Abstract: An air driven positive displacement pump is positioned to take a suction from a source of shotcrete accelerator. A shotcrete applicator tube receives pressurized shotcrete from a source thereof. A manifold is adapted to the applicator which has a first inlet connected to the output of the pump to receive accelerator at a pressure in excess of the pressure of the shotcrete passing through the applicator. The manifold also has a second inlet connected to an external source of compressed air to receive compressed air at a pressure higher than the pressure of the shotcrete passing through the shotcrete applicator. The manifold has a body in which the accelerator and compressed air from the first and second inlets respectively are intermixed. The manifold has at least two outlets positioned about the applicator to inject the accelerator and air mixture into shotcrete passing therethrough.