How to make a hedgehog before pouring a pool concrete slab. The earthwork is finished (9 m x 5) with a depth of 1.50 m on one side and 0.50 m on the other (sloping ground). The soil is stable (original without backfill with rock). Is it possible to provide a hedgehog of 10 cm over the entire washed rolled gravel surface of 4/12 (I already have the raw material on site or 10/20, if really necessary)? Will the result be sufficiently stable for laying the structure of welded mesh and concrete? Should we pose before the hedgehog a geotextile film to avoid the rise of the earth (in my case as already indicated the soil is stable with rock)? Should a polyane film be applied to seal the hedgehog before laying the concrete?
According to pool specialists, a hedgehog is not needed. A layer of 5 cm of gravel is enough, and is really necessary only if the soil is clay or impervious, if the pool is at the bottom of a sloping ground (which seems to be your case), if there is has a water table in the basement finally if the region is very rainy and / or snowy. Geotextile felts and polyane films are of no use here. You will find the information concerning the realization of a raft in the file Realization of a swimming pool buried in isolating block to bancher.
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