Abstract: A feeder-dispenser for conveying measured amounts of bulk materials, in particular for mortar and concrete, in which a rotor is mounted on a driving shaft, and placed between a pair of stationary cover discs. The rotor is formed of a plurality of chambers regularly distributed about its periphery and open at each end. The chambers are covered on their internal surfaces with an elastic material lining. The top disc has a feed orifice and an air supply opening angularly offset from it. The bottom disc is provided opposite the air supply opening with a discharge orifice. Air under compression ejects the material from the chamber and cooperates with the elastic lining to prevent retention and deposition of material in the chamber.