Aritzia’s fashion boutiques feature natural materials, ambient lighting, and warm finishes for a casual, lounge-like atmosphere. Before the clothing store opened a new location at Hamilton, Ontario’s Lime Ridge Mall in November 2013, one of the first tasks was to transform the space’s uneven, scarred concrete slab into a showroom-level floor.

Flooring contractor TTM Finishes Inc. took on the project, which included grinding and surface prep; putting down a moisture barrier, epoxy, sand bonding layer, and concrete overlay; and round-the-clock polishing and burnishing.

The concrete around several support columns was 1 to 1.5 inches higher than the surrounding concrete slab. (The mall’s GC had placed self-leveling concrete in an attempt to make the floor acceptable to the new tenant.) TTM ground down those areas and performed spot grinding on various other high spots, bringing the floor flatness variation down from 3 inches to ¾ inch. The contractor also shotblasted heavily damaged and pitted areas. Next, a three-man team armed with an Ardifix polyurethane structural crack repair compound, sand, and a putty knife worked their way across the floor, patching and slightly overfilling gouges and holes so they could be ground flush to the floor later.

Because the floor is a slab on ground, the contractor also tested the relative humidity at 40% of the slab thickness and found that it measured 90% to 96%. To control moisture vapor emissions, the TTM crew applied by squeegee two coats of Ardex MC Rapid moisture barrier, backrolling it for consistent coverage. They used a modified leaf blower to broadcast sand onto the second coat.

Applying the concrete overlay

The contractor divided the floor into five roughly 9x100-foot aisles. Pouring narrow sections allows for better control so you can get the depth of material that you want, says Marco Chiesa, owner of TTM. The crew also mixed and poured batches by hand instead of using a pump, again for better control of material. Workers spread the overlay with gauge rakes, and followed with spiked rollers to pop air bubbles and break the surface tension of the overlay material. The process resulted in a smooth, uniform surface. They also scraped edges to ensure better transitions between sections.