that purpose, the chamber preferably comprises at least one inspection door of the movable cover type. Two inspection doors are advantageously placed in opposition on opposite sides of the chamber the doors opening vertically or laterally, for the purpose of rapid cleaning out of plugs of sand.
"Cobs" are mortars based on soil which is frequently clayey, and sand mixed in varying proportions according to the nature of the soil, with an admixture of bonding materials determined in terms of the dry mass of the initial aggregates (earth and sand) and an admixture of water.
These mortars are then normally placed between two parallel boards and tamped by hand with a rammer, resulting in an increased application time and thus affecting costs. This explains the virtual disappearance of this techniquesince 1945.
Other variations on the basis of stabilized earth have also been suggested, which variations call for the making of air-dried bricks by pressing; these bricks are then placed in position in known manner, which entails the costs of manual labour very similar to those of conventional concrete blocks (Rollow agglomerates).
Machines suitable for projecting compositions of mortars by a process referred to as "wet" (the mortar receiving its final supply of water before passing into the machine) are known, for example according to the principle of the "MOINEAU" pump (this includes a steel rotor in the form of "a pig's tail", rotating in a stator of flexible matter such as rubber or the like, sheathing the inner surface of a tubular duct of steel or cast iron). These