a thing.

How best for one man band to mix?
Mix and tip most of the concrete, rake roughly, see if you need any more mixing, then level it proper

What do I do with the finished slurry? Can’t put down the drain.
Only if you want to block it

 

[Dave Lockyer]

As a newbie I laid a 4m x 5m 100mm deep base in Jan with a borrowed mixer. You'll certainly ache but it's doable. I used buckets to measure the materials. Some water and ballast went in first which helped keep the mixer from clagging up and then the rest of the ballast and water to the right consistency. I poured into the formwork with a barrow and smoothed the concrete down once I had about a metre of mix in place. It wasn't the prettiest base but came out nice and level. It's worth ensuring that the formwork is completely square and level...