1. Blocks

Blocks and other masonry products, as well as floor joists, are always manufactured by immediate de-moulding using vibratory presses.

These machines, once mobile, are now more often than not fixed. They use the same principle as the first machines from the 1920s. This is based on filling a metal mold with "dry" concrete, then compacting it under the combined effect of vibration and compression.

Whatever the type of machine, the operating cycle is as follows (figure 1 ).

• The mold, with its wooden or metal base, is filled with concrete using a mobile drawer.

• The concrete in the mold is compacted by vibration, then compressed by a pestle.

• The products...