The practical and technical issues of repairs on concrete structures, especially on modern architecture with an exposed concrete surface, is not a new subject. Nearly 20 years ago, Docomomo published The Fair Face of Concrete, recounting many significant concrete restoration projects and discussing philosophical questions concrete repair that still plague us today. However, within the past few years there has been an increased intrigue surrounding modern, exposed concrete buildings, especially among the general public, as evidenced by the sheer number of books, articles, and blogs on the subject. This heightened attention is changing how we determine treatment and preserve these buildings today. Seemingly, now more than ever, restorations are honoring the intended exposed concrete surface, which in the past was subject of contempt, often coated over for aesthetic but also protective means.

Over the course of this past year, my thesis work set out to evaluate the restoration and repair work done to the body of work of one particular architect, Bertrand Goldberg. His structures are dynamic works of engineering, characterized by monumental sculptural concrete forms and often designed with an exposed concrete finish. Recently, two of his buildings have been in the news; Prentice Women’s Hospital lost its preservation battle and was razed in 2015 while Marina City was granted landmark status by the city of Chicago in March 2016.

Goldberg is among a generation of architects who designed their work in reinforced concrete for both the freedom of form that it permitted and the economy that it provided. Many of these buildings have gone through major restorations, renovations, and repairs throughout the years.  Because the aesthetic of exposed concrete has generally been either dismissed or entirely despised, Goldberg’s buildings and many others, have been subject to coating treatments which completely transforming the character of the building. These repairs and restorations are often inconsistent with, and insensitive to, the intentions of the original architects who prioritized the surface of the concrete exterior as part of the overall expression of the architectural work. I looked at three sites designed by Goldberg – the Marina City residential towers, the Raymond Hilliard Center buildings, and the River City II complex – to illustrate this point. Designed and constructed over the course of nearly 30 years, each of the structures were intended to have an exposed concrete surface that has seen a variety of treatments throughout their history. 

Marina City

The Marina City towers were the tallest residential buildings and the tallest reinforced concrete structures in the world when they were completed, topping out at 588 feet each.¹  The iconic towers were built as part of a development project bordering the north side of the Chicago River. The structure, a central core with radial beams and 16 perimeter columns, was constructed of structural light-weight concrete. It was this same concrete that was intended to remain exposed as the smooth finished surface. The formwork to achieve the smooth surface was constructed of lightweight fiberglass. In the 1960s, fiberglass forms were becoming increasingly popular as they provided a means of producing a finished concrete surface without additional work of grinding, allowed for any special pattern or design to be directly set into the concrete, were economical when reused repeatedly throughout construction, and withstood multiple pours without deformation.² The forms created for Marina City by Engineered Concrete Forms of Chicago were successful for all these reasons.

In 1977, the property management company, as part of the towers’ conversion to condominium units, embarked on a major “improvement” campaign. As part of this, the concrete was repaired with high modulus epoxy and the entire surface of the buildings was coated with Modac, an acrylic solvent based waterproofing coating, thus changing the color of the towers from gray to light tan.³ Although this decision to coat the towers was based purely on aesthetic preference by the owner, by the late 1980s the concrete and coating were quickly deteriorating. A report by Wiss, Janney, Elstner in 1989 attributed the concrete failure to two main sources; inadequate concrete cover over the reinforcement in certain locations and even more deleterious, chloride ions in the concrete.⁴ 

Based off on WJE recommendations, major repair work began in the 1990s that included replacing large areas of the concrete, especially at the balconies, and recoating the surface.  This re-applied coating reduced the on-going corrosion of the embedded reinforcement.⁵ Marina City was last painted in 2003. Overall, the rate of repairs over the years have considerably dropped since these major repairs took place, and the repair work to the façade has sought to retain the appearance of the building from when it was coated in the late 1970s.

Hilliard Center

Completed in 1966, the Hilliard Homes were a project of the Chicago Housing Authority. Goldberg, whose Marina City venture proved successful, was asked by the CHA to design their newest site. The relative “success” of Hilliard was attributed to design that focused on community engagement.⁶ Goldberg’s scheme for the project involved four concrete towers (two circular towers for elderly housing and two curved towers for families), a low-lying glass and steel box for community activities, and an outdoor auditorium and courtyard. The residential structures were innovative in that they had an exterior loadbearing “shell” of concrete. Goldberg, in an attempt “to achieve optimal structure and living space within one shell form” was able to open up the core area to allow for community space and create “dynamic” curving interiors that created a sense of individuality among the units’ inhabitants.⁷ The towers were built using slip-form construction. While originally used in the 1920s as a method for constructing grain silos and other tall industrial structures, the Hilliard buildings were among the first non-industrial buildings to be constructed using this technique.⁸ The board formed texture, with the boards running in a vertical direction, was intended to be left as the exposed finish texture on the towers.⁹ Goldberg felt that the tower’s lack of dramatic form could be compensated with a highly textured surface created by the wooden boards.¹⁰

The building’s exposed concrete surface remained as such until the early 21st century. By the mid-1990s the towers were in extreme disrepair but despite the dilapidation, there was a clear intention to spare the buildings from demolition.¹¹ Peter Holsten, a developer in Chicago, purchased the property, the site was placed on the National Register in 1999, and the project of renovating affordable family and senior apartments moved forward using Federal Historic Tax Credits. The concrete failure, caused by inadequate surface cover over the steel rebar, proved to require costly repairs and the chief architect at the Illinois SHPO who reviewed the project asserted that realistically, without a coating, the newly patched concrete would spall again within a few years.¹² Sharon Park, Chief of the Tax Credit Section of NPS, approved the practice of coating the concrete on this project as complying with professional standards. After clear coatings were deemed too glossy, an opaque coating was chosen that was color matched to the original, clean concrete. TammsCoat, a high performance, water-based acrylic coating, was chosen based its ability to retain the concrete texture and visibility of the vertical board formed ribbing.¹³  Although the concrete was coated, there was a point to retain as much of the intended surface texture as possible. Today, sporadic patching is required on the buildings’ surfaces but not to the extent that it was needed in the early 2000s.

River City

River City, completed in 1986, is considered a culmination of all Goldberg’s previous forays into housing and mixed-use programming. According to architectural critic Ross Miller, the project was an opportunity for Goldberg “to develop and refine an engineering, architectural and sociological program on a grand scale.”[14] The mid-rise housing complex featured commercial, retail, educational, & recreation space as well as 446 residences.¹⁵ The structure of River City functions similarly to that of the Hilliard towers in that the exterior concrete shell provides much of the structural support of the building. The cast-in-place concrete was built using formwork that was designed and detailed by BGA. Like with all of his works in concrete, Goldberg payed close attention to the surface texture and the majority of the building’s surface is concrete with vertical, protruding “V”-shaped ribs, resulting from the formwork.¹⁶

Although River City was constructed relatively recently, poor construction management and workmanship led to issues with the concrete from the beginning. According to meeting minutes from the project, the contractor was caught using grooved finform plywood instead of the approved, grooved fiberglass-lined formwork.¹⁷ In addition, forms were not cleaned between pours, there were gaps between form and concrete where forms had been placed against existing slab edges, and patching material was applied in freezing temperatures.¹⁸

From the time the building was completed until the present day, many of the spalls and cracks in the concrete shell exterior were filled in with an epoxy sealant. Recently, however, the residents, understanding the significance in retaining the original appearance of the exposed concrete, have begun to make improvements to the structure of River City. One of these projects, potentially starting this year, will be to remove the unsightly epoxy fills and patches and replace them with a highly compatible cementitious fill that would match the existing concrete both physically and aesthetically.

As time goes on, the preservation community and society at large is not only recognizing the significance of Goldberg’s architecture, but coming to appreciate the aesthetic of exposed concrete architecture and embrace the narrative that modern concrete buildings can be significant and worth saving. Thus, when it comes to rehabilitation work to the exterior of Goldberg’s buildings, we now tend to value features of the architect’s original design, including the surface appearance. A building’s exterior surface, especially when it is expressed in one solid material (in this case concrete) is integral with the building’s design and often highly designed. Through researching Goldberg, his particular use of concrete, and his intentions for these buildings, clearly the surface of his structures was a highly significant feature of his buildings. Moving forward, a great effort should be made to retain what is left of the concrete surfaces of Goldberg’s works. In general, it does seem that more appropriate decisions are being made as evidenced by the recent and future work on River City.

About the Author

Andrea will be completing her MS in Historic Preservation this May from Columbia University and is being thoughtfully advised by Theodore Prudon. Prior to moving to New York, she graduated with a degree in architecture form the University of Illinois in Champaign-Urbana and worked in Chicago as a junior architect. Andrea is a pursuing a career as a preservation architect and currently works at Beyer Blinder Belle in New York City. She is also a current member of Docomomo US.

Notes

[1] “Marina City-World’s Tallest: Apartment Buildings, Reinforced Concrete Buildings” Concrete Facts (Expanded Shale, Clay and Slate Institute, Vol. 8, No. 1), 2-3.

[2] Richard J. Kirby, “Fiberglass Forms – A Progress Report”, 1962, The Aberdeen Group.

[3] “The End is Coming: Marina City goes Condo,” The Biography of Chicago’s Marina City. http://www.marinacity.org/history/story/goes_condo.htm
[4] Wiss, Janney, Elstner Associates, Inc. “Investigation of the Exterior Concrete and Waterproofing on Marina Towers for the Marina Towers Condominium Association Chicago, Illinois” WJE NO. 881397 October 20, 1989. Source: Bertrand Goldberg Archive, Ryerson and Burnham Library at the Art Institute of Chicago, Series VI, Box 18, Folder 18.6 (accessed Thursday December 29, 2016). 

[5] Duntemann, John and Brian Greve, “Marina City – The History and Restoration of an Iconic Façade,” IABSE Conference – Structural Engineering, Providing Solutions to Global Challenges, September 23-25 2015, Geneva, Switzerland.
[6] Betty J. Blum, Oral history of Bertrand Goldberg, interview (1993): 185.

[7] John W. and Heinrich Klotz, Conversations with Architects (New York: Praeger, 1973), 125.

[8] Carl W. Condit, Chicago, 1930-70: Building, Planning, and Urban Technology (Chicago: University of Chicago, 1974), 58.

[9] Spec section: Division D-4A Cast-in-place Concrete:  4A-09.5 Exposed-Finished Surfaces, source:

[10] John W. and Heinrich Klotz, Conversations with Architects (New York: Praeger, 1973), 143.

[11] Maya Dukmasova, “The Goldberg Variation: High-rise Public Housing That Works.” Chicago Reader, Nov. 5, 2016.

[12] Carol Dyson, email to author, December 1, 2016.

[13] Greene, Thom. Thom Greene to Mike Jackson and Carol Dyson Re: Hilliard Homes Exterior Concrete Finish, September 12, 2003. Letter. Courtesy of Greene & Proppe Design Inc., email from Thom Greene February 6, 2017.
[14] Betty J. Blum, Oral history of Bertrand Goldberg, interview (1993): 254.

[15] Geoffrey Goldberg. “Bertrand Goldberg: A Personal View of Architecture” Chicago Architecture: Histories, Revisions, Alternatives edited by Charles Waldheim and Katerina Ruedi Ray (Chicago: University of Chicago, 2005), 237.

[16] Specifications Section 03300 Structural Concrete: Section 13.2
[17] “River City II Project Meeting Minutes” June 26th, 1984 (Tuesday) 8:30AM; source: Bertrand Goldberg Archive, Ryerson and Burnham Library at the Art Institute of Chicago, Series VIII, Box 23, Folder 23.20.

[18] Cunov, Robert C, Bertrand Goldberg Associates, “Field Inspection Report” November 6, 1984, River City II; source: Bertrand Goldberg Archive, Ryerson and Burnham Library at the Art Institute of Chicago, Series VIII, Box 23, Folder 23.20.