Originally conceived as a low technology floor construction method that needed no skilled labour, Pal-Kal has been very popular with contractors who rely on casual labour. Its basic weakness is the risk of a cold joint between the first 50mm of concrete poured and the rest of the concrete in the slab.
This first layer contains the main reinforcing mesh. Once the concrete is poured, workers move onto the slab to position the inverted trough section corrugated steel void formers. These are supposed to be pushed 1015mm down into the hardening concrete before the rest of the concrete is poured and an upper layer of anti-crack mesh placed.
After a series of failures in shear along the cold joint the system was modified to include hairpin shear links between the void formers close to the end supports. These were also supposed to be pushed into the green concrete of the first layer. These modifications failed to convince the engineering authorities that Pal-Kal could comply with Israeli building codes.