APPARATUS FOR PNEUMATICALLY PLACING SEMI-FLUID MATERIALS
Quick-setting concrete is applied to a work surface by air conveying wet concrete through a hose to a nozzle and air conveying a dry accelerator powder for the wet concrete through a separate hose into juncture with the stream of suspended wet concrete a predetermined distance back of the nozzle. A positive metering concrete pump meters the concrete into a T-intersection where compressed air entering through one side of the top of the T impinges at substantially right angles to the flow of wet concrete through the base of the T resulting in shearing off of discrete pieces of wet concrete which are conveyed through a hose attached to the other side of the T-intersection. The positive metering concrete pump is directly attached to a positive metering device for the accelerator powder so as to maintain the ratio of wet concrete to accelerator constant.