GB798091A - An improved process and device for the internal treatment of fresh concrete - Google Patents

Abstract

798.091. Moulding and hardening concrete. BILLNER, K. P. Aug. 18, 1955, No. 23800/55. Classes 22 and 87(2). [Also in Group X] Hardening of fresh concrete is assisted by placing an inflatable core 1 surrounded by a vacuum chamber and filtering wall 6 in shuttering in the expanded state, pouring in concrete, evacuating the vacuum chamber to draw water from the concrete, deflating the core and finally removing the vacuum. The filtering wall 6 is supported around the core by an expansible and contractible cage 20 which provides a chamber connected by a pipe 29 to vacuum. The cage 20 is formed of interlaced helices of wire or parallel tubes connected by belts, Fig. 4 (not shown). The core can be wholly immersed in the concrete up to the level of the closure 2 which carries a cap connected to vacuum, Fig. 1 (not shown). In Fig. 3, in which the core is intended to be only partially immersed, the cage 20 is completed by sleeves 23, 24 at the top and bottom, the sleeve 24 also comprising a cap 25 closing the end of the core, the sleeve 23 being connected by a metallic network to the closure 2. The core is engaged in a conduit 18 in set concrete to the level N, inflated to engage the sleeve 24 with the conduit and further concrete poured to cover the folded part of a rubber skirt 28 which seals the vacuum chamber and the concrete then treated with vacuum. To cast a further layer the core is partially deflated, the vacuum removed and the skirt 28 turned up to a higher position and further concrete poured. The skirt 28 and wall 6 may be replaced by a paper sleeve. The core may be of circular section or may be made of square section with the aid of four tubes symmetrically arranged, Fig. 6 (not shown), to form the corners. Several air chambers may be used and the expansion of the cage may be limited by cables or strips of cloth.