A couple of weeks ago Dan Simoneau, a Project Manager at Capform, invited me to drop by and see the cast-in-place architectural concrete work they have been doing at the Kimbell Art Museum in Ft. Worth, Texas. https://www.kimbellart.org/ For those of you that aren’t familiar with the Kimbell, it was designed by Louis Kahn and is widely recognized as a prime example of CIP architectural concrete. Now the Kimbell is adding the Piano Pavillion, named for renowned architect Renzo Piano and not for the musical instrument. With BECK as the General Contractor, Capform provided the forming and placing services for the project. If you understand architectural concrete and know what you are looking at, the results this group have achieved are nothing short of amazing!
For those of you familiar with architectural concrete, when you look at the concrete at the existing Kimbell museum you may wonder why the concrete is so highly regarded, since the concrete is covered in imperfections. However, if you think about it for a bit, it doesn’t take long to have an “ah ha” moment when the light bulb goes on. What follows is strictly my interpretation of the building and may not reflect what Kahn intended, but I like mine anyway.
There is no doubt that the Kimbell is an outstanding art museum. The American Alliance of Museums ranks it as #36 in its “Top 100 Art Museums”. That’s pretty good considering that most of the museums ranked higher are in much larger cities, including New York, Chicago, Washington DC and San Francisco. Add to that the fact that at first glance Ft. Worth doesn’t seem like a cultural mecca. In fact, it bills itself as “Cow Town”. The museum is located in the Ft. Worth cultural district, not too far from where the Ft. Worth Stock Show and Rodeo is held each year. If the Kimbell had been constructed with glass and marble, it would have been perceived as a diamond in a coal bin – totally out of place. Kahn’s use of architectural concrete provided an oyster shell that fit right in with the solid, down-home nature of Ft. Worth society, but when it was opened it revealed the pearls held within. (Yes, I know this interpretation is sugary sweet, but that doesn’t make it any less valid.)
Since the Kimbell was completed in 1972 (just 2 years after I moved to Dallas) Ft. Worth has changed. Water Gardens, designed by New York architects Philip Johnson and John Burgee, was built as an oasis in downtown Ft. Worth. It later served as a site for part of the old sci-fi thriller Logan’s Run. First United Tower, a 42 story cast-in-place architectural concrete office building, became the tallest downtown building. Tadea Ando designed the Ft. Worth Museum of Modern Art. Cow Town has slicked back its hair and shined its boots. Some of the greatest cultural events in Texas occur in Ft. Worth. Touring art exhibits routinely bypass Dallas and Houston and head to Ft. Worth.
Reflecting this change, but staying rooted in the past, Renzo Piano has designed an addition that brings the Kimbell forward into modern Ft. Worth. Its main structure is smoother and sleeker than the original Kahn building, but remains tied to its original roots. Again, those who know what to look for will be amazed by what Capform has been able to do with Piano’s design. While I took lots of pictures during my tour, I promised not to publish any before the opening of the new building so as not to detract from the grand unveiling by exposing the unfinished elements in the building. However, I do want concrete aficionado’s to be aware of what to look for when they visit the museum.
One of the first things that will be noticeable is the massive concrete walls that make up the structure. Not only do these walls define the limits of the exhibit spaces in the museum, but they also reflect and direct light into the building. Some of the walls slope slightly to better capture and redirect sunlight without creating glare. Most concrete people, when they think of architectural concrete walls, think of walls broken up into a 4’ x 8’ pattern of exposed plywood butt joints. Not so at the new Kimbell. Oversize high-density overlaid plywood was used to minimize form butt joints. Even on some of the 20 foot walls, the only butt joints are vertical joints, and those vertical joints are space much farther apart than the normal 4 feet. The form butt joints that were required were treated with silicone caulk to reduce leakage to almost zero.
Even the use of tie holes is minimized. In one gallery a special heavy duty brace was used to support wooden forms so that ties were used every 20 feet or so (I didn’t have a tape measure to measure the actual dimensions). This totally blew me away.
In the parking garage, lined Sonotube was used to avoid the barber-pole effect often exhibited by round concrete columns. The same types of forms were used in some of the interior public spaces in the Ft. Worth Museum of Modern Art. In my opinion this is the type of formwork that should be used in all round exposed concrete columns.
Of all the things that could have gone wrong on this building, about the only things that did go wrong were a shadowing of the reinforcing steel on the concrete surface and some discoloration due to what I think was release agent staining. (Let me state for the record that I have been involved with architectural concrete for over 35 years and, given the architectural finish objective and the high wall placements I don’t know of any way to eliminate reinforcing steel shadowing in this case. If any reader knows how to do it, please let me know! As for the release agent staining, I think this should minimize over time. Cleaning with a non-acid masonry cleaner may help, but it may also change the color of the concrete so the process needs to be tested on a non-exposed area first.)
Almost every architect I meet wants their concrete walls to appear monolithic with no form ties or form butt joints. This project comes as close to achieving that goal as any I have ever seen. Any architect who wants more should specify paint. However, this appearance came with a major cost. Multiple mockups were cast to determine the best materials and procedures to use on the building. Fortunately most of the mockups were cast as part of the non-exposed structure and were not throw-away items. The materials and techniques used cost a substantial premium. The final add-on to the price was the planned cost of removing work that didn’t meet Piano’s requirements. Fortunately very little concrete had to be removed.
Any Architect or Contractor who wants to design or build architectural concrete should come see this building after it opens, presumably in late 2013. However, architects need to be aware that specifying the finishes achieved in this building will add a major premium to the cost of the concrete. This building can be used as an extreme example of what can be achieved, provided the Owner wants to pay the price. Normal architectural finish alternatives will be a much more attractive alternative after comparing the costs of the alternatives.
Thanks again for the invitation to visit, Dan. I enjoyed getting out of the office and visiting your project.
For those of you interested in architectural concrete, I found a great blog – CONCRETEDESIGNBLOG – http://concretedesignblog.com/. Check it out for examples of architectural concrete, not only in buildings but also other elements.
Until next time,