The transformation of the concrete floor from steel-troweled to polished in the newly built Donald V. Fites Engineering Innovation Center at Valparaiso University in some ways resembles the mission of the College of Engineering, of transforming high school students into engineering professionals.
In both cases, there’s some grinding and polishing.
“We decided early that we wanted sustainable flooring for laboratories and public spaces,” said Project Architect Victor Ritter, LEED AP and Principal of Chicago and Valparaiso, Indiana-based Design Organization. Tile, vinyl and other flooring choices were considered before deciding on polished concrete.
“It has several advantages no other flooring has,” he said.
In addition to its durability, one of the main advantages for the project was the fact that no other flooring material needed to be bought — and transported — to be put on top of the concrete. “Using concrete saved resources, and also eliminated the use of adhesives, which can have a negative effect on indoor environmental quality,” said Mr. Ritter, who indicated the goal for the project is LEED Gold certification.
The building also boasts low-VOC paints and sealants; a highly insulated, reflective roof; lots of day-lighting, and exterior hardscaping of reflective concrete rather than heat-absorbing asphalt. Also, construction manager Turner Construction, number-one in Engineering News Record’s top 100 green contractors, instituted an aggressive recycling program throughout the construction period, Mr. Ritter said.
The $6.9 million project is actually an addition connected to the south side of Gellersen Center, which houses the College of Engineering and Department of Mathematics and Computer Science. It creates a second “front door” for the College.
A little over half of the building’s 13,600 square feet is polished concrete, according to polishing contractor Bill Fansler, a vice president, estimator and project manager at Smock Fansler Corporation, Indianapolis.
Mr. Fansler and crew got the nod to go to work in January, about a month after the slab was poured and the building shell was up. Following the procedure they developed on their test panel, they flattened and “opened” the concrete with 650-pound grinders equipped with 40-grit metal-bond abrasive diamond pads, and moved up to 80- and 150-grit.
“Bond” refers to the matrix that holds the diamonds on the pad. For grinding, it takes metal to hold the diamond “teeth” solidly and immovably to the pad. Polishing pads hold their diamonds to the pad with resins. That more flexible bond keeps the diamonds from gouging the concrete as deeply as a metal bond.
In some places, the concrete had unexpected densities due to variations in the way it was troweled, and the operators had to change pads to adjust, Mr. Fansler said.
A three-day winter storm Jan. 31- Feb. 2, nicknamed the “Groundhog Day Blizzard” added another complication. As snow blew in the temporary exits, or was tracked in on boots it melted on the concrete floor. The water, where it wasn’t mopped up right away, pulled salts out of the concrete, which hardened into insoluble white deposits on the surface.
“Re-grinding was the only way to get rid of them,” Mr. Fansler said.
The storm also helped, Mr. Fansler said. The deep snow marooned the polishing crew at the jobsite and at their hotel across the street — they had nowhere to go and nothing to do except work on the floor. Other trades, who were local or housed further away, weren’t able to make it to the campus through the snow, so Smock Fansler had the floor to themselves for a few days.
After getting the floor to a 150-grit metal-bond finish, they switched to softer resin-bond diamonds of 100- 200- and 400 grit.
At 400 grit resins, generally considered the line between grinding and polishing, it was time to harden and densify the floor. Consolideck LS (lithium silicate) Hardener/Densifier was specified and used. Applied with pump-up sprayers and micro-fiber applicatoers, LS hardens and densifies concrete by filling the concrete pores with rock-hard calcium silicate hydrate. That’s the same durable material that makes concrete hard to begin with.
Along with being more abrasion- and spill-resistant, the hardened concrete polishes faster and more easily.
Because the treatment penetrates easily and rapidly, there’s no scrubbing in or flushing excess, as with older potassium- and sodium-silicate hardener/densifiers, so jobs go quicker.
After hardening/densifying, the techs took the floor up to a 1500-grit finish with softer resin-bond diamonds.
They protected it with a micro-thin coating of Consolideck LSGuard. The “LS” prefix means the protective coating contains lithium-silicate, like LS, for a further hardening/densifying effect.
LSGuard heats up while being burnished on, and “melds” with the concrete, providing a protective gloss that never needs to be stripped or replaced – a huge savings over the life of a floor compared to other flooring choices.
Heavy propane burnishers running specialized Consolideck HEAT burnishing pads are the recommend application tools, but Mr. Fansler’s crew only had a light-weight electric burnisher.
“Even though we had the HEAT pads, our burnisher didn’t have enough weight. We couldn’t create the amount of friction we needed to heat up the LSGuard to the temperature needed to get the gloss level we were after,” Mr. Fansler said.
They switched back to their 650-pound grinding-polishing machines — which easly had enough weight — equipped with the 1500-grit resin bond diamonds.
“That did the trick,” Mr. Fansler said. “In some places you look down the hallway and you can’t even see the floor. All you can see are the lights and walls reflected in it.”
“We’ve done acid-stained and epoxy floors, but this was our first experience with polished concrete,” Mr. Ritter said. “We won’t hesitate to recommend polished concrete again on projects where appearance, performance and sustainability are the priorities.”
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Students file into the recently completed Donald V. Fites Engineering Innovation Center at Valparaiso University. photo courtesy Design Organization