Improved waterstops

Abstract

 A waterstop having a body comprising an elongate web (10) with a keying formation (11,12) at or near each edge of the web by which the waterstop can be secured in adjacent respective bodies of concrete so as to seal the gap between such bodies, and a plurality of transverse ribs (13) each extending over at least part of the width of the waterstop, the ribs (13) being spaced apart along the length of the waterstop.

Description

[0001] This invention relates to waterstops.

[0002] Waterstops are extruded or moulded sections of rubber or other flexible moisture proof materials such as plastics material such as polyvinyl chloride, which are used to prevent the passage of moisture or water through the joints which are provided in concrete structures such as floors, bases and walls when such structures are formed in successively cast sections.

[0003] Waterstops of the so called internal type are conventional structures having enlarged formations at or near both longitudinal edges, or having projections on both faces. These allow the waterstop to be anchored in the concrete so as to bridge the gap between adjacent bodies which are poured in situ, so that it is not pulled out when the concrete bodies move apart as they inevitably will in time and with the change of weather and seasons. The waterstops have to be of strong flexible material in order to withstand movement without tearing out or rupturing. In practice about half the waterstop is first cast into and secured in the first formed body of concrete defining a joint, and subsequently the other half of the waterstop is cast in the adjacent, subsequently cast concrete body.

[0004] A second type of waterstop is the so called external type the subject inter alia of British Patent No. 1008811 in which keying formations are provided on only one face of the waterstop so that the waterstop spans one longitudinal edge of a concrete joint. Single or double sets of keying formations are provided on respective sides of the longitudinal centre line of the waterstop. In the finished structure the waterstop is on the external face or the construction, spanning the gap between the adjacent concrete bodies.

[0005] Most waterstops are obscured from view once a building is completed so that their subsequent performance is not readily monitored. Most are thought to work adequately but occasional complaints of failure to prevent water or moisture penetration do arise. Possible causes are air collection under the waterstop section at the time of casting concrete around the section, leading to weakened porous concrete, and stretching and thinning of a waterstop on concrete shrinkage and building movement leading to the section drawing away from the concrete.

[0006] The utilization of plural rows of keying formations on each side of the centre line in an external waterstop is generally thought to improve the water proofing properties of such waterstops and provide a more effective barrier against water ingress. Even in these situations however leakage may be possible. With these waterstops, and indeed with other types including internal waterstops, any leakage is thought likely to follow a tortuous path. While it is normally expected that the best sealing occurs around the region of the enlargements or keying formations, it may be that such a seal is not effective throughout the length of the waterstop. Accordingly moisture penetrating the joint at one point may run parallel to the web of the waterstop, between it and the concrete or in the concrete if it is porous or missing, for some distance before reaching what may be a small and isolated area where sealing between the waterstop and concrete is again weak and penetration can occur. Thus there may be longitudinal traverses between points of sealing weakness in the various seals around the waterstop leading to eventual penetration through the structure.

[0007] It is an aim of the present invention to reduce these problems.

[0008] The present invention seeks to restrict the above discussed problem by providing the waterstop with transverse ribs extending at least part of the way across the waterstop and spaced apart from each other along the length of the waterstop. This is to prevent, or at least confine any such longitudinal penetration and thus prevent, or limit, leakage.

[0009] According to the present invention there is provided a waterstop having a body comprising an elongate web with a keying formation at or near each edge of the web to be embedded in concrete and by which the waterstop can be secured in adjacent respective bodies of concrete so as to seal the gap between such bodies and a plurality of transverse ribs each extending over at least part of the width of the waterstop, the ribs being spaced apart along the length of the waterstop, the spacing being substantially greater than the thickness of the ribs in tne longitudinal direction.

[0010] The waterstop may be of the external type with keying formations on only one face. The transverse ribs may extend entirely across that face of the waterstop, that is between the two outer keying formations, if there are two each side of the centre line. It can also extend outwards to the edge of the waterstop. The transverse ribs can alternatively extend only between the two inner keying formations. Also, they can extend between the two formations of each pair, and not between the two innermost ones. In that case it is also possible for them to extend outwards to the edge of the waterstop. Preferably the transverse ribs are at least as high from the web as the keying formations and they can be higher with advantage. Waterstops of the invention may also be of the internal type with a transverse rib on one or both faces extending between the keying formations in the same possible ways, and with similar preferences as to height. Again, the transverse ribs may extend outwards beyond the keying formations, and can be made to extend around the edges of the waterstops.

[0011] In practice waterstops will firstly be partially embedded in one body of concrete and then in another. During the embedding in the first body of concrete shuttering needs to be placed against the waterstop. In certain forms of the invention the need to cut notches in the shuttering so as to accommodate the transverse ribs where these traverse the longitudinal centre line can be avoided by providing a generally centrally located longitudinal shuttering support.

[0012] In order that the invention may be more clearly understood the following description is given by way of example only with reference to the accompanying drawings in which:-

Figure 1 is a perspective view of a segment of a waterstop of the external type with transverse ribs in accordance with the invention.

Fig 2 is a cross-section through a waterstop of a second type with the transverse rib only between pairs of outer keying formations.

Figure 3 is a cross-sectional view through an third embodiment of a waterstop with a transverse rib only between the two inner keying formations.

Figure 4 is a cross-sectional view of an internal type waterstop provided with a transverse rib on one side of the web.

Figure 5 is a cross-section through another form of internal waterstop with a transverse rib on both sides of the web.

Figure 6 is a cross-sectional view of a waterstop of the external type provided with a shuttering strip to eliminate the need to notch shuttering.

Figure 7 is a cross section through another form of internal waterstop, shown embedded in adjacent concrete bodies.

[0013] As shown in Figure 1 a waterstop of well known type has a web 10 and, on each side of the longitudinal centre line of the web, a respective pair of keying formations 11 and 12 to be embedded in respective concrete blocks and to hold the waterstop therein. The keying formations extend generally throughout the length of the waterstop. At intervals along the waterstop such as each 2 to 5 metres (6 to 15 feet) and preferably 3 to 4 metres (9 to 12 feet) a transverse rib 13 is provided. In this embodiment the rib extends all the way between the two outer keying formations; that is between the extremities of the keying formations. The rib could also if desired extend some way outwardly beyond the outer keying formation for instance to the edges of the waterstop. As shown the rib has the same height and cross section as tne keying formations 11 and 12 and this is a preferred feature. A lower height may nevertheless provide very useful protection while a greater height may also assist.

[0014] In use of a waterstop of the Figure 1 type any moisture managing to penetrate around an outer one of the keying formations 11 and 12 will, in order to penetrate into the concrete joint located between the two inner keying formations, additionally have to penetrate round the inner of the keying formations 11 and 12. Previously such might be possible insofar as the entire length of such inner formations could have been exposed to the possibility of water running along the length of the waterstop between the formations and able to penetrate at any weak spot. With the transverse ribs of the invention however the possibility for longitudinal water penetration is severely curtailed. If as a result of this precaution water penetration should nevertheless occur, then it will at least be certain in which area the actual leakage to behind the waterstop has occurred, because it must be in the length between the adjacent transverse ribs to the manifestation of the leakage on the inside.

[0015] Figure 2 shows a cross-section of an alternative embodiment offering an alternative form of protection wherein the transverse rib 13 is provided only between the two keying formations of the pairs of keying formations 11 and 12. The transverse rib could, here again, extend outwards beyond the outer keying formations.

[0016] Figure 3 shows another arrangement where penetration into the concrete joint again will be limited by the provision of the transverse rib 13 between the two inner ones of the keying formations.

[0017] Figure 4 is a cross-section of a waterstop or the internal type of the well known dumb bell configuration having a transverse rib 24 of the invention extending between the two keying formations 21 and 22 provided near the edges of the web 20.

[0018] Figure 5 differs only in having a transverse rib 24 on each side of the web 20.

[0019] Figure 7 shows another embodiment of internal waterstop modified to have the transverse rib 50 extend around the edges of the waterstop outwards of the keying formations, this being shown embedded in adjacent concrete bodies 70, 71. All other illustrated waterstops can be similarly embedded.

[0020] The transverse ribs described above can be formed in various ways. In one way they are formed of strips of the same material as the waterstop which are welded in place. They may alternatively be formed in moulded sections of the waterstop which sections can then be welded to continuous sections of the waterstop in which there are no transverse ribs. Instead of being of the same material as the rest of the waterstop, they can be of a different material e.g. a foam material or possibly of a water swellable plastics material. They could further be of a composite of the same material as the waterstop (generally PVC) and of water swellable material. Water swellable materials offer the advantage of reacting with any ingressed water to swell and tend to provide the seal as soon as it is needed.

[0021] Conceivably, where separate strips are provided in a non integral manner, these could be applied on site for instance by way of the strips having a self adhesive layer. The water swellable hydrophilic materials are already obtainable with self adhesive layers on one side.

[0022] The waterstop shown in Figure 6 is like that of Figure 1 but additionally with a longitudinally extending central projection 60 upon which the shuttering is based when concrete is first cast. Such a projection is known for use where expansion joints are created, that is to say joints across which concrete reinforcements do not extend, and which on construction are intended to receive a sealing board, panel or other mechanism between the adjacent concrete blocks. Arrangements of this type can be useful in waterstops of any type according to the present invention if the upstanding member is of the same height of any transverse rib extending across the centre line of the waterstop. This will ease the job of those positioning shuttering in place, who otherwise have to notch the shuttering to accommodate the transverse ribs while the majority of the edge of the shuttering sits upon the waterstop. Other forms of waterstop with fins provided in the central section upon which the shuttering can rest could also be adapted for this purpose by having fins of a greater height approaching or equal to that of the transverse ribs. These fins are normally provided to prevent the seepage of grout between the shuttering and waterstop and thus to ensure formation of dense non porous concrete in the region of the waterstop. The form of the central longitudinal support of the shuttering could be like that of the keying formations or could be a simple plain upstanding rib of relatively little width say 10 mm or so, as shown in this Figure.

[0023] The invention extends to a concrete joint made with the waterstops as described above and to a method of making a concrete joint including such waterstops.

[0024] Plasticised polyvinylchloride is a preferred material for waterstops of the invention, partly because welding is easily and effectively performed.

[0025] Water swellable materials, if used, can be one of the materials now available, e.g. of rubber or flexible plastic with a water swellable component e.g. of bentonite or a polyacrylic acid.

Claims

1. A waterstop having a body comprising an elongate web (10) with a keying formation (11, 12, 21, 22) at or near each edge of the web to be embedded in concrete and by which the waterstop can be secured in adjacent respective bodies of concrete so as to seal the gap between such bodies, characterised by a plurality of transverse ribs (13, 24) each extending over at least part of the width of the waterstop, the ribs being spaced apart along the length of the waterstop, the spacing being substantially greater than the thickness of the ribs in the longitudinal direction.

2. A waterstop according to claim 1 which is of the external type with keying formations extending on only one face of the web, and wherein there is one keying formation on each side of the longitudinal centre line of the web and the transverse ribs extend between the longitudinal keying formations.

3. A waterstop according to claim 1 which is of the external type and wherein there are two keying formations on each side of the longitudinal centre line of the waterstop and the transverse ribs extend between the keying formations of each pair.

4. A waterstop according to claim 3 wherein the transverse ribs additionally extend between the two inner keying formations.

5. A waterstop according to claim 2, 3 or 4 wherein the transverse ribs extend outwards beyond the, or the outer, keying formations to the edge of the web.

6. A waterstop according to claim 1 which is of the internal type with keying formations which project from both faces of the web and wherein the transverse rib extends between the keying formations on one or both faces of the web.

7. A waterstop according to claim 6 wherein the transverse ribs extend between the keying formations on both faces of the web outwards to and around the edges of the web.

8. A waterstop according to any preceding claim wherein the transverse ribs are at least as high from the web as are the keying formations.

9. A waterstop according to any preceding claim including on one face of the web a central support for shuttering which support is as high as the transverse ribs.

10. A waterstop according to any preceding claim wherein the transverse ribs are spaced every 2 to 5 metres along the waterstop, and preferably every 3 to 4 metres.

11. A waterstop according to any preceding claim wherein the transverse ribs are integral with or welded to the waterstop.

12. A waterstop according to any preceding claim wherein the transverse ribs are of water swellable material.

13. A waterstop according to any one of claims 1 to 11 wherein the transverse ribs are of foam material.

14. A concrete joint formed between two concrete bodies characterised by a waterstop according to any preceding claim embedded in the respective concrete bodies.

15. A method of providing a concrete joint characterised in that a waterstop according to any one of claims 1 to 13 is embedded in a first concrete body (70) and subsequently in a second concrete body (71) to seal the joint or gap between the two concrete bodies.

Drawing