Note: Descriptions are shown in the official language in which they were submitted.
CA 02858874 2014-08-11
Attorney Docket No. DSB-062
MONOLITHIC PROTECTIVE WATERPROOFING SYSTEM
FIELD
[0001] The present disclosure relates to a waterproofing system for
railroad bridge decks and similar structures and more particularly to a
monolithic
protective waterproofing system or product for light rail and intermodal class
I
railroad bridges and similar structures and a method of installing same.
BACKGROUND
[0002] The statements in this section merely provide background
information related to the present disclosure and may or may not constitute
prior
art.
[0003] As the nation's transportation infrastructure ages, attention is
returning to enhancing the service life of existing structures and ensuring
that
new structures are built with the most modern techniques and materials to
provide the maximum attainable service life.
[0004] One of the most difficult service environments exists on light
rail
transit bridges and internnodal class I railroad bridges. Heavy loads,
exposure to
high humidity and often salt spray and the placement of rock ballast on the
bridge
deck which supports the railway ties and track all contribute to aging of the
structure. The ballast has a particularly deleterious effect on concrete
bridge
decks as sharp corners and edges of the ballast (which is crushed rock)
concentrates loads. What begins as surface cracking and spalling leads to
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significant deterioration of the concrete as water and often salt flows into
the
deck itself.
Deterioration through the freeze ¨ thaw cycle and corrosion of
reinforcing steel in the concrete follow. Even steel bridge decks are not
immune
from such deterioration as the ballast is capable of puncturing, abrading and
wearing even the most rugged deck coatings. Cracks, gouges and
discontinuities in a deck coating commence a process of deterioration by
rusting.
[0005] From this
background, it is apparent that materials, systems,
products and processes of application which extend the service life of
railroad
bridges and similar structures are highly desirable. The present invention is
so
directed.
SUMMARY
[0006] The present invention provides a monolithic protective
waterproofing system or product for light rail and intermodal class I railroad
bridges and similar structures and a method of installing same. The
waterproofing system is a multi-layer product installed in-situ on either new
structures or structures previously in service. It includes a primer, an
elastomeric
membrane having a thickness of between approximately 60 and 120 mils, a
second layer of elastomeric membrane having a thickness of 20 mils that is
utilized as an adhesive that is rapidly covered and upon which is pressed a
rubber mat having a thickness of approximately 8 mm, a second layer of a
primer
and a top coat of elastomeric membrane of between approximately 30 to 50 mils.
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[0007] Before the
various layers are applied to a bridge deck, the
deck is cleaned by, for example, sand blasting to remove any loose material
such
as rust, spalled or damaged concrete, previous coatings and anything that
might
interfere with achieving a tight and continuous bond between the bridge deck
and
the product. New bridge decks or recently replaced decks may only require
inspection. Then, the first layer of primer is applied and allowed to dry
followed
by the first layer of membrane which is also allowed to dry. A second, thinner
layer of membrane, which functions as an adhesive, is next applied followed
quickly by application of adjacent strips of a resilient, preferably rubber,
mat. The
resilient mat is supplied in rolls of, for example, four or six feet by fifty
feet (1.219
or 1.829 meters by 15.24 meters). A second layer of primer is then applied to
the top of the resilient mats and a final layer of membrane is sprayed onto
the
primer and mats, completing the installation process. The track ballast,
railroad
ties and railroad track are then installed and the bridge is placed in or
returned to
service.
[0008] It is thus
an aspect of the present invention to provide a
monolithic protective waterproofing product for railroad bridges and the like.
[0009] It is a
further aspect of the present invention to provide a
method of building up a monolithic protective waterproofing product in-situ on
a
railroad bridge or similar structure.
[0010] It is a
still further aspect of the present invention to provide a
monolithic protective waterproofing product having layers of primer, membrane
and resilient mat.
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[0011] It is a still further aspect of the present invention to provide
a
monolithic protective waterproofing product having first layers of primer and
membrane, a resilient, rubber mat and additional layers of primer and membrane
on a railroad bridge or similar structure.
[0012] It is a still further aspect of the present invention to provide
a
method of building up a monolithic protective waterproofing product having
layers
of primer, membrane and resilient mat on a railroad bridge.
[0013] It is a still further aspect of the present invention to provide
a
method of building up a monolithic protective waterproofing product having
first
layers of primer and membrane, a resilient, rubber mat and additional layers
of
primer and membrane on a railroad bridge or similar structure.
[0014] Further aspects, advantages and areas of applicability will
become apparent from the description provided herein. It should be understood
that the description and specific examples are intended for purposes of
illustration only and are not intended to limit the scope of the present
disclosure.
DRAWINGS
[0015] The drawings described herein are for illustration purposes only
and are not intended to limit the scope of the present disclosure in any way.
[0016] Figure 1 is a perspective view of a light rail bridge or similar
structure from which the ballast, railroad ties and railroad track have been
removed which is undergoing a cleaning step prior to installation of the
waterproofing product of the present invention;
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[0017] Figure 2 is a top, plan view of a railroad bridge or similar
structure schematically and sequentially showing certain steps of the method
of
installation of the waterproofing product according to the present invention;
[0018] Figure 3 is a fragmentary, sectional, schematic view illustrating
the application of the first layer of primer and the first layer of membrane
to the
bridge deck;
[0019] Figure 4 is a fragmentary, sectional, schematic view illustrating
the application of the second layer of membrane and the resilient mat to the
bridge deck;
[0020] Figure 5 is a fragmentary, sectional, schematic view illustrating
the application of the second layer of primer and the second layer of membrane
to the bridge deck;
[0021] Figure 6 is a greatly enlarged, fragmentary, sectional view of
the
layers of a monolithic waterproofing product according to the present
invention
installed on a bridge deck or similar structure; and
[0022] Figure 7 is a flow chart presenting the installation steps of a
monolithic waterproofing product according to the present invention, including
a
bridge deck preparation step.
DETAILED DESCRIPTION
[0023] The following description is merely exemplary in nature and is
not intended to limit the present disclosure, application, or uses.
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[0024] With reference to Figure 1, a railroad bridge or similar
structure
either new or undergoing updating, repair, refurbishment or rehabilitation is
illustrated and generally designated by the reference number 10. The bridge 10
may be disposed across a river or a stream 12 or other obstacle and includes a
horizontal deck 14 which may be fabricated of wood, concrete or steel upon
which one or multiple railroad tracks 20 are supported and carried. Each
railroad
track 20 includes ballast (crushed rock) 22 which supports ties 24 which, in
turn
support and locate the rails 26 of the track 20. Because the bridge 10 is
undergoing repair or rehabilitation, the ballast 22, the ties 24 and the rails
26
have been removed from the bridge deck 14, as illustrated.
[0025] It will be appreciated that the product 40 and the method of the
present invention is intended for and is usable on both new construction and
bridges 10 that have been in service and are undergoing updating, repair,
refurbishment or rehabilitation. In the latter case, a first or preliminary
step to the
in-situ installation of the waterproofing product 40 of the present invention
is
cleaning the bridge deck 14 and removal of any loose material such as rust,
spalled or damaged concrete, previous coatings and anything that might
interfere
with achieving a tight and continuous bond between the bridge deck 14 and the
waterproofing product 40. If the bridge deck 14 is concrete and is spalled,
pitted
or contains other defects, it must be sand blasted or metal shot blasted
through
the use of conventional sand or metal shot blasting equipment 32 and an
operator or technician 34 to remove laitance and other contamination and then
patched with a concrete patching material. If the bridge deck 14 is steel it
should
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be prepared similarly to SP 6 or near white. If the bridge deck 14 is new or
has
been recently replaced, this step may simply involve inspection of the bridge
deck surface to ensure its integrity and relative smoothness and cleanliness.
[0026] Referring now to Figures 2 and 3 and 7, the building up or in-
situ installation of the waterproofing product 40 according to the present
invention
begins with the spraying, squeegeeing or rolling of a first layer of primer 42
onto
the bridge deck 14. The first layer of primer 42 is preferably applied at a
rate of
approximately 130 to 200 square feet per gallon (3.12 to 4.8 square meters per
liter) over concrete surfaces and at a rate of approximately 200 to 400 square
feet per gallon (4.8 to 9.6 square meters per liter) over steel surfaces. If
the
bridge deck 14 is steel and has a 5 mil profile or better, i.e., less, use of
the first
layer of primer 42 is not necessary. The first layer of primer 42 is
preferably one
of polyurethane, polyurea, methyl methacrylate, a polyurethane hybrid or an
acrylic. The first layer of primer 42 is preferably allowed to become tack
free
before the next step is undertaken.
[0027] The first layer or base coat of membrane 44 is then sprayed on
the first layer of primer 42 at a rate of approximately 20 square feet per
gallon
(.48 square meters per liter) to a minimum thickness of approximately 80 mils
and allowed to cure. The thickness of the first layer or base coat of membrane
44 may be increased to 120 mils and even thicker if desired. The first layer
of
membrane 44 is preferably an elastomer and is one of polyurethane, polyurea,
methyl methacrylate, a polyurethane hybrid, bitumen or an acrylic.
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[0028] Referring now to Figures 2, 4, 6 and 7, a second, thinner layer
of elastomeric membrane 46 is sprayed onto the surface of the first layer of
membrane 44 by an operator or technician 34 just prior to the application of a
layer of a resilient mat 50. The resilient mat 50 is unrolled, preferably in
closely
adjacent transverse or longitudinal strips, on the bridge deck 14. Transverse
strips or panels of the resilient mat 50 are illustrated in solid lines in
Figure 2 and
longitudinal strips or panels of the resilient mat 50 are illustrated by a
phantom
line in Figure 2. The strips or panels of the resilient mat 50 are pressed
into
position by a cushioned roller 52 on a moveable frame or trolley 54 that also
carries a roll 56 of the resilient mat 50. As such, the second layer of
membrane
46 functions as an adhesive which, because it is still liquid and the
resilient mat
50 is pressed into it, will flow and enter surface irregularities, interstices
and
voids 51 in the resilient mat 50, intimately bonding it to the first layer of
membrane 44.
[0029] The resilient mat 50 (and the roll 56 thereof) is preferably
rubber
and is, or is similar to, a product sold under the trademark Regupol 6010 for
a
type of impact sound acoustic underlayment manufactured by Regupol Pty. Ltd.,
Smeaton Grange, N.S.W. The resilient mat 50 may also be constituted of or
include reclaimed rubber, ground rubber, virgin rubber, vinyl,
polyvinylchloride or
polyvinyl acetate preferably having approximately 40% air filled interstices
or
voids 51 by volume that has been formed into a continuous sheet that, for ease
of handling and installation, is preferably four or six feet (1.219 or 1.829
meters)
wide and is cut and rolled into rolls of, for example, fifty feet (15.24
meters) in
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length. It will be appreciated that the spring rate of the resilient mat 50
may be
increased by reducing the volume of the air filled voids 51 to 30% or less or
may
be reduced by increasing the volume of the air filled voids 51 to 50% or more.
Different materials and combinations thereof will also provide differing
spring
rates. The thickness of the resilient mat 50 may be varied from 6 millimeters
(,236 inches) or less to 12 millimeters (.472 inches) or more, 8 millimeters
(.315
inches) having been found to be a widely useful, nominal thickness.
[0030] If desired, the resilient mat 50, in the same or various
thicknesses, may be installed in additional layers depending upon protection,
sound transfer, vibration dampening and load carrying requirements. To install
multiple layers of the resilient mat 50, an additional layer of the thinner
membrane layer 46 is applied to the upper surface of each previous layer of
the
resilient mat(s) 50 and an additional layer of resilient mat 50 is installed
while the
additional thinner membrane layer 46 is still liquid and pressed into intimate
contact with the thinner membrane layer 46 on the upper surface of the
previous
layer of the resilient mat 50 by the cushioned roller 52 so that a portion of
the
additional thinner membrane layer 46 is forced into the voids and interstices
of
the resilient mat 50, as described above. If multiple layers of the resilient
mat 50
are installed, care should be taken to stagger or offset the seams between
adjacent resilient mats 50 of each layer.
[0031] Referring now to Figures 5, 6 and 7, after the bridge deck 14 is
completely covered by the resilient mats 50, a second layer of primer 62 is
sprayed onto the surface of the resilient mats 50 at a rate of 30 to 50 square
feet
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per gallon (.72 to 1.2 square meters per liter). When the second layer of
primer
62 is only slightly tacky, a third layer of elastomeric membrane 64 of one of
the
materials previously listed is sprayed on the second layer of primer 62 to a
thickness of approximately 30 to 50 mils and preferably about 40 mils.
[0032] After these steps, installation of the monolithic waterproofing
product 40 is complete and the ballast 22, the ties 24 and the rails 26 of the
railroad track 20 may all be installed or re-installed on the waterproofing
product
40 on the bridge deck 14.
[0033] It will be appreciated that the monolithic waterproofing product
40 of the present invention provides numerous benefits. The waterproofing
product 40, particularly because of the resilient mat(s) 50, is thicker than
similar
products and the resilient mats 50 may be applied, as noted above, in multiple
layers. Such increased thickness is projected to provide better sound and
vibration attenuation than competing products. The preferred resilient mat 50,
described above, contains approximately 40% air filled voids or interstices
which
allow the membrane layers to penetrate the resilient mats 50 and achieve an
intimate bond therewith. This stiffens the entire waterproofing product 40 and
provides a mechanical lock with the resilient mats 50.
[0034] Additionally, because of the material and surface finish of the
third and final layer of membrane 64, namely tough and stiffly resilient,
which is
also the result of the resilient mats 50, the ballast 22 will create small
depressions or pits in the surface of the membrane 64 but will not puncture
it.
This action tends to hold the ballast 22 in place, thereby providing a more
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roadbed and generating less noise as trains pass. Finally, because of the ease
of building up the various layers of the waterproofing product 40 and the
speed
and uniformity with which the resilient mats 50 are installed, not only is the
final
product better from the standpoints of strength, durability and resistance to
water
penetration but its total cost (material and installation) is also less than
competing
products.
[0035] The
description of the invention is merely exemplary in nature
and variations that do not depart from the gist of the invention are intended
to be
within the scope of the invention. Such variations are not to be regarded as a
departure from the spirit and scope of the invention.
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