Maximizing concrete’s benefits
As a building material with measurable and adjustable flowability, concrete can be cast into virtually any shape; this yields an infinite number of project solutions. Tilt-up permits the creation of massive vertical form from a material that easily flows across the form created horizontally. During the forming stage, the tilt-up contractor is basically creating a mold. From the finishing of the casting slab to the caulking of the form joints, the attention to detail and high quality is important.
This level of craft was evidenced by the crew that constructed the Korean War Veterans Memorial in Kansas City, Missouri. The project consists of three panels—two for the wall and one for the roof. The overall shape of each was a parallelogram with 45-degree angles. However, the two faces of the panel were designed to be misaligned. At the bottom of the panel, the faces were offset 203 mm (8 in.) in one direction and at the top 203 mm in the other direction. The edge of the panel in between the two faces was to be triangulated, creating a faceted edge. All this was done within the 203-mm tall edge forming; the faces of the panels were flat.
There are two specific aspects or details of this project that need further explanation. The first is the way the edges were formed. Each one is bent along an axis shifting in orientation. The forming of this condition was very interesting. To complicate things further, this bend was interrupted by several different reveal strips and panel recesses. This simple technique added drama and depth to the form not traditionally expected from flat panels.
The second detail of this project that took advantage of the fluidity of concrete is on the exterior of the memorial where two large images, one on the outside face of each wall, are cast into the concrete. Grooves of varying depths and widths affect light cast on the structure to reveal the imagery. To create the required formliners, photographic images were carved into a wooden ‘tool’ or mold using a computer numerical control (CNC) milling machine. Each mold was then used to create the elastomeric liner.
Another huge advantage of building with tilt-up is the ability to work horizontally. Since tilt-up panels are formed and cast horizontally, there are endless opportunities for unique forms and innovative textures (as discussed in the aforementioned museum project).
The ability to easily deliver form creativity is one of many attributes of tilt-up construction contributing to the resurgence of craft. The form of a tilt-up panel can be manipulated in plan, elevation, or both. Curved, angled, and shaped panels are regularly used and offer designers flexibility not economically practical on most projects.
Photos © Dror Baldinger
Delivering on expectations
As these techniques become more common, it is important there be a tool for communicating expectations. Later this year, the Tilt-Up Concrete Association (TCA) is publishing an updated guideline specification. The new document intends to aid in the communication between project team members, serving as a script for the working relationship between the contractor and the owner’s design team. After all, this team sets the stage for evaluation of the work with a defined set of acceptance standards.
According to Jim Baty, TCA technical director, while specifications do not limit the level of craftsmanship, they do establish the benchmark for expectations.
“The tilt-up industry continues to promote a high level of standard for this benchmark through a packaged guideline specification,” he explained. “The new update to this document that will be issued in the second quarter of 2013 will reaffirm this attention to quality and craftsmanship through minimum expectation language recommended by the professionals found throughout the Tilt-Up Concrete Association.”
Conclusion
Construction is often seen as the necessary means to an end. However, it is imperative design professionals take time to celebrate the tangible ways in which construction plays the most significant role, once again, in the way buildings are achieved. The rate at which the quality of the design and construction of tilt-up buildings is improving is astonishing. Each year, there are projects breaking new ground with a unique finish, an unbelievable form, incredible size, incredible speed, or new applications. Craftsmanship and pride in the industry continues to soar, as tilt-up concrete construction becomes the answer for more projects.
Mitch Bloomquist is a staff member at the Tilt-Up Concrete Association (TCA), the international nonprofit trade association for the global tilt-up concrete construction industry. He earned his master’s degree in architecture from Washington University (Saint Louis, Missouri). Bloomquist contributes to, and oversees, production of multiple publications, including Tilt-Up Today, The Construction of Tilt-Up, and The Architecture of Tilt-Up. Currently, he is working with TCA members on a third publication, The Engineering of Tilt-Up. He serves as the staff liaison to TCA’s safety, promotions, and awards committees, and oversees the organization’s Tilt-Up Achievement Awards Program, Student Design Competition, and Safety Awards Program. Bloomquist was involved in many major projects as an associate with Novak Design Group, an architectural firm in Cedar Rapids, Iowa. He can be contacted via e-mail at mbloomquist@tilt-up.org.
