2014 Readers' Choice Winner
When TTM Finishes Inc. began the job, the mall’s general contractor had dumped self-leveling concrete all over the floor in an attempt to level it, but instead actually left quite a mess with large drops in floor height and mounds of concrete materials in other areas.
TTM Finishes ground off this underlayment material and measured the floor with lasers, finding high spots around the columns. The slabs around the support columns were separate pours from the surrounding floor. Height differences throughout the floor measured more than 3 inches. The polishing contractor used a concrete shaver and a scarifier to get these large height discrepancies down to a reasonably flat condition of about 1/2- to ¾-inch throughout the floor.
The crew used Diamatic 780 grinders to grind the entire floor as flat as possible. In areas with significant pitting and deep scrapes in the surface, crew members used a shotblaster to go over the surface to clean out the pits. They then patched the floor where necessary and filled some trenches created for electrical conduit and plumbing with CPD Rapidcrete concrete. Afterward, they reground sections of the floor.
TTM then did moisture testing and found very high readings, so the contractor decided to put down a double coat of Ardex MC Rapid Moisture Barrier epoxy with a broadcast of white lightning in the second coat to serve as the bonding material for the Ardex PC-T Concrete.
Once everything was dried and cured, workers swept and vacuumed the entire surface and began laying out a dyke/pour pattern. They divided the floor into five relatively even sections and began the concrete pour in section one and continued in three and five before removing the dykes and pouring concrete in sections two and four to complete the floor.
The following day, they began to grind and polish the floor, starting with 80-grit diamonds from NuFinish on the Diamatic 780 grinders.
TTM did have some extra work on the pour joints themselves and used an HTC-500 grinder with NuFinish 55-grit diamonds. The crew continued the process up to the 150-grit metal bond diamonds. They then dropped down to the 100-grit resin diamonds, went to the 200-grit, and then up to the 400-grit resin.
Crew members then densified the floor with Ardex PC-10 nano lithium silicate densifier. After densifying, they used the HTC-500 grinders with HTC Fenix pads starting with 200-grit pads and finishing with the 800 grit pads.
After finishing and again vacuuming the floor, they applied a coat of Ardex/Diamatic floor finish Stainguard and burnished the floor using a 1500-grit diamond burnishing pad from HTC.
With the floor complete and total height discrepancies down to ¼-inch throughout the floor, TTM turned it over the general contractor and the client, Aritzia Corp.
Editor’s note: This project was showcased in the August 2014 issue of Concrete Surfaces. Read the article, "Showroom Quality."