Concrete is a highly sophisticated material … the beauty of what you create comes if you honor the material for what it really is.
~ Louis Kahn


mills studio visited and documented buildings throughout the United States that are either known for their use of exposed concrete as a primary design element, were designed by architects known for their use of exposed concrete, and / or attempt to use exposed concrete in an innovative way. Although mills studio had visited many of these buildings previously, it was important to see and document them with fresh eyes focusing specifically on the character of the concrete in the context of designing and constructing the DTS Project House. mills studio visited particularly relevant projects with the Owner. It was important to see and touch the concrete in person as no matter how good the photography, the context and the visual and tactile qualities of concrete can only truly be experienced in person.

What’s nice about concrete is that it looks unfinished.
~ Zaha Hadid

mills studio purposely visited and documented buildings with very different contexts and scales, and buildings with a great variety of concrete finishes, textures, and colors. It was important to see each building’s exposed concrete in both sun and in shade to see how the concrete either captured or reflected the light, and how the character of the concrete changed whether in sunlight or shade. It was also important to see how the concrete looked and felt during the day and then at night, and in both natural and in artificial light. It was important to see how the concrete was either treated the same or differently from the building’s exterior to interior. It was important to see how the concrete interacted with water elements and did or did not capture the water’s reflections.

It was important to see how different architects combined exposed concrete with other materials and elements and how joints between the concrete other materials were either avoided or were detailed. It was important to see how infrastructure, such as electrical outlets and switches, integrates with the exposed concrete, whether surface mounted or recessed, and how its installation did or did not affect the visual and experiential solidity of the concrete.

It was important to see how the concrete affected other senses than just the eyes. How did the different textures affect touch; how did the different textures affect the temperature of the concrete? How did the different textures affect the acoustical experience of the spaces? It was most critical to see how the concrete first made an overall impression and then how further experience of the smaller scale detailing either reinforced or changed the initial overall impression.

The concrete material itself that we see in the finished buildings has less to do with its final appearance and experiential qualities than what we never see in the finished building. It is the formwork that the concrete is poured against and is absent in the finished building that determines the appearance and character of the finished concrete. Thus, the erection and installation methods for the concrete formwork are in a way what is most important to understand. Cast and precast methods can achieve different results, but whether cast or precast, the formwork used to pour the concrete against leaves its mark in one way or another.

As an organic material, concrete’s appearance is not completely controllable in the construction process, but to a large extent the architect determines the intentional and accidental marks that the formwork leaves in the finished building. The precise material used as the formwork liner and any releasing agents used will determine the finished surface, from smooth and velvety to rough. The lack of or number, size, and spacing of the concrete ties installed to hold the formwork in place during the concrete pour will determine the visual pattern of the finished concrete. The size and configuration of the liner materials will determine the scale and pattern of the visible joint pattern and will determine how the concrete appears to align or not align with other building elements. The sequencing of the concrete pours will necessarily create a pattern of joints also. The detailing of the joints in the liner helps determine if the joint pattern is barely visible or is accentuated; it determines if the concrete recedes or protrudes at the joints.

Although the formwork mostly determines the finished appearance, there are decisions the architect makes regarding the concrete mix, concrete installation, and then treatment of the concrete that also affect the finished appearance and surface qualities. The size of the aggregate, how much water is added, if additives, including color, are added all affect the finished appearance. The temperature of when the concrete is poured, the height the concrete is dropped from the hose, and the time between pours affects the final appearance. The time between the pour and removal of the formwork, and then treatments to expose the aggregate, and application of sealers will all also affect the finished products appearance.      

Since exposed concrete’s finished appearance is the result of all the decisions made and not made during the construction process, it is critically important to understand the details of the process that achieved the results that mills studio viewed, experienced, and documented. Once the Owner and mills studio determined the desired results, we needed to know how to achieve that result. Thus, after seeing in person what was achieved, considerable time was then spent researching in print and video how the various results were achieved. Luckily there is now extensive literature on architects like Louis Kahn and their obsessive attention to the details of how to achieve specific results in concrete.  Louis I. Kahn: Exposed Concrete and Hollow Stones, 1949-1959 (EPFL Press, 2014), written by Roberto Gargiani and Anna Rosellini’s Towards the Zero Degree of Concrete, 1960-1974 (EPFL Press, 2014) are examples of such literature. The stories of the design and construction of many of the relevant buildings are now documented on video, such as the DVD Making the Modern: Tadao Ando creates a museum for the new millennium, 2003, which shows the process behind Ando’s signature concrete.

Along with doing the research to understand as many of the construction details as possible that the architects implemented to provide for certain results in the finished concrete, mills studio also researched to the extent possible what each architect intended for the exposed concrete to specifically contribute to the building as a whole. This research was purposely done after visiting each work, so that mills studio’s impression of the concrete’s contribution to the building was as little biased as possible, but instead based as much as possible only on the first hand experience of the building and its concrete. Determining how the actual experience of the concrete matches up with the architect’s intentions for the building and its concrete, helps mills studio make decisions about how its decisions regarding the concrete will match up with our intentions for the DTS Project House.     

Tadao Ando and Louis Kahn are two of the architects most noted for their use of exposed concrete as their primary architectural expression, and interestingly they approach concrete in very different ways. mills studio visited and documented multiple works by both architects to see how context did or did not alter their approach.  

mills studio visited projects where concrete is combined with another distinctive material like Moshe Safdie’s 1996-2012 Skirball Center in Los Angeles, California, which combines exposed concrete with directly adjacent highly finished stainless steel panels. Morphosis’ 2004 Caltrans Building uses board formed concrete as the base for a steel and glass structure.

mills studio visited projects employing different methods to create texture, from the very heavily textured finish on Allied Works’ 2012 Clyfford Still Museum in Denver, Colorado, achieved with shaped formwork lining, and Machado Silvetti’s 1996-2006 Getty Villa in Los Angeles, California, employing multiple methods, formwork and exposing aggregate, to achieve multiple and varied textures.   

It was very instructive to see buildings like Allied Works’ 2003 Contemporary Art Museum and  Tadao Ando’s 2001 Pulitzer Art Foundation directly adjacent to one another in St. Louis, Missouri. One can more easily see the subtleties of each project’s concrete whenyou can see both projects in a single view. Fort Worth, Texas is home to three adjacent exposed concrete buildings including Tadao Ando’s 2002 Fort Worth Modern, Louis Kahn’s 1972 Kimble Art Museum, along with Renzo Piano’s 2013 Kimble expansion. Todd Williams Billie Tsien’s 1995 Neuroscience Institute in just down the street from Louis Kahn’s 1965 Salk Institute in Lajolla, California, but each project takes a very different approach toward exposed concrete.

Rudolph Schlindler’s 1922 Kings Road House and Todd Williams Billie Tsien’s 1996 Phoenix Art Museum show the use of precast concrete to very different effect and how joints between precast panels can be handled very differently. Carl Maston’s 1962 Hillside Residence in Los Angeles shows how exposed aggregate completely changes the character of exposed concrete. On the opposite extreme, Hagy Belzberg’s 2010 Holocaust Museum and Levitating Mass at LACMA both in Los Angeles, California, make concrete with a plaster like finish showing no joints or other marks indicating the existence of formwork.

The purpose of the exposed concrete in the DTS Project House is defined by mills studio’s architectural agenda. The purpose of visiting and documenting projects employing exposed concrete is not to help determine the purpose of the exposed concrete in the DTS Project House, but to see how the exposed concrete either supports or weakens the architects intentions for the building. And ultimately the purpose is to see how the experience of various exposed concrete options will reinforce the architectural agenda for the DTS Project House.   

Concrete is my material, it’s also a universal material. It does not set limits and the designer can work it at will.
~ Tadao Ando