Perfection Not Required
December 31, 2012
Before I get started on today’s blog, I would like to take this opportunity to wish everyone “Happy Holidays”. I would also like to wish everyone a happy, peaceful and prosperous New ear.
As part of our Christmas festivities this year, our whole family went down to the new Perot Museum of Nature and Science, www.perotmuseum.org, in Dallas, Texas. There are a lot of great things about this brand new museum that just opened on December 1, 2012, the best of which for most is that the place was packed with people. Both kids and their parents are clamoring to see the museum and explore science and nature. However, I must admit I will be glad to go back in about a year after the crowds have died down.
The best part of the trip for me was seeing the building itself. The primary architectural material in the museum is architectural concrete. While much of the industry knows me for my work with quality control software, another large segment recognizes the Shilstone name for my father’s and my work with architectural concrete. In fact, when my father left Shilstone Testing Lab in 1962, he formed a company called Architectural Concrete Consultants, Inc. Even today I still do limited architectural concrete consulting in my spare time. It gives me the opportunity to see concrete not only from the producer and contractor side, but also from the design side.
Anyway, back to the building. The majority of the exterior building surface is composed of precast panels with a series of ridges and ledges along the face. Inside there are concrete shear walls, columns and beams that are exposed to public view. A lot of money was spent on the building and when I first approached it I was in awe of the beauty of the concrete surface. Then I looked a little bit closer. There were mistakes everywhere!
I saw form leakage at the bottom of walls. I saw honeycomb in the middle of walls. I even saw a wall where a section of rustication had fallen off of the top of the form and become embedded in the face of the wall. I was flabbergasted (which means “really amazed” to people who don’t speak English well). I was taking so many pictures of the problems with the concrete that my family was becoming embarrassed. My daughter said, “Dad, everyone is having a great time in this wonderful museum and you are taking pictures of the concrete.”
Then I started watching the people. My daughter was right. Except for a couple of people who were obviously in the industry, no one cared how the concrete looked. I watched 50 people walk right past the wall with the fallen rustication in the middle and not a single person looked at it. I then looked at the concrete again. It was by no means ugly. In fact, there were a lot of good features about it. The form butt joints didn’t leak (much). The tie holes were nice and crisp, with a recessed patch plug. The lift lines I saw were minimal and were level. The squared off corners of the columns were very clean, with almost no leakage. In short, the concrete looked solid and strong. It gave confidence that the building was going to last for a long time. An exhibit about the building discussed the sustainability value of the concrete structure. In other words, this was “good” concrete.
I later realized that, even though there were multiple “defects” in the concrete, there was no attempt to patch the flaws. In particular, the spot with the broken rustication could have been patched and no one would have realized what the original problem was. The Architect elected to leave the defects as they were. The result was that the concrete had “character”. It wasn’t perfect. It told a story to those who knew how to read it. Most of all, it was good enough to not detract from the main theme of the museum, which was to teach about science and nature. I got the feeling that Thom Mayne, of Morphosis Architects, really understood concrete in a way that many architects don’t.
When I work with a lot of architects, they expect concrete to be something it isn’t. They will stand right in front of a concrete wall and nit-pick it to death, even though ACI 303, Cast-in-Place Architectural Concrete, says that architectural concrete should be evaluated from a distance of about 20 feet (6 meters). They either expect the concrete to all be a uniform color, like paint, or they expect to be able to dictate the size, quantity and location of every exposed aggregate particle. They won’t accept that the concrete construction process is variable, and that concrete sometimes requires patching. They don’t understand the concrete construction process and expect a contractor to be able to cast a 30 foot high wall with no form joints or construction joints. Concrete isn’t perfect, but its imperfection gives it character. The Sphinx, in Cairo, is missing its nose, but does that reduce its value to humanity? If anything, this imperfection emphasizes the transience of all man’s works and gives it more value.
My father use to say that “concrete is the only manufacturing process that takes place on a construction site”. A cast-in-place concrete column does not exist until it is created in the structure. Everything else on the project is just assembling Tinker Toys. Windows, carpet, HVAC and other components are manufactured elsewhere, then assembled at the jobsite. Architects who understand the concrete manufacturing process can design their buildings to fit within the process, resulting in a more attractive, economical structure. The Mississippi Power and Light building, a 7 story office building located 1 block from the ocean in Gulfport, Mississippi, has survived two Category 5 hurricanes with only minor damage.
Do I want everything to be perfect on my architectural concrete projects? Of course I do. I try to take into consideration every possible variable when I work on a project, but of course no one and nothing is perfect. After 35 years I am still learning things about concrete. However, concrete is a variable material and will have a variable appearance. Formwork has tolerances which must be allowed form. Segregation and variable placement processes take place. The result is defects in the concrete. However, many of the defects I see will only be noticed by another architectural concrete consultant or an architect. The vast majority of the public will only see “concrete” – an imperfect material for an imperfect world.