Method and apparatus to minimize the air gap and slurry during the gypsum slurry flow

A method for providing a gypsum slurry improved mixed additive uniformly in a band, comprising: inserting calcined gypsum and water in a mixing chamber (16) of a mixer (12) through at least one inlet (26 , 28) of the mixing chamber (16); agitating the contents of the mixing chamber to form a slurry comprising an aqueous dispersion of calcined gypsum; passing the slurry from an outlet (34) of mixer (12) to a grout delivery apparatus (36) including a conduit (38); introducing an additive that includes a foam with an air content in the slurry at a point (40) along a length of conduit (38) in the delivery apparatus grout (36) to achieve a current flow of a mixture slurry / additive through conduit (38); characterized by changing a direction of current flow in a first corner (52) of the duct (38) while not changing a cross section of the flow stream and then expand a cross section (60) of the flow stream in the duct (38) while not changing a direction of current flow, and then changing a direction of current flow in a second curve (54) while not changing a cross section of the flow stream before which flow stream out of an outlet (42) of the conduit (38).