An apparatus and method for the continuous generation and placement of a foamed cement grout. The assembly is mounted on a fixed or mobile frame. There is a continuous foam generator, and this supplies finished foam to an intake port of a screw-type, positive-displacement pump. Cement slurry is also supplied to the intake portion of the pump, and this is mixed with the foam in the body of the pump and discharged from this through a conduit to the injection site on a continuous basis. The ratios of foam and slurry can be adjusted on a continuous basis to compensate for variations in grout quality which are observed at the injection site. The assembly is also provided with an onboard power generator and a water pump for flushing the grout out of the injection lines.