Cement Age / Concrete Nation

Histories of modern concrete use have rested largely on two features of the material, both deriving from its fluid nature: its relatively inexpensive character for large- scale application compared to older “batch” methods such as masonry or carpentry; and its suitability for expressing elaborate aesthetic intentions.  While these narratives have helped us see the profoundly interconnected nature of materiality and design in the history of building, a deeply consequential pattern of social relations might also be exposed by historicizing this familiar material: a set of conditions associated with capitalism and its labor systems that have undergirded both the commercial and aesthetic appeal of concrete construction in the United States.

Through a critical history of commercial cement and concrete use, we can probe prevailing conceptions of efficient and affordable building processes and how these determinations have supported capital investment.  The priority long given by building firms and owners to cost savings, in other words, frames the historical question, not the answer to our investigations of concrete’s unceasing popularity.  We can find in the 20th-century expansion of concrete use in the US a powerful record of industrial labor relations, including ideas of fair occupational opportunities, reliable technical knowledge, and the origins of both in racial and gender ideologies.  By bringing out the role of majority interests in the wide take-up of concrete, we confront the embeddedness of architecture in timelines of wealth and social influence and engage with the inescapable problem of how as historians we can most fully account for our built and social environments.

For as much as we tend to think of materials as given things, what a material is is historically and disciplinarily contingent. This talk will look at the long period between the industrialization of Portland cement production in the 19th century through to the unprecedented mass deployment of concrete in the postwar period. In doing so, it will trace the impact of the institutions, ideas, and techniques in Western Europe from the turn of the 20th century through the interwar period that helped unleash the flood of concrete in the postwar period. 

This will be a history of the concrete in architecture rather than architecture in concrete with the aim of understanding the ways a material is designed on the way to becoming a structure. Yet, to be clear, this is not viewed as a one-way relationship in which architects or architecture received and made use of something that had already been conceptualized and produced. Architects and architecture were key actors in shaping concrete. 

Concrete was not a fixed material. It was not—as one dominant narrative goes—introduced as a new material in the 19th century and then mastered by engineers and later architects. Over and over again, concrete was designed and redesigned. Its composition changed. Its consistency changed. Its intended uses changed. The means of delivery changed. Its surface changed. And, perhaps most powerfully, conceptions of the material also changed. While trying to understand what is embedded in materials, this talk will also reveal the power of discourse. Concepts about concrete often developed as guiding visions for what the material would become, even at times when such ideas were hard to square with concrete as it existed at the time such visions were put forward. Once established, these notions about concrete continued to change, again reflecting larger societal concerns.

With the naked eye, it's hard to see how a drab gray powder has made such an impact on modern society. Yet, under the microscope, portland cement is shown to be a carefully engineered artificial rock made to suit an ever-growing number of structural, functional, and aesthetic purposes.  While we celebrate the anniversary of Aspdin's invention, it is important to recognize that portland cement development was as much evolution as revolution.  From the mid-eighteenth century, discoveries of rocks that naturally produce hydraulic binders when calcined instigated a search for an artificial cement recipe better suited to industrial process.  Improvements in that recipe continue to be made today.

Viewing portland cement under the microscope allows us to track the evolution of the product and observe how designers have made best use of its properties.  At its earliest in the United States, engineers imported British cement to create artificial stone that could not be made successfully with any other American product.  Once made in the United States, innovative designers such as Rafael Gaustavino could adapt the now inexpensive and reliable product to the creation of sound-absorbing tiles for his soaring vaults and domes.  A small modification of the cement chemistry provided the industry with a non-staining product for marble and limestone masonry of any scale.  Major infrastructural projects of the twentieth century benefited from the Abrams water-cement ratio law and early belite-rich cements that were volume stable.  Further benefit to infrastructure relied on the addition of supplementary cementitious materials that react with portland cement hydrates to yield a more chemically stable and water-resistant matrix. 

"Cast stone,” also known as “concrete stone,” was precast concrete intended to imitate natural stone. This building material evolved dramatically in the US at the end of the 19th and the  beginning of the 20th centuries. In the third quarter of the 19th century, before domestically produced Portland Cement became widely available, a number of different cementing systems were used, generally with natural sands as aggregates. After Portland was adopted, greater verisimilitude was achieved by using crushed stone and slag as aggregates, chiefly to imitate uniform fine grained granites, as well as limestones and marbles. As the material became widely popular, significant increases in production were enabled by switching from casting in rigid molds (cast iron, or plaster and gelatin) to sand casting in a clay sand mix similar to that used to cast iron. This method increased production dramatically, but also required surface tooling of the cast elements to remove a cement-rich mold skin. This tooling gave the cast elements an even more realistic appearance.

Changing tastes in natural stone for architecture in the beginning of the 20th century necessitated different methods of production to imitate newly popular banded and figured sandstones, coquinaceous limestones, and colored granites. Numerous techniques were used, and the resulting products vary dramatically in appearance. 

This talk will review the changes in production that allowed cast stone fabricators to respond to increased demand as well as changing tastes in stone for architecture.

Schokbeton was a company and patented system of Dutch origin for prefabricating reinforced concrete building components. Originally patented in 1934, Schokbeton was hugely successful, as evidenced by its export, licensing, and franchising around the globe. The essence of the Schokbeton patent was lifting and dropping the mould at a high frequency while pouring the concrete (with a low water-cement-factor), instantly compacting the concrete, resulting in very dense concrete, hardly permeable for water and oxygen.

Concrete precasting was a response to a variety of economic, environmental, and social forces working against in-situ concrete construction. After the turn of the twentieth century, ever-increasing labor costs made in-situ construction economically uncompetitive, particularly for architectural-quality concrete. In response, precasting introduced systematized concrete production in a weather-protected plant for more efficient production, manageable construction schedules, consistency, and elevated quality than site construction could achieve.

Schokbeton arrived in the US with the first mainland franchise in 1960 to a newly formed company, Eastern Schokbeton. Eventually, Schokbeton was licensed and franchised nationwide in the US and produced architectural precast concrete for many prominent American mid-century architects.

The intrinsic durability of the material, the high quality of engineering and technical design within the company as well as the cooperation with renowned architects allow for a retrospective analysis of the architectural legacy and impact of Schokbeton.

This duo-presentation will trace Schokbeton’s interesting post-war path from the Netherlands to the USA and its distribution of franchisees and licensees across the USA. It will show many buildings, dive into concrete recipes and refer to archival material to elaborate on the introduction, growth, maturity and decline of Schokbeton. By doing so it will explore how precasting changed concrete architecture was designed and constructed.

Reinforced concrete was an integral part of the construction and development of the Pacific Northwest in the 20th century.  In the 1920s, concrete ‘skyscrapers’ remade a downtown core.   During the Great Depression and WWII, concrete box girder bridges became so lightweight they began to float.  In the post-war period, geometrically precise formwork led to unparalleled thinness and efficiency in thin-shell concrete construction.  

In the early 1950s, the architectural engineer Jack Christiansen emerged as a significant designer of thin-shell structures, bringing a logic of construction and economic efficiency to the architecturally expressive medium.  Because of this approach Christiansen was able to design hundreds of cost-effective, thin-shell structures in the Northwest and beyond, joining a global cohort of thin-shell designers like Felix Candela and Heinz Isler as one of the most prolific in the world.  His design work culminated in the Seattle Kingdome (1976-2000) – the largest, free-standing concrete dome in the world in its time.

Christiansen’s design career provides insight into the particularities of thin shells of reinforced concrete, revealing their latent capabilities and potentials as well as their shortcomings.  The range of structural forms and architectural uses speak to their strength and versatility.  However, building performance concerns of waterproofing, insulation and acoustical treatment often complicated their future success.

In the Spanish Caribbean (Cuba, Puerto Rico, and the Dominican Republic), imported materials and construction techniques helped produce buildings that were fire, water, and vermin-proof, during the first decades of the 20th century. Prefabrication, standardization, manufacturing speed and installation, as well as innovative means and methods, revolutionized the construction industry of the region.  Often earlier than in the United States, and almost immediately adopted, was imported “Portland” cement. As one of the most innovative materials of the 19th century, cement in barrels as well as prefabricated ornamental floor tiles were imported, embraced, and used in these island-countries since the late 1900s.  Cement was used to produce blocks or artificial stone, cast-stone, ornamental floor tiles, reinforced concrete, and many other molded cladding materials used as covering for steel-framed structures.  The use of cement (quick-setting due to the high humidity of the local tropical climate) produced long-lasting individual components and buildings that would survive indefinitely in these territories affected by high marine salinity, earthquakes and hurricanes. 

Regional cement factories were established as early as 1895 in Cuba, facilitating faster fabrication methods, since the lighter new buildings were constructed with the use of repetitive processes facilitated using reusable molds. This mostly early 20^th century molded architecture, with an infinite series of combinable elements such as columns, balconies, ornament, as well as roofs and walls made with Portland cement, quickly filled neighborhoods in Cuban, Puerto Rican and Dominican environs. Catalogs produced in each of these countries included innovative prefabricated cement architectural elements, which would maintain the essence of local traditional architecture translated into cement and reinforced concrete. The new cataloged “cement architectural kit of parts” would help evolve original designs, while maintaining popular layouts with the front balcony as a recurring and important architectural element for cultural communication.

Concrete was employed as a building material in India during the first half of the 20^th century. However, the modern architectural movement developed after India’s independence in 1947, shaped by the first Prime Minister's vision of new democracy and industrialization. During this period, concrete was primarily used for structural framing.

Beton brut, or exposed concrete in its raw, unaltered form emerged with its innovative implementation in Chandigarh and Ahmedabad, paving the way for brutalist architecture in India. In the 1960s and 1970s, Indian architects and engineers started experimenting with concrete to develop distinctive architectural forms and finishes. This included the use of large cantilevers, folded plates, diaphragm plates, shear walls, and ribbed and radial beams, all crafted as monolithic concrete, representing a significant departure from earlier practices. Previously unseen aesthetic finishes were achieved, showcasing unadorned, form-finished concrete with textured surfaces created through meticulously handcrafted formwork and the careful selection of aggregates. All these advancements were accomplished despite the difficulties of working with new techniques, inadequately trained workforce, and resources suited for such specialized work. After more than fifty years in the tropics, combined with the effects of climate change and the challenges of concrete conservation as a new field in India, most of these buildings are now exhibiting signs of distress.

These buildings are outstanding examples of nation-building through design, technological, and material innovation, contributing to the context of the 20th-century modern Indian narrative and yet their significance in India remains largely unrecognized. The lack of identification, conservation and insufficient protection has led to the recent demolition of many notable buildings, destroying a vital part of the cultural heritage.

This paper will examine the culture of exposed concrete in India, focusing on transnational exchanges, key contributors, and the development of innovative techniques. It will draw on interviews, publications, archival drawings and images, trade journals, and concrete handbooks.

The Brion Memorial (1969-78) by Carlo Scarpa (1906-1978) is an exceptional study case because of its monumental character, combined with the author's desire to imagine its ageing, (not its damage) over time. The almost exclusive use of reinforced concrete for the built architecture and the choice of experimental technical solutions place this architectural complex within the field of contemporary architecture preservation, due to the theoretical and operational difficulties in defining the intervention. Furthermore, the preservation problems of exposed concrete characterised by peculiar formal values, are well known. Actually, Scarpa's concrete processing techniques provide a wide range of surfaces and related forms of degradation, which require specific approaches to their preservation.

An original and complex system of surveying and interpreting the construction elements is applied, also proposing a specific rendering methodology - graphic, photographic and descriptive -in order to represent both technological characteristics and degradation phenomena, as well as operative indications such as diagnostic investigations or preservation and maintenance interventions.

This knowledge path led to the definition of the necessary interventions: the outcome of the investigation phase allowed the interventions to be tested on a portion of the artefact (2018); once validated, it was extended to the entire complex. The restoration of the Brion Memorial provided an extraordinary opportunity to reflect on the methods and limits of preservation interventions and to update the current state of the art in terms of technical solutions. The restoration was completed in 2020.

One hundred and eight years ago, architectural sculptor John J. Earley unveiled the potential for exposed aggregate concrete as an architectural finish material. Over the next three decades, he established not just a single architectural finish, but a family of techniques to create a vast range of forms, colors and textures with concrete. In their total effect, John J. Earley’s innovations breathed life and spirit into concrete as a modern architectural material.

Earley’s greatest project was the stunning Baha’i House of Worship in Wilmette, Illinois. The Temple’s design presented Earley with both an opportunity and a set of new challenges that required ingenious technical developments. In 1933, for the Temple’s dome, Earley Studio created some of the first architectural precast concrete panels installed on a structural steel framework. For seventeen more years, the Studio produced ornamentation for the Temple’s exquisitely beautiful, architectural finishes. 

When areas of the Baha’i Temple needed restoration, no similar repairs of exposed aggregate concrete had been done. The team not only had to identify the problems’ causes and design solutions, it had to rediscover John J. Earley’s process and adapt his historical methods to the requirements of modern material science. Restoration projects between 1987 and 2010 required extensive research, testing and experimentation to create repairs that match John J. Earley’s original work. 

This presentation will survey John J. Earley’s key projects and technical innovations, dive into Earley Studio’s construction of the Baha’i Temple’s cladding, and share methods developed for restoration of extraordinary architectural concrete.

Completed in 1908 and featured on the cover of Frank Lloyd Wright’s Wasmuth Portfolio, Unity Temple changed the course of architecture. While not the first building made solely of cast in place concrete it was an early use of the material and forcefully demonstrated the power and possibilities of this modern material. Being an early example of concrete being used in this way, its long-term behavior was poorly understood. As a result, by the 1970s the building exhibited significant deterioration.  A repair program prepared by removing approximately an inch of the existing concrete surfaces and applying “shotcrete” to protect the underlying structure. This stemmed the tide of deterioration for some time, but by the late 1990s the overhangs were in a deplorable state and needed major repairs. That work was completed by removing and recasting the overhangs and applying shotcrete to the underside. While these repairs addressed the most pressing problems, the rest of the building was in dire need of attention. The Unity Temple Restoration Master Plan was completed in 2006 and finally in fall of 2014 funding was in place and the planning began for complete $25M restoration of the building.

The restoration included addressing the entire concrete façade. The work in the 1970s and been done in a manner that made matching the existing surfaces extraordinarily challenging. Months of planning and mockup trials were needed to establish an acceptable methodology and matching protocol for the work. Once that was completed, the work proceeded in an orderly manner with only a few instances of problems that were eventually resolved. The result was a return of Unity Temple to its stunning presence on Lake Street in Oak Park. The building is now one of eight Frank Lloyd Wright sites listed at World Heritage.

The presentation will describe the restoration process in detail and will be made by the architect and specialty contracting team who executed the work. 

The 1962 Seattle World’s Fair was a global exposition of technological ambition in the Space Age.  The US Science Pavilion at the fair, designed by the architect Minoru Yamasaki and structural engineer Jack Christiansen, pushed the technological and practical boundaries of pre-stressed concrete to create a light, expressive and durable Pavilion complex.  Aligned with the mission of the Pavilion to promote scientific advancements, the pre-stressed concrete itself was celebrated a legitimate “material of the future”.

The US Science Pavilion consisted of five, low-rise rectangular buildings grouped around a central courtyard.  Each building was made of ribbed, precast concrete bearing walls that supported long-span prestressed concrete T-beams.  Intricately patterned and faced with crushed quartz, the panel walls were pure white and glistened in the sun.  The courtyard was marked by a series of post-tensioned elevated platforms and overhead lattice domes – which were playfully referred to as having a ‘Space Gothic’ design. Combined, these structures created a dramatic yet serene oasis in the middle of the busy fair.

Execution of the US Science Center was only possible because of close collaboration between Yamasaki, Christiansen, and the precast concrete contractors – drawing on a growing local knowledge base in prestress.   Tight coordination of mix design, tolerances, and construction schedule were essential to a successful project, and resulted in a remarkably durable Pavilion.  Current renovation efforts have largely preserved the original design intent and revealed only few instances of concrete in need of repair or preservation. Operating today as the Pacific Science Center, the Pavilion continues to celebrate scientific achievement and attract young visitors.

Deborah Slaton, Wiss, Janney, Elstner Associates, Inc.

Katherine Frey, Mills + Schnoering Architects, LLC

Keith Kesner, Simpson Gumpertz & Heger, Inc.

Joshua Freedland and Tim Redar, Bulley & Andrews

Justin M. Spivey, Axiom Project Development Services, LLC

Jingyi Luo, University of Pennsylvania and RWDI

Elizabeth Davidson, The National Trust for Scotland

Edward FitzGerald, Jablonski Building Conservation, Inc.

In 2014, the Getty Conservation Institute (GCI) organized an experts meeting to assess the concrete conservation field and identify actions that could help practitioners deal with the many technical challenges in conserving this material. This was based on a recognition that reinforced concrete is an integral part of much of 20th century’s built heritage worldwide, and an important contributor to the cultural significance of these sites. The conclusions from this experts meeting have been guiding GCI’s activities to date.

In response, part of GCI’s work has focused on making existing knowledge more accessible to conservation practitioners through publications, and training opportunities. In addition, these dissemination activities aimed to reinforce the connections between the broader concrete field and conservation. That is the guiding premise of the methodology presented in the Conservation Principles for Concrete of Cultural Significance published in 2020.

More recently, the GCI embarked in an international collaboration with Historic England and Laboratoire de Recherche des Monuments Historiques, France, to study the performance of patch repairs executed with the intent to match architectural concrete surfaces. The evaluation of twenty-one sites across the three participating countries was conducted in two phases, starting with documentation and non-destructive assessment of all sites, followed by in-depth investigation of a select number of sites, including sample collection for laboratory analysis. The results of this research reinforce the need for more consistent adoption of a methodology based on sound concrete repair and conservation knowledge, and the need for more craftspeople, engineers, architects, and conservators skilled in concrete conservation. The goal is to use these results to provide practical guidance in the repair of culturally significant concrete, adding to the already existing resources to help guide and train more professionals in the concrete conservation field. 

The presentation will cover: Who the International Masonry Institute and International Masonry Training and Education Foundation are and what our function is with the Bricklayers Union. We will talk about our collaboration with International Concrete Repair Institute (ICRI) and the certificate program. We will also talk about our other certificate programs and how they function in specification language in construction projects. We will talk about how and why the concrete repair certificate program was developed and what training we do for the concrete program. We will dive into our infrastructure here in the United States and what will be needed for concrete repair. We will talk about condition assessment concerning concrete and how to better educate our craftworkers not only of the repairs themselves but also for them to gain knowledge to what can cause certain failures and some of the testing that associated with condition assessment. After the diagnostic part of the repair class we get into repair materials, methods and techniques. We will talk about mix design for repairing historic concrete structures. The mix design will cover the use of different types of gravels, sands and Portland cements. We will cover consolidation and compaction of materials along with key application requirements and finishes to match existing concrete structures.

CONCRETO is an Alliance for Enterprises and Education Project within the Erasmus Plus program, spearheaded by the Pier Luigi Nervi Foundation. Launched in January 2024, CONCRETO unites a broad consortium of 13 partners from five countries: four EU countries (Italy, Spain, Belgium, the Netherlands) and 1 extra EU country (Türkiye). This diverse group includes organizations focused on modern heritage preservation, universities, vocational training organizations, and national trade associations of architects and engineers. The consortium brings together public and private entities, academic researchers and practicing professionals with the mission to bridge the gap between academia and the professional world, with a focus on modern concrete heritage.

Inspired by the great architectural legacy of Pier Luigi Nervi, CONCRETO responds to the urgent need to develop specialized skills for the safeguard of the modern concrete heritage. The program aims to foster and promote the expertise necessary for this task through an innovative and collaborative training program. 

Each year, students from architecture and engineering schools, craftworkers and young professionals are selected to take part in this 1-year program. The CONCRETO Journey starts with distance learning and the program slowly becomes more practical culminating with a full immersion hands-on experience transforming the students into apprentices during the MASTERPIECE in Ivrea. The CONCRETO MASTERPIECE is the closing activity of the program and takes place at the UNESCO Site of the Industrial City of Olivetti in Ivrea, Italy. 

The CONCRETO ACADEMY represents an enduring opportunity of knowledge, growth and exchange. The overall aim of CONCRETO ACADEMY is to transmit and promote the green rehabilitation of European concrete heritage architecture.

The future of cementitious materials is changing, and this session lays out the vision for the pursuit of greater sustainability for construction by the cement and concrete industry. The Portland Cement Association’s Roadmap to Carbon Neutrality outlines opportunities at all stages of the value chain for cement-based construction.

One way that cement manufacturers are responding to environmental concerns is with an increased range of products and formulations. Blended cements offer an opportunity to reduce the global warming potential (GWP) of cement that in turn reduces the carbon footprint for concrete construction. The ASTM C595 blended cement standard provides four blended cement types to offer greater choices to specifiers and other users. As of mid-2023, more than 50% of cement used in the U.S. was blended cement, largely due to the increased uptake of Type IL portland-limestone cement (PLC) that began in 2021. In 2024, cement manufacturers continue to explore additional blended cement formulations to reduce their environmental impacts. A switch from ASTM C150 portland cement to an ASTM C595 blended cement requires evaluation of fresh and hardened concrete properties to understand appropriate adjustments to mixtures and installation practices when necessary. Based on lessons learned from the experience with PLC, this session describes common issues to consider and potential modifications to practices that will enable successful implementation of any blended cement.

Much of the discussion of decarbonization focuses on changes to cement production, however, there are many opportunities for reducing the carbon emissions associated with concrete construction that can be applied pervasively and immediately when we look beyond the cement plant. This presentation will provide a comprehensive overview of strategies for reducing life cycle emissions from cement-based products. We will take a detailed look at one misunderstood mechanism for decarbonization – permanent storage of CO2 in cement-based products during its use and end-of-life. Specifically, this presentation will discuss what we know about the rate and extent of carbon uptake in cement based products such as cast-in-place and masonry concrete, how those are enhanced, and what are some of the key remaining knowledge gaps.

Portland cement has a long history, but recent goals for enhanced durability, recyclability, and carbon neutrality have raised questions about what we might build with in the future. Innovative alternatives to Portland cement include biologically derived binders. These binders employ bacteria, fungi, and algae to create a bonded matrix without the environmental burden of sintering. Additionally, some approaches leverage bacteria for the manufacture of grains or limestone. Introducing these materials into practice raises interesting new questions and challenges. Placement requirements of some alternative cements results in different optimal geometries for hardening. This opens the doors to new designs for masonry units. Differences in mechanical performance enable structural forms, such as arches, due to higher tensile capacity. This talk with conclude with a discussion laboratory implementation of various innovative products in a wall and floor system.

Non-destructive evaluation (NDE) is an umbrella term for structural health monitoring (SHM) as well as non-destructive testing (NDT). While the former includes techniques that use sensors to monitor changes of structural performance over time, the latter provides a snapshot of the properties of a structural member and its condition. The objective of NDE is to ensure the proper functioning and safety during the service period of a structure. Additionally, the information generated can be used to enable optimal asset management and preservation. This presentation gives an overview of NDE, proposes a framework that integrates SHM and NDT, and discusses some recent case studies in which NDE was used to extend the service life of concrete structures. Finally, a new educational program will be discussed aimed at educating a future workforce in engineering and preservation of structures, a focus area that is currently not offered widely.

8:00 AM - 2:00 PM