I am about to pour my footings, up to 950mm deep (mass concrete required to buttress old house foundations, so no strip footings allowed). I'm still not sure if vibration is really required. But, then I came across Lafarge Agilia Trenchflow concrete. Not sure if its price, but it is described as no vibration required, self-compacting, can be levelled by one person, virtually self-levelling. Anyone know about this, and if it sounds like a good idea, since I may be short of manpower on the day I want to pour. Simon.
It is basically 3 sides of a rectangle, total length about 9 metres. It will be pumped by pipe or boom depending. But definitely not a wheelbarrow. I guess the stuff is just super-plasticized concrete. Simon.
Well I used this "agilia" self compacting concrete (I had to find out !). It was pumped in from one location and flowed around all 3 sides. It self-levelled and I did not touch it once, did not tamp it or do anything. It filled like a bath. If you had normal concrete wetted this much, it would have lost it's ballast. The concrete pump guy said it was a dream to pump. Which left me to sort out the small pile that could not be pumped from the hopper. After 24 hours, I scraped off a loose foamy layer on top which was actually a mixture of air bubbles from the self-compacting process, some additive from the concrete and the diesel that the pump guy used as a release agent. Apart from a few localised high spots that I chipped away, it was surprisingly flat, and more importantly, level. The only snag was that the level on either side of the shuttering around the sewer pipe was slightly different (by 30mm), requiring a different stragegy on each side to get the brick courses at the right height. A bit of fiddling with 73mm bricks and concrete blocks will fix that below ground. The concrete was 78 quid per cube (normal lafarge was 70 quid), which sounds like it may be a little expensive, but it meant I could do the job easily on my own.
Things I did wrong (may help others):
Did not consider that the levels either side of the shuttering may end up different.
Did not insist we filled from 2 locations (possibly avoiding point
1)
Allowed the guy to empty his pumping pipe (around 12 metres of 4 inch pipe) into the trench, which took the levels higher that the height pegs I had in. This means I may have to chip a bit of the foundation away to get the roddable bottle gullies in close to the wall at the correct height. No problem for an SDS though.
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