already on the market are not technically workable, and therefore even less commercially viable, due to numerous operational difficulties, for the projection of cob mortars with lower contents of binding materials and water, which are nevertheless necessary for the making of very thick walls (layers of more than 5 cm in thickness placed into position in one single operation on a movable, light, bottom support).
Such mortars with a low admixture of binding materials and water, in fact bring about the rapid formation of an air pocket in currently used machines, at the level of the mixture of the cob mortar in the supply tank of the machine adjacent and above the supply impeller. This causes the frequent loss of priming of the mortar pump and the need todrain the supply tank completely, in order to "break" the arch of mortar hanging over the impeller, thus causing the complete loss of the batch in progress and causing a considerable loss of operational time.
Also the low content of binding material brings about a rapid segregation of part of the sand from the cob-mortar mixture statically waiting in the supply tank of the main body of the machine; this sand then accumulates in non-elastic plugs in the dead spaces of the supply tank and in particular at the inlet of the supply orifice of the mortar pump, this providing a further cause for the loss of priming of the pump, and even the danger of a complete blockage of the entire machine. This results in a renewed need