Historic Concrete Structures Research Articles

Data informed performance assessment and structural health monitoring for existing and historical concrete structures

AbstractOur generation inherits this cultural heritage of historic material and historic reinforced concrete structures and thus bears a certain responsibility to preserve these historic buildings with the help of the new technologies of lifetime management, conservation concepts and the new digitalization as well as the emerging safety concepts of our time. The aim of this article is to analyze the new technologies of data‐based service life management in relation to the assessment of historic reinforced concrete structures and to test the applicability of these methods to these historic buildings.

Case Study of Seismic Assessment of a Short Irregular Historic Reinforced Concrete Structure: Time-History Vs. Pushover Nonlinear Methods

ABSTRACT The selection of appropriate analysis method for the seismic assessment of existing structures and the reliability of its results are of utmost importance, as they determine the magnitude of potential damage in a future seismic event, as well as the demands for strengthening and ductility during retrofitting. This paper examines a historical concrete building in Nicosia, Cyprus, that exhibits strong irregularities, both in plan and elevation. The aim is to compare the results of the static pushover to the nonlinear time-history analysis method, to better understand the applicability limits of the pushover analysis when applied on irregular, historic concrete structures.

Seismic assessment of historic concrete structures: The case of Pedieos Post Office in Nicosia, Cyprus

Monuments are buildings in which historical, archaeological and cultural values are displayed, yet their lack of seismic detailing and design renders them dangerous for public use and prone to collapse and permanent loss, especially in countries located in seismic zones. Furthermore, the existing European regulatory framework does not oblige the owners of such structures to assess and retrofit them against earthquakes, thus leading to dangerous user safety conditions and possible permanent loss of historic concrete structures in a seismic scenario. This paper examines one of the culturally significant historic concrete structures of Cyprus. It assesses the seismic capacity of the structure by means of comparing various analysis methods and highlights the urgent need for a new relevant regulatory framework regarding historic concrete structures. The results are used to formulate recommendations that should be incorporated in future regulations in order to protect both the users and the concrete heritage structures themselves.

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.

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): 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): 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.

Restoration of existing historic concrete structures with PE fiber strain hardening cementitious composites

Important historic buildings of the 20th century located in the seismogenic zones of the Mediterranean have been designed without the provisions of Eurocode 8; thus, they require strengthening to account for seismic excitations and to be rendered safe for use by future generations. A common disadvantage in historic concrete buildings is the insufficient or even null reinforcement in shear, which usually results in brittle shear failures. This research focuses on the use of a self-compacting, fiber reinforced cementitious composite, which can be applied as cover replacement, or in a thin layer around the perimeter of an existing column, thus providing confinement to the original core and increasing the shear strength of the structural member. Different mix designs prepared in various countries have been examined, all incorporating the use of industrial by-products, such as silica fume or fly ash. The aforementioned mixtures were replicated with the use of locally available raw materials at the laboratories of the University of Cyprus. Polyethylene (PE) fibers, with or without coating, measuring 12 and 18 mm in length were also included in the various mix designs. The mechanical properties of the hardened specimens were compared through compression, tension and flexure tests at 28 and 90 days of curing. Based on the results, a self-compacting mixture, presenting particularly high strengths in direct tension and bending, was eventually chosen to investigate the strengthening of existing historic concrete members.

Reactivity of slag in 15 years old self-compacting concrete

The paper summarizes changes in slag microchemical composition and its hydration products in Portland cement self-compacting concrete after 15 years of exposure in water under laboratory conditions. Scanning electron microscopy (SEM) and X-ray microanalysis (EDX) techniques show the results of the degree of hydration of blast furnace slag particles. The experiment showed a connection between the slag content and the hydration process. It was verified that the average values of the base-forming oxides ratio (MgO + Al2O3)/CaO are inversely proportional to the slag content in the mixture. The results of these procedures provide valuable information not only in the long-term predictions of the effect of slag and other additives in cement concrete, but also in the evaluation of slag hydration in historical concrete structures.

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.

Concrete conservation: outstanding challenges and potential ways forward

PurposeThe purpose of this paper is to present current challenges in concrete conservation and how the Getty Conservation Institute (GCI) is responding to these challenges. The Concrete Conservation Project initiated by the GCI is aimed at advancing the practice of conserving historic concrete structures through the creation and dissemination of information.Design/methodology/approachThe scope of the project was defined through discussions in experts meetings, development of annotated bibliography and literature review. The project proposes to face the identified issues with the dissemination of information on case studies, development of guidance documents, training opportunities and scientific research.FindingsDespite the existing well-established repair industry for concrete structures generally, current data on concrete repair do not meet the needs of conservation professionals, there is little information on the efficacy and durability of existing repair solutions, shortage of training opportunities, and there is a lack of technical guidelines focused on concrete conservation.Originality/valueConserving concrete is a nascent area of preservation practice facing multiple challenges. Reinforced concrete is the most commonly used building material of the twentieth century. As the heritage of the twentieth century is increasingly recognized as worthy of conservation, conserving concrete has become a priority. The history of this material reveals a story of innovation, radical advancement in material and structural engineering, and correspondingly daring responses by architects, together creating a huge array of reinforced concrete structures from the ordinary to the extraordinary.

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.

New warning sensors to detect corrosion risk in reinforced concrete

Corrosion is the most frequent but also the most deleterious deterioration mechanism affecting reinforced concrete. In addition to the economic impact of the repair works, for historical concrete structures, corrosion can generate irreversible losses of original material of great cultural value. If the usual non-destructive electrochemical methods have highlighted their efficiency in evaluating on-going corrosion activity, they also have pointed out their drawbacks for accurate extrapolation and prevention. To prevent the corrosion phenomenon, by detecting the penetration of aggressive agents, a new warning sensor system has been developed. The principle of the technique is to embed thin metallic sheets (called orphan blades) in the concrete cover, at different distances from the surface to the reinforcing bars. Then the corrosion of those very reactive orphan blades is followed during the propagation of the carbonation front and/or the penetration of chloride ions using stimulated infrared thermography. The corrosion of the sensors at different depths is indicative of the ingress speed of the front and can alert about the risk of corrosion of reinforcing bars in the concrete. The purpose of this study is to present this new technique and the first results obtained in the laboratory on corroded and non-corroded sensors.

Restoration of Historic Concrete Structures with Modern Materials - A Case Study

Today the requirements for concrete restoration are not only aspects of retrofitting or restoration of bearing capacity but increasingly aspects of preservation of historic structures, such as industrial monuments, civil engineering structures and buildings of the 60s. The Polymer modified self-compacting concrete (PSCC) is a suitable material to be applied in this field, as it not only has excellent mechanical properties (e.g. high bond strength, low Young's modulus) but it is also possible to imitate colours and textures similar to those of the original surfaces. PSCC is therefore an interesting alternative to well established materials, such as PCC, sprayable PCC (SPCC) and shotcrete.Presented in this paper are the results of the further development of PSCC for a particular scenario where due to limited accessibility, the application method and therefore the mix design had to be optimised. Characteristic fresh and hardened concrete properties were investigated and special attention was given to deviation of the fresh concrete with regard to variations in the amounts of source materials.It is shown that although PSCC is a high-performance material, dosage of its source materials, mixing and application of the material itself can be done with simple conventional building site equipment. At the same time a robust fresh concrete as well as excellent surface properties of the hardened concrete can be obtained. Purpose-made mix designs can be developed for various applications with excellent results in performance and appearance.

Corrosion condition evaluations of historic concrete icons

Corrosion condition assessments of historic concrete structures can provide the owner with invaluable information regarding the current condition of the structure, the factors contributing to the corrosion damage, and can also project when the structure may exhibit further material loss. This information is vital to be proactive in the repair process which is imperative to minimize loss to the structure. When dealing with a highly significant concrete structure, the investigative team is often faced with restrictive parameters limiting the amount of data which can be collected. This paper discusses challenges in preserving ‘historic concrete’ and provides four case studies of predictive corrosion condition assessments which were carried out to help in the decision making process.

Evaluation of the Durability of Hydrophobic Treatments on Concrete Architectural Heritage

Abstract The protection of historical concrete structures is a challenge for the coming years. Hydrophobic treatment may reduce the deterioration process while providing protection against water penetration. Existing commercial products - mainly silane or siloxane in either water or solvent based formulations - were submitted to different ageing processes including UV radiation, dry-wet cycles, thermal shocks, freeze-thaw cycles, carbonation and their effectiveness has been evaluated on the basis of contact angle, vapour and chloride permeability and, capillarity water absorption. The results obtained clearly show that hydrophobic treatments display a good behaviour under the main ageing conditions.

Evaluation of the Durability of Hydrophobic Treatments on Concrete Architectural Heritage

The protection of historical concrete structures is a challenge for the coming years. Hydrophobic treatment may reduce the deterioration process while providing protection against water penetration. Existing commercial products —mainly silane or siloxane in either water or solvent based formulations– were submitted to different ageing processes including UV radiation, dry-wet cycles, thermal shocks, freeze-thaw cycles, carbonation and their effectiveness has been evaluated on the basis of contact angle, vapour and chloride permeability and, capillarity water absorption. The results obtained clearly show that hydrophobic treatments display a good behaviour under the main ageing conditions.

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

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

Study on Analytical Methods for Historic Concrete Structures

Study on Analytical Methods for Historic Concrete Structures