| 摘要 |
458,708. Drying concrete. BILLNER, K. P., 30, Rockefeller Plaza, New York, U.S.A. Dec. 13, 1935, No. 34602. Convention date, Oct. 5. [Class 34 (ii)] [See also Group V] Laid or formed concrete in plastic condition is subjected, in order to harden it, to suction behind a movable element while excluding air from between the element and the concrete. On the surface of the concrete in a mould 1 is placed a screen 3 of fine wire or canvas and on this a flexible cover 4 of rubber &c. The undersurface of the cover 4 is provided with grooves or channels which communicate with pipes 7 leading to a suction pump 13. The edges of the cover 4 are sealed by weighted flaps 15. In a modification, a rigid metal cover may be used which may be curved when forming roads &c. The action of the suction removes water from the concrete and also causes a heavy atmospheric pressure to be exerted on the cover 4, thus compressing the concrete. For operating continuously, a number of covers may be used end to end, a cover being moved from one end to the other as the concrete is laid. Instead of providing sealing flaps, the screen 3 may be reduced in size so that the cover 4 contacts with the concrete round the edges and acts as a seal. |
