Note: Descriptions are shown in the official language in which they were submitted.
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Expansion Joint and Method
Field of the Invention
The invention relates generally to rubber or polymeric waterproof expansion
joints.
Background of the Invention
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.
Summary of the Invention
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
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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 1/8 to 3/4.
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.
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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 malts secured to the surface. The fibrous matts
are separated by
an elongated strip of bare surface. The first and second fibrous malts 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 malts 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 malts are located adjacent the first and second
edges of the
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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 malts. 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.
Description of the Drawings
Figure la is an isometric, not-to-scale view of a three-dimensional expansion
joint
installation such as may incorporate aspects of the present invention;
Figure lb is a cross-sectional view of a horizontal portion of an installation
such as
that of Figure la, in which the thickness of the expansion joint is
exaggerated;
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Figure 1c is a cross-sectional view of an application of a roof-to-wall
expansion joint
portion of an installation such as that of Figure la, in which the thickness
of
the expansion joint has been exaggerated;
Figure 2a is a plan view of an embodiment of an expansion joint according to
an
aspect of the present invention;
Figure 2b is a cross sectional view of the expansion joint of Figure 2a taken
along
line section `2b - 2b' of Figure 2a;
Figure 2c is an expanded view of a portion of Figure 2b showing details of the
edge
of an aperture;
Figure 3a is a plan view of an alternate embodiment of expansion joint to that
of
Figure 2a, in which the expansion joint has a series of open ended slots;
Figure 3b is a plan view of a further alternate embodiment of expansion joint
to that
of Figure 2a, in which the expansion joint has a series of non-circular slots;
Figure 3c is a plan view of a further alternate embodiment of expansion joint
to that
of Figure 2a, in which the expansion joint has a series of closed parallel
slots;
Figure 3d is a plan view of a further alternate embodiment of expansion joint
to that
of Figure 2a, in which the expansion joint has a series of angled slots;
Figure 3e is a plan view of a further alternate embodiment of expansion joint
to that
of Figure 2a, in which the expansion joint has a series of arcuate slots;
Figure 3f is a plan view of a further alternate embodiment of expansion joint
to that of
Figure 2a, in which the expansion joint has a staggered series of slots; and
Figure 3g is a plan view of a further alternate embodiment of expansion joint
to that
of Figure 2a, in which the expansion joint has a staggered series of slots
having angled edges yielding a serpentine or sawtooth edge.
In the drawings like characters of reference indicate corresponding parts in
the
different figures.
Detailed Description of the Invention
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.
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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 Figures la, lb, 1c, 2a, 2b and 2c, an expansion joint is shown
generally
as item 20. It includes a flat elongated sheet or slab or member 22 of rubber
material that
may be considered conceptually to be a membrane in which the through thickness
is small as
compared to the overall width, and, typically, the width is small or very
small as compared to
the length. That is, the width, D20, may be of an order of magnitude greater
than the
thickness, t20. For example, t20, may be in the range of perhaps 3/32" to
5/32" (1.8 mm,
2mm, 2.2 mm or 3 mm, +/-) thick, whereas the overall width D20 of may be in
the range of,
for example, about 7" to 22" (175 mm to 540 mm), or perhaps more, with mid-
range sizes of
perhaps about 10" or 10-%2" (270 mm, +/-), about 13 - 13 1/2 (340 mm, +/-), or
about 15" or
16" (400 mm, +/-). Thus the aspect ratio of the material in terms of width to
thickness may
be of the order of about 80:1 or 100:1 to about 300:1 or 400:1, depending on
the installation.
The length may be considered potentially to be substantially infinite as
compared to the
width since, in general, the joint is supplied in a roll that is paid out
linearly along the
discontinuity to be sealed, which may be 20, 30, 50, or 100 or more feet long.
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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 advhesives (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).
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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 Figure la, which is not to scale, seal 20 has many portions. There is a
first portion 36,
which is an end portion, that runs across a flat roof, and has a combined
length of LI + L2.
First portion 36 is intersected by a second portion 38 that runs
perpendicularly away from
portion 36 (it need not be perpendicular) a distance L3. Second portion 38
ends at a corner,
40, whence another portion 42 runs distance L2 back toward a wall 44. There is
another
corner 46, and a portion 48 that runs a distance L4 along the junction between
wall 44 and
roof 50. Portion 48 ends at a further corner 52 where wall 44 and roof 50 meet
another
vertical wall 54 (which need not be vertical). A further portion 56 runs a
distance L5 up the
junction between walls 44 and 54 to reach the intermediate level roof 60,
where there is
another corner, 58, and a portion 62 that runs a distance L6 across roof 60 to
another wall 64,
at which there is a corner 66, which is the opposite hand to corner 46.
Portion 66 of joint 20
runs a distance L7 along the junction of roof 60 and wall 64. At another
corner 66 portion 72
ascends wall 64 a distance L8 to reach roof 70. A portion 74 runs across the
width L9 of roof
70, and then a final, end portion 76 runs down rear wall 78 a distance L10 to
its end.
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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 Figure la has a T -
junction, and
various corners 40, 46, 52, 58, 66. These corners are factory fabricated by
vulcanising.
Vulcanised curved joints and multilevel joints can be made in this way. These
joints or
seams may be made under factory controlled conditions, and provide consistent
flexibility. It
may tend to eliminate the use of glue, tape or caulking. The entire pre-sized
assembly is then
packaged and delivered to the installation site. Joint 20 is intended to be
what is termed a
"flat profile expansion joint", and is to be contrasted with current existing
expansion joints
such as bellows type joints, prefabricated metal joints, bunched-up membranes,
or
membranes mounted over a backer rod. Joint 20 is substantially flat, or, in
the context of
folded joints such as 48 or 66, each selvage edge is substantially flat and
has a small or very
small effective through thickness, either as compared to its own width, or as
compared to
those previous joint types. As compared to previous types of expansion joint,
a flat, or
substantially flat, roughly zero profile waterproof joint may tend not unduly
to obstruct the
flow of water thereacross, and may tend to reduce the tendency of water to
pool behind the
joint, as if the joint were a dam.
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 Figures 2a, 3a, 3b,
3c, 3d, 3e, 3f,
and 3g herein, or combinations or variations of them. Figure la is intended to
illustrate that
arrays of marginal apertures 80 may be formed in both margins, as in portions
38, 72 and 74,
or only one margin as in portion 68. They may be used throughout the entire
running length
of joint 20, or only portions thereof. The apertures may be used on a vertical
face, whether
gravity is acting predominantly along joint 20 as in portion 72, or across
joint 20 as in portion
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68. Alternatively there may be portions, such as 36 and 42 in which apertures
80 are not
employed at all.
Figrues lb and lc 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.
Figure lb 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.
Figure lc 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
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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 figures 2a, 2b and 2c, the material forming sheet or slab or
member
22 may be made of a synthetic rubber which is both flexible and resilient and
which may
tend to remain flexible in a wide range of weather conditions. Several
suitable polymeric
materials are available for forming sheet or slab or member 22, and several
currently
available polymeric sheets for use in forming flexible expansion joints may be
used.
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
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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 ='/2( 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
CA 02668073 2009-06-02
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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 W14o 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 Figure 2b,
each aperture passes through sheet 22 and the fibrous matting of the roughened
strips, 132,
134, 136 and 138, as may be. As seen in the enlarged detail of Figure 2c,
apertures 144, 146
may each have a right angled edge portion 148 where the bore of the aperture
intersects or
meets surfaces 114 and 116.
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 Figure 2 to
which the joint is
bonded. However, the apertures may tend to decrease the amount of creep. It is
believed that
the right angled edges 38 of the apertures may act in a conceptually similar
manner to the
treads of a car tire, increasing the amount of "traction" between the sheet
and the bonding
agent, be it tar or some other resin applied to bond the expansion joint to
the substrate.
Ridges or creases in the sheet may act is a similar way, however, forming a
resilient sheet
with ridges and the like is quite awkward and expensive compared to simply
punching a
series of apertures through the sheet.
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
CA 02668073 2009-06-02
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the illustrations of Figures 2 and 3 member 12 is shown slightly away from the
substrate
members, by a small gap. This is intended to be representative of the space
occupied by the
resin. The size of the gap and the vertical relative thickness of the parts is
exaggerated for
the purposes of illustration. That bonding layer may tend to be cycled in
shear during
contraction, expansion or shifting of the adjacent underlying roof panels.
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.
In the embodiment of Figures 2a, 2b and 2c, the apertures have closed
perimeters,
being circular, straight through bores penetrating through the selvage
margins. The
Apertures need not be circular, and they need not necessarily have closed
peripheries. For
example, in the embodiment of Figure 3a, an expansion joint 200 has an array
of apertures
202 each of which has the form of an open-ended slot that extends inboard from
the
respective edge 204. The inboard end of the slot, or the head of the slot, may
have a bulbous
enlargement as at 206. To the extent that joint 200 may be taken to be
symmetrical, another
similar array of slots may be understood to be formed in the opposite selvage
edge.
In the embodiment of Figure 3b an expansion joint 220 employs arrays of
apertures
222 that are not circular, but have the form of a polygon, in this instance a
triangle. The
triangles of the array are alternating as at 224, 226, such as to leave
alternatingly angled
intermediate strut portions 228, 230 that may tend to yield a wedge-like
resistance to shear
force application in the plane of joint 228.
In the embodiment of Figure 3c, an expansion joint 240 has a series of ovate
slots 242
having closed peripheries (as compared to slots 202 that each have an open
ended periphery)
Slots 242 have a long axis that is substantially perpendicular to the running
direction or x-
axis, of joint 240 more generally. Although only an half view is shown, the
other half may
be taken to be symmetrical. The pitch between the slot centers in the x-
direction may be
CA 02668073 2009-06-02
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greater than 3/4 of the lateral length L242 of the slots, and may tend to be
in the range of 3/4 to
3/2 times the length L242=
In the embodiment of Figure 3d, an expansion joint 260 has a series of slots
262, not
unlike slots 242, except that slots 262 include left hand and right hand
angled slots 264, 266
that have a mutually wedging orientation, and that leave alternating wedge-
like tab areas 268,
270. Again, joint 260 may be symmetrical, in which case matching apertures are
also formed
in the opposite selvage edge. The angles of the slots relative to the x-axis
are indicated as
alpha and beta. Although it is convenient that these angles be the same, they
need not be.
The angles may tend to be greater than 45 degrees and may lie in the range of
60 to 75
degrees. The pitch spacing of apertures 282 is similar to that of apertures
242.
In the embodiment of Figure 3e, an expansion joint 280 has an array of
apertures 282,
in which the apertures have a generally curved shape. In this instance the
curve is gently S-
shaped. The pitch spacing of apertures 282 is similar to that of apertures
242. Again, as with
all of Figures 3a, 3b, 3c, 3d 3e and 3f, although only half the item is shown,
the other half
may be taken as being substantially symmetrical, and may be a mirror image.
In the embodiment of Figure 3f, and expansion joint 300 has an array of
apertures 302
in which the array has an alternating inboard and outboard stagger, the
inboard apertures
being indicated as 304, and the outboard apertures as 306. While apertures 304
and 306 are
round circular apertures, any of the oval, triangular of curved apertures of
the other
embodiments of Figures 3a, 3b, 3c, 3d, and 3e could also have an inboard-
outboard
alternating stagger. The pitch spacing of apertures 282 is similar to that of
apertures 242.
In the embodiment of Figure 3g, and expansion joint 320 has an array of
marginal
fingers 322 and corresponding apertures 324 defined between those fingers, the
edges of
fingers 322 and corresponding wedge-shaped apertures 324 being alternately
angled at angles
phi and theta. These angles are comparatively sharp, and may be greater than
60 degrees
relative to the running direction of the joint. Expressed in the context of
the lateral direction,
the tangent portion of the edge, or the average angle if the edge is not
straight, may be in the
range of perhaps 10 - 30 degrees. Again, while these angles may be equal, and
repeating,
they need not necessarily be so. The resultant feathered edge may be termed
undulating,
serpentine, saw toothed, deviating, and so on. A deviating edge as show will
necessary have
a longer edge length than the straight line running distance of the joint.
While apertures 324
are of the same size, they could also have an inboard-outboard alternating
stagger. A
CA 02668073 2009-06-02
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serpentine or deviating edge may also be used in combination with closed
periphery
apertures such as shown in others of the embodiments presented herein.
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 1/3 of the lateral extent of the selvage edge, and may
be in the range of
1/8 to '/4 of that width. In absolute terms the length of the aperture may be
in the range of 3/4"
to 2'/2", 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 are 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.
