Abstract: The present invention refers to a method and a device for the manufacture of fibre reinforced building structures, surfing coatings and similar, by spraying cement, concrete, mortar or the like through a spraying nozzle, at which disintegrated fibre- or rod-shaped reinforcing material is introduced into the spraying nozzle by means of pressure air. The reinforcing material is brought through a central passage extending through substantially the whole length of the spraying nozzle, and the structural material is brought through a passage in the spraying nozzle, which passage concentrically surrounds said central passage. In this way the reinforcing material will be surrounded by a casing of structural material during a substantial part of the transport from the nozzle to the land surface, thus avoiding the loss of any large quantities of reinforcing material.

Abstract: The invention refers to fibre reinforced shotcrete and it more particularly resides in an improved method for manufacturing structures of such concrete by means of shotcrete. According to the new method a dry mixture of a binding agent and ballast is supplied with chopped fibrous reinforcing material through a feed opening located in the spraying nozzle of the spraying apparatus upstream from the position in which water is added to the mixture.

Abstract: Spraying of materials, which prior to the spraying operation have been mixed from two airborn material flows in a spray nozzle, results in a high wastage rate. It has now been found that this wastage can be highly reduced, if in an appropriate apparatus one of the material flows is restricted, whereas the other material flow is allowed to expand when introduced axially into and mainly in the center of the first restricted flow of material, the second expanding flow of material thereby further being used to create by ejector effect a suction acting upon the restricted flow of material.

Abstract: The invention provides a method and apparatus for preparing precut steel fibers initially packed in bundles or occurring as closely packed lumps for mixing with concrete as a sprayed mass, the method comprising the steps of tumbling the bundles or lumps of fibers, dropping quantities of the fibers onto an inclined plane, subjecting the fibers to an air stream to cause said fibers to become parallel to each other, and mixing the fibers with a mass of concrete in the air stream.