Critiquing Polishable Self-leveling Cementitious Toppings

HTS polishing and grinding machine being used on a polishable self-leveling cementitious toppingFour manufacturers of concrete resurfacing and repair products took on the challenge presented by the Operative Plasterers & Cement Masons International Association (OPCMIA) Local 528 last July in Seattle.

The challenge: Apply competing brands of self-leveling toppings in grey and white bases onto a temporary concrete substrate on Monday morning. Grind, polish and add a few design treatments on Wednesday and Thursday, and on Friday, invite Seattle-based architects, designers and contractors to critique the results of each of these manufacturers’ products.

Under the watchful eyes of Concrete Decor magazine and Local 528 training directors Mark Maher and Frank Benish, representatives from ProSpec, Ardex Engineered Cements, Raeco Inc. and Mapei Corp. proved to be gentlemen, demonstrating support and respect for one another and the facilities. Not only was the event educational, it also made a statement about the OPCMIA’s interest in playing a leading role as educators regarding the latest innovations in decorative concrete.

Installing Prospec’s Level Set Wear Topping was Prospec’s product manager, Peter Golter, along with territory sales representative Jim Partridge. Installing Ardex SD-T and SD-M were director of application developments Bruce Newborough and territory sales representative Don Richards. Raeco SLT-HS was installed by technical manager David Landrey and general manager Tony Christopher. Finally, Mapei’s territory sales representative was the first on Monday to make minor crack repairs, apply bonding primer, and have his demo area coated — in his case, with Mapei Ultraplan M20 Plus in grey and white bases.

With little time to spare, the race was on to get these respective products installed and cured by sunrise on Wednesday. That’s when HTC Inc. territory sales representative Tim Herz hit the switch on the HTC 500 planetary grinder and began his initial pass on each of these overlays with an 80-grit metal pad. As the polishing process continued, routine inspections were made to evaluate swirl patterns in order to make mechanical adjustments and ensure the best-quality finishes for each overlay.

Grind, polish and add a few design treatments on Wednesday and Thursday, and on Friday, invite Seattle-based architects, designers and contractors to critique the results of each of these manufacturers’ products.As the polishing proceeded, Raeco took advantage of a window to apply a hardener/densifier. Raeco’s David Landrey says that in order to get a consistent salt-and-pepper finish, they used slightly less water in their mix to keep the sand evenly dispersed. With overlays containing higher cement content, this kind of adjustment is recommended only when the applicator has consulted with the manufacturer’s technical support.

As Thursday gave way to another sunny day in Seattle, random cracks that were not addressed on Monday during the surface preparation phase started showing up again. They created opportunities for applicators to exercise some creativity. Given the fact that these products were being applied to a temporary and substandard slab, this was an ideal time to demonstrate that these kinds of overlays can provide customers with a range of sheen levels, as well as design options that might involve integral coloring, grooving and colored grouts, topical stains and dyes, and all kinds of stencil patterns. A light burnishing was the finishing touch.

I was thoroughly impressed with the overall finish that each of these manufacturers delivered. So too were a number of architects and contractors who stopped by that Friday to evaluate the results and enjoy a presentation by Tanya Wattenburg Komas, Ph.D., of California State University, Chico, on historic concrete bunkers at Pointe-Du-Hoc, France.

These products also answer an important call from designers and building owners who are striving to earn LEED credits with “green” products. Manufacturers

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