GB498147A - Improvements in and relating to shuttering for use with vibrating apparatus for the consolidation of concrete cast in situ - Google Patents

Abstract

498,147. Casting concrete in situ. DURLEY, T. C. July 23, 1937, Nos. 20425 and 26040. [Class 20 (ii)] A method of controlling the vibration of concrete which is cast in situ consists in mounting a shutter panel k so as to allow it to have a limited amount of movement in a direction approximately normal to its own plane. For this purpose, the panel k is connected to a device comprising, as shown in Fig. 1, a sleeve a which passes through a centrally-apertured plate b and is screw-threaded externally to receive a pair of nuts c, between each of which and the plate b is fitted a rubber or other resilient ring e or a spring ; lock-nuts f are provided to fix the nuts c in position. As shown in Fig. 5, two panels k are fixed together by bolts n which pass through panel-spacers p and stiffeners q fixed on the panels. Each bolt n is rigidly connected to the sleeve a of the mounting device. The plate b is free within limits to move relatively to the sleeve a and is rigidly connected by bolts or otherwise to frame members r which are fixed in space, such as by connection to the ground or to existing hardened concrete. Alternatively, the plate b may be secured to one of the panels k and the sleeve a secured by the bolts n to the fixed framing. The panels are adapted to be vibrated by a vibrator mounted upon one of the panels. The joint between adjacent panels consists of a rubber or other flexible strip which is interposed between the panels and is adapted to fit the edges of the latter by complementary projections and recesses. The strip h shown in Fig. 5 has two wedge-shaped portions adapted to provide opposed grooves j for the reception of the chamfered edges of the panels ; one or more longitudinal holes m may be provided in each strip. The strips hare shown in Fig. 5 as interposed between the vibrated panels k and shutters k<2> which are rigidly fixed to the already-cast concrete s. Strips of this form are also adapted to be used in the vertical joints between adjacent panels. An alternative form of strip is shown in Fig. 6, and comprises two sector-shaped parts h<1>, h<2> between which the panels are adapted to fit either at an angle to each other or in line. The first Provisional Specification describes also the mounting device for the panels as comprising a spider or hollow boss which is connected at its outer periphery to the panel and is centrally apertured for mounting on a sleeve through which passes a bolt for clamping the latter to a fixed support. A flanged cup, which is mounted at each end of the sleeve, is fitted with a rubber ring for cushioning the cup and sleeve from the central part of the boss. The cup outside the boss abuts against the face of the fixed support. The spider or hollow boss may be replaced by a length of trough adapted to stiffen the shutter. The rubber rings may be replaced by either a series of metal springs mounted between the panel and the sleeve or a spring diaphragm of domed shape anchored at its periphery to the panel and at its centre to the sleeve. The second Provisional Specification describes also the following modifications in the jointing means between adjacent panels, viz. : (1) The provision on the flexible joint strip of one or more tongues of square cross-section for engaging corresponding grooves in the edges of the panels ; when the panels to be jointed are in alignment, the strip is of rectangular cross-section, and, when the panels are at an angle to each other, the strip is either of trapezoidal cross-section, or, if the edges of the panels are suitably splayed, of square cross-section. (2) The tongues of the joint strip may engage between the flanges of metal channels provided on the edges of the panels. (3) A unit in the form of a flexible joint strip secured between two narrow panels by metal strips or wires passing transversely through these members is mounted temporarily by battens or clips on larger shutter panels ; the ends of the metal strips or wires are secured to the narrow-width panels and the portions of the strips or wires passing through the flexible strip are formed into springs which tend to pull the panels together and maintain the said strip in a state of initial compression.