One aspect of the present invention pertains to an apparatus for forming a rigid foamed cementitious core within a plurality of article shells. In general, the apparatus can be comprised of a shell bank (98) for retaining a plurality of article shells and comprising a sled (104) and a plurality of reinforcement shells, a filing station (100) for delivering a gas-entrained cementitious material, and a pump. The gas­-entrained cementitious material cures to form a rigid foamed cementitious core within each article shell in the plurality of article shells.