MANUFACTURE OF PRECAST CONCRETE COMPONENT

PURPOSE:To improve accuracy and productivity of a precast concrete component used combinedly as a mold with a hollow section or a U-shaped channel by inserting an inner mold to be formed into a square section into an outer mold by force feeding gas, and then force feeding the gas placing concrete between the inner and outer molds, and then exhausting the gas and releasing. CONSTITUTION:An inner mold 1 is a closed type with its four sides formed by rigid flat plates 3 and its four corners by an elastic film body 5 as an elastic material, and an air inlet and an air outlet are formed at one end. For the manufacture of a precast component for a pole which is combinedly used as a mold provided with the peripheral edges in an outer mold 6, main bars 7 and hoop bars 8 are disposed on the peripheral edge sections in the outer mold, and an inner mold 1 is inserted inside the outer mold. Then, gas is fed forcibly into the inner mold 1, and the flat plate 3 is restrained by the hoop bars 8 to form a square section of given dimension. Concrete 9 is placed between the inner and outer molds 1 and 6 in the state, and after curing, the gas is exhausted or vacuum exhausted to contract the inner mold 1. The inner mold 1 can be released easily by the arrangement.