GB486452A - Improvements in and relating to the manufacture of concrete building blocks and units - Google Patents

Abstract

486,452. Moulding concrete building- slabs. RUEGG, A. E. Dec. 8, 1936, No. 33688. [Class 87 (ii)] [Also in Group X] In moulding reinforced concrete blocks, the concrete is vibrated and subjected to vacuum and gradually raised to an elevated pressure which is finally reduced to normal atmospheric condition. The blocks A preferably have tongued and grooved ends C, D and central cavities B to reduce weight. They may also be formed with window or door openings. The mould is formed of side members 10, top and bottom members 13, 14, and end members 12. The side members 10 are formed with two walls 38, 39 connected by metal struts to withstand pressure and are connected by bolts. The end members 12 are clamped to the members 10 by clamps 42. Wedge-shaped keys 15 hold the mould rigid. End sections 11 for forming the tongues and grooves are formed in a number of pieces for easy removal. The bottom 14 has transverse slots 28 to receive loops of the reinforcing steel E, the slots being afterwards filled by fillets held in place by a longitudinal key bar. The steel E may protrude through holes in the top sealed by conical rubber sleeves. Hollow rubber cores 32 are positioned in the mould by spacers 34 and pins 44. The top of the mould has a pressure manifold containing ducts 36 leading to the cores. In operation, the mould is assembled, the steel E is subjected to an initial tension, and the concrete is poured in. The mould is next vibrated and the concrete is subjected to vacuum through ducts in the top manifold. The cores 32 are then gradually expanded by fluid pressure which rises to 5,000 1b. per sq. in. while the temperature is raised to 300‹ F. by hot air in the cores. The pressure and temperature are finally slowly reduced to normal and the mould is dismantled. The whole process is preferably performed as the moulds pass along a trackway.