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Hyson Cells with concreteRelease of hydrostatic pressureWater and air may be trapped beneath a cast concrete slab and empty canals or swimming pools may rupture when the water table rises. Hyson Cells channel liners are, however, observed to weep as they release these pressure. Release of hydrostatic pressure Although the joint gap in a Hyson Cells "cell slab" is not large enough to allow the escape of fines, and Hyson Cells canals are observed to be comparable with conventional concrete canals with respect to seepage, the <12 µ gap in the jointing will allow air and trapped water to vent under pressure. In an extreme case, it was reported that a canal wall had formed a "blister". However when the pressure had been released the blister flattened of its own accord. It is likely that a conventional concrete panel would have ruptured under these conditions. What a pity there are no photographs - but the fault went away. |
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