Aerospace Epoxy Test Bed
University of Southern California Project
Precision Epoxy Products
a division of :
Rock Art, Ltd.
4279 Midway Drive
Douglasville, Georgia 30134
Phone : (770) 489-0340
University of Southern
California Information Sciences Institute
Space Engineering Research
Center
Microsatellite Dynamic Test
Facility (MDTF)
When we were contacted by David
Barnhart, Director of the MDTF at USC in Los Angeles, California, we were told that
the 1100 square foot Epoxy
Test Bed they wanted installed would be the second largest test arena of its kind for use in the Aerospace
Industry in the world, just behind the one at the Marshall Space Lab in
Huntsville, Alabama. David was in a bind, and way behind schedule after several failed attempts by inexperienced contractors
who were way in over their heads. After nearly a year lost by USC, Precision Epoxy was
discovered and contracted to install this history making test bed. We had to
develop a brand new epoxy formulation and design all new specialized equipment
to handle the size and complexities for an installation of this size in order to deliver the
desired results needed for this project to continue forward. The test bed was
completed by Rock Art in November, 2008, and fulfilled all the requirements and
specifications needed by the Space Engineering Research Center. All in all, what USC was describing as a history making
test bed installation, was simply another day at the office for us. This is
a fine example of the old saying 'There is no substitute for experience'. Many
manufacturers and/or contractors describe their products and/or services with
regards to floors as being level in an extremely misleading manner. When it
comes to level, being close doesn't matter, it either is level or it is not
level. If you need a level floor for your project, then your choice is clearly
Precision Epoxy. No one
can match the experience and results provided by Rock Art and Precision Epoxy for perfectly flat and
level floors, surface plates or test beds.
Our
experience with perfectly level epoxy floors started in the Motorsports Industry
in the early 1980's with the Epoxy Surface Plate. The Steel Surface Plate
had been the
standard of the Motorsports Industry for fabrication and set-up work since that first jig table had its legs removed and was laid on the floor so that a car could be rolled
on and off and the first steel floor plate was born. Since
that time motor sports engineers and fabricators have been trying to improve on this idea to try and make
the use of a steel plate more reliable. We developed the Epoxy
Surface Plate because
there was a need for a set-up plate with even greater accuracy and reliability
as the technological aspects of racing evolved. The average size of a motor
sports set-up plate is 180 to 240 square feet. This was also the size range of
our first few aerospace test bed floors. The relatively small size of these
installations made for the corrections in uneven or wavy concrete more
predictable as the poured epoxy material filled the framed out area. The smaller
jobs are also less involved with regards to manpower, volume of materials
needed, logistics and transportation.
The challenges of much larger floors present themselves in
many ways and are less predictable and forgiving. The time involved and the volume of materials to correct
and level larger areas elevates these projects to a whole other scale.
The concept of our level flooring is simple. We pour a specially formulated
epoxy liquid into a framed out area and gravity levels the epoxy like water in a
bowl. The epoxy can only be poured at an average thickness of ¼ inch at a time
and multiple pours are made until the lowest point in the concrete substrate is
filled to the height of the highest point within the framed out area. At this
rate the
average thickness of four pours would be 1 inch; however, the actual thickness of
the epoxy at any one point in the poured area would be determined by how high or
low the concrete was at that point. This can be a difference of paper thin to
several inches thick in the epoxy. Considerations for minimum structural
thickness of the epoxy are also determined and generally additional pours
will be needed after the epoxy surface plate has reached level. Our Job
Proposals anticipate worst case scenarios and pricing for our installations are based on a specific number of pours; however, some projects with very
irregular concrete may require additional pours. If additional pours are needed
to level an area to meet the customer's requirements, then the customer will be
responsible for the additional cost of materials, labor and travel expenses.
Installation of the USC Project
Once we were contracted and received the
deposit for this project, it took approximately five months of preparation
before we could start the installation. Raw materials had to be ordered in and
1500 gallons of
our exclusive epoxy formulations manufactured. The custom designed aluminum
retaining wall was fabricated. Special one-of-a-kind tools and equipment were
designed and constructed to support the unique aspects encountered by a job of
this size. All tools, materials and supplies were carefully loaded and shipped
to the project site in southern California from Atlanta, Georgia. A highly
skilled and elite five person crew lead by Mike and Dianne Ramy were assembled
and dispatched to Los Angeles. On October 27, 2008 we arrived and saw the job
site for the first time. We completed the installation on November 20, 2008.
Although we have extensive application experience for smaller surface plate
installations, this was our first large project. The tools, equipment and
epoxy formulations we designed, implemented and perfected for this and all
future projects of this size are now in place. We can and will deliver results for large
perfectly level surface plate floors of over 1000 square feet that meet or
exceed the customer's requirements and expectations.
1)
We start by locating and setting up our mixing shop. The
mixing shop should be as close to the work area as possible to stage and
mix epoxies, to access application tools and to prepare and clean up as needed. The shop
must be in a controlled
environment and large enough to spread out materials and tools and to accommodate crew members.
Plastic and cardboard are laid down first as a sub-floor to protect existing flooring from spills and/or
splatter that can occur while mixing epoxies. Our shop was located just
outside the double door accessing the room where the Test Bed was to be
installed. The size of our mixing shop was limited due to available space but
we were able to set-up our equipment and make it work for our needs. The 35
each 55 gallon drums of epoxy remained stored in the shipping containers in
which they arrived. The appropriate amount of material needed for each day's
pour was brought in and processed, with empty drums being returned to the
shipping containers located in the adjoining outside parking lot. The mixing
shop is a crucial aspect of any surface plate installation; however, the larger
projects require added elements. Adequate lighting and electrical outlet power
sources are needed. Although we only require 110 volt outlets, each of the 5
to 7 1500 watt drum heaters will require their own 15 to 20 amp circuit. This
means we have to have 5 to 7 outlets on separate circuits. We come prepared
with enough extension cords to reach the outlets needed on different circuits
within and outside the work area to establish the power sources needed to
properly operate our mixing shop.
2)
The Surface Plate is laid out using the permanent aluminum retaining wall from
the original design drawings. Then final approval is made by the customer for
its ultimate lay-out and location of the Epoxy Test Bed. The retaining wall is removed and
stored for later.
Then the temporary aluminum 'L' angle retaining wall is
mounted to contain the initial pours of the Floor Plate Epoxy. The temporary
form work is mounted 6 inches wider and longer than the actual completed plate
size. This allows for the 4 inch tall permanent aluminum 'L' angle
retaining wall with its 3 inch mounting base to be mounted onto the level
epoxy floor surface. This eliminates the twisting or warping of the 'L' angle
that would occur if it was mounted to the uneven concrete. It also assures a
uniform wall height along the entire perimeter of the surface plate.
3)
The concrete substrate is prepared as needed for proper bonding. The method of
preparation and equipment used is determined by the condition of the concrete.
Surface preparation is always an
important aspect of the surface plate application and should be given the time and
effort needed to complete properly.
Ideally, new concrete is the easiest and most predictable application environment for
installing the surface plate system; however, any floor can receive this
system with proper substrate preparation. Basically the substrate should be clean, dry and
free of oils, grease, silicones, waxes, existing coatings, etc. These
contaminants are generally saturated into the pores of the concrete and can
prevent penetration, limit proper bonding and/or cause 'Fish Eyeing' of the
epoxy primer. Due to the variety of situations that can exist with older
substrates and the numerous ways to deal with these situations, Precision Epoxy
should be consulted to discuss your individual project to determine the best
course of action. After preparing the concrete substrate, our IG-100 flexible
penetrating epoxy primer system would be applied. The primer seals the concrete
and eliminates porosity that can create air bubbles in the first pour. It will
also absorb thermal movement characteristics of the concrete normal with
changes in temperature from hot to cold.
The concrete floor for this project had a brand new painted
on, so called, self leveling epoxy applied by one of the two contractors we
followed. The lack of levelness this type application and system
offers is a long way from what is needed to actually create a level floor
surface. It was however an epoxy coating installation that we were able to use
as our primer coat. We had to sand the surface in preparation for our first
pour of Floor Plate Epoxy.
Additional considerations and preparation techniques are applied
to expansion joints, stress fractures and/or spalling areas should they be
present in the concrete substrate.
The room
is then thoroughly cleaned and maintained as a 'Clean Room' environment with
regards to debris, dust and humidity during the remainder of the installation
process. The tolerances required of the Robotic Spacecraft Simulators that use
our test bed are so close, that a small piece of lint or dust that floats onto the
final epoxy pour can flaw the surface.
4)
The temporary form work is waterproofed to properly contain the epoxy liquid.
We also isolate the aluminum from contact with the epoxy poured within the
form work. This prevents the epoxy from bonding to the aluminum and allows for
easier removal of the temporary form work when needed.
5)
Now we stage and process the 174 gallons of Floor Plate Epoxy to be used on
the first pour of the six total pours to be made on this project. The poured
epoxy yields coverage of 6.4 square feet per gallon at a depth of ¼ inch.
Our formulas are 100% solids, zero VOC products this means when we pour ¼ inch of
material,
that's what you have on the floor when it cures. The resin component of our 2
part system is measured out into the five mixing drums and heated to
lower viscosity and increase flow. We use 55 gallon open head steel drums and 
the product is stirred during the heating process to assure even heat
distribution and a uniform color in our pigmented systems.
The one
of a kind drum jig pictured was specially designed and constructed for this
project to heat and stir the five each 55 gallon drums needed for the volume of epoxy to be
used per pour on this project. Uniform consistency of the epoxy resin within all five drums is essential
to produce an overall uniform pour. Once the resin reaches the desired
temperature, the drums are rolled onto the surface plate area and staged. This
process is performed each time one of the six total pours is made.
It should
be noted that all the epoxies and application techniques for this type application have been
developed over the years by Precision Epoxy. Special application
techniques and formula modifications can and will be incorporated as needed to adjust
for conditions or changes that may present themselves during the duration of
the installation process to achieve the best results possible.
6)
The hardener is added to the pre-measured and processed resin in the drums and the components are stirred
for the exact amount of time needed.
The
mixture is then poured evenly onto the concrete surface and allowed the flow
and seek its own level.
The process is repeated for
all five drums until the entire area is flood coated. An access point for rolling
items on and off the plate area has to be damned up after all equipment is
removed and before the final epoxy is poured.
7)
The initial pours of FP-90 Floor Plate Epoxy has a very slow rate of cure to
allow for maximum time to flow out and level; then it is allowed to cure for 48 hours. When work resumes, the surface plate is sanded in preparation of the next pour.
The processing, heating and staging of the epoxies is repeated as before and
the second pour is made.
As each pour is made, the height of the
surface plate grows taller from the original concrete substrate surface. This situation created
the need for a specially designed ramp to access equipment on and off the
plate. Our custom made ramp has adjustable jack bolts to adjust to the proper height
as each one of the consecutive pours is made.
Additional various techniques are employed to aid the epoxy
in the leveling process.
Notice in the pictures throughout this page, the obvious difference in the
flatness of our black floor surface to the uneven gray surface of the original
floor.
8) Additional
pours are made as needed until the surface plate has reached a levelness to
within one
percent of perfect. The consistency and accuracy required
over a large area makes the time and tools needed to measure one of our Aerospace
Epoxy Test Beds very expensive and with questionable accuracy. In reality; however, no matter how the surface is
measured, what really matters is how the Robotic Spacecraft Simulator floats
on the epoxy floor. An ideal test bed surface provides for little to no
drifting of the float unit at any location on the test bed surface. If the float unit
sits perfectly still when it is floating above a flat surface on a cushion of
air in a state of weightlessness, then there is no doubt that the surface is
perfectly level. Our goal is to have the surface plate level to within
0.001 of an inch or better. This means that the criteria for acceptance would be the
float unit can drift no more than 24 inches in 15 seconds.
The USC Microsatellite Robotic
Spacecraft Simulator is floated on the surface plate after the four base pours
have been made to
validate accuracy. At this point we must determine if additional base pours
are needed or whether the plate has the desired accuracy to proceed to the next
phase of the installation.
Precision Epoxy has designed and built
its own Float Unit that allows us to test the progress of each pour made
during the installation of our Epoxy Surface Plates and Test Beds. This gives
us a much better understanding and clearer insight of each project as the work
progresses. Our float unit is also quite useful for projects where customers
may not have a simulator ready at the time of installation or the larger size of their simulator makes it to
costly or inconvenient to use for testing purposes. See Float
Unit for additional information.
Prior to the start of the Epoxy Test
Bed project, USC had determined the concrete floor was off by about 1 inch.
After pouring 1 inch of our Floor Plate Epoxy, the temporary form work was
removed and the surface plate edge was exposed. We had a varying thickness at
the outer perimeter from 1/8 inch to 1½ inches. The following pictures give
you an indication of the relation between the uneven concrete floor and the
level plane of the Epoxy Surface Plate.
9) The
four base coat pours of the FP-90 Floor Plate Epoxy has correctly leveled the
concrete substrate and we are ready to proceed to the final stages of the
Aero Space Test Bed installation. We remove the temporary aluminum 'L' angle
retaining wall and detail the plate perimeter to remove our waterproofing tape
and the meniscus lip created by the epoxy.
The entire epoxy surface plate is sanded and detailed.
10)
The next step is to mount the permanent aluminum retaining wall along the
epoxy surface plate perimeter. The retaining wall is staged, prepared and
polished prior to mounting. As discussed earlier, the retaining wall is
mounted onto the level epoxy surface plate perimeter using anchor bolts. Once mounted, the
Epoxy Test Bed's useable surface area will be the actual size contracted by
the customer.
Then a special caulking process is performed to waterproof
the entire surface plate area.
11)
After the retaining walls are installed and the removable access gate
completed, we are ready to install our grounding system. The grounding system
is installed as a part of our epoxy floor plate applications to control  static
electricity. Our Epoxy Surface Plate has come a long way since 1985 when it first became an idea and put into application.
One of our developments through the years has been the elimination of static electricity from our plates. When we first started installing
the epoxy floor plates, we did not realize that a possible static problem could develop to some degree. After several years
from our first plate installation, we started working on a grounding system that can be effectively installed into the plates.
Through years of research and development and nearly 500 floor plates installed, we
perfected the ‘Advanced Grounding System’ which is now installed in every one of our plates to eliminate static.
Static electricity refers to the accumulation of excess electric charge in a region with poor electrical conductivity (an insulator), such that the charge accumulation persists. The effects of static electricity are familiar to most people because we can see, feel and even hear the spark as the excess charge is neutralized when brought close to a large conductor (for example, a path to a ground), or a region with an excess charge of the opposite polarity (positive or negative). With this in mind, we have designed a grounding system that is installed and hidden within the Epoxy Surface Plate to dissipate the accumulation of static charge. This grounding system, along with the use (as needed) of Staticide’s Anti-static Cleaner
to control surface
static, our plates are now
able to maintain an electrically neutral state.
The Advanced Grounding System is composed of ½ inch conductive copper foil tape with a conductive acrylic adhesive
applied onto the completed base coat pours and laid out in a 12 inch grid pattern for
our standard
applications. Each end of the copper tape strips extend up the aluminum retaining
wall and are connected to each other with two runs of ¾ inch copper tape
along upper and lower points on the wall. The
entire grid system is then connected to a grounding source to complete the
system. For ground slab concrete a ½ inch x 8 foot long grounding rod is installed through the ground slab concrete sub-floor
and used as the grounding point. The ground rod is placed at the access ramp
area and connected to the grid system by using copper ground wire tucked up to the lip of the
base pours. The ground rod will be hidden within the access ramp once
installed.
For above grade concrete
substrates or if drilling through the sub strate is not an option, an alternative
grounding source will need to be located. The USC Project required an
alternate source which called for an electrician to come in and install a
grounding plate on an adjoining wall next to the test bed. Fortunately there
was an electrical room next to the Test Bed Laboratory with a readily
available grounding source. Pictured below are the grounding rod within the
access ramp method (left) and the alternative grounding plate method (right).
12)
The Epoxy Test Bed is now ready to receive the final two pours of Floor Plate
Epoxy. This will give the plate the structural thickness desired at the thinnest
areas throughout the entire plate. The final pours will also allow us to
achieve the perfect level surface needed for this project. The first of the
two pours is made in a similar manner and with all the aspects as the base
pours and allowed to cure.
13) The last pour or the 'Money Coat' is the
one everything is riding on. If not right for whatever reason then, with
regards to this pour, everything has to be done all over again. We start by
installing the permanent access ramp at the removable gate area. The ramp
installation is as follows:
-
Using an 8" worm drive saw with a
dry cut diamond blade we cut a ¼" deep groove creating
the outer edge of our access ramp. The saw rides in a specially designed
wheeled tray to keep from scratching the existing floor finish and to allow
for proper spacing to achieve the 6" width of the ramp. We use a saw
guide to get as straight a cut as possible. A vacuum attachment is used in
conjunction with the saw to minimize any dust.
-
An 'L' angle zinc strip that is the
exact height of the thickness of the final pour is mechanically attached
to the plate perimeter at the gate opening.
-
The grounding tape taps are carefully
laid out of the way back onto plate. Tape taps are fragile and must
not be broken.
-
The grounding system is completed with
the installation of the grounding rod through the concrete sub-strate,
mounting of the copper connecting wire and the making of all our
connections to the grid system.
-
Any existing floor covering on the
concrete substrate within ramp area not cleaned during initial prep work
is now removed by hand so as not to damage the existing floor outside the
ramp area.
-
We mask off the plate perimeter using 1" masking tape
and 12" masking paper to protect plate and reduce clean up. Taping is done on
the zinc form work's vertical facing and onto the plate. This assures that Santex
ramp material is not inadvertently bonded at the zinc seam.
-
Next the outer perimeter of the ramp is masked off using
2" tape and applied to the existing floor at the outer edge of the saw cut.
-
The concrete within the ramp area is primed with the IG-100
flexible penetrating epoxy.
-
Access ramp is then hand troweled into
place with our Epoxy Santex System (see Santex
System for additional information) in a matching or contrasting color from the top of the zinc form work down
into the ¼" saw groove that we made earlier in the concrete substrate. By finishing our Santex material into the saw groove, we
are able to maintain a structural thickness that eliminates future chipping
of ramp edge from rolling equipment on and off the plate. The saw groove
also gives the ramp edge, where it meets the existing floor, a nice straight
'Factory' finish.
-
Troweling of the ramp is done in a fashion that maintains a
'wet edge' at both ends to give a seamless finish when completed.
-
The 2" masking tape on the existing floor is pulled as
we proceed. The ramp adjoining the existing floor receives final detailing and the existing floor is
cleaned as needed.
-
The area is isolated to foot traffic and
the ramp allowed to cure over night.
-
The detailing of the masking tape and
paper is done the next day once the Santex has cured.
14)
The 'Money Coat' is poured after special preparation, staging and processing
of the Floor Plate Epoxy System. Extensive cleaning of the entire room and
tack ragging of the plate surface is performed. The scheduling and timing
considerations of the final pour are also critical factors and cannot be taken
for granted. There is only one shot to get it right the first time. The final
pour is made and allowed to cure.
15)
After adequate time is allowed for the Epoxy Test Bed to cure out enough to be
tested, the final test is made with the
Robotic Spacecraft Simulator Float Unit to confirm the criteria of acceptance
for levelness and flatness by USC. To say they were very pleased with the
results and to have this derailed project back on line is an understatement.
16)
Once the Epoxy Test Bed surface is completed and accepted, we begin the final
detail work. The access ramp receives 3 coats of our FS-190 Floor Sealer
Epoxy (see Floor Sealer for additional
information) to complete. The interior vertical surface of the retaining wall
receives a ¼" thick, high density black foam padding. Our epoxy mixing
shop is dismantled and loaded out. Everything is loaded up and sent home.
That is basically how a
large perfectly flat and level Epoxy Floor Plate is installed. Some projects
may require variations from the outlined application techniques herein due to
the condition of the substrate, location of job site, size of the project,
shape of the completed surface plate, designs and/or
artwork in the finish, special equipment needed, any unusual
factors associated with the project, etc. Please note:
Precision Epoxy only offers this type floor surface as a professional
installation by Rock Art, Ltd. Some proprietary information has been deliberately
omitted from this installation paper. No one has been trained or is authorized
as a contractor to represent themselves as able to install this type flooring
as offered by Precision Epoxy Products and Rock Art, Ltd.
All the plastic in place at the ceiling, doors
and windows was installed by USC prior to our arrival. They were to remove the
plastic as a part of the additional work planned. The lab was to have a filtered
air system, a swivel crane / hoist unit, a GPS system, a compressed air system
and on and on. We regrettably, as of yet, have not received photographs of the completed laboratory
as promised by USC for this paper. All the photographs contained within this
technical bulletin regarding the USC Project are courtesy of the University of Southern
California Information Sciences Institute.
We would
like to thank David
Barnhart, Director of the MDTF at USC, his assistant on the project and USC
engineer Jeff Sachs and graduate student on this project Steve Schultz for all
their assistance. They made the entire job as well as our time in Los Angeles
a pleasant and memorable experience.
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