Historic Concrete Research Articles

Comparative interpretation of results after application of different non-destructive and portable techniques on historic concrete in the Centennial Hall in Wrocław

Many concrete buildings erected during the 20th century are assuming a cultural and historical value, and their conservation against the climate changes and the urban impact represent a major challenge for the heritage science for the future. A key aspect for their preservation is the development/application of innovative testing approaches based on non-destructive and portable techniques (NDPT) for diagnostics and monitoring the state of conservation. This research activity has been conducted on the case study of the Centennial Hall exhibition centre in Wroclaw (Poland), where the physical and mechanical characteristics of cementitious materials were estimated through indirect methods and therefore compared to prove their efficiency and usefulness in the limitation of invasive inspections. These methods were focused to control the hardness and compactness of the material (by ultrasonic pulse velocity and rebound tests), the surface permeability (by sponge test method), the water and salts content of the material (by Evanescent Field Dielectrometry - EFD), and the change of colour (by colorimetric measurements). In order to test the strength of the proposed approach, all these techniques (except the EFD) were made in duplicate by two different teams, using different instruments but following a similar protocol. The data were compared in between, and the environmental conditions were also considered. The results showed a good repeatability, furnishing useful information about the quality of concrete and its state of conservation, as well as possible forethoughts for a proper interpretation. This multi-technique approach could support the conservation decisions making process for the management of historic concrete building.

Performance evaluation of patch repairs on historic concrete structures (PEPS): a bibliographic review of patch repair durability

Concrete repair and, more specifically, patch repair, is a complex process, which still presents challenges and results in durability issues. Durability of a patch repair is affected by many factors occurring throughout the repair process, such as diagnosis of the existing structure, design of the repair material, surface preparation, workmanship, loading, and exposure conditions [1]. Each phenomenon should be individually understood, but, for an efficient and durable repair, a holistic approach is advisable as every parameter is likely to affect several other variables in a different way [2]. This topic is abundant in the scientific literature related to contemporary concrete structures, but few are dedicated to historic concrete. All the considerations for modern buildings are relevant for concrete heritage, but additional specific requirements must be considered in order to preserve its cultural significance. The purpose of this bibliographic study is to highlight the key factors for evaluating the performance of concrete patch repair in the peculiar context of cultural heritage. Particular focus is put on compatibility issues between the repair system and the original historic material.

Performance evaluation of patch repairs on historic concrete structures (PEPS): Preliminary results from a selection of French case studies

Within the frame of the international research project PEPS, ‘Performance Evaluation of Patch Repairs on Historic Concrete Structures (PEPS)’, dedicated to the durability of patch repairs in the context of culturally significant structure, a series of repaired monuments was examined in detail. Thus, the operational phases of the project are composed of in situ tests and laboratory analysis on samples performed on a selection of representative historic concrete structures in the three countries who are partners in the project: United States of America, United Kingdom and France. In this paper, cases studies and some results obtained on three of the five French sites will be presented: Le Raincy church built by Auguste Perret between 1920 and 1924, and Rezé housing unit and Jaoul houses built by Le Corbusier respectively in 1955 and in 1953. The assessment methodology followed is the one developed between the three institutions partners on the PEPS project: the Getty Conservation Institute (GCI), Historic England (HE) and Laboratory of Research in Historical Monuments (LRMH). All the selected French sites were repaired several decades ago. For Le Raincy church and the Jaoul houses, the conservation campaign of 1991 was considered, while for Rezé housing unit it was the 1995-1997 campaign. All the case study structures have different construction dates and concrete compositions. Various repair materials and application techniques were used. The conditions of exposure differ from one site to another. All these variations make the evaluation highly complex but also fully instructive, and able to meet the objectives of the project: producing practical guidance helpful for companies and conservators repairing historic concrete.

Performance evaluation of patch repairs on historic concrete structures (PEPS): the evolution of conservation repairs on the Historic England Phase II test sites and PEPS Phase II results

Historically, little effort had been made to match patch repairs to culturally significant reinforced concrete structures so that they are effective and sustain the aesthetic values of the structure. The collaborative research project, Performance Evaluation of Patch Repairs on Historic Concrete Structures (PEPS), being undertaken by Getty Conservation Institute (GCI), Historic England (HE) and the Laboratoire de Recherche des Monuments Historiques (LRMH), seeks to address this problem. Through its advice on grant-aided projects, Historic England has tried to achieve effective like-for-like repairs over the last 20 years. The ten English sites selected for the PEPs Phase II non-destructive testing (NDT) includes some of the buildings and structures where this repair work was carried out. Data on site location, specification of repair, environmental conditions, test results and tentative conclusions from this phase of the research is presented in this paper. Five of the sites will be subject to further NDT and destructive testing and sampling as part of Phase III.

Performance evaluation of patch repairs on historic concrete structures (PEPS): a methodology for in situ and laboratory analyses

While there have been many studies on the performance criteria of concrete patch repairs, there are few specific studies on the long-term performance of patch repairs designed to preserve the aesthetic significance of the original fabric of culturally significant concrete structures. In order to address this issue, the Getty Conservation Institute (GCI), Historic England (HE) and the Laboratoire de Recherche des Monuments Historiques (LRMH) commenced work on an international collaborative research project, ‘Performance Evaluation of Patch Repairs on Historic Concrete Structures’ (PEPS). Begun in 2018, the PEPS project aims to produce practical guidance that will help those repairing historic concrete through the assessment of case studies in the USA, England and France within a variety of climatic and environmental conditions, typologies and repair materials. The operational phases of the research project consist of in situ tests and laboratory analysis performed on both the original concrete and previous patch repairs. This paper provides an overview of the assessment methodology that has been developed by an inter-disciplinary team of professionals working in the field of concrete conservation, and includes a variety of traditional and non-traditional non-destructive, mechanical, chemical, and electro-chemical characterization and diagnostic techniques.

Performance evaluation of patch repairs on historic concrete structures (PEPS): preliminary results from an American case study

While there have been many studies on the performance criteria of concrete patch repairs, there are few specific studies on the long-term performance of patch repairs designed to preserve the aesthetic significance of the original fabric of culturally significant concrete structures. In order to address this issue, the Getty Conservation Institute (GCI), Historic England (HE) and the Laboratoire de Recherche des Monuments Historiques (LRMH) commenced work on an international collaborative research project, ‘Performance Evaluation of Patch Repairs on Historic Concrete Structures’ (PEPS). Begun in 2018, the PEPS project aims to produce practical guidance that will help those repairing historic concrete through the assessment of case studies in the USA, England, and France within a variety of climatic and environmental conditions, typologies, and repair materials. The operational phases of the research project consist of in situ tests and laboratory analyses performed on both the original substrate and previous patch repairs. In this paper, preliminary results from the Phase II & III in-situ assessments of a single case study in the United States of America are presented, and the differences in aesthetic and technical performance between repairs from three different intervention campaigns are discussed.

Rehabilitation Design of a Historic Concrete Arch Bridge in Prague from the Early 20th Century

AbstractThis article presents a proposal of a method for the restoration and rehabilitation of Liben Bridge, a historic concrete vaulted arch bridge structure from the early 20th century. The bridg...

Challenges in the Analysis of Historic Concrete: Understanding the Limitations of Techniques, the Variability of the Material and the Importance of Representative Samples

ABSTRACT The number of historically-significant concrete structures which require conservation and repair is ever-increasing. The use of unsuitable proprietary materials has led to poor quality repairs of historically-significant structures in the United Kingdom, some of which have resulted in damage to the historic character of the structure and accelerated deterioration of the substrate. As a result, the approach to the repair of historic concrete structures has shifted from the use of mass-produced proprietary repair materials to purpose-made ‘like-for-like’ replacements which, theoretically, have similar mechanical and aesthetic properties. In order to create like-for-like repair materials, the original mix proportions and water/cement (w/c) ratio of the substrate have to be established. However, there are concerns regarding the accuracy of existing techniques and standards used for the analyses of hardened concrete. Furthermore, due to a lack of available material, analyses are often carried out on samples that are much smaller than the minimum requirement for a representative sample, or from areas which are not representative. This paper discusses these issues and hopes to provide information to conservators and analysts on the limitations of techniques, the variability of the material and the importance of representative samples.

The Practical Building Conservation series: evolution & content

<p>Practical Building Conservation es una serie de diez volúmenes que ofrece una guía completa para la restauración de un amplio rango de materiales, desde el vidrio, madera y metales, hasta el hormigón. Los dos volúmenes de fundamentos proporcionan el marco de base a los libros sobre materiales de construcción. ConservationBasics describelahistoriadelarestauración, la práctica legal actual y la metodología. Building Environment define los factores medioambientales que afectan a los sistemas de construcción y hasta qué punto una buena restauración es sostenible. Este artículo explora la génesis de la serie, desde los cinco pequeños libros publicados en 1988, hasta la serie actual con más de 5.000 páginas. El nuevo trabajo muestra la evolución de la restauración arquitectónica de las últimas décadas, promoviendo intervenciones holísticas basadas en la valoración del significado, las condiciones y el riesgo. La serie hace referencia a la práctica de la restauración en Inglaterra. Sin embargo, la mayoría de la información proporcionada es de naturaleza genérica, por lo que es aplicable en otros contextos.</p>

Performance of silane -based surface treatments for protecting degraded historic concrete

Surface treatment is an effective way to protect existing historic concrete architectures from decay. Silane-based products could be considered as efficient protective materials to improve the concrete durability. However, preservation damages like appearance alteration and expansion stress of surface coatings have been reported. In addition, the long-term effect of silane coating has not been fully studied. In order to evaluate the efficiency of surface treatments and select appropriate materials for protecting historic concrete, three commercial silane-based products were applied on concrete specimens. The properties of the surface treatments on concrete in terms of appearance alterations, contact angles, compressive strengths, penetration depths and pore size distributions were investigated. An accelerated aging test was carried out in order to obtain a comprehensive understanding of the long-term preservation performance of commercial coatings. The results suggested that the three commercial products all showed protective features with little appearance change. However, some materials may lead to the white salt crystallization on the concrete surface, and strong hydrophobicity can easily generate tension and finally accelerate the concrete decay.

Performance of patch repairs on historic concrete structures: a preliminary assessment

Carrying out patch repairs to historic concrete buildings and structures needs to be done carefully if their cultural value and significance is to be maintained. This often means repairs using custom designed materials and mixes for compatibility with the original concrete, and with great care paid to good workmanship. But with most repairs, commercial mixes are used which are not compatible with the host concrete but are justified because they adhere well, cure quickly and require limited skills to implement. A research collaboration has been established to test the performance of both approaches. The Performance Evaluation of Patch Repairs on Historic Concrete Structures (PEPS) began in 2018 and is a collaboration between the Getty Conservation Institute, Historic England and the Laboratoire de Recherche des Monuments Historiques. Its purpose is also to better understand key design and specification parameters and application methods. The research is based on assessing case studies in USA, England and France within a variety of climatic and environmental conditions, typologies and repair materials. This paper will present the methodology adopted to evaluate the repairs in the first phase. This will also include historical research on the specification and application of the repairs, preliminary field assessment and some testing.

Extending the Life of Historic Concrete Arch Bridges: State of the Art

Open-spandrel, concrete arch bridges were a common bridge design in the United States during the early 1900s. Many of these bridges are now urban landmarks and listed historic structures that local jurisdictions wish to rehabilitate for years to come, including widening of the deck to more safely accommodate pedestrians and bicyclists. However, decades of exposure in harsh climates have led to advanced deterioration and reduced load ratings for most extant examples. Furthermore, the original concrete is non-air-entrained, potentially lower-strength, and often chloride-contaminated and deeply carbonated, all of which make the concrete difficult to repair and vulnerable to future deterioration. Further complicating rehabilitation, the height, and arch-reliant behavior of these bridges make construction access, staging, and maintenance of traffic challenges. Drawing upon the authors’ experience with several bridges of this type, this paper discusses best practices and special considerations for investigating and rehabilitating historic concrete arch bridges to extend their life.

Colour alterations of historic concrete surfaces during the Dutch Interwar Period

In the 1920s, the improved concrete technology and growing acceptance of concrete as an aesthetical material resulted in an increased application of coloured concrete. This includes the use of organic and inorganic pigments, ground natural stone, consciously chosen coarse aggregates, and also a new technique: metallisation. This rare, yet internationally applied, technique was patented in the Netherlands in 1917 and allowed a colour change of the hardened concrete by applying metal salts on its surface.In conservation practice, there are misconceptions with respect to the period of application of exposed concrete and, in particular, of coloured concrete. The application of exposed concrete during the Interwar period (1918–1930s) is often not considered during inspections; this impacts the quality of value assessments, diagnosis of damage causes and choice of conservation strategies.Besides limited knowledge of the varieties of coloured concrete, the fact that many historic concrete buildings have since been plastered or painted impedes its correct identification. This poses a challenge, as the deviating properties of historic concrete, both due to production methods and use of unproved constituents, can affect the durability of concrete. This paper focuses on the characteristics which can be encountered during visual inspections, an early and influential phase within the conservation process.

Moisture-Related Problems of Historic Concrete Structure

In the 30's a lot of military defensive lines were built in many European countries (France, Germany and more). These were a sophisticated concrete bunkers protecting the borders of the State. A lot of concrete fortresses were built also in the territory of Czechoslovakia as a protection against Nazi Germany. These bunkers are currently almost 80 years old and they are an important part of the Czech cultural-technical heritage. The paper describes moisture-related failures of the bunker R-S74 which is situated in Eagle Mountains in the Czech Republic with additional material testing of the permeability of used concrete. Present experimental study is unique due to the significant differences in the cement and concrete composition 80 years ago in comparison to the actual state of concrete technology. The results of the laboratory analysis showed that the bunker's concrete is very inhomogeneous and it has very different properties in terms of its permeability.

Excessive reverberance in an outdoor amphitheater

The historic Ford Theatre in Hollywood, CA, is undergoing an overall renovation and expansion. Its centerpiece is the inexplicably asymmetrical 1200 seat outdoor amphitheater, built of concrete in 1931 after the original 1920 wood structure was destroyed by a brush fire in 1929, and well before the adjacent Hollywood Freeway was nearly as noisy as now. Renovation includes reorienting seating for better symmetry while maintaining the historic concrete, and improving audio, lighting, and support spaces. Sited within an arroyo overlooking a busy highway, and in view of the Hollywood Bowl, the new design features an expanded “sound wall” that will help to mitigate highway noise while providing optimal lighting and control positions. New sound-absorptive treatments will address the Ford’s excessive reverberation, currently more than might be anticipated for an entirely outdoor space. The remarkably uniform distribution of ambient noise and apparent contributions by the arroyo to the reverberation will be discussed, along with assorted design challenges.

Quantitative Comparison on Surface Quality of Historic Concrete Structures by Field Investigation

Quantitative Comparison on Surface Quality of Historic Concrete Structures by Field Investigation

Historic Concrete : Background to Appraisal

Historic Concrete : Background to Appraisal

Soldier Field Stadium: Corrosion Mitigation for Historic Concrete

Demonstrates how new technologies in corrosion mitigation for steel are applied to the preservation of historic concrete structures. The article deals specifically with the Soldier Field Stadium in Chicago, Illinois, constructed between 1922 and 1926. The main challenges to effective preservation of this structure were the high chloride content in the concrete in the coffered ceilings and the deep carbonation in the exhibition-hall concrete. After materials testing, performance trials and cost analyses, the study recommended installing a sacrificial distributed zinc-anode CP (cathodic protection) system throughout the colonnade ceiling beams. Additionally, the most cost-effective repair approach for the exhibition halls called for not installing any corrosion-mitigating measures, but rather continuing with annual inspections and periodic patching of the overhead concrete.

Rehabilitation and Preservation of Oregon’s Historic Concrete Coastal Bridges

Oregon’s Coastal Bridge Program was designed to preserve the economic and cultural resources invested in Oregon’s coastal bridges. The Oregon Coast Highway contains a significant concentration of bridges listed on or eligible for the National Historic Register. Many of these reinforced concrete structures are suffering extensive corrosion damage resulting from years of exposure to the marine environment. Oregon has developed this program to evaluate, prioritize, and preserve these magnificent bridges. Preservation of these bridges has relied on the innovative application of cathodic protection technology. This new technology has been applied successfully through a project design and construction process that includes ongoing interaction among design engineers, researchers, construction project management personnel, and contractors.

Historic Concrete Preservation Problems at Fort Washington, Maryland

Historic Concrete Preservation Problems at Fort Washington, Maryland