"We primarily use Scofield," Paredes says. "We have a good rapport with them and have been happy with the quality of the product."
The concrete was then finished with standard straight-edge screeds by hand.
"We couldn't use power screeds because that would push the rock down and ruin the look," McGill says.
When the concrete reached the proper texture, a 125 topcast retarder was applied. The concrete was then covered with plastic for the night. The next day it was cleaned with an acid wash and sprayed with a pressure washer to remove residue. The concrete was sealed with Diamond Clear VOX, a water-based sealer.
"Solvent-based is what we usually use, but in a high-traffic area like this we wanted the better penetration we'd get with water-based," Paredes says.
Decorative cuts were made in the finished concrete to create a system of 10-ft. by 10-ft. squares.
Landing the job
With a project this complex, there are only a few companies in Atlanta that could have taken on the challenge. Precision's experience with difficult jobs and the company's relationship with the general contractor and MARTA were key to getting the contract.
"We've done quite a few projects with Beatty Construction and we have a lot of experience working in MARTA stations, so that was probably the biggest factor," Stimmel says. "We have competent people that do the work — good employees who know what they're doing. That's why we're able to be successful."