Movement joint

Abstract

A free movement, arris protection, construction joint has a pair of arris protection members formed complementarily from strips of sheet with a continuous trapezium wave form. A divider one of the members is typically 100 mm deep for a nominal 0.1 m deep slab. The other one is typically 50 mm deep. The members are of steel plate. The wave form is comprised of flanges extending in the length of the joint and of webs angled to the flanges and the length of the joint. The flanges are spaced on opposite sides of a mid-plane of the joint. The members are bolted together with flangible nylon bolts, with their top (in use) edges flush. Welded to the outer ones of the flanges are L strips having apertures in their flats extending from the flanges for anchoring the joint to its slabs.

Claims

1. A free movement, arris protection, construction joint for dividing a concrete during pouring of slabs on opposite sides of the joint, the joint having a top-to-bottom depth in the joint's use orientation, giving depth to the slabs, the joint comprising: a pair of elongate fabrications of steel one for each side of the joint, the pair of elongate fabrications each having: a top and a bottom edge separated by the top-to-bottom depth; and means for frangibly fastening the pair of elongate fabrications together, in metal-to-metal contact prior to and during pouring of the slabs; and the pair of elongate fabrications including: means for anchoring the pair of elongate fabrications in the slabs on opposite sides of the joint; two arris protection members, one in each elongate fabrication of the pair of elongate fabrications for protecting an arris of one of the slabs at one of the opposite sides of the joint; the two arris protection members: being complementarily formed along a length of the joint with a regular wave shape, with each arris protection member extending with a regular wave shape across a mid-plane of the joint from one side to the other side and back again at successive positions along the joint at least whilst the pair of elongate fabrications remain frangibly connected; having a width transverse the length of the joint giving the joint the top-to-bottom depth, the width being suitable for the depth of load bearing slabs; being single pieces configured to act together as a divider for dividing the slabs with the top edges flush with each other and with the bottom edges flush with each other; and the regular wave shape extending throughout the depth of the arris protection members, including each arris protection member, whereby on pouring, the slabs are formed with interdigitated concrete fingers edged at the slabs' arrises by the arris protection members and extending through the entire depth of the slabs; and dowels, which are welded-in-place extending outwards of the mid-plane of the joint on one side of the joint and having sleeves extending on the dowels on the other side of the joint for transferring a vertical load between the slabs on opposite sides of the joint, wherein: the means for anchoring comprises continuous welded-on members, the welding being at the furthest extent of the arris-protection members from the mid-plane of the joint, that is at lateral wave peaks; the dowels being welded to the arris-protection member on the one side of the joint and to the continuous welded-on anchor members at this one side of the joint; whereby after casting and shrinkage of the slabs, the free movement, arris protection, construction joint has: each of the arris protection members abutting one of the slabs, with a pair of arris protection members being separated by shrinkage of the slabs, with the frangible fastening together of the arris protection members being broken; and each dowel remaining within a respective one of the sleeves on the other side of the joint.

2. A free movement, arris protection, construction joint according to claim 1, wherein the regular wave shape is selected from the group consisting of: curved, sinusoidal, angular, saw tooth, triangular, square and trapezoidal.

3. A free movement, arris protection, construction joint according to claim 1, wherein the continuous welded-on members are angle members with apertures punched for anchoring in the concrete.

4. A free movement, arris protection, construction joint according to claim 1, wherein the continuous welded-on members are lengths of reinforcing bar.

5. A free movement, arris protection, construction joint according to claim 1, wherein the means for anchoring are set down from flush top edges of the arris protection members.

6. A free movement, arris protection, construction joint according to claim 5, wherein the means for anchoring or part thereof is set down from the top of the joint by not more than one third the top-to-bottom depth of the slab.

7. A free movement, arris protection, construction joint according to claim 5, wherein the dowels are set down from the top of the joint by more than one third the top-to-bottom depth of the slab.

8. A free movement, arris protection, construction joint according to claim 5, wherein the dowels are a plate.

9. A free movement, arris protection, construction joint according to claim 5, wherein the dowels are a bar.

10. A free movement, arris protection, construction joint according to claim 5, wherein an end of the joint is complementarily formed for connection of another such joint to the end of the joint, the joint having: a portion of one arris protection member extending beyond an other arris protection member at one end, a complementary portion of an other arris protection member extending beyond the one at an other end and means for frangibly fastening the portion and the complimentary portion together for fastening the joint to another such joint.

11. A free movement, arris protection, construction joint according to claim 10, wherein part of the means for anchoring at a side of the joint having one portion extends onto and is fixed onto the one portion and is fixed onto the means for anchoring of the joint short of the complementary portion of the other arris protection member.

12. A method of casting concrete slabs, comprising: providing, on a sub-base, a free movement arris protection joint according to claim 1, along either side of which concrete slabs are to be cast; casting a first slab against a first side of the joint; and casting a second slab against an other side of the joint, whereby the first and second slabs are cast with a horizontally castellated edge, the horizontally castellated edge of the first slab being interdigitated with the horizontally castellated edge of the second slab, each horizontally castellated edge being bound by an arris protection member and extending through a full depth of the slab to the sub-base.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) To help understanding of the invention, a specific embodiment thereof will now be described by way of example and with reference to the accompanying drawings, in which:

(2) FIG. 1 is a plan view of a free movement, arris protection, construction joint according to the invention;

(3) FIG. 2 is a perspective view of the joint of FIG. 1, when closed as in FIG. 1;

(4) FIG. 3 is a view similar to FIG. 2 of the joint when open as induced by concrete shrinkage;

(5) FIG. 4 is a side view of second joint of the invention;

(6) FIG. 5 is a plan view of the second joint of FIG. 5;

(7) FIG. 6 is a perspective end view of the second joint of FIG. 5;

(8) FIG. 7 is a scrap plan view of the joint of FIG. 5 connected to another such joint;

(9) FIG. 8 is a plan view of the joint of FIG. 5 between two concrete slabs on initial curing of the concrete;

(10) FIG. 9 is a plan view similar to FIG. 8 after concrete shrinkage and joint opening;

(11) FIG. 10 is a perspective view of a wheel supported at the joint of FIG. 5;

(12) FIG. 11 is a cross-sectional end view of the joint and concrete on the line XI-XI in FIG. 10, i.e. through joint members on the mid-plane of the joint, with the wheel centred on the mid-plane;

(13) FIG. 12 is a similar cross-sectional view on the line XII-XII in FIG. 10, i.e. through a castellation extending from one slab with one side of the wheel supported on this slab and its castellation; and

(14) FIG. 13 is a similar cross-sectional view on the line in FIG. 10, i.e. through a castellation extending from the other slab with the other side of the wheel supported on this other slab and its castellation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(15) Referring to the drawings, a free movement, arris protection, construction joint 1 has a pair of arris protection members 2,3 formed complementarily from strips of sheet with a continuous trapezium wave form. A divider one 2 of the members is typically 100 mm deep for a nominal 0.1 m deep slab. The other one 3 is typically 50 mm deep. The members are of 2 mm steel plate, either mild (possibly galvanised) or stainless.

(16) The wave form is comprised of flanges 4,5, typically extending 150 mm in the length of the joint and of webs 6, extending at 45° to the flanges and the length of the joint. The flanges 4,5 are spaced 150 mm on opposite sides of a mid-plane 7 of the joint. The members 2,3 are bolted together with flangible nylon bolts 8, with their top (in use) edges flush.

(17) Welded to the outer ones of the flanges are L strips 9 having apertures 10 in their flats 11 extending from the flanges for anchoring the joint to its slabs. The bolts pass through welded on ones 12 of the flats of the divider plate anchor strip.

(18) Beneath the anchor members, extending out from every other flat 5 of the deep divider one 2 of the protection members are load transfer dowels 14, with sleeves 15 on their extent across the mid-plane and beyond.

(19) In FIG. 3 the joint is shown separated, albeit without concrete being shown. It will be appreciated that the concrete is cast with a horizontally castellated edge, castellations at positions 16 being bounded by the divider member 2. Complementary castellations on the other side of the joint at the positions 17 interdigitate with the first castellations 16. As the joint opens, with concrete slab shrinkage, the castellations and their arrises are edged and protected by the members 2,3. The castellations extend to the full depth of the slabs. Thus as a vehicle moves over the joint, the load applied down onto the castellations is compressively transferred to the sub-base, below the slabs. The castellations are full depth to the sub-base and in the absence of impact loads, with the wave-form gap developing between being too small for the vehicle's wheel to enter, the castellations can be expected to have a long life. With no or negligible impact loads the arrises of the castellations will not be subject to crack inducing stresses. The members 2,3 are kept in close contact with their castellations where these are bounded by at the gap by the relatively short flanges 4,5 which are tied back by the webs 6 to the other flanges 4,5. The latter are anchored to the concrete by the anchoring strips 9.

(20) Turning now to FIGS. 4 to 11, the second joint is essentially similar to that of FIGS. 1 to 3, except that the webs 106 are set at 60° to the flanges 104,105. The pitch of the wave form is 150 mm, the flanges are spaced nominally by 50 mm on opposite sides of the mid-plane 107 and the flanges are nominally 42 mm long. The skilled reader will (i.) appreciate that with each of the arris protection joint members 102,103 being comprised of flanges 104 and flanges 105 interconnected by webs 106, for the members to fit closely together, each of the flanges 104,105 are of slightly shorter and slightly longer ones, lying against each other and connected to webs lying against each other, and (ii.) be able to calculate the exact dimensions of the shorter and longer flanges to enable the members 102,103 to fit together. As shown, both members 102,103 are nominally 175 mm wide for this depth slab.

(21) The outside/longer ones of the flanges 104,105 have two lengths of 8 mm rebar welded to them. Three of four of these lengths 91,92,93 are set 30 mm from the edges of the members. The fourth 94 is set 60 mm from its respective edge. At this level it has 20×20 mm square dowels 140 extending above it, the dowels being welded to this bar and to the joint member having this rebar welded to it. The dowels are provided at every other peak of the sinuosity of the joint on one side thereof. They extend 160 mm from the rebar. On the other side of the joint, the dowels extend by 200 mm and each has a plastic sleeve 150. This further extension allows for 40 mm of joint opening and still the same 160 mm within the sleeve, for load transfer. This arrangement places the dowels below one third of the depth of the joint, whereby they are not liable to be cut into if and when the slabs are saw cut for stress relief—normally to one third the depth of the slab. On the other hand, the upper anchoring rebar lengths 91,92 are within the top third of the depth of the joint and are liable to be cut into in saw cutting. Nevertheless, they retain their efficacy in anchoring the joint members at the saw cut due to their regular welding to the flanges of the members.

(22) It will be noted that the joint members 102,103 have a series of apertures 110,111 for known supports to hold the joint at installation height above the sub-base 112. The apertures are provided in pairs on adjacent flanges 104,105 on opposite sides of the joint, whereby the joint can be supported from either side. Further, the joint members are frangibly connected together by nylon bolts 80 spaced along the joint between the dowels and at the same height as them. Further frangible bolts 81 and wing nuts 82 are provided for interconnecting joints end to end for an extended joint. At one end of the individual joints, the rebar lengths 92,94 are welded onto an outer flange 105, with the inner flange being omitted here. At the other end, the inner flange 105 is present, and the rebar lengths are welded to the ends of the web 106 of their joint member. The ends are complementary and are bolted together in use by a bolt 81 and wing nut 82. This arrangement provides continuity along the joint of divider capability for concrete pouring.

(23) Once slabs 155, 156 are cast on opposite sides of the joint, the rebar lengths are embedded in the concrete for anchoring of the joint members. The slabs extend as inter-digitated castellations 160,170 separated by the sinuosity of the joint. The castellations extend to the sub-base 112. Progressive load transfer from one slab to the next can the appreciated from FIGS. 8 to 11. Initially the wheel is supported on one slab 155. As it approaches the joint, load is transferred to the other via the dowels. At the joint, it is supported first primarily on a castellation 160 of the first slab 155 and progressively on a castellation 170 of the other slab 156 as it rolls over the joint obliquely along the webs 106 beneath it. Thus there is a progressive transfer of load from one slab to the other.

(24) The invention is not intended to be restricted to the details of the above described embodiments. For instance, other sinuous wave forms could be used in particular sinusoidal. Further it is not essential for both of the arris protection members of the joint to be of full slab depth. For deep slabs, material can be economise on by the bottom of one stopping short of full depth. With such an arrangement, one rebar anchor can be envisaged for this member but two will normally be provided.