All the stars aligned when Innovative Concrete Systems (ICS) began work on the Cross Border Xpress in San Diego’s Otay Mesa neighborhood. After more than six years of planning, design, and permitting with government agencies on both sides of the U.S./Mexico border, a private investment group was finally building a pedestrian bridge between the two countries.

Instead of spending two to four hours driving across the border, Americans traveling to Mexico check in at a new terminal in the U.S., take an escalator up a floor, and walk 390 feet over the border directly into the Tijuana International Airport terminal.

ICS General Superintendent David Klemaske figured everything was under control. He and his team had:

  • Won the job of polishing 48,300 square feet as subcontractor to concrete placement contractor Triton Structural. Although ICS and Triton are subsidiaries of T.B. Penick & Sons Inc. in San Diego, Triton doesn’t automatically awards decorative and polishing contracts to ICS.
  • Helped Triton deliver the flattest floor possible by specifying American Concrete Institute (ACI 117) floor flatness (FF) number 50 (1/8 inch in 10 feet)
  • Persuaded the architect and owner that 1/8-inch strips of zinc inserted in saw cuts and epoxied into place would be prettier and easier to maintain than tile bands between the joints.
  • Ensured the client was confident that any damage to the polished surface would be skillfully remediated.

Owner Challenge: Find the Crack

One standard operating procedure is central to ICS’s success. To make sure clients get the floor they envision, the company polishes a 20-foot-by-20-foot section to the specified finish before each job.

Cross Border Xpress floors were integrally colored with Davis Colors’ Palomino 5447 pigment. ICS showed the client three polish levels: cream, which polishes the cream of the concrete surface and shows little to no sand; cream/sand, which also polishes the cream but shows sands; and heavy sand/aggregate, which shows a lot of sands and starts exposing aggregates in the slab. The owner chose cream/sand.

To prove ICS could seamlessly repair cracks and other damage, the general contractor took a sledgehammer to the floor around a core sample. ICS was told to fill the hole and repair the radiating cracks and spalling.

Crews got a 5-gallon bucket of the cement and a 5-gallon bucket of the sand used in the mix from the plant that supplied the concrete. Then they used a piece of plywood to make a palette of fill colors based on Hi-Tech Systems’ Spall FX2 and Spall TX3 epoxies. Formula A is the base color; say, one cup epoxy and two teaspoons pigment. Pigment amount is adjusted up or down to make the fill lighter or darker and each formula written next to the fill color. When the palette’s dry, crews have the instructions for making whatever fill they need to match integral concrete’s mottling at any given spot.

ICS opens the crack with a 1/16-wide dremel, overfills with the selected color, grinds the surface, and then polishes.

“We’ve done the same thing with deep grinds,” Klemaske says. “We get the aggregate from the plant. We take a hammer and smash it up; we widen the crack and fill it in. Then we grind it and polish it. Sometimes we can’t make a crack completely disappear, but it’s not visible to the untrained eye.”

In the case of the Cross Border Express, the owner had to get down on hands and knees to see.

Keeping it Safe

Polishing occurred months after the pour because this was new construction. Other trades would be erecting steel-frame walls, installing the roof, etc. Windows would be installed while polishing crews were on site and baseboards installed after polishing.

Klemaske requested Skudo USA floor protection because ICS has had positive experience with the products. That was fine with the general contractor, which didn’t look forward to maintaining plywood or Masonite for months on end while other trades did their work.

After removing the floor protection, ICS crews used Terrco Inc.’s Model 701-S two-head polisher equipped with Syntec Diamond Tools Inc. Syn-OCTTO 80 mm resin pads in 50, 100, 200, and 400 grit.