GB2247272A - Tie device for formwork and water bar - Google Patents

Abstract

A water bar for a tie device (3) is in the form of a body (4) having an opening (5) to receive the device (3). The body (4) is formed from a malleable swellable material which expands on contact with wet concrete to form a water-tight seal around the device (3). A preferred method of forming a water bar on a tie device is also disclosed, involving wrapping the swellable material around the tie, preferably with the aid of a scissors-type device. <IMAGE>

Description

TIE DEVICE AND WATER BAR This invention relates to a tie device for use in the casting of concrete structures and the use on such a device of a water bar acting to prevent water from flowing along the device left embedded in set concrete.

In our British Patent No. 1375856, a tie bolt of high tensile steel in the form of a straight bolt of mainly circular cross-section is provided with an annular surrounding washer of elastomeric material, the internal peripheral surface of which seals against the outer periphery of the bolt to prevent the flow of water along the bolt. This arrangement is effective in practice when the outer surface of the bolt is relatively smooth, but will not reliably prevent water flow along a relatively rough bolt or one having an outer surface in the form of a screw thread or thread-like formation.

An object of the present invention is to provide a water bar which is effective on tie devices having nonsmooth external surfaces and/or having relatively complex shapes not susceptible to sealing by simple conventional means, and a tie device incorporating such a water bar.

According to one aspect of the present invention a water bar is in the form of a body having an opening therein to receive a tie device, the body being formed from a malleable swellable material such that, when swollen, in use, within set concrete, the body forms a water-tight seal around an outer surface of the tie device so as substantially to preclude the flow of water along the device.

Preferably, swelling of the body is activated by contact with water.

In one convenient form, the water bar may include a pair of relatively rigid generally annular flanges, as of plastics material for example, with the body of material disposed between the flanges and the opening therein in general alignment with the internal openings of the flanges.

Preferably, in such an arrangement, a radially facing support surface is provided between the flanges such as to provide support for the body of material whilst not precluding sealing contact of the body with the tie device when the body swells in use.

Conveniently, said support surface is on a hollow spigot extending between the flanges and forming a passage aligned with the flange internal openings.

Typically, support surfaces are formed on respective axially inwardly directed spigots of which the free inner ends are mutually spaced to permit contact of the body with the tie device.

According to another aspect of the invention, there is provided a combination of a tie device with a water bar, wherein the water bar is in the form of a body of malleable swellable material placed around a surface portion of the tie device, the arrangement being such that, with the tie device extending through a body of set concrete, the body, when swollen, forms a water-tight seal around the outer surface of the tie device so as substantially to preclude the flow of water along the device.

According to a further aspect of the invention, a method of forming a water bar on a tie device for use in the casting of concrete structures comprises placing a generally U-shaped piece of malleable swellable material around the tie bar with the arms of the U projecting generally laterally of the tie bar, deforming the piece of material so that it substantially entirely surrounds the tie bar, and severing any excess length of material to leave a generally circular water bar surrounding the tie bar.

According to a yet further aspect of the invention, a device for use in the method of the invention comprises a pair of lever handles pivotally interconnected at an intermediate location and having respective corresponding end portions in the form of oppositely directed cups which when brought together, define a space having the shape of the water bar to be formed.

The invention will now be described, by way of example, with reference to the accompanying drawings in which:- Figure 1 is a diagrammatic illustration of one form of the water bar of the invention and a tie rod forming part of a formwork assembly; Figure 2 illustrates the assembly of Figure 1 after the pouring of concrete into the formwork; Figures 3 to 6 illustrate respectively different forms of the water bar of the invention; Figure 7 is a diagrammatic view of an alternative form of water bar of the invention in place on a tie rod; Figure 8 illustrates an initial step in a method of forming a water bar around a tie rod; Figure 9 illustrates a subsequent step in the method as well as a device for performing this step, and Figure 10 illustrates an alternative embodiment of formwork system incorporating the water bar of the invention.

Referring to Figures 1 and 2, these illustrate diagrammatically a form work assembly which includes a pair of opposed form work panels 1, 2, between which extends a tie rod 3 for maintaining the spacing between the panels, in conventional manner. The tie rod 3 is threaded along its length and would normally be very difficult if not impossible to seal by way of a conventional water bar against the travel of water along the thread after a concrete casting operation.

A water bar of the invention is illustrated at 4 and is composed of a body of malleable swellable material placed around the tie rod 3 and having an aperture 5 therethrough for passage of the latter. A typical example of suitable water bar material is that sold under the trade name VOLCLAY WATER STOP'RX which, in contact with water, potentially swells to many times its dry volume.

As can be seen from Figure 2, the space between the formwork panels 1, 2 is filled with flowable concrete 6 which subsequently hardens around the water bar and tie rod. When one side of the hardened concrete is in contact with water, as when the cast structure forms a dam or retaining wall for example, the water tends to migrate along the tie rod and come into contact with the water bar 4, thereby causing the water bar to swell in all directions so that it fills the thread formations of the tie bar and forms a water tight seal around the bar.

This mitigates or eliminates the traditional problem of water migration causing unsightly rust staining of the exposed surfaces of the cast concrete structure adjacent the bar ends. The expansion of the swellable material of the water bar also acts to fill any small voids in the concrete around the water bar 4, further contributing to the prevention of possible water migration.

The water bar can take many convenient forms, some of which are illustrated in Figures 3 to 6. In the embodiment of Figure 3, a strip of the appropriate material is deformed to form a water bar 4 in the form of an annulus having a central aperture 5, the adjacent ends of the material being brought together to form a joint 7 at which the ends may conveniently be held together by the inherent stickiness of the material, or by appropriate securing means, if required. The embodiment of Figure 4 is used to surround a tie device having a pair of parallel rods 8, usually connected at either end by coils in conventional manner, the water bar 4, in this case, forming a joint 9 longitudinally thereof and enveloping portions of the rods 8.Upon swelling of the water bar, the material thereof comes into close contact around the entire covered surface of each rod to prevent water flow, as previously. Figure 5 illustrates an arrangement similar to Figure 1 but forming a longitudinal joint 10 of the kind illustrated in Figure 4. The water bar of Figure 6 is formed in two parts 4A, 4B, the parts being held together along their parallel mating surfaces by the inherent stickiness of the material and/or by suitable clamping means (not shown).

A water bar assembly is illustrated in Figure 7 and comprises a pair of spaced flanges 11 having respective generally central hollow cylindrical spigot portions 12 through which the tie rod 3 extends. The portions 12 are directed towards one another and their outer cylindrical surfaces 13 act to support a body 4 of malleable swellable material of generally annular shape disposed between the flanges 11. The dotted lines illustrate the initial position of the internal surface 14 of the body 4 and it can be seen that the central opening 5 defined by the surface 14 is generally aligned with the hollow spigot portions 12.In use, the water bar assembly 11 may readily be slid into position along a tie rod, similar to that shown in Figures 1 and 2 for example, and swelling of the material upon contact with water causes the body 4 to expand through the gap between the portions 12 and into intimate sealing contact with the outer surface of the tie rod 3.

A preferred method of forming and installing a water bar on a tie rod is illustrated in Figures 8 and 9.

The water bar is formed from a strip of swellable material 40 which is conveniently bent into a general Ushape around a tie 41, although it may be pre-formed into a U-shape and placed on the tie thereafter. The next step is performed using a scissor-like forming device 43 having a pair of handles 44 pivoted at 45. The working ends of the handles are formed as part-cylindrical cups 46 which when placed in opposed relationship as shown, define a generally cylindrical enclosure having an internal diameter corresponding to the external diameter of the water bar 47 to be formed.

In order to form the water bar 47 around the tie rod 41, the device 43 is placed with the cups 46 around the U-shaped strip of Figure 8, bending the arms 40A thereof around the tie to form the complete water bar 47.

Any excessive lengths of strip 40B may be severed, either by providing cutting edges 46A on the outer edges of the cups 46 as illustrated, or by using a separate cutting tool. Upon removal of the forming device, the joined edges of the water bar adhere to each other by the inherent stickiness of the material, or are held together by securing means.

Figure 10 illustrates another embodiment of formwork system using the water bar of the invention. In this arrangement, the tie rod 41 carrying the water bar 47 has threaded ends onto which are screwed respective "she-bolts" 48 which are withdrawn from the concrete in conventional manner when the latter has set. In this embodiment, the formwork panels 49 are provided with openings 50 of sufficiently large diameter to permit the passage therethrough of the water bar 47, thereby enabling the tie rod and she-bolts to be connected together prior to installation in the formwork, which greatly facilitates on-site assembly procedures.

It will be understood that the water bar of the invention may take many alternative forms other then those described and shown herein, according to requirements. For example, in the assembly illustrated in Figure 7, the cylindrical portions 12 may be part of a single cylindrical portion extending from one flange 11 to the other and formed with appropriate slots or apertures to ensure that the material of the body 4 may expand therethrough to form a water-tight seal against the tie rod 3. It is possible to form the water bar as a discrete body of appropriate swellable material in the form, for example, of a cylindrical slug having a longitudinal aperture therethrough enabling it to be passed along a tie rod to a desired position. The body could be enclosed in a covering of netting, muslin or other suitable material to facilitate the handling and use thereof.

The forming device 43 may also take alternative forms. For example, the lever arms 44 may be pivotally interconnected at their ends in the form of a "nutcracker" with the forming cups 46 of any appropriate form located inwardly of the pivot.

Claims (17)

1. A water bar in the form of a body having an opening therein to receive a tie device, the body being formed from a malleable swellable material such that, when swollen, in use, within set concrete, the body forms a water-tight seal around an outer surface of the tie device so as substantially to preclude the flow of water along the device.

2. A water bar according to Claim 1, wherein swelling of the body is activated by contact with water.

3. A water bar according to Claim 1 or Claim 2, further including a pair of relatively rigid generally annular flanges, with the body of material disposed between the flanges and the opening therein in general alignment with the internal openings of the flanges.

4. A water bar according to Claim 3, wherein a radially facing support surface is provided between the flanges such as to provide support for the body of material whilst not precluding sealing contact of the body with the tie device when the body swells in use.

5. A water bar according to Claim 4, wherein said support surf ace is on a hollow spigot extending between the flanges and forming a passage aligned with the flange internal openings.

6. A water bar according to Claim 5, wherein support surfaces are formed on respective axially inwardly directed spigots of which the free inner ends are mutually spaced to permit contact of the body with the tie device.

7. A water bar according to any one of the preceding claims, wherein the body of material is unitary.

8. A water bar substantially as hereinbefore described with reference to Figures 1 and 2, Figure 3, Figure 4, Figure 5, Figure 6 and Figure 7 of the accompanying drawings.

9. A combination of a tie device with a water bar, wherein the water bar is in the form of a body of malleable swellable material according to any one of Claims 1 to 8, placed around a surface portion of the tie device, the arrangement being such that, with the tie device extending through a body of set concrete, the body, when swollen, forms a water-tight seal around the outer surface of the tie device so as substantially to preclude the flow of water along the device.

10. A method of forming a water bar on a tie device for use in the casting of concrete structures, comprising placing a generally U-shaped piece of malleable swellable material around the tie bar with the arms of the U projecting generally laterally of the tie bar, deforming the piece of material so that it substantially entirely surrounds the tie bar, and severing any excess length of material to leave a generally circular water bar surrounding the tie bar.

11. A method according to Claim 10, wherein the deformation and cutting are preformed in a single operation.

12. A method of forming a water bar on a tie device substantially as hereinbefore described with reference to Figures 8 and 9 of the accompanying drawings.

13. A device for use in the method of Claims 10 to 12, comprising a pair of pivotally interconnected lever handles having respective portions in the form of oppositely directed cups which when brought together, define a space having the shape of the water bar to be formed.

14. A device according to Claim 13, wherein the outermost sides of the cups form cutting edges.

15. A device according to Claim 13 or Claim 14, wherein the cups are of generally semi-circular crosssection.

16. A device according to Claim 13, wherein the handles are pivotally interconnected at an intermediate location and the cups are formed at end portions of the handles.

17. A device for use in the method of Claims 10 to 12, substantially as hereinbefore described with reference to Figure 9 of the accompanying drawings.