When the management team met in early 2003 to begin work on the new Global Engine Manufacturing Alliance (GEMA) plant, a joint venture of DaimlerChrysler, Hyundai, and Mitsubishi Motors, GEMA president Bruce Coventry asked the design group to “work outside the box” while conceptualizing and constructing “the best engine plant in the world.”
The new GEMA plant in Dundee, Mich., is really two 487,000-square-foot facilities, about 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 September 2005, and the South plant, finished and being equipped for a 2007 startup, will have the combined capacity to build 840,000, four-cylinder engines annually.
The advanced modular crossover facilities were designed to carry the heaviest loads required, while still remaining flexible enough to handle all potential manufacturing operations. The engine plants also had to have incredibly strong and stable concrete floors because of the massive process machinery, trenches, and flumes. The interior slabs on-grade utilized 25,000 cubic yards of concrete.
A brief history
Holly DuMont, a facilities architect for DaimlerChrysler's AME Core Facility & Launch Building Group, looked at the project as an opportunity, especially in the area of the critical concrete flooring requirement. She had already done research on polished concrete. Rather than moving ahead with a standard clear sealer or a two-part epoxy paint, she 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,” says DuMont. “This is the real thing: concrete slabs specifically designed to be ground and polished with diamonds like granite, producing a lifetime shine.”
With more than 15 years of 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.
DuMont then wrote clear 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. Armed with her newly completed Industrial and Architectural Slab specifications, DuMont and the construction manager, Walbridge Aldinger, interviewed the PC companies provided by the general contractor.
It became clear that concrete polishing companies with the skills to grind and polish at seven- to 10-day post wet cure using wet and or dry methods were few and far between.
“It was necessary that they demonstrate in-depth knowledge of concrete slab differentials and have high-end professional equipment capable of providing a level slab, regardless of the condition of the slab pre-grind,” says DuMont. “They must understand concrete chemistry and the best penetrating densifiers.”
The concrete polishing provider they chose provided a detailed system approach for diamond grinding and diamond polishing. “They understood a pour in February inside an enclosed heated building would provide a very different result than the same mix design poured in April,” DuMont explains.
“With the quartz shake about ¼-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,” says Karlos Melgar of Walbridge Aldinger. One of the most important requirements in the specification was the required proof of training and experience in diamond grinding and polishing (both wet and dry) concrete slabs at seven to 10 days, post wet cure.
Increasing lighting levels
A diamond ground (flat) slab polished to a 400 grit (NW3) level will yield a minimum additional 35% reflected light compared to traditional sealed or painted floors offering no more than 7%, 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.
Ribbon windows and suspended metal halide (400 watt) pendant fixtures illuminate the GEMA facilities. The quartz floor was polished to a 100 grit level (NW1), allowing 12 fixtures per bay to provide the light levels of 15 fixtures.
Maintenance was another overriding concern. “The minimal maintenance required over the life of the PC floor attracted me to the polished concrete concept,” says DuMont.
In manufacturing plants, daily maintenance includes chemicals, strippers, degreasers, and other expensive non-environmentally friendly products. Heavy abrasives are a common method of cleaning rough concrete floors that catch and hold dirt, grease, and tire marks. “With polished concrete, all you need is neutral pH soap, clean water, and a soft nylon head on a standard scrubbing machine,” explains DuMont.
After all of the efforts to ensure the success of the finished product, DuMont was concerned 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,” says DuMont.
“Maintaining PC floors yields further costs savings by requiring fewer man-hours, no costly detergents or degreasers, the elimination of annual chemical top-coat touch up, and removal and replacement of epoxy paint over the lifetime of the floor,” says Mike Strohschein, owner/ engineer construction representative.
Overcoming flooring problems
Crews encountered several problems during the project. The slabs were designed, poured, and finished so they would yield the best surface to be ground and polished.
This was a brand new idea to everyone. 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 floor flatness (FF) and floor level (FL) being of prime focus. Polishing concrete floors often is an afterthought, costing up to $12 a square foot. With proper planning, a flat, impervious, shiny, maintenance-free floor can cost as little as 88 cents a square foot.
A more serious problem occurred during polishing at the North plant during winter 2004. The concrete placing and finishing equipment's internal combustion engines and portable direct-fired heaters inside the enclosed building shell all produce carbon dioxide.
“The CO2 sits low over the new slab since it is heaver then air and is absorbed into the bleed water to form carbonic acid,” says DuMont. “This acid reacts with the calcium hydroxide found in the curing slab, causing carbonation.” The polisher came onsite to inspect the slabs at seven days after wet cure, recognized the soft porous surface, and modified how to properly accommodate the new slab.
“At 10 days post-wet cure, they were grinding the floor with a different diamond head 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,” she says.
“Without a clearly documented polished concrete scope of work and specification for Industrial and Architectural Slabs, a general contractor will use traditional methods of construction, resulting in wasted time and money,” says DuMont.
The general contractor on the South Plant paid great attention and adjusted the sequence of construction accordingly. 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, DuMont suggests. Reinforce any heavy interior wall locations with a thickened slab rather then a typical footing, eliminating the 2 feet or so of finished slab running along the wall that is tough to work and polish.
This project presented many obstacles. But if DuMont had to choose one very important lesson learned during the construction of the GEMA facilities it was this: “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 he has been placing concrete for 35-plus years, that he knows it all.” “He must listen to and address all issues,” she adds.
He must discuss all aspects of the job with the polishing contractor upfront to avoid costly mistakes. A typical overworked, blackened slab with 3 feet of its perimeter void of any cream and fines is not what polishing contractors are looking for.
The polished concrete expert can save all involved time and money by avoiding several 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 scheduled completion dates.
The author is director of sales and marketing for Concrete Polishing Technologies. David Padgett, vice president of marketing and business development for Concrete Polishing Technologies, spearheaded this project and was supported by Perfect Polish craftsmen.