Re: pouring the concrete slab tomorrow - HELP!

Posted by Rado (144.134.149.177)

In Reply to: pouring the concrete slab tomorrow - HELP! posted by wade

Wade, this large stone bolder should be firmly stable in the ground. Sounds as interesting project. How big is the bolder? It shouldn t be a lot smaller under the slab surface. Dome is heavy needs to be well balanced on top. If the slab on top of the stone outlays on sides it would have to be reinforced with metal bars more on these edges because the heat differences in this slab will create cracks. (In center, under the fire, the slab is hot more then in sides. Center wants to expand, but the sides are cooler, sides are cool and want to stay as they are - unexpanded, and so sides experience tension.)

If I saw the bolder platform I could comment on insulation between the slab and stone. (I am not sure if the heat could crack the stone so rather we should assume yes, heating could crack it.)
Best way to solve this would be to use two slabs and insulation in between. First you put a smaller, but still strong slab on the stone. Leave it to cure and apply insulation on (leave about 5 - 7cm or 2-3inches clean all around the first slab edges where the second slab will sit. The insulation is soft and second slab would be too heavy to be placed directly on it.)

Re: pouring the concrete slab tomorrow - HELP!