Abstract: A machine for forming concrete slabs by a continuous process without using conventional casting forms. This requires that the consistency of the concrete mix be such that the concrete will be self-supporting before it has hardened. The machine to be disclosed is designed to utilize self-supporting concrete mixes of the optimum consistency, and enables close control of the forming process at each phase of the operation. The machine includes a carriage that is advanced by winch and cable along a track over a flat surface. A portion of the carriage coacts with the flat surface to form a mold cavity, and concrete mix from a hopper mounted on the carriage is delivered to the cavity by a novel feed and packing arrangement. Vibration means are associated with the mold cavity to consolidate the concrete mix and improve its flow.