Abstract: A concrete feed bunk is formed and cured in a series of like dimensionally stable yet expansible multi-surfaced molds. Each mold is separated from a cured concrete portion of the bunk formed by such mold by a first step of automatically splitting the concrete from the mold along vertically extending surfaces of juncture and along horizontally extending surfaces of juncture of mold and cured concrete followed by a second step of raising and concurrently expanding the mold to avoid damage to the cured concrete mass. A novel degree of rigidity of moving mold wall parts provides for the uniformity of the splitting action and surface characteristics of final concrete product and the mold structure provides for automatic and reliable dimensions of the cured concrete mass and rapid operation.