Residential Winner: New Construction
The design by Jeff Gillam originally called for a concrete wall to be covered with thin-cut natural stone to make the bench. This bench was the centerpiece of the project, to entice people to the courtyard area from the covered kitchen. Continuity was an important aspect for the overall flow, with the stone also being used on the fireplace and exterior wall of the kitchen. The owner had some concerns about how comfortable sitting on the rough-surfaced limestone would be, and how the wall would feel when leaning back while sitting. At this point, Boulder Polishing introduced the idea of polishing the concrete wall instead of applying stone. A small curved mock-up was made, and the owner was pleased with the potential.
A large footing was built to give a platform to frame up the wall for the bench, and dug down below the frost line to minimize movement. The complex part of framing the bench was not just making a curved form, but also sloping the backrest portion for comfort while keeping the back wall vertical. This was accomplished by separating the front forms at the bench line, using stiff backs to brace from, and achieving a 2-inch variation from the top of the bench seat to the top of the wall, allowing the client to lean back slightly as in a chair.
Boulder Polishing worked with Salina Concrete Products (SCP) to design a mix that would achieve the strength needed while also keeping in mind the environment. For an aggregate, Boulder worked with the local sand pit, Alsop Sand, and found a pea gravel that they considered a waste product because it was too small to be considered river rock. Then Boulder used 50% fly ash as part of the mix design. Since the concrete was to be colored brown, this allowed Boulder to cut back on pigment by 20%. The bench seat was done separately without the fly ash, using a 5-pound-per-sack ratio; it matched perfectly. Also, the bench matched well with the stamped concrete border that is part of the courtyard.
Polishing a curved wall presents challenges. Boulder Polishing wanted to expose the aggregate as much as possible, but was concerned that the deeper they ground, the more imperfections would surface. These flaws could change how the daylight would reflect across the surface. As a solution, Boulder took over very thin layers, continually going around the wall, avoiding any cupping by the wheel. The result was a smooth, level surface.
The clients love how the bench is a focal point of the courtyard, and how comfortable it is to relax on while entertaining. Their daughter was married this past summer and the bench received the most compliments of the whole project.