Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS FOR AND METHOD OF FORMING CONCRETE
AND TRANSFERRING LOADS BETWEEN CONCRETE SLABS
BACKGROUND OF THE INVENTION
[0001] Conventional concrete pavement installation involves preparing then
positioning
forms around an area intended for pavement. The forms have vertical inner
surfaces to
receive and contain poured concrete. The forms have horizontal top surfaces,
which
typically are level with the surface of the poured concrete, or, once cured,
pavement
surface. The forms have back surfaces that rest against appropriately-spaced
stakes
for holding the forms in place. To provide clearance for finish troweling,
concrete
workers often field cut chamfers between the top and back surfaces of the
forms.
[0002] Very large pavements require substantial form preparation and
positioning. This
is especially true if stock materials for forms are short and/or flexible.
Short and flexible
forms require more staking than longer, more rigid forms to ensure true,
unwavy
pavement edges. Short forms also require more setup time for chamferring.
Regardless of whether the forms are long or short, field chamferring requires
considerable time for large pavement areas.
[0003] Ideally, the forms used for receiving poured concrete should have a
true height
for providing a true slab thickness. Unfortunately, forms in the field
typically have a
height that is less than a true height for an appropriate slab thickness.
These forms of
inadequate height typically may be positioned so that the top surfaces are at
an
appropriate height relative to the desired pavement surface height, but
present bottom
surfaces that do not contact, thus admit gaps through which poured concrete
leaks.
This wastes concrete and requires additional work to remove the excess
portions.
[0004] Concrete leakage from the forms, especially at the butt joints, leaves
depressions in a finished slab surface causing poor aesthetics. The
depressions also
impair surface coverings, such as tile, because the uneven surface promotes
uneven or
incomplete covering layout and adhesion. Cured leaked concrete also impinges
on
adjacent slabs causing voids and/or increasing the chances of obtaining a
locked
construction, which leads to cracks and joint failures. Finally, removing the
cured
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excess typically damages the slab from which the excess is chiseled. Thus,
avoiding
form leaks is highly desirable.
[0005] Unfortunately, none of the foregoing provides a method of forming
concrete and
an apparatus for same that includes stiff, infinitely long, pre-chamferred
forms with
predetermined true height.
[0006] In construction of concrete pavements for highways, airport runways,
large
warehouse buildings and the like, preventing random cracking of the concrete
necessitates dividing the pavement into convenient slab sections. To this end,
concrete
workers pour a monolithic concrete slab that is allowed to set for a short
period. Then,
the workers cut transverse grooves, having a depth on the order of one-fourth
of the
slab thickness, across the slab, with spacing between cuts selected in
accordance with
the application and design. Spacings from 12 to 40 feet are common for highway
pavements.
[0007] As the concrete of the slab cures, forces derived from the exothermal
curing
reactions cause generally vertical cracks to develop through the slab
thickness at the
reduced cross-sections below each groove. This controlled cracking effectively
divides
the slab into predetermined separate slab sections.
[0008] The vertical cracks or joints define adjacent and interlocking faces
formed by the
cement and aggregates in the concrete. The interlocking faces transfer
vertical shear
stresses among adjacent slab sections, a phenomenon commonly referred to as
"aggregate interlock," as heavy objects, such as motor vehicles, pass over the
joint.
[0009] Aggregate interlock causes wear among slab intersections with
increasing use
of the pavement. Additionally, cyclical and extreme temperature changes
decrease
slab volumes. Thus, over time, as traffic continuously passes over a joint,
the
intersections wear and become smooth, then fail altogether, resulting in
relative vertical
displacement of adjacent slab sections, hence a rough pavement surface. Joint
failure
also becomes increasingly susceptible to water intrusion, which may freeze and
cause
damage among adjacent slabs.
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[0010] To discourage relative vertical displacement among adjacent slabs,
prior art
techniques provide for implanting dowels in concrete extending across the
joint
intersections. Some dowels are smooth steel rods with diameters on the order
of one
inch and lengths of two feet. Each rod is coated or otherwise treated so that
it will not
bond to concrete along its length or at least on one end thereof. Thus, as a
slab
expands and contracts during curing and subsequently with temperature changes,
the
dowel is free to move horizontally relative to, yet maintain vertical
alignment of adjacent
slabs, augmenting the aggregate interlock to transfer vertical shear stresses
across the
joints. See, for example, United States Patent No. 3,397,626, issued August
20, 1968, '
to J.B. Kornick et a/. for Plastic Coated Dowel Bar for Concrete and United
States
Patent No. 4,449,844, issued May 22, 1984, to T.J. Larsen for Dowel for
Pavement
Joints.
[0011] Among other problems, the foregoing techniques involve significant time
and
labor to produce and place the dowels.
[0012] Another technique to discourage relative vertical displacement among
adjacent
slabs involves embedding square-shaped load plates in adjacent slabs with
opposed
corners of the load plate aligned with the joint. To avoid shrink- or
thermally-induced
stress creation between the plate and a slab, concrete workers first embed a
blockout
sheath in one vertical joint face for receiving a load plate. To this end, the
workers nail
onto a form a mounting plate, from which a blockout sheath extends, then
position the
form to receive poured concrete. Once the concrete is cured and bonded to the
blockout sheath, the workers remove the form board and leave the blockout
sheath in
place. Then the workers insert a load plate into the blockout sheath. Finally,
the
workers pour an adjacent slab, which bonds to the exposed portion of the load
plate.
See, for example, U.S. Patent No. 6,354,760 ('760 patent), issued March 12,
2002, to
Boxall et al., for System for Transferring Loads Between Cast-in-Place Slabs,
which is
incorporated by reference herein.
[0013] Drawbacks of the foregoing include the cost and labor associated with
producing separate mounting and load plates, then assembling same following
curing
of a first concrete slab.
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[0014] Referring to Fig. 13, a concrete floor 1100 typically is made up of a
series of
individual blocks or slabs 1102-1 through 1102-6 (collectively 1102). The same
is true
for sidewalks, driveways, roads and the like. Blocks 1102 provide several
advantages,
including relief of internal stress due to drying shrinkage and thermal
movement.
Adjacent blocks 1102 meet at joints 1104-1 through 1104-7 (collectively 1104).
Joints
1104 typically are spaced so that each block 1102 has enough strength to
overcome
internal stresses that otherwise would cause random stress relief cracks. In
practice,
blocks 1102 should be allowed to move individually, but also should be able to
transfer
loads from one block to another block.
[0015] Transferring loads between blocks 1102 usually is accomplished with
smooth
steel rods, also referred to as dowels, embedded in two blocks 1102 defining
joint 1104.
For instance, Fig. 14 shows a side view of dowel 1200 between slabs 1102-4 and
1102-5. Fig. 15 shows a cross-sectional view along line XV-XV in Fig. 14 of
several
dowels 1200 spanning joints 1104 between slabs 1102. Typically, a dowel or bar
1200
is approximately 14 to 24 inches long, has either a circular or square cross-
sectional
shape, and a thickness of approximately 0.5-2 inches. Such circular or square
dowels
are capable of transferring loads between adjacent slabs 1102, but have
several
shortcomings.
[0016] U.S. Pat. Nos. 5,005,331, 5,216,862 and 5,487,249, issued to Shaw et
a/.,
which are incorporated by reference herein, disclose tubular dowels receiving
sheaths
for use with dowel bars having circular cross-sections.
[0017] Referring to Fig. 16, a shortcoming of circular or square dowels is
that if
dowels 1200 are misaligned, or not perpendicular to joint 1104, they can
undesirably
lock the joint together causing unwanted stresses that could lead to slab
failure in the
form of cracking. Such misaligned dowels can restrict movement in the
directions
1400-1 and 1400-2.
[0018] Another shortcoming of square and round dowels is that they typically
allow
slabs to move only along the longitudinal axis of the dowel. As shown in Fig.
17,
movement is allowed in direction 1500, parallel to dowels 1200, while movement
in
other directions 1502-1 and 1502-2, and directions into and out from the page
is
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restrained. Such restraint of movement in directions other than parallel to
the
longitudinal axes of dowels 1200 could result in slab failure in the form of
cracking.
[0019] U.S. Pat. No.4,733,513 ('513 patent) issued to Shrader et al., which is
incorporated by reference herein, discloses a dowel bar having a rectangular
cross-section and resilient facings attached to the sides of the bar. As
disclosed in
column 5, at lines 47-49 of the '513 patent, such bars, when used for typical
concrete
paving slabs, would have a cross-section on the order of 1/2 to 2-inch square
and a
length on the order of 2 to 4 feet.
[0020] Referring to Figs. 18 and 19, yet another shortcoming of prior art
dowel bars is
that, under a load, only the first 3-4 inches of each dowel bar transfers the
load. This
creates very high loadings per square inch at the edge of slab 1102-2, which
can result
in failure 1600 of the concrete below dowel 1200, as shown in Figs. 18 and 19.
Such a
failure also could occur above dowel 1200.
[0021] Unfortunately, none of the foregoing provide a method of forming
concrete and
an apparatus for same that includes partially coated load plates carried in
slotted forms.
[0022] What are needed, and not taught or suggested in the art, are a method
of
forming concrete and an apparatus for same that provide partially coated load
plates
carried in pre-slotted, stiff, infinitely long, pre-chamferred forms with
predetermined true
height that: (1) increase relative movement between slabs in a true direction
parallel to
the longitudinal axis of the joint; (2) reduce loadings per square inch close
to the joint;
(3) maximize material at the joint for transferring loads between adjacent
cast-in-place
slabs efficiently; (4) minimize raw materials needed in a load plate; and (5)
promote
exact load plate positioning to foster better perpendicular and parallel
alignment with
the joint and upper concrete surface.
SUMMARY OF THE INVENTION
[0023] The invention overcomes the disadvantages noted above by providing a
method of forming concrete and an apparatus for same that provide partially
coated
load plates carried in pre-slotted, stiff, infinitely long, pre-chamferred
forms with
predetermined true height. An embodiment configured according to principles of
the
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invention of an apparatus for transferring a load between a first concrete
slab and a
second concrete slab, defining a joint, includes a plate configured to
transfer a load
between concrete slabs, a form having a slot configured to closely receive a
first portion
of the plate prior to pouring concrete thereon, and a sheath configured to
receive a
second portion of the plate.
[0024] An embodiment configured according to principles of the invention of a
method
of forming concrete includes providing a plate configured to transfer a load
between
concrete slabs; providing a form having a slot configured to closely receive a
first
portion of the plate; positioning the form to receive concrete; inserting the
first portion in
the slot wherein a second portion of the plate is exposed; pouring a first
volume of
concrete on the form and the second portion; curing the first volume of
concrete and
defining a first slab; removing the form from the first slab and exposing the
first portion;
and disposing a sheath on the first portion.
[0025] An embodiment configured according to principles of the invention of a
method
of forming concrete includes providing a plate configured to transfer a load
between
concrete slabs; providing a form having a slot configured to closely receive a
first
portion of the plate; positioning the form to receive concrete; inserting the
first portion in
the slot wherein a second portion of the plate is exposed; disposing a sheath
on the
second portion; pouring a first volume of concrete on the form and the sheath;
and
curing the first volume of concrete and defining a first slab.
[0026] An embodiment configured according to principles of the invention of a
method
of forming concrete includes providing a form configured to secure a sheath
thereto,
thereby orienting an exterior of the sheath for contacting concrete when
poured
thereon; positioning the form to receive concrete; securing the sheath to the
form;
pouring a first volume of concrete on the form and the exterior; and curing
the first
volume of concrete and defining a first slab.
[0027] The invention provides improved elements and arrangements thereof, for
the
purposes described, which are inexpensive, dependable and effective in
accomplishing
intended purposes of the invention.
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[0028] Other features and advantages of the invention will become apparent
from the
following description of the preferred embodiments, which refers to the
accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The invention is described in detail below with reference to the
following figures,
throughout which similar reference characters denote corresponding features
consistently, wherein:
[0030] Fig. 1 is an environmental perspective view of an embodiment of an
apparatus
for forming concrete configured according to principles of the invention shown
adjacent
to concrete;
[0031] Fig. 2 is a top front right side elevational view of another embodiment
of an
apparatus for forming concrete and transferring loads between concrete slabs
configured according to principles of the invention;
[0032] Fig. 3 is cross-sectional detail view, drawn along line 3-3 in Fig. 2;
[0033] Fig. 4 is a plan view of a plate of the embodiment of Fig. 2;
[0034] Fig. 5 is a schematic view of an embodiment of a method of making an
apparatus configured according to principles of the invention;
[0035] Fig. 6 is a schematic view of an embodiment of a method of forming
concrete
configured according to principles of the invention;
[0036] Fig. 7 is a plan view of an embodiment of an apparatus for forming
concrete and
transferring loads between concrete slabs configured according to principles
of the
invention, shown partially in cross-section;
[0037] Fig. 8 is a plan view of another embodiment of an apparatus for
transferring
loads between concrete slabs configured according to principles of the
invention;
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[0038] Fig. 9 is a plan view of a portion of the embodiment of Fig. 8 received
in a
concrete slab, a dashed-line outline of a diamond-shaped plate being
superimposed
thereon;
[0039] Figs. 10 and 11 are perspective views of the embodiment of Fig. 1
receiving the
embodiment of Fig. 8;
[0040] Fig. 12 is a top view of the embodiment of Fig. 1 receiving the
embodiment of
Fig. 8, shown partially in cross section;
[0041] Fig. 13 is a plan view of a plurality of concrete slabs defining a
pavement;
[0042] Fig. 14 is a vertical cross-sectional detail view of adjacent concrete
slabs and
an interposed prior art dowel;
[0043] Fig. 15 is cross-sectional detail view drawn along line XV-XV in Fig.
14;
[0044] Fig. 16 is an enlarged horizontal cross-sectional detail view of a
plurality of
concrete slabs with interposed prior art dowels that are misaligned;
[0045] Fig. 17 is an enlarged horizontal cross-sectional detail view of a
plurality of
concrete slabs with interposed prior art dowels;
[0046] Fig. 18 is a vertical cross-sectional detail view of adjacent concrete
slabs and
an interposed prior art dowel wherein one slab exhibits a failure;
[0047] Fig. 19 is a cross-sectional detail view drawn along line XVIV-XVIV in
Fig. 18;
[0048] Fig. 20 is a plan view of a further embodiment of an apparatus
configured
according to principles of the invention;
[0049] Fig. 21 is a cross-sectional detail view drawn along line XXI-XXI in
Fig. 20;
[0050] Fig. 22 is an environmental perspective view, shown partially in cross-
section, of
yet another embodiment of an apparatus for transferring loads between concrete
slabs
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configured according to principles of the invention and a concrete slab
prepared for
receiving same;
[0051] Fig. 23 is a cross-sectional detail view of yet a further embodiment of
an
apparatus for transferring loads between concrete slabs configured according
to
principles of the invention received in a concrete slab;
[0052] Fig. 24 is a schematic view of an embodiment of a method of forming
concrete
configured according to principles of the invention;
[0053] Fig. 25 is a schematic view of an embodiment of a method of installing
a load
transfer apparatus configured according to principles of the invention.
[0054] Fig. 26 is a top front right side elevational view of another
embodiment of an
apparatus for forming concrete and transferring loads between concrete slabs
configured according to principles of the invention;
[0055] Fig. 27 is a top front right side elevational view of another
embodiment of an
apparatus for forming concrete and transferring loads between concrete slabs
configured according to principles of the invention;
[0056] Fig. 28 is a schematic view of an embodiment of a method of forming
concrete
configured according to principles of the invention;
[0057] Fig. 29 is a schematic view of an embodiment of a method of forming
concrete
configured according to principles of the invention;
[0058] Fig. 30 is a top front right side elevational view of another
embodiment of an
apparatus for forming concrete and transferring loads between concrete slabs
configured according to principles of the invention;
[0059] Fig. 31 is an enlarged side elevational view of a form of the
embodiment of Fig.
30;
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[0060] Fig. 32 is a top front right side elevational view of another
embodiment of an
apparatus for forming concrete and transferring loads between concrete slabs
configured according to principles of the invention;
[0061] Figs. 33 and 34 are plan views, partially in cross-section, of another
embodiment of an apparatus for forming concrete and transferring loads between
concrete slabs configured according to principles of the invention,
respectively before
and after proper assembly;
[0062] Fig. 35 is a plan view of the embodiment of Figs. 33 and 34 improperly
assembled; and
[0063] Figs. 36-67 are successive plan and side elevational views of
additional
embodiments an apparatus for transferring loads between concrete slabs
configured
according to principles of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0064] The invention includes an apparatus for and method of forming concrete
and
transferring loads between concrete slabs that provide partially coated load
plates
carried in pre-slotted, stiff, infinitely long, pre-chamferred forms with
predetermined true
height.
[0065] Referring to Fig. 1, an embodiment of an apparatus for forming concrete
configured according to principles of the invention includes a form 100. Form
100 has a
side surface 105, a top surface 110, a back surface 115 and a bottom surface
120.
Side surface 105 and back surface 115 define a width 125 ranging from 0.875 to
2.500
inches. Top surface 110 and bottom surface 120 define a height 130 ranging
from 3 to
18 inches or more, depending on the thickness required for pavement.
[0066] Form 100 has a chamfer 135 between top surface 110 and back surface
115.
Chamfer 135 defines an angle 140 relative to top surface 110 ranging from 10
to 89 ,
preferably 22.5 to 45 . Side surface 105 and chamfer 135 define a top surface
width
143 ranging from 0.125 to 0.875 inch. Chamfer 135 provides clearance for
trowels and
other finishing tools and allows for faster concrete finishing.
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[0067] Width 125, height 130, angle 140 and top surface width 143 vary as
needed to
provide a desired overall stiffness of form 100. Form stiffness dictates the
amount of
staking required to maintain form 100 in place against the great weight of
poured
concrete 155. Stiffer forms 100 require less staking, thus less labor to place
forms 100
where needed.
[0068] More importantly, form stiffness impacts the trueness of an edge 145
defined by
side surface 105 and top surface 110, which forms a corresponding edge in
concrete
155 when cured. Good trueness is important to the overall appearance of a
pavement
defined by multiple slabs having adjacent edges. For example, if an edge of
one slab
has poor trueness and is adjacent to another slab edge that has poor trueness,
the gap
defined between the un-true edges will exhibit unsightly non-uniformity, or
portions of
the gap that may be too narrow followed by portions that may be too wide. This
gap
non-uniformity contributes to an overall non-professional image of the area
and
associated business.
[0069] Preferably, form 100 is constructed of oriented strand board (OSB). OSB
stock
may be manufactured to assume virtually any dimension, which may be machined,
as
described below, to define forms 100 of virtually any length. As the invention
is
intended for constructing large-scale pavements, forms 100 with very large
lengths are
desirable because fewer abutting forms 100 are needed to define a continuous
side
surface 105 and edge 145, hence slab side. This reduces the labor needed to
limit
and/or treat discontinuities that may occur in the slab side. OSB stock also
is preferred
because it may be machined to define a desired height 130. This eliminates the
occurrence of concrete leaks between the bottom surface of prior art forms of
inadequate height and the supporting surface underlying the concrete.
[0070] Form 100 also may be constructed of dimensional lumber, particle board,
metal,
plastic, cardboard, fiber board, polyurethane foam, Styrofoam , or other rigid
synthetic
or other suitable materials commensurate with the purposes described herein.
[0071] A release overlay 160 is disposed on side surface 105. Release overlay
160 is
constructed of phenolic paper, kraft paper, acrylic, latex, melamine, Formica
, foil, oil,
high density overlay, metal, wood veneer or other suitable material that
provides a
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smooth, closed-celled surface, substantially free of pores for retaining
poured concrete
without adhering to or marring the finished surface thereof when cured and
separated
from form 100. The foregoing materials may be combined to define release
overlay
160, such as a wood veneer that normally would be oiled.
[0072] Referring to Fig. 2, another embodiment of an apparatus for forming
concrete
configured according to principles of the invention includes a form 200 and
one or more
load transfer apparatuses or plates 300 for transferring loads that are
received in form
200. Form 200 is constructed similarly to form 100 and has slots 260 for
receiving
plates 300. Slots 260 have a spacing 261 of about two feet, or other dimension
suitable for purposes described herein.
[0073] Referring to Fig. 3, each slot 260, preferably, is formed by plunge
cutting with a
rotary saw blade (not shown). Slot 260 is defined by annular surfaces 263,
each having
curvatures corresponding to the radius of the plunge-cutting saw blade.
Annular
surfaces 263 and side surface 205 (comparable to side surface 105 of form 100)
define
opposed proximal intersections 265. Annular surfaces 263 and back surface 215
(comparable to back surface 115 of form 100) define opposed distal
intersections 270.
[0074] Referring to Fig. 4, each plate 300, preferably, is constructed of
steel or any
material, metallic or non-metallic, that is suitable for a load transfer
device between
adjacent concrete slabs in a pavement. To economize production costs, plate
300 may
be shear-cut. Plate 300 has a preferred thickness ranging from 0.1875 through
0.375
inches and side dimensions 303 of approximately 4.5 inches, or other dimension
suitable for purposes described herein. Preferably, plate 300 has a length 305
that is
greater than or equal to a width 310. Thus, plate 300, in plan view, assumes
the shape
of a rhombus or square.
[0075] Plate 300 has a first portion 315 and a second portion 320, delineated
by a
plane 321, defined by the intersections of sides 322 and 323, that is aligned
with side
surface 205. First portion 315 may be untreated. Second portion 320 has an
elastomer coating 325 configured to adhere to plate 300 only enough to prevent
elastomer coating 325 from separating from plate, for example during shipping,
but
when emplaced, may adhere to concrete, but not to plate 300. Elastomer coating
325
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is constructed of polymers, grease or other materials suitable for the
purposes
described herein.
[0076] In practice, when a first concrete slab adheres to elastomer coating
325 on
second portion 320 and a second concrete slab adheres to first portion 315,
lateral
movement among the slabs, due to shrinkage, etc., will not cause localized
stresses
because the first and second slabs are not fixed to plate 300, rather, one
slab is
permitted to move relative to plate 300 because it is adhered to elastomer
coating 325.
While elastomer coating 325 originally adheres to plate 300 when plate 300 is
manufactured, curing concrete exerts forces on elastomer coating 325 which
urges
elastomer coating 325 to slide relative to plate 300 once installed.
[0077] Alternative embodiments of elastomer coating 325: (1) adhere to plate
300, but
not to concrete, thereby allowing concrete to slide relative to the coating;
or (2) do not
adhere to plate 300 or concrete, thereby allowing concrete to slide relative
to plate 300
and/or the coating.
[0078] Referring again to Fig. 2, first portion 315 is received in slot 260.
Preferably,
slot 260 has a tolerance of 0.03125 inch among horizontal surfaces of slot 260
and first
portion 315. This close tolerancing promotes closely receiving first portion
315 in slot
260. This provides for maintaining plate 300 at a desired attitude. Elastomer
coating
325 is likely to have a thickness exceeding this tolerance that would prevent
slot 260
from receiving second portion 320.
[0079] Referring to Figs. 3 and 4, plate 300 is configured such that
intersections of
sides 322 and 323 at the widest extremes of plate 300 mate with proximal
intersections
265 of form 200. This configuration promotes a gap-free junction between plate
300
and form 200 that discourages concrete from seeping therethrough. This ensures
that
concrete only contacts elastomer coating 325 and not plate 300.
[0080] Plate 300 also is configured, and the radius of a saw (not shown) used
for
plunge cutting slot 260 is selected, such that distal intersections 270 in
form 200 firmly
cradle first portion 315. This configuration prevents plate 300 from undesired
rotation
or movement relative to form 200 despite significant forces exerted on plate
300 by
concrete when poured on form 200 and plate 300.
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[0081] Referring to Fig. 7, another embodiment of an apparatus for
transferring loads
between concrete slabs configured according to principles of the invention is
a plate
700 that has a first portion 715 and a second portion 720 delineated by a
plane 721.
First portion 715 may be untreated. Second portion 720 has an elastomer
coating 725
that is similar to elastomer coating 325.
[0082] In practice, first portion 715 is received in a slot 860 in a form 800
in a direction
aligned with a side 730 extending along first portion 715 and second portion
720.
Coating 725, having a preferred thickness of about 0.03 inches, or a thickness
sufficient
to prevent second portion 720 from passing through slot 860. Coating 725 may
be
compressible to allow a cured slab (not shown) adhered thereto to move
somewhat
relative to second portion 720 along a joint between adjacent slabs (not
shown).
[0083] Referring to Fig. 8, another embodiment of an apparatus for
transferring loads
between concrete slabs configured according to principles of the invention is
a plate
900 that has a hexagonal shape. Plate 900 has elongated bases 930, each with
adjacent sides 935. Preferably, each base 930 and side 935 define an angle 940
of
about 100 . Angle 940 may exceed 100 in any amount that maximizes the
material
and/or stress dissipation nearest the joint between concrete slabs.
[0084] As with the embodiments described above, plate 900 has a first portion
915 and
a second portion 920 delineated by a plane 921. First portion 915 may be
untreated.
Second portion 920 has an elastomer coating 925 that is similar to elastomer
coating
325.
[0085] In practice, when a first concrete slab adheres to elastomer coating
925 on
second portion 920 and a second concrete slab adheres to first portion 915,
lateral
movement among the slabs will not cause localized stresses because the first
and
second slabs are not fixed to plate 900, rather, one slab is permitted to move
relative to
plate 900 because it is adhered to elastomer coating 925.
[0086] Referring to Fig. 9, plate 900 is shown received in the vertical face
of a concrete
slab. The hexagonal geometry of plate 900, as compared with a diamond-shaped
plate
D, as shown in dashed lines in Fig. 9, provides more support material 945 at a
joint
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between concrete slabs. This is due to the preferred 1000 angle between base
930
and side 935, which provides nearly 18% additional support material over that
provided
by a diamond-shaped plate D.
[0087] Hexagonally-shaped plate 900 allows for faster and more efficient
stress
dissipation at the joint. This is because a hexagonal plate presents more
perimeter in
areas of high stress concentration in a cement slab. This allows for reducing
the
material thickness needed in a load plate, which saves material costs and
machine
wear. For example, a plate 900 interposed between four-inch slabs having a
compressive strength of 3000 pounds-per-square-inch need only have a 3/16-inch
thickness, whereas a diamond-shaped plate must have at least a 1/4-inch
thickness.
Reduced plate thickness also promotes plate yield before concrete failure. An
advantage of this is that, under great loading, plate 900 yields, rather than
causing
failure in the adjacent concrete slabs plate 900 ties together. Thus, the
vertical
relationship of slabs still is contained, without catastrophic concrete
failures that would
require slab replacement.
[0088] Another advantage of hexagonally-shaped plate 900 relative to a
diamond-shaped plate is that concrete tends to consolidate better under plate
900
because plate 900 presents less area under which concrete flows. This reduces
the
potential for pockets and voids forming under plate 900, which could lead to
joint failure
or ineffective load transfer.
[0089] A further advantage of plate 900 is that plate 900 presents surfaces
that are
more stable, or less likely to move, during pouring of concrete. This assures
that the
load plate will assume proper placement and orientation relative to the joint,
thus is
more likely to perform as intended.
[0090] Referring to Figs. 10 and 11, as with plate 300, plate 900 is intended
to be
received in slot 260 in form 200.
[0091] Referring to Fig. 12, plate 900 is configured such that intersections
of sides 935
define a widest extreme of plate 900 that mate with proximal intersections 265
of form
200. This configuration promotes a gap-free junction between plate 900 and
form 200
CA 02541659 2006-04-03
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that discourages concrete from seeping therethrough. This ensures that
concrete only
contacts elastomer coating 925 and not plate 900.
[0092] Plate 900 also is configured, and the radius of a saw (not shown) used
for
plunge cutting slot 260 is selected, such that distal intersections 270 in
form 200 firmly
cradle first portion 915. This configuration prevents plate 900 from undesired
rotation
or movement relative to form 200 despite significant forces exerted on plate
900 by
concrete when poured on form 200 and plate 900. The hexagonal shape of plate
900
renders plate 900 more stable in, and less prone to moving relative to form
200 than
diamond-shaped plates during pouring.
[0093] Referring to Figs. 20 and 21, a further embodiment of an apparatus for
transferring loads between concrete slabs is a plate 1000 having edge banding
1005.
While plate 1000 may assume any geometry appropriate for an installation,
preferably
plate 1000 is constructed similarly to plate 900, having a first portion 1015
and a
second portion 1020 delineated by a plane 1021. First portion 1015 may be
untreated.
[0094] Edge banding 1005 preferably is disposed on vertical surface 1007
and/or
vertical surface 1009 of second portion 1020 of plate 1000. Preferably,
surfaces 1007
and 1009 are not parallel with plane 1021, hence the joint between concrete
slabs
when emplaced. While not excluded from the scope of the invention, in
practice, edge
banding 1005 has not been found to be needed along surfaces parallel to the
joint.
Abutting concrete slabs will compress each other in a direction perpendicular
to the
joint, but, absent joint failure, will not compress plate 1000 excessively or
to the point of
joint failure. Thus, little benefit may be realized from employing a plate
that is
compressive in a direction perpendicular to the joint.
[0095] However, abutting concrete slabs do move relatively along the joint.
This
imparts great shear forces on interslab load plates. To reduce these shear
forces and
provide greater horizontal relative slab mobility, edge banding 1005 is
compressive and
resilient. Edge banding 1005 may be constructed of any material to obtain
these
characteristics, but preferably is constructed of a natural polymer and/or
synthetic
polymer.
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[0096] Edge banding 1005 is configured so as to reduce intersiab shear forces,
provide great horizontal relative slab mobility or other desired functionality
in
consideration of slab sizing, concrete composition, shrinkage expectations and
other
emplacement considerations. In practice, edge banding 1005 with a thickness
1030
ranging from 0.025 to 0.25 inches has been found to perform optimally.
[0097] Preferably, second portion 1020 has an elastomer coating 1025 that is
similar to
elastomer coating 325. Elastomer coating 1025 also coats edge banding 1005.
Similar
to elastomer coating 325, while edge banding 1005 originally adheres to plate
1000
when plate 1000 is manufactured, curing concrete exerts forces on elastomer
coating
1025 and edge banding 1005 that urges sliding among one or more of elastomer
coating 1025, edge banding 1005 and plate 1000 once installed.
[0098] Plate 1000 is well suited for very large concrete slab installations in
which the
slabs require great degrees of horizontal freedom. Without this added
mobility, the
slabs can "lock up" and develop one or more cracks parallel to the joint
anywhere from
a foot therefrom to the center of the slab.
[0099] As with plate 300, plate 1000 is intended to be received in slot 260 in
form 200.
[0100] Yet another embodiment of an apparatus for transferring loads between
concrete slabs configured according to principles of the invention is a plate
1000 that
includes independent edge banding (not shown) disposed on surfaces 1011 and/or
1013 of first portion 1015. Once installed in cured concrete, edge banding
(not shown)
may slide relative to plate 1000 and/or the cured concrete as needed.
[0101] Referring to Figs. 22 and 23, yet a further embodiment of an apparatus
for
transferring loads between concrete slabs configured according to principles
of the
invention is a dowel 1100 that has edge banding 1105 with or without an
elastomer
coating 1115, as described above. Dowel 1100 may be constructed from 5/16-2-
inch
square or round stock 1110 in 12-inch lengths.
[0102] While dowel 1100 is configured in accordance with industry norms for
retro-
fitting an existing concrete slab to receive a load plate, the invention is
not limited to
square or round stock. The invention also includes plunge-cutting or otherwise
slotting
CA 02541659 2006-04-03
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an existing concrete slab for receiving epoxy and any of the plates described
herein,
with or without edge banding or an elastomer coating.
[0103] Referring to Fig. 5, an embodiment of a method 400 of making an
apparatus for
forming concrete configured according to principles of the invention includes:
a step
405 of providing a sheet; a step 410 of disposing a release overlay on the
sheet; a step
415 of cutting the sheet into a plurality of forms; and a step 420 of cutting
a chamfer in
each of the plurality of forms.
[0104] Step 405 of providing a sheet of material includes material suitable
for
performing as a concrete form, preferably OSB stock material. However, the
material
may be dimensioned lumber, particle board, steel and other suitable materials
if
commensurate with the purposes described herein. OSB material is preferred
because
it can assume virtually any width, length or thickness that may be machined
into forms
of appropriate, true dimensions for defining the desired pavement. The length
of the
material, ideally, should be as long as the longest side of the pavement
desired.
However, manufacturing material that is, e.g. two miles long, is problematic
for
contemporary manufacturers.
[0105] Step 410 of disposing a release overlay on the sheet includes an
overlay that is
suitable for retaining poured concrete without adhering thereto or marring the
finished
surface thereof when the concrete cures and is separated from the form.
[0106] Step 415 of cutting the sheet into a plurality of forms ties into step
405 in that
the material to be cut should be selected to maximize the number of forms
machined
and minimize any scrap not suitable to be a form. The number of forms derived
from
the sheet depends on the thickness of pavement desired, which dictates the
height of
the forms needed. Ideally, the width of the sheet of material provided in step
405
should be an even multiple of the form height, plus some allowance for
cutting.
[0107] Step 420 of cutting a chamfer in each of the plurality of forms
involves
machining each form derived from step 415 with a chamfer machine that cuts
chamfers
in board stock. The chamfer may assume any angle suitable for purposes
described
herein, but preferably ranges from 22 to 45 . Step 420 provides tremendous
labor
savings over prior art techniques and materials. Ordinarily, concrete workers
field cut
CA 02541659 2006-04-03
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chamfers into concrete forms on site, which consumes considerable time.
Providing
workers with pre-chamfered forms eliminates this on-site step and allows for
faster
completion of the paving job at hand.
[0108] Referring to Fig. 6, an embodiment of a method 500 of forming concrete
configured according to principles of the invention includes: a step 505 of
providing a
plate with a plate coating disposed on a first portion thereof; a step 510 of
providing a
form having a slot configured to receive a second portion of the plate; a step
515 of
inserting the second portion in the slot; a step 520 of positioning the form
to receive
concrete; a step 525 of pouring a volume of concrete against the form and the
first
portion; a step 530 of curing the volume of concrete and defining cured
concrete; and a
step 535 of removing the form from the cured concrete, wherein the plate
remains in
the cured concrete.
[0109] Step 505 of providing a plate with a plate coating disposed on a first
portion
thereof involves preparing a plate 300 as described above. An elastomer
coating,
configured to adhere to concrete, but not to the plate, is disposed on the
first portion of
a plate.
[0110] Step 510 of providing a form having a slot configured to receive a
second
portion of the plate involves plunge cutting the side surface of a form with a
rotary blade
having a pre-determined radius selected according to the configuration of the
plate
received in the slot, as described above.
[0111] Step 515 of inserting the second portion in the slot represents a
significant cost
savings over prior load plate installation apparatuses and methods. Rather
than
attaching to a form a mounting plate and blockout sheath, then, after the slab
has
cured, removing the form while breaking free the blockout sheath followed by
inserting
a load plate in the blockout sheath, the present method embeds a load plate
directly
into the concrete slab as it cures. Once the concrete cures, the forms are
removed with
the load plate already embedded in the concrete and no further installation
required.
[0112] Step 520 of positioning the form for receiving concrete also represents
an
advance over many typical concrete pouring techniques in use. Because the
forms are
precisely cut prior to being staked around the desired pavement area, they
present a
CA 02541659 2006-04-03
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true height from support surface to pavement surface. This deters concrete
from
leaking through any gap that often exists between the support surface and the
bottom
surface of inadequately sized prior art forms.
[0113] Step 525 of pouring a volume of concrete against the form and the first
portion
and step 530 of curing the volume of concrete and defining cured concrete are
conventional, thus described no further.
[0114] Step 535 of removing the form from the cured concrete wherein the plate
remains in the cured concrete, as described above, represents a significant
departure
from current practices. Once the concrete cures, the forms are removed with
the load
plate already embedded in the concrete. Other methods require detaching a form
from
a mounting plate previously attached thereto, then installing a load plate in
the pocket
formed in the concrete.
[0115] Referring to Figs. 22-24, an embodiment of another method 1200 of
forming
concrete configured according to principles of the invention includes: a step
1205 of
providing a plate having a first portion and a second portion and edge banding
disposed
on a surface of the first portion; a step 1210 of providing a form having a
slot configured
to closely receive the second portion; a step 1215 of inserting the second
portion in the
slot; a step 1220 of positioning the form to receive concrete; a step 1225 of
pouring a
volume of concrete on the form and the first portion; a step 1230 of curing
the volume
of concrete and defining cured concrete; and a step 1235 of removing the form
from the
cured concrete.
[0116] Step 1205 of providing a plate having a first portion and a second
portion and
edge banding disposed on a surface of the first portion involves preparing a
plate 1000
as described above. As shown in Figs. 20 and 21, edge banding 1005, with or
without
elastomer coating 1025, is disposed on vertical surface 1007 and/or vertical
surface
1009 of plate 1000.
[0117] Steps 1210, 1215, 1220, 1225, 1230 and 1235 are similar to steps 510,
515,
520, 525, 530 and 535 above.
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[0118] Referring to Fig. 25, an embodiment of a method 1300 of installing a
load
transfer apparatus configured according to principles of the invention
includes: a step
1305 of developing a recess in a concrete slab; and a step 1310 of introducing
a first
portion of a load transfer apparatus in the recess.
[0119] Step 1305 of developing a recess typically involves developing a recess
in an
existing concrete slab adjacent to which a second concrete slab is intended.
As shown
in Figs. 22 and 23, dowel 1100 represents an industry standard for retro-
fitting an
existing concrete slab to receive a load plate. Thus, to accommodate a square
or
round dowel 1100, step 1305 would involve boring or reaming a hole in the
concrete
slab. However, method 1300 is not limited to dowel 1100, and may include any
plates
or dowels described herein or not described, but appropriate for use in retro-
fitting an
existing concrete slab to receive a load plate for maintaining vertical
alignment relative
to a concrete slab to be poured an adjacent thereto. Therefore, step 1305 may
involve
plunge-cutting or otherwise developing a slot in the concrete for receiving a
plate.
[0120] Preferably, following step 1305, method 1300 includes filling the
recess
sufficiently with an epoxy or suitable material for bonding the dowel or plate
to the
concrete.
[0121] Step 1310 of introducing a first portion of a load transfer apparatus
in the
recess preferably involves a dowel or plate that has edge banding and/or an
elastomer
coating as described above. The concrete worker would have to take care that
the
epoxy adheres only to the edge banding and/or an elastomer coating and not to
the
untreated portion of the dowel or plate. Once the epoxy cures, and a second
concrete
slab may be poured so as to encapsulate the untreated portion of the dowel or
plate.
The edge banding and/or elastomer coating permits the slabs to move
horizontally
along and perpendicularly to the joint therebetween.
[0122] An embodiment of a method 1400 of adapting existing and freshly-poured
concrete slabs for transferring a load therebetween configured according to
principles
of the invention includes: a step 1405 of installing a load transfer apparatus
in an
existing concrete slab according to method 1300; and a step 1410 of pouring a
second
volume of concrete on a second portion of the load transfer apparatus.
CA 02541659 2006-04-03
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[0123] Step 1405 of installing a load transfer apparatus in the existing
concrete slab is
described above with respect to method 1300.
[0124] Step 1410 of pouring a second volume of concrete adjacent to the cured
concrete and on a second portion of the load transfer apparatus involves
encapsulating
only the untreated end of dowel or plate.
[0125] Referring to Figs. 26 and 27, another embodiment of an apparatus for
forming
concrete and transferring loads between concrete slabs configured according to
principles of the invention includes a form 1500, one or more load transfer
apparatuses
or plates 1600 for transferring loads between concrete slabs closely received
in form
1500, and a like number of sheaths 1700 closely received on each plate 1600.
[0126] Preferably, form 1500 is constructed similarly to form 200 with slots
1560
comparable to slots 260 for receiving plate 1600.
[0127] Plate 1600 is constructed similarly to plate 300. However, rather than
having an
elastomer coating 325, sheath 1700 is selectably installable on plate 1600.
Sheath
1700 may be constructed similarly to the blockout sheath described in the '760
patent.
[0128] Alternatively, sheath 1700 may be constructed of material and/or
configured to
allow: (1) concrete to slide relative thereto; and/or (2) plate 1600 to slide
relative
thereto. Sheath 1700 should have sufficient integrity to permit a concrete
worker to
handle and install sheath 1700 on plate 1600 or form 1500, withstand pouring
concrete
thereon, and perform the functions described above.
[0129] Sheath 1700 may include a mounting plate 1705, as shown in Fig. 26, and
as
described more fully with respect to the blockout sheath and mounting plate
described
in the '760 patent.
[0130] Referring to Fig. 28, an embodiment of another method 1800 of forming
concrete configured according to principles of the invention includes: a step
1805 of
providing a plate configured to transfer a load between concrete slabs; a step
1810 of
providing a form having a slot configured to closely receive a first portion
of the plate; a
step 1815 of positioning the form to receive concrete; a step 1820 of
inserting the first
CA 02541659 2006-04-03
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portion in the slot wherein a second portion of the plate is exposed; a step
1825 of
pouring a first volume of concrete on the form and the second portion; a step
1830 of
curing the first volume of concrete and defining a first slab; a step 1835 of
removing the
form from the first slab and exposing the first portion; and a step 1840 of
disposing a
sheath on the first portion.
[0131] Step 1805 of providing a plate configured to transfer a load between
concrete
slabs involves preparing a plate 1600 as described above. Plate 1600 may, but
preferably does not, include an elastomer coating and/or edge-banding as
described
above.
[0132] Step 1810 of providing a form having a slot configured to closely
receive a first
portion of the plate, preferably, involves plunge cutting the side surface of
a form with a
rotary blade having a pre-determined radius selected according to the
configuration of
the plate received in the slot, as described above.
[0133] Step 1815 of positioning the form to receive concrete is comparable to
step 520
above.
[0134] Step 1820 of inserting the first portion in the slot wherein a second
portion of
the plate is exposed is comparable to step 515 above in that it represents a
significant
cost savings over prior load plate installation apparatuses and methods. While
this
embodiment employs a blockout sheath, neither time nor accuracy are sacrificed
positioning then attaching the blockout sheath as in prior applications.
Rather, the
blockout sheath is installed on a plate that already is properly positioned in
a cured
concrete slab.
[0135] Steps 1825 and 1830 are conventional and described no further.
[0136] Step 1835 of removing the form from the first slab and exposing the
first portion
is comparable to step 535 above.
[0137] Step 1840 of disposing a sheath on the first portion, preferably,
involves placing
on the plate a blockout sheath as described in the '760 patent. However, a
sheath may
assume any form appropriate for the function desired, specifically, to allow
the concrete
CA 02541659 2006-04-03
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slab to move relative to, or prevent bonding with the plate. To this end, the
sheath
simply may be a coating of grease or other debonding agent known in the art.
The
sheath also could be constructed of an elastomer coating, somewhat as
described
above, but configured with sufficient integrity so as to allow for
installation on a plate
without disintegration.
[0138] Referring to Fig. 29, an embodiment of another method 1900 of forming
concrete configured according to principles of the invention includes: a step
1905 of
providing a plate configured to transfer a load between concrete slabs; a step
1910 of
providing a form having a slot configured to closely receive a first portion
of the plate; a
step 1915 of positioning the form to receive concrete; a step 1920 of
inserting the first
portion in the slot wherein a second portion of the plate is exposed; a step
1925 of
disposing a sheath on the second portion; step 1930 pouring a first volume of
concrete
on the form and the sheath; and a step 1935 of curing the first volume of
concrete and
defining a first slab.
[0139] Steps 1905, 1910, 1915 and 1920 are comparable to steps 1805 1810, 1815
and 1820 above.
[0140] Step 1925 of disposing a sheath on the second portion is comparable to
step
1840 above with the only difference being that, in step 1840, the plate is in
cured
concrete, while in step 1925, the plate is in a form.
[0141] Step 1930 pouring a first volume of concrete on the form and the sheath
is
comparable to step 1825 above with the only difference being that, in step
1825,
concrete directly contacts the plate, while in step 1930, the concrete
directly contacts
the sheath.
[0142] Step 1935 is conventional and described no further.
[0143] Referring to Figs. 30 and 31, another embodiment of an apparatus for
forming
concrete and transferring loads between concrete slabs configured according to
principles of the invention includes a form 2000 and one or more sheaths 2100,
with or
without mounting plates 2105 as shown in Fig. 30, for mounting on form 2000,
preferably at predetermined intervals. A like number of load transfer
apparatuses or
CA 02541659 2006-04-03
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plates (not shown) for transferring loads between concrete slabs are
configured to be
closely received in each sheath 2100 once disposed in cured concrete and form
2000 is
separated therefrom.
[0144] Sheath 2100 is similar to sheath 1700 and optional mounting plate 2105
is
similar to optional mounting plate 1705. Where sheath 2100 does not include
mounting
plate 2105, sheath 2100 defines a proximal outer perimeter 2110. Where sheath
2100
includes mounting plate 2105, mounting plate 2105 defines a proximal outer
perimeter
2115.
[0145] Unlike form 200, form 2000 does not have slots comparable to slots 260
for
receiving plate 1600. Rather, form 2000 has slots 2060 configured to mate with
or
closely receive a portion of outer perimeter 2110 when sheath 2100 is
configured
without optional mounting plate 2105. When sheath 2100 is configured with
optional
mounting plate 2105, slot 2060 is configured to mate with or closely receive
outer
perimeter 2115 of mounting plate 2105.
[0146] Slots 2060 are spaced according to load conditions anticipated for the
load
plates (not shown) ultimately installed in adjacent concrete slabs. With
either
embodiment, form 2000 mates with sheath 2100 (or mounting plate 2105) such
that
only the outer surface thereof contacts concrete when poured thereon. Once the
concrete here's, and form 2000 is removed, sheath 2100 remains embedded in the
cured concrete with the interior exposed for receiving a plate (not shown).
Thereafter,
another volume of concrete may be poured adjacent to the previously cared slab
containing sheath 2100 and on the plate, thereby providing for load transfer
between
the adjacent slabs.
[0147] The plate (not shown) intended for use with this embodiment is
configured
similarly to plate 1600 and described no further.
[0148] Referring to Fig. 32, another embodiment of an apparatus for forming
concrete
and transferring loads between concrete slabs configured according to
principles of the
invention includes a form 2200 and one or more sheaths 2300 for mounting on
form
2200, preferably at predetermined intervals. A like number of load transfer
apparatuses
CA 02541659 2006-04-03
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or plates (not shown) for transferring loads between concrete slabs are
configured to be
closely received in each sheath 2300.
[0149] Form 2200 differs from previously described embodiments in that form
2200
does not provide a slot for receiving a load plate. Rather, as described
below, form
2200 provides for mounting sheath 2300 thereon. Preferably, form 2200 has sets
of
pre-drilled holes 2205 for receiving fasteners for fixing sheaths 2300 on form
2200,
spaced according to where sheaths 2300 are desired. As with slots 2060,
spacing of
the sets of holes 2205 corresponds to loading conditions anticipated for the
load plates
(not shown) ultimately installed in adjacent concrete slabs.
[0150] Sheath 2300 has a mounting plate 2305 that provides for fixing sheath
to form
2200 so that the interior 2320, which is configured to receive a load plate
(not shown),
is disposed toward form 2200, preventing poured concrete from entering. To
this end,
mounting plate 2305, preferably, has througbores 2310 that receive threaded
fasteners
2315 for engaging holes 2205. Mounting plate 2305 also may be configured to
provide
integral protrusions or pins (not shown) for engaging holes 2205.
[0151] While form 2200 is described as having the "female" components and
sheath is
described as having the "male" components of whatever fixing convention is
employed,
such may be reversed. Other mounting conventions may be used that are
appropriate
and render fixation easy and inexpensive.
[0152] Referring to Fig. 33, an embodiment of another method 2400 of forming
concrete configured according to principles of the invention includes: a step
2405
providing a form configured to secure a portion of the sheath thereto, thereby
orienting
an exterior of the sheath for contacting concrete when poured thereon; a step
2410 of
positioning the form to receive concrete; a step 2415 of securing the sheath
to the form;
a step 2420 of pouring a first volume of concrete on the form and the
exterior; and a
step 2425 of curing the first volume of concrete and defining a first slab.
[0153] Referring also to Fig. 30, step 2405 of providing a form 2000
configured to
secure a portion of the sheath thereto may involve providing the form with
slots 2060 for
closely receiving the outer perimeter at the opening or mouth of the sheath,
or a
mounting plate defining same, such that the open end of sheath interior 2120,
which is
CA 02541659 2006-04-03
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configured to receive a load plate (not shown), is disposed toward form 2000,
preventing poured concrete from entering. Thus, the poured concrete would
contact
and cure or adhere to only the exterior of sheath 2100, leaving interior 2120
free of any
concrete that could interfere with desired mobility of a plate in sheath 2100.
[0154] Referring to Fig. 32, step 2405 of providing a form 2200 configured to
secure a
portion of the sheath thereto alternatively may involve providing the form
with pre-drilled
holes for receiving fasteners for fixing sheath thereto. Other affixation
conventions may
be employed as appropriate, easy to use and economically sensible.
[0155] Step 2410 of positioning the form to receive concrete is conventional.
[0156] Referring again to Fig. 30, step 2415 of securing the portion to the
form, where
form 2000 has slots 2060 for receiving sheath 2100, involves inserting sheath
2100 in
slot 2060. Where sheath 2100 has a mounting plate 2105, step 2415 would
involve
inserting mounting plate 2115 in slot 2060.
[0157] Steps 2420 and 2425 are conventional and described no further.
[0158] Referring to Figs. 33 and 34, another embodiment of an apparatus for
forming
concrete configured according to principles of the invention includes a form
2500. Like
form 100, form 2500 has a side surface 2505, a top surface (not shown), a back
surface 2515 and a bottom surface (not shown). Form 2500 has a chamfer (not
shown)
that is comparable to chamfer 135 between top surface (not shown) and back
surface
2515. Side surface 2505 and chamfer (not shown) define a top surface width
(not
shown)that is comparable to top surface width 143. Preferably, a release
overfay 2560
comparable to release overlay 160 is disposed on side surface 2505.
[0159] Form 2500 has a slot 2510 that closely receives a plate, such as plate
2600.
Slot 2510 is constructed so as to encourage proper assembly of form 2500 and
plate
2600, as shown in Fig. 34. Proper assembly promotes proper orientation of form
2500
so that concrete is poured against release overlay 2560, not back surface
2515. Proper
orientation of form 2505 relative to a concrete pouring area facilitates ready
release of
form 2500 from the concrete when sufficiently cured, and promotes a cleaner or
more
finished joint surface.
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[0160] Accordingly, slot 2510 is configured to enable or promote complete
insertion of
plate 2600 therein along direction 2520, and incomplete insertion when
attempted in
the opposite direction. Thus, a concrete worker may readily observe upon
insertion
whether plate 2600 is fully received in slot 2510 and confirm that form 2500
is properly
oriented. To this end, slot 2510 may be configured to have at least two
sections, a first
section 2523 and a second section 2525. First section 2523 is proximate to
back
surface 2515, defining a lip 2527 at the intersection therewith. Second
section 2525 is
proximate to side surface 2505 and, being larger than first section 2523,
defines a
shoulder 2530 at the intersection therewith.
[0161] Figs. 33 and 34 also show another embodiment of an apparatus for
transferring
loads between concrete slabs configured according to principles of the
invention
including a plate 2600. Like plate 300, plate 2600 has a first portion 2615
and a second
portion 2620, delineated by a plane 2621. First portion 2615 may be untreated.
Second portion 2620 may have an elastomer coating 2625 that is comparable to
elastomer coating 325. Second portion 2620 also may have one or more surfaces
2640 on which edge banding 2645, comparable to edge banding 1005, may be
disposed.
[0162] First portion 2615 is configured to be closely received in slot 2510
and promote
complete insertion of plate 2600 therein along direction 2520, and incomplete
insertion
when attempted in the opposite direction. To this end, first portion 2615
preferably has
a like number of corresponding segments as slot 2510 has sections. Thus, first
portion
2615 may have a first segment 2630 and a second segment 2635 that respectively
correspond to first section 2523 and second section 2525.
[0163] When inserted properly, first portion 2615 nests snugly in slot 2510
and plate
2600 appears to be fully received, as shown in Fig. 34. If plate 2600 is
inserted into slot
2510 in an incorrect direction 2521 opposite to direction 2520, first segment
2630 may
be received in first section 2523 of slot 2510, but second segment 2635 is not
received
in second section 2525 and plate 2600 does not appear to be fully received, as
shown
in Fig. 35.
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[0164] When plate 2600 is properly received in form 2500, as shown in Fig. 34,
second
segment 2635 abuts shoulder 2530 preventing passage of plate 2600 through form
2500. When incorrect insertion of plate 2600 is attempted, as shown in Fig.
35, second
segment 2635 abuts lip 2527 preventing complete reception of plate 2600.
[0165] Referring to Fig. 34, the positive stop provided by second segment 2635
and
shoulder 2530 also operates to prevent coating 2625 and/or edge banding 2645
from
accidental dislocation from plate 2600. While coating 2625 and/or edge banding
2645
are dimensioned to prevent passage through slot 2510, the weak bond between
coating
2625 and/or edge banding 2645 and plate 2600 could allow for separation if
subjected
to especially vigorous insertion. The positive stop prevents even excessive
insertion
from stripping off coating 2625 and/or edge banding 2645.
[0166] The sectioned slot 2510 and segmented first portion 5615 also promote
ready
form removal from a cured concrete slab. While a concrete slab cures, form
2500 and
plate 2600 are positioned as shown in Fig. 34. Once cured, form 2500 must be
removed. Plate 2600, having been snugly installed in form 2500, is not easy to
remove.
Therefore, reducing the contact or interference fit between first portion 2615
and slot
2510 reduces the force necessary to remove form 2500 from the slab. To this
end,
rather than having to pull first segment 2630 of first portion 5615 through an
entire form
2500, first segment 2630 only has to clear from first section 2523 of slot
2510, reducing
the overall amount of effort needed to remove form 2500 from the cured
concrete slab.
[0167] To promote even greater ease of form removal, either or both of second
segment 2635 and second section 2525 may have curved or radiused surfaces (not
shown). Where both of the second segment 2635 and second section 2525 surfaces
are radiused, such should be complementary. The preferred radius is 18 inches.
[0168] Figs. 36-67 show alternative embodiments of an apparatus for
transferring
loads between concrete slabs configured according to principles of the
invention. In
each figure, "A" generally designates a plate and "B" generally designates an
elastomeric coating with or without edge banding, as described herein. As with
the
embodiments described above, a first concrete slab is intended to adhere to
only the
coating and/or edge banding, while a second concrete slab is intended to
adhere to
only the portion of the plate that is not coated or edge banded. Thus, the
joint between
CA 02541659 2006-04-03
Docket No. 7013.018 30/44
the first and second concrete slabs corresponds with line defined by where
coating
and/or edge banding B discontinues on A.
[0169] As used herein, "normal" obtains its customary meaning, perpendicular
to a
surface or the tangent of a curved surface. "Predominating normal" or cognates
thereof
refers to an average of the normals of a nonuniform surface.
[0170] Referring to Figs. 38, 39, 40, 41, 52, 53, 60, 61 and 64-67, some
embodiments
have coated portions of the plate A that have surfaces that, when emplaced,
are not
predominantly normal to the joint between concrete slabs. When the concrete
cures,
the concrete shrinks away from the surface along that predominantly normal
direction.
A void forms between the concrete and the apparatus corresponding to the
amount that
the concrete shrunk. When the first and second slabs move horizontally along
the joint,
the void provides clearance for plate A to move therein, thus preventing
compressive
forces from growing to an amount sufficient to cause localized concrete
failures. The
amount that the slabs may move relatively along the joint is a fraction of the
amount
that the concrete shrinks away from the surface in the predominantly normal
direction,
according to standard trigonometric principles.
[0171] Referring to Figs. 36, 37, 46, 47, 50, 51, 54, 55, 58, 59, 62, 63, 64
and 65 some
embodiments have coating and/or edge banding having a thickness or resiliency
that
differs according to location on surface on which the coating and/or edge
banding is
disposed. In addition to any void that develops between the concrete and the
coating
and/or edge banding, a moving concrete slab also may compress the coating
and/or
edge banding without developing compressive forces to an amount sufficient to
cause
localized concrete failures. Similar to the above, the joint travel distance
may be
tailored by fine tuning the coating and/or edge banding thickness or
resiliency.
[0172] Another embodiment provides for tailoring the joint travel distance by
coordinating both the surface, hence predominant normal, and the coating
and/or edge
banding thickness or resiliency.
[0173] The invention is not limited to the particular embodiments described
and
depicted herein, rather only to the following claims.
