Levelling base of a concrete pond - Best method

[Chris_o]

Basically I'm going to be constructing a concrete pond for someone.

I've got 5.5 cubic metres of readymix being poured next friday in to what is essentially a large irregular hole in the ground, about 4 foot deep. What would be the best method of levelling this off when it's being poured? Make up some level form work to follow the curves of the pond and just use a straight edge to level as you go? Bearing in mind you've obviously got to be in it as well.

Thanks in advance!

[lutonlagerlout]

have you ever done this type of work before chris?

concrete can be a cruel mistress in the wrong hands

will you have a liner ?

is there any subbase going under the concrete?

is any rebar going in the concrete?

ponds are notorious for leaking are you suing DPM?

food for thought

LLL

[Chris_o]

Thanks for the reply.

I have poured a fair amount of concrete before, smallish driveways, shed bases, footings etc, but never in this scope of work.

There will be a hardcore layer going in first, and a252 steel mesh in the slab itself. The slab will ultimately be circa 200mm thick.

No liner involved, sides will be made up of 215 hollows filled with rebar and concrete, and the insides will be rendered, with an sbr slurry going on first. 2 weeks after the render has been applied it will then have it's layers of g4 pond sealer applied.


Any hints/tips on the levelling of the base? Form work the best way to go?

[lutonlagerlout]

when you say levelling is the base going to be level or will there be dips etc?

obviously if its level you need a youngman or other type of board you can move around to tamp and level the concrete

i cant see how formwork would help you

If it was me I would lay a base level with starter bars sticking up around the perimeter

then use blocks to achieve the required shape

you may be able to get a waterproofer additive added to the concrete

I have a feeling that sika do summat like this

I built a small pond with a 9 inch slab and engineering brick years ago and it emptied within a day

I then had to render it internally with a strong mix and it was ok after that

cheers LLL

[Chris_o]

Base will be level, and then blocked up off. So use starter bars around the circumference set to height of finished slab? Then just tamp it level using bars as a guide?

Apparently with this g4 pond sealer stuff the concrete shouldn't have a waterproofer in, as apparently it wont enable it to 'bind' in to the concrete properly or something!

[lutonlagerlout]

the starter bars can be tied to new stuff as long as they stick 225mm out of the concrete
dont forget those little plastic things that you put on them to stop injury
is the concrete being barrowed ,dumpered or pumped in?

LLL

[GB_Groundworks]

http://youtu.be/sy1FEU0AW0I

Hire a small magic screed, there's a few videos of us pouring concrete on my YouTube

[seanandruby]

If it was me i'd blind it with 50 ml concrete and trowel finish it, then prime it before laying a waterproof tanking liner like preprufe.

[Chris_o]

Will update this with plenty of pics when i've got time. All done apart from the g4 pond sealer which I will be applying end of next week