Patent Application
20100307093
The invention relates generally to rubber or polymeric waterproof expansion joints.
Rubber expansion joints are often used in construction to help water proof roofs, slabs, and walls, thereby to protect the structure from effluent damage, which may typically be water damage. Traditionally, these expansion joints have included an elongated flat sheet of rubber, vinyl or some other flexible, resilient polymeric material. These expansion joints are usually laid over a joint between two walls or two sheets of waterproofing tiles or fabric. Expansion joints are typically secured to the surface of the joint by adhesive such as tar or the like.
Rubber expansion joints may be present some challenges or disadvantages. For example, on hot summer days, the tar or adhesive used to bond the joint to the underlying substrate and to hold the joint in place may soften or weaken. This may result in the joint to becoming dislodged and slipping or creeping or migrating away from its desired position. That is, when the bond holding the joint softens, the joint may tend to move, or creep, across the surface of the substrate to which the joint is bonded. This creeping of the joint may result in the failure of the waterproof joint. So far, the only way to ensure that the joint is well adhered is to maximize the surface area of contact between the joint and the adhesive used to bond the joint. This can be done by increasing the surface area dimensions of the sheet, i.e. providing a wider sheet, and or by increasing the surface area of the sheet by roughing up the surface by means of bonding fibrous matting to the surface of the sheet. While these approaches are effective in increasing the adhesion of the joint to the adhesive, increasing the dimensions of the sheet increases its cost; and fibrous matting bonded to the sheets often dislodge from the sheet surface do to poor adhesion of the fibrous matt to the sheet.
In an aspect of the invention, there is a substantially flat expansion joint. The expansion joint has first and second elastomer based selvage edges and an elastomeric gland located between the selvage edges. The gland is for deployment in a lengthwise direction along an underlying structural interface. At least a portion of the first selvage edge has a plurality of apertures formed therethrough.
In a feature of that aspect of the invention the first selvage edge has a total edge length that includes the edge lengths of the apertures. A ratio of the total edge length per unit of running length of the portion in the lengthwise direction is greater than 125%. In another feature the ratio exceeds 200%. In a further feature, the apertures include an array of slots pitched along the running direction, the slots have a major dimension, and the major dimension is predominantly transverse to the lengthwise direction. In still another feature the apertures are formed in an array of apertures having edges oriented obliquely to the lengthwise direction. In another feature apertures on successive pitches are oriented on alternating left hand and right hand oblique angles. In a yet further feature the apertures have a closed periphery. In an alternate feature the apertures have an at least partially open periphery. In still yet another feature the first selvage edge includes at least a first scrim, and the apertures are formed at least in part through the scrim. In again another feature the first and second selvage edges each have a first surface for placement against structure to which the expansion joint is to be applied, and a second face for orientation facing away from the structure, and both the first and second faces include a scrim.
In another feature the selvage edges have a transverse width, W. The selvage edges have a most transversely outboard third. The apertures have an extent, L, transverse to the lengthwise direction. The apertures are located in the most transversely outboard third. The extent, L, has a magnitude that is in the range of one eighth to one third of W. In still yet a further feature the first and second selvage edges each have an array of the apertures formed therein, the apertures are circular, closed periphery apertures formed in an outermost one third of each the selvage edge respectively, and the apertures have a diameter to pitch spacing ratio in the range of ⅛ to ¾.
In a still yet further feature the joint includes first and second portions meeting at a corner, the first and second portions have respective rubber-based matrices; and the first and second portions are vulcanized together. In another feature the expansion joint has first and second portions, each of the first and second portions having respective first and second selvage edges; the first portion has arrays of the apertures formed in both of the selvage edges, and the second portion has at least one selvage edge that is free of the apertures.
In another aspect of the invention, there is a method of installing a flat expansion joint on a structure. The structure has first and second portions, and an interface between the first and second portions. The expansion joint has a rubber based matrix. The expansion joint has a lengthwise running gland located between a pair of first and second selvage edges that run along the gland and extend laterally away therefrom. Those selvage edges have apertures formed therethrough. The method includes treating a surface portion of each of the first and second portions of the structure with a resin; placing the first selvage edge in the resin on the first portion of the structure; placing the second selvage edge in the resin on the second portion of the structure; smoothing the expansion joint in place; observing occupation of the apertures with the resin as the expansion joint is smoothed in place; and applying a further amount of resin to cover the selvage edges while leaving the gland uncovered. In a feature of that aspect of the invention, the method further includes applying a mechanical protector over the gland. In another feature the expansion joint has a fibrous scrim mounted to each the selvage edge, and the method includes saturating the fibrous scrim in the resin.
In another aspect of the invention there is an expansion joint. It has an elongated flat sheet of flexible and resilient polymeric material having a width, opposite upper and lower surfaces, and opposite first and second edges. One of the opposite surfaces is a first surface, and has a fibrous section including a section of the sheet having a plurality of fibers secured to the surface. The fibrous section extends along the first surface adjacent one of the edges. A series of apertures passes through the sheet and is positioned on the fibrous section, with the apertures being positioned adjacent one of the side edges.
In a feature of that aspect of the invention, each of the upper and lower surfaces have the fibrous section. In another feature each of the fibrous sections comprises a parallel pair of first and second fibrous matts secured to the surface. The fibrous matts are separated by an elongated strip of bare surface. The first and second fibrous matts are located adjacent to the first and second edges of the sheet, respectively, with the apertures forming a parallel pair of first and second rows of apertures positioned adjacent the first and second edges.
In another aspect of the invention there is an expansion joint. It has an elongated flat sheet of flexible and resilient polymeric material having a width, a length, opposite upper and lower surfaces and opposite first and second edges. The sheet has a parallel pair of fibrous first and second matts secured to each of the opposite surfaces along the length of the sheet. The parallel fibrous matts on each surface are separated by an elongated strip of bare surface. The first and second fibrous matts are located adjacent the first and second edges of the sheet, respectively. Parallel rows of first and second rows of apertures are positioned adjacent to the first and second edges, respectively. Each of the row of apertures passing through the sheet and the fibrous matts. In a feature of that aspect of the invention, each of the apertures have substantially right angled edges. In another feature the apertures are substantially circular.
In a further aspect of the invention there is an expansion joint. It has an elongated flat sheet of flexible and resilient polymeric material having a width, a length, opposite upper and lower surfaces and opposite first and second edges. The sheet has a parallel pair of elongated first and second rough strips formed on each of the opposite surfaces along the length of the sheet. The rough strips on each surface are separated by an elongated strip of bare surface. The first and second rough strips are located adjacent the first and second edges of the sheet, respectively. Parallel first and second series of apertures are positioned adjacent to the first and second edges, respectively. Each aperture passes through the sheet and the rough strips.
In a feature of that aspect of the invention, a portion of each of the rough strips includes fibrous material secured to the sheet. In another feature the rough strips each include a fibrous matt secured to the sheet. In another feature each of the apertures has a substantially right angled edge. In another feature the apertures are substantially circular. In another feature the apertures are substantially polygonal. In a further feature the apertures are substantially triangular. In an alternate feature the apertures are curved. In a further feature the apertures are substantially S-shaped. In another feature the apertures are slots. In another feature the slots have closed peripheries. In another feature the slots are on alternating oblique angles relative to the longitudinal direction to give a wedge arrangement. In an alternate feature, the slots have a closed periphery. In a further feature the slots have a closed and, an open end, and walls that converge from said open end to said closed end.
These and other aspects and features of the invention may be understood with reference to the description that follows, and with the illustrations of a number of examples.
a is an isometric, not-to-scale view of a three-dimensional expansion joint installation such as may incorporate aspects of the present invention;
b is a cross-sectional view of a horizontal portion of an installation such as that of
c is a cross-sectional view of an application of a roof-to-wall expansion joint portion of an installation such as that of
a is a plan view of an embodiment of an expansion joint according to an aspect of the present invention;
b is a cross sectional view of the expansion joint of
c is an expanded view of a portion of
a is a plan view of an alternate embodiment of expansion joint to that of
b is a plan view of a further alternate embodiment of expansion joint to that of
c is a plan view of a further alternate embodiment of expansion joint to that of
d is a plan view of a further alternate embodiment of expansion joint to that of
e is a plan view of a further alternate embodiment of expansion joint to that of
f is a plan view of a further alternate embodiment of expansion joint to that of
g is a plan view of a further alternate embodiment of expansion joint to that of
In the drawings like characters of reference indicate corresponding parts in the different figures.
The description that follows, and the embodiments described therein, are provided by way of illustration of examples of particular embodiments of the principles, aspects or features of the present invention. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the invention. In the description, like parts are marked throughout the specification and the drawings with the same respective reference numerals. The drawings are generally to scale in plan view. However, in view of the aspect ratios of thickness to width, the thickness has been exaggerated or enlarged in some views for the purposes of clarity of illustration.
The terminology used in this specification is thought to be consistent with the customary and ordinary meanings of those terms as they would be understood by a person of ordinary skill in the art in North America. Following from decision of the Federal Circuit in Phillips v. A WH Corp., the Applicant expressly excludes all interpretations that are inconsistent with this specification, and, in particular, to forestall overly broad interpretation under the rule of broadest reasonable interpretation, excludes all interpretations other than those interpretations that are consistent with actual usage in the industry as understood by persons of ordinary skill in the art, or that are expressly supported by this specification.
In terms of general orientation and directional nomenclature, for expansion joints as described herein a Cartesian frame of reference may be employed in which the longitudinal direction is defined as being coincident with the running direction of the joint, and may be considered to be the x-axis or x-direction. Similarly the width of the joint perpendicular to the running direction may be considered the y-direction. The through thickness may be considered the z-direction. In the context of the joint as an whole, the term lateral, or laterally outboard, or transverse, or transversely outboard refer to a distance or orientation relative to the longitudinal centerline of the joint.
Referring to
In terms of a general overview, expansion joint 20 has the form of a strip having a pair of first and second lengthwise running margins, or portions, called selvage edges 24, 26 and a central portion called a gland 28. The selvage edges include an embedded stiffening element, termed a scrim and indicated as 34. Scrim 34 may also be fibrous to promote better adhesion on installation, as described below. The scrim may be a partially exposed surface layer, or it may be fully embedded within the matrix of the expansion joint margins.
In one type of expansion joint, 20, the waterproofing material of the expansion joint may typically be a continuous material strip compounded from a rubber based elastomer. During the manufacturing process a scrim, i.e., a reinforcement, which may for example be in the form of a polyester fleece, is embedded in the gelling elastomer matrix in the selvage edge on both sides of the joint. In some instances, as with a mop applied tar joint, the reinforcing is at least partially external, leaving a roughened or fibrous surface to which the binder, or resin, be it epoxy or tar, or some other material, may be applied. In each case, the reinforcing material does not extend to the expanding or stretching section, namely gland 28. Another type or embodiment of expansion joint employs a scrim that is embedded as a middle layer in a flame proof rubber matrix, such as may be installed using a flame-heated resin. In a third type or embodiment of expansion joint the scrim is again fully embedded in the rubber matrix, and may be for use with an epoxy resin in installations as a swimming pool or other liquid-containing tank seal, and such as may include potable water containing structures. In each of the second and third instances, the upper and lower surfaces or the selvage edges may be roughened, or moulded to have a non-smooth surface, such as may, for example, have the appearance of being knurled.
The elastomeric base material may tend to be rubber, and that rubber may tend to be a rubber that is resistant to one or several of UV light, ozone, alkalis, acids, saline solutions, alcohols and ketones. Depending on the circumstances, the joint may be secured in place with a resin, such as may be chosen from the set of resions that includes roofing tars and asphalts; asphaltic saturants; built-up-roof materials (BUR); coal tar pitch (CTP); modified bitumen (SBS/APP); hot rubberized asphalt (HRA); cold adhesives (CAA); spray polyurethan foam (SPF); liquid applied membranes (LAM); Epoxy Resin (ER); EPDM Tie-in or PVC/TPO tie-in. One type of rubber based material typically has an initial Durometer A hardness of approximately 45±5 according to ASTM D2240. The gland will have an elongation to breaking under ASTN D412 of greater than 500%, and a tear resistance under ASTM D624 of at least 220 lbf/in, (approx. 40 N/mm).
Installation may include the use of a resin such as one of the resins noted above. For example, an asphalt or bitumen tar, may be mopped onto the substrate. The substrate may be some type of base ply roofing layer. The expansion joint is then laid over the joint to be sealed, and then further resin is applied to cover at least the selvage edges. Further materials, such as pea gravel in the case of a built-up roof, may overlay the selvage edges. A protective mechanical layer may in turn bridge across the gland and overlap the inner portions of the selvage edges to provide mechanical protection to the gland, without being attached to, or interfering with the operation of, the gland.
Although expansion joints of this nature may typically be applied across a substantially flat joint, i.e., where, at least initially, the substrates on either side of the joint are substantially co-planar, this need not necessarily be so. For example, an expansion joint may be applied between a substantially horizontal planar portion and a substantially vertical planer portion, as where a building addition of one height meets a taller existing structure, or where the joint lies closely adjacent an upstanding feature, such as a skylight surround. In these cases one selvage edge may lie in the plane of the roof, and adhere to an underlying roof substrate, while the other selvage edge may bear against, and by the use of a suitable resin may adhere to, a flashing or other like element.
The geometry of the expansion joint, and its orientation may vary along its length. Expansion joints such as those described herein need not merely run in a single straight line. In
As can be seen in this example, expansion joint 20 does not necessarily run merely in a straight line. It may have planar portions, such as 36, 38, 42, 62, and 74 that each run in a flat, substantially horizontal plane or planar portions that run in an inclined plane such as the plane of a sloped roof It may have substantially planar sections, such as 72, that run along or across a substantially or predominantly up-and-down (i.e., vertical) wall. It may have portions such as 48 and 66 in which one leg lies in, and is adhered to, a substantially horizontal plane of an underlying substrate, and one leg to a vertical or inclined plane. It may have portions such as 56 in which each leg lies in a different inclined or vertical plane, as in a valley, or at the meeting of two walls or partitions. In each case it is held in place by mechanical adhesion to the underlying substrate with the aid of a resin, such as noted above.
As may be noted, joint 20 as shown in the layout of
In looking at the various portions of joint 20, we see, for example that various portions have arrays of apertures 80 formed in their outboard marginal edge regions. These arrays of apertures 80 are intended to be generic. That is, they could be any of the forms of apertures shown in the various embodiments described in
b and 1c show cross-sections of typical installations. In each case the through-thickness of the various layers has been greatly exaggerated in proportion to the width of the joint for the purpose of conceptual illustration.
b shows a flat roof installation at a joint or gap in a roof B20, where a concrete structure B22 meets a fabricated steel structure B24. The joint is packed with compressible batt insulation as at B26, and a vapour barrier or retarder B28 is provided. An appropriate substrate may include a layer of compatible insulation material, B30, B32 respectively. A base sheet substrate layer B34 overlays the joint. Layer B34 may be of any suitable material, of which one example is a modified bitumen membrane layer. A slit B36 is made in the base sheet, i.e., layer B34, along the joint. The lower portion of an encapsulating layer is applied to base sheet substrate layer B34 on either side of joint B36 to a width comfortably greater than the width of seal 20. This encapsulating layer B38 may be a suitable resin such as may be selected from those listed above, and in one example may be an asphalt or bitumen encapsulating layer applied with a mop or other suitable spreading device.
Joint 20 is then placed atop the layer of resin, and pressed down to seat well. This may be done by hand, or, alternatively, a platen or roller may be used as an aid. One indication of good application may be shown by the visible presence of resin squishing up inside apertures 80. Once joint 20 has been applied and smoothed down, an overlay of the encapsulating resin is applied, e.g., by mop, or other suitable means to complete encapsulating layer B38. The overlay is not mopped onto the gland. Left and right hand cap sheets B40, B42, which may be of the same material as the base sheet, are then placed to cover and adhere to the upper surface of the encapsulating resin. An optional layer in the nature of a shield, or mechanical protector B44 may be placed overtop of the margins of sheets B40 and B42. Protector B44 may be secured on one side and substantially free to move on the other, and may overspan gland 28. Protector B44 may add, for example, a further layer of puncture resistance.
c shows a flat roof installation at a joint or gap in a structure C20, where a roof structure C22 meets a predominantly vertical wall structure C24. The joint is packed with compressible batt insulation as at C26, and a vapour barrier or retarder C28 is provided. An appropriate substrate may include a layer of compatible insulation material, C30, applied to roof structure C22. A base sheet substrate layer C34 overlays insulation material C30 and terminates at a margin running along and adjacent to the joint. Layer C34 may be of any suitable material, of which one example is a modified bitumen membrane layer. On the other side of the gap, or joint, a base layer, such as may be a flashing C32 is mounted to wall structure C24. Flashing C32 may be a two ply flashing, which may be a modified bitumen membrane flashing, and which may include a termination bar. The first portion of an encapsulating layer is applied to base sheet substrate layer C34 on one side of the joint to a width comfortably greater than the width of seal 20. This encapsulating layer B38 may be a suitable resin such as may be selected from those listed above, and in one example may be an asphalt or bitumen encapsulating layer applied with a mop or other suitable spreading device.
One leg or side, or margin 24 of joint 20 is then placed atop the layer of resin, and pressed down to seat well. This may be done by hand, or, alternatively, a platen or roller may be used as an aid. One indication of good application may be shown by the visible presence of resin oozing, or squishing, or welling up inside apertures 80 such as to fill or partially fill the aperture. Once joint 20 has been applied and smoothed down, an overlay of the encapsulating resin is applied, e.g., by mop, or other suitable means to complete encapsulating layer B38. The overlay is not mopped onto the gland. A cap sheet B40, which may be of the same material as the base sheet, is then placed to cover and adhere to the upper surface of the encapsulating resin. The other leg or margin 26 of joint 20 is placed to lie against, and run along, the inner layer of the two-ply flashing. The second, or outer, layer of the two ply flashing overlies the upper edge of margin 26 of joint 20. By observation, gland 28 has been bent out-of-plane to permit the other selvage edge to seat against vertical wall structure C24.
Considering now
Member 22 may have a first or upper surface 114, and an opposite, second, or bottom, surface 116. Member 22 has first and second lengthwise extending opposed side edges 118 and 120. Member 22 has three regions. There may be first and second marginal or edge regions 124, 126, and a third or central, or intermediate region 128 running lengthwise along member 22 between the two edge regions. The central region may have a substantially smooth surface on one or, more typically, both faces. The adjacent edge regions 124, 126 may have a more roughened surface. One way to obtain this rougher surface is to apply a fibrous element, such as fibrous matting, or scrim, in the form of fibrous strips 132, 134, 136, 138 to those edge regions of the first and second surfaces respectively. One way to do this is to embed one face of a fibrous matt or strip in the rubber during construction, as at curing, or to bond the fibrous sheet to the elastomeric substrate, or to roughen the rubber surface mechanically as by abrasion. The roughened surface, or the dense array of bonded or embedded fibres provides a greater surface area for anchoring in a bonding or resinous material, be it a polymer resin or a more traditional medium such as roofing tar. The roughened marginal edge regions, with, for example, embedded fibrous material may be referred to as, and may define selvage edges 24, 26. The width of the selvage edges D24 is half of the overall width, D20, less the mean width of the gland, D28, arithmetically D24=½(D20−D28).
Selvage edges 24, 26 are of equal width. While this is typically so, if need not necessarily be so, and the edges may be of unequal widths, particularly if one edge is to lie horizontally, and one edge is to bend upward and bear against a wall or wall flashing.
Surface 114 has rough strips 132 and 134 and surface 116 has rough strips 136 and 138. Rough strips 132 and 136 may be are arranged parallel to rough strips 134 and 138. Rough strips 132, 136 lie adjacent to side edge 118, while rough strips 134 and 138 lie adjacent to side edge 120. Rough strips 132, 134 and 136, 138 form areas of surface 114 and 116, respectively, that have been treated to augment or enhance the surface area to which an adhesive resin may bond. Quite thin regions along the very edges of member 22 laterally outboard of roughened strips 132, 134, 136, and 138 respectively may be smooth, as at 133, 135, 137, and 139. Alternatively, the rough strips may extend fully to the edge of the member 22. The width of these thin regions is indicated as D135, and, as noted, may be as small as zero.
The third, or central region or portion 128 defines central gland 28 of member 22 and may have bare or smooth portions 140 and 142 on surfaces 114 and 116 respectively. These portions are positioned, in this instance generally centrally, between strips 22, 24 and 26, 28, respectively. The selvage edges may be relatively stiffer than the gland in tension and shear. That is, the gland may be “stretchier”, or of greater elasticity than the selvage edges. This may be due to a different, i.e., slightly greater, thickness than the gland, and due to the embedded strips of rougher material, those strips tending to be more inelastic than the underlying (typically rubber) matrix. The respective widths W140 and W142 of smooth portions 140, 142 need not be equal. Where a rough partially external scrim is used, for example, the width of the lower smooth region may be narrower than the upper smooth region. Expressed differently, to the extent that the scrims stiffen the joint, the unstiffened portion of joint 20 on the underside will be narrower, and the portion on the upper side will be wider. In other embodiments, such as those in which the stiffening scrim is fully encapsulated in the elastomeric matrix, widths W140 and W142 may be the same. The mean gland width, D128 may be taken as the average of widths W140 and W142.
A series, or array, of apertures 144, 146 is formed in each of the selvage edges, namely regions 124, and 126. These apertures are positioned along member 22 adjacent, edges 118 and 120, respectively, running generally parallel thereto. As seen in
A series of apertures, such as 144, 146, may tend to reduce the creep of the finished and installed expansion joint. This may be considered a surprising or counter intuitive view. One might expect that providing apertures along the rough strips would decrease the surface area of contact between the joint and the bonded substrate, S, of
That is to say, the premise of expansion joint 20 is that it overlies an underlying structure, such as mating roof panels, or substrates, S1 and S2, that meet along a crack or joint ‘C’, and that are susceptible to a measure of relative movement at that crack or joint ‘C’, such that a flexible expansion joint member of some kind is required. The interface between the substantially planar face of member 22 and the underlying substrate portions, S1 and S2, is substantially planar, as symbolized by interface plane, P. Even when applied generously, the bonding agent will form a relatively thin layer between member 22 and substrate S. In the illustrations of
The bonding agent apertures permit the sealing resin to flow and accumulate in the out-of-plane direction away from plane P. The bonding agent may then gain a mechanical grip on the non-planar edge or face of the aperture that stands away from, e.g., typically some distance perpendicular to, interface plane, P. Furthermore, to the extent that the resin forms a semi-solid plug in the aperture, the aperture edges may tend to act somewhat analogous to fillet welds in shear. Another feature of an aperture that penetrates through the thickness of the material is that it permits relatively easy visual inspection of the presence of the bonding resin at the bonding interface, and in the apertures.
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In each of the embodiments described, the various apertures are located in the laterally outermost third or quarter of the respective selvage edges. The lateral extent of each aperture is less than ⅓ of the lateral extent of the selvage edge, and may be in the range of ⅛ to ¼ of that width. In absolute terms the length of the aperture may be in the range of ¾″ to 2½″, depending on the size of the joint.
In the case of non-circular apertures, it may be that the major axis of the aperture, or major portions of the edge of the aperture, tend not to be parallel to the x-direction, or to the nominal direction of edges 118, 120. Rather they have a component that is perpendiuclar, or predominantly away from those edges, even if obliquely so.
The resistance of the selvage edge to creep may to some extent then be a function of the arc length of the sum of the perimeters of the apertures. That is, the resistance to creep may be enhanced where the effective length of the selvage edge is greater than the nominal straightline length of that edge. One proxy for the effective length of that shear edge is the sum of the length of the edge itself plus the lengths of the apertures, divided by the nominal straightline length of the edge, expressed as a ratio or as a percent. In all of the illustrated embodiments that ratio is greater than 100%. It may be greater than 150%, and may be in the range of 180-250% of the corresponding straight line running length.
A specific embodiment of the present invention has been disclosed; however, several variations of the disclosed embodiment could be envisioned as within the scope of this invention. It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.
