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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:

  1. 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.

  2. 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.

  3. The grounding tape taps are carefully laid out of the way back onto plate. Tape taps are fragile and must not be broken.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. The concrete within the ramp area is primed with the IG-100 flexible penetrating epoxy.

  9. 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.

  10. Troweling of the ramp is done in a fashion that maintains a 'wet edge' at both ends to give a seamless finish when completed.

  11. 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.

  12. The area is isolated to foot traffic and the ramp allowed to cure over night.

  13. 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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Precision Epoxy Products
4279 Midway Drive
Douglasville, Georgia 30134
Mike Ramy
(770) 489-0340
mramy@netzero.net

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