When the management team met in early 2003 to begin work on the new GEMA (Global Engine Manufacturing Alliance Plant) a joint venture of DaimlerChrysler, Hyundai and Mitsubishi Motors located in Dundee Michigan, GEMA’s president Bruce Coventry requested that the design group “work outside the box’ while conceptualizing and constructing “the best engine plant in the world.”
The new GEMA plant is actually two 487,000 square foot facilities approximating the size of 20 football fields with North and South employee service facilities, a plant management and operations facility and the GEMA world headquarters building. The North plant, operating since Sept. 2005, and the South plant, finished and being equipped for a 2007 startup, combined will have the capacity to build 840,000, four-cylinder engines annually. The advanced modular crossover facilities were designed to carry the heaviest loads required while remaining flexible enough to handle all potential manufacturing operations over the respective lifetimes. In addition, the engine plants had to have incredibly strong and stable concrete floors due to the required precision operations of the massive process machinery, trenches and flumes. The interior slabs on-grade utilized 25,000 cubic yards of concrete.
A brief history
The directive to find and implement innovative solutions that produce improved, cost effective results can become self-defeating for many reasons such as risk, unknowns, safety, fear, complacency, and the list goes on. In this case, one of the design team members took the directive quite literally.
Holly F. DuMont, a facilities architect for DaimlerChrysler’s AME Core Facility & Launch Building Group, considered the directive an opportunity – especially in the area of the critical concrete flooring requirement. She had become aware of polished concrete and had researched the subject quite seriously. Rather than moving ahead with a standard clear sealer and-or a two-part epoxy paint covering the future nearly one million square feet of steel pin reinforced manufacturing floors, DuMont proposed diamond polished concrete (PC). “Polished concrete is not burnished or buffed with a pan or a polished topcoat of chemical hardener that simply wears off. This is the real thing – concrete slabs specifically designed to be ground and polished with diamonds like granite producing a lifetime shine,” said DuMont.
With more than 15 years experience in the design and construction industry, DuMont knew strong support would be required if she hoped to move forward with PC. She decided to approach plant manager Bruce Baumbach with the polished concrete concept and associated data. “He took the time to listen and encouraged me to keep moving forward with his backing – it just wouldn’t have happened without his support,” DuMont stated.
DuMont’s next move, writing a clear and detailed scope of work and detailed specifications for the future Architectural and Industrial Slabs designed to be diamond ground and polished. She requested the assistance of Harry Peck, a highly experienced and knowledgeable specifications writer, to help create a solid set of spec documents during the design phase of the project. Armed with her newly completed Industrial and Architectural Slab specifications containing all acquired concrete polishing expertise, DuMont and the construction manager Walbridge Aldinger, conducted interviews with the PC companies provided by the general contractor. Upon a detailed inspection of all requirements as defined in the specifications, it became clear that concrete polishing companies with the skill set to grind and polish at 7 to 10 day post wet cure using wet and or dry methods were few and far between.
According to DuMont, “It was necessary they demonstrate in-depth knowledge of concrete slab differentials, have high-end professional equipment capable of providing a level slab, regardless of the condition of the slab pre-grind. They also must understand the chemistry of concrete and the best penetrating densifiers to put on at the best time. Their procedures must include how they tests a floor prior to beginning a job as concrete floors can be very different depending on a multitude of factors. “
The concrete polishing provider chosen provided a detailed system approach for diamond grinding diamond polishing. “They understood a pour in February inside an enclosed temp heated building would provide a very different result than the same mix design poured in April” explained DuMont
According to Karlos Melgar of Walbridge Aldinger, “With the quartz shake about one-quarter-inch thick, it wouldn’t take much for an inexperienced polishing contractor to grind through into the metal pin reinforcing concrete substrate creating a patchwork floor that in the end would have to be scarified and painted with epoxy.” Each company’s references and resume were verified for accuracy. According to DuMont, one of the most important requirements defined in the specification was the required proof of training and experience diamond grinding and polishing (both wet and dry) concrete slabs at 7 to 10 days post wet cure.
With the remainder of construction and the entire process installation waiting on the slabs, the concrete polish provider chosen had the know how to diamond grind and finish polish the entire manufacturing floor before any of the other polishing companies would even begin their polishing processes. “Climbing out on a limb to provide the first diamond ground and polished quartz shake concrete manufacturing floor makes you an extremely cautious individual – my career was literally on the line.” said DuMont.
Floor Reflectivity Increasing Lighting Levels
A diamond ground (flat) slab polished to a 400 grit ( NW3) level will yield an minimum additional 35 percent reflected light as compared to traditional sealed or painted floors offering no more then 7 percent regardless of floor color. This is not the perception of more light often attributed to white or light colors but the actual light reflected back into the facility as measured with a specular gloss measurement device. Illumination for the GEMA manufacturing facilities is provided with ribbon windows and suspended metal halide (400 Watt) pendant fixtures. The GEMA quartz floor was polished to a 100 grit level (NW1) allowing 12 fixtures per bay to provide the light levels of 15 fixtures.
DuMont had a clear understanding as to the care and maintenance of the polished concrete floors. “The minimal maintenance required over the life of the PC floor was one of the things that attracted me to the polished concrete concept.” explained DuMont.
In manufacturing plants daily maintenance includes chemicals, strippers, degreasers and other expensive non-environmentally friendly products for daily and weekly cleaning. Heavy abrasives are a common method of cleaning rough concrete floors that catch and hold dirt, grease, and tire marks etc. “With polished concrete all you need is neutral PH soap, clean water and a soft nylon head on a standard scrubbing machine” said DuMont.
After the extraordinary efforts made to ensure the success of the finished product DuMont was concerned that the maintenance staff would fall back on traditional cleaning products and methods. “The facility management company at GEMA approached the new PC floors as if they were polished granite and began a successful cleaning program immediately” said DuMont. “The minimal requirements to maintain PC translate to further costs-savings by requiring fewer man hours, no costly detergents or degreasers, the elimination of annual chemical top-coats touch up and or removal and replacement of epoxy paint over the life time of the floor ” said Mike Strohschein owner/engineer construction representative.
Overcoming Flooring Problems
Throughout the construction of the plant floors, there were a number of problems encountered. The fact that the industrial slabs were designed poured and finished in a manner that would yield the best surface to be ground and polished was a brand new idea to everyone involved. The rule of the day is edge of slab to edge of slab – with consistency in the fines and cream at the surface and the tested FF(floor flatness) and FL (floor level) being of prime focus. Most often the polishing of concrete floors is an after thought costing upwards of $12 a square foot. With the proper planning a flat, impervious, shiny, maintenance free floor can cost as little as $.88 a square foot.
An example of a more serious problem occurred during the polishing of the North plant during the winter of 2004. “The internal combustion engines of the concrete placing and finishing equipment and portable direct fired heaters inside the enclosed building shell all produce carbon dioxide (CO2). The CO2 sits low over the new slab as it is heaver then air and is absorbed into the bleed water to form carbonic acid. This acid reacts with the calcium hydroxide found in the curing slab causing carbonation” explained DuMont. The polisher came on site to inspect the slabs at seven days after wet cure, recognized the soft porous surface and modified their means and methods to properly accommodate the new slab. “At 10 days post wet cure they were out grinding the floor with a different diamond head selection and revised methods of grinding and polishing that resulted in a tight, durable, dust free, reflective floor requiring minimal maintenance for the life of the slab” said DuMont.
Lessons Learned During Manufacturing
“Bottom line – without a clearly documented Polished Concrete scope of work and specification for Industrial and Architectural Slabs a general contractor will assume traditional methods of construction resulting in wasted time and money.” said DuMont.
The general contractor on the South Plant paid great attention and adjusted their sequence of construction accordingly. By working closely with DuMont and using the “critical path” method to address the revised flow of construction they were able to make it all work. “The construction schedule is a bit reversed with polished concrete. As soon as the building envelope is completed, depending on weather, and all the overhead trades have installed as much of their infrastructure as possible you pour, finish, wet cure, grind and polish the concrete. Do not put up any interior walls until the slab(s) have been polished and cleaned. Reinforce any heavy interior wall locations with a thickened slab rather then a typical footing eliminating the two feet or so of finished slab running along the wall that is tough to work and therefore to polish” said DuMont. The general contractor; working closely with the concrete provider, followed up with a methodical installation plan divided by traditional disciplines facilitating the construction speed while avoiding potential problems.
Ultimate Lesson Learned
Since “out-of-the-box” thinking encourages higher risk taking, there certainly were many obstacles to overcome. But if Holly DuMont had to choose one very important lesson learned during the construction of the GEMA Facilities it was the following: “In the case of the concrete contractor hiring the polishing contractor: the general contractor must listen to the polished concrete experts. When a problem is identified in the field by the polisher, the concrete contractor can no longer assume, because they have been placing concrete for 35 plus years, that they know all. They must listen to and address all issues. They must discuss all aspects of the job with the polishing contractor upfront, avoiding costly mistakes. “A typical over worked, blackened slab with 3’ of its perimeter void of any cream and fines is not what polishing contractors are looking for” explained DuMont. “We were fortunate on the South Plant with a general contractor and concrete provider who assigned knowledgeable individuals with flexible project management and superintendent skill sets” In addition, the general contractor must be ready to apply their years of experience in the field to rethinking the construction mile stone dates and schedules.
Holly DuMont believes that the polished concrete expert can save all involved time and dollars by avoiding numerous construction “assumptions” that lead to a variety of problems, improve the installation flow of the subcontractors and assist the construction manager, general contractor, designer of record, and the owner by helping to minimize confusion while meeting the scheduled completion dates.