|
David, Once you know the diametre of your dome, prepare a pad that is a little wider than the diametre. Excavate all of the soil out of your pad area - soil is organic and will move even after compaction, so find a solid base ie clay, and compact the base, and as Baz said allow for an edge beam, if you are wanting to put in power, now is the time to run your conduits if you want them to come into your dome area from under ground. Put in a layer of road base that is at least 100mm thick - if you get it dry you will have to add water and make sure that it gets all the way through the road base - you will know that you have the right amount of water in it when you can sqeeze an amount in your hand and it makes like a sausage that you can break into two. If it crumbles it's too dry. Compact the road base, then apply further water and compact again - this will create a slurry on top and close up the gaps in your road base, and let it sit a couple of days to bake out (if you find that you need a thicker layer of road base, compact it in two layers - assuming that you will use a vibrating plate). Set up your form work to allow for 100mm of concrete and install the Rio (rebar), here in Australia we would use F62 - a sheet of mesh, this will stop shrinkage cracking. Make sure that you leave about a 50mm gap between the rio and the formwork, so that no rio is exposed after you've poured the concrete. Pour the concrete and level and round the edges, once the surface has a dry layer over it, run a broom over it from one side to the other - this will make it non-slip. If you are in a hot area, you could sprinkle water over the top of the concrete regularly (morning and afternoon)whilst the concrete is drying - this will stop surface cracking. Let the concrete cure for at least 4 days, best to let it sit for a week (concrete will have 95% of its strength after 4 days). Then construct your dome. I hope this helps a little. If you don't have a solid base, your concrete will crack eventually.
Regards, Dutch
|