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Although widely recognized as imperative for reducing global emissions and the amount of waste generated by the architecture, engineering, and construction (AEC) sector, a large-scale shift from a linear to a circular economy has not yet happened in practice. This paper highlights practitioners’ needs for implementing circularity in the AEC sector in Switzerland, and how digital platforms could support it. We hosted two workshops with industry practitioners in the Swiss AEC sector to find out their needs from academia, government, and industry to implement such a shift. The first workshop revealed a need for digital reuse platforms, so we focused a second workshop specifically on digital platforms. Results from the second workshop made clear the need for better practices of gathering data and integrating platforms. Financial incentives, social innovation, policy measures, and digital tools were also identified as necessary to increasing circularity in the sector. Our findings reveal the promising potential of digital technologies and stakeholders’ networks to better capture data on building products and methods for extending their life cycle.

Heutzutage werden viele Stahlbetonbauten, die meist keine oder nur geringe strukturelle Defekte aufweisen, aus sozioökonomischen Gründen abgerissen. Wenn die Erhaltung eines bestehenden Gebäudes nicht möglich ist, erlaubt die Wiederverwendung der tragenden Bauteile in einem neuen Projekt, die schädlichen Umweltauswirkungen des Rück- und Neubaus zu verringern. Die Bauteile des obsoleten Gebäudes werden dabei sorgfältig demontiert, ohne sie zu Schutt zu zerkleinern. Sie werden gereinigt, möglicherweise repariert oder eingepasst und wiederverwendet, wobei ihre ursprüngliche Geometrie und ihre Eigenschaften so weit wie möglich erhalten bleiben. Die Anwendung dieser alternativen Strategie erfordert Änderungen im Planungsprozess der Abriss- und Neubauprojekte. Als Grundlage dafür muss das obsolete Bauwerk inventarisiert und analysiert werden, um die mechanischen und geometrischen Eigenschaften sowie die Dauerhaftigkeit der Stahlbetonbauteile zu bestimmen und ihre Wiederverwendbarkeit zu beurteilen. Das vorliegende Dokument beschreibt eine Methodik zur Beurteilung der Wiederverwendbarkeit und ein Verfahren für die Bestandsanalyse eines Stahlbetonbauwerk, das demnächst rückgebaut werden soll. Um den Planern beim Prüfen der verschiedenen Wiederverwendungsmöglichkeiten für ein Bauteil zu helfen, wird zunächst ein Werkzeug zur Beurteilung der Wiederverwendbarkeit vorgestellt. Es basiert auf den vorhandenen Schäden des Bauteils, seiner zukünftigen Nutzung und den für die Instandsetzung der Bauteile erforderlichen Massnahmen. Die Schadensbewertung wird vor dem Rückbau des Spendergebäudes durchgeführt. Die Nutzungsklasse - die die künftige Beanspruchung des Bauteils ausdrückt - und die Massnahmenklasse - die den Unterhalt und die nötigen Anpassungen des Bauteils beschreibt - hängen vom Bau des Empfängergebäudes ab. Nach der Klassifizierung der Schäden, Nutzung und Massnahmen eines Bauteils ergibt sich der Wiederverwendbarkeitsgrad, der eine Empfehlung für die Wiederverwendung und die damit verbundenen Kontrollen im Empfängergebäude ausdrückt. Diese Methodik zur Beurteilung der Wiederverwendbarkeit soll die Subjektivität der Analyse des Wiederverwendungspotenzials von Stahlbetonbauteilen verringern. In diesem Bericht werden die Schritte zur Durchführung einer vollständigen Bestandsanalyse von Stahlbetonbauwerken und deren Bauteilen beschrieben. Die Bestandsanalyse sammelt alle Informationen, die zur Beurteilung und Planung der zukünftigen Wiederverwendung der Bauteile erforderlich sind: Kategorisierung und Quantifizierung der Bauteile, Einstufung der vorhandenen Schäden, Untersuchungen der Geometrie und der Materialeigenschaften sowie Ermitteln weiterer Merkmale (Ästhetik, Zugänglichkeit, Tragwiderstand, Umweltauswirkungen). Diese systematische Methodik hat zum Ziel, die Subjektivität einer solchen Analyse zu verringern. Die hier beschriebenen Methodiken und Verfahren ermöglichen es, den Rückbau eines veralteten Stahlbetonbauwerks zu planen und dabei Mittel anzuwenden, die die Wiederverwendung der Bauteile mit dem grössten Potenzial begünstigen. Sie liefern auch die Informationen für die vorläufige Planung eines Empfängerbauwerks. In späteren Planungsphasen können zusätzliche Untersuchungen am Bestand erforderlich sein., See also English version. DOI: 10.5281/zenodo.7457909

Today, many reinforced concrete structure, most of the time with no or small structural disturbances, are demolished for socio-economic reasons. When the preservation of an existing building is not possible, reusing the structural component in a new project is a strategy that allows the diminution of the detrimental environment impacts of deconstruction and new construction. The components of the obsolete building are carefully dismantled without being crushed. They are cleaned, possibly repaired or trimmed and reused while maintaining as much as possible their pre-existing geometry and properties. Adopting this alternative strategy implies changes in the design processes of the demolition and new construction projects. As a starting point, the obsolete existing structure must be inventoried and assessed to define the mechanical and geometrical properties as well as the durability of its reinforced concrete components and to evaluate their reusability. The present document describes a reusability assessment method and a resource assessment protocol for a soon-to-be deconstructed RC structure. To help the designers evaluate the different reuse options for a component, a reusability assessment tool is first presented. It is based on the pre-existing damages of the component, its future use and the intervention required to rehabilitate the components. The damage assessment is conducted before the deconstruction of the donor building. The use class – expressing the structural demand for the component – and the intervention class – describing maintenance and modifications on the component – depend on the design of the receiver building. Once the damage, use and intervention of a component have been classified, the reusability grade is obtained, expressing recommendation for the reuse and the related monitoring in the receiver structure. This reusability assessment tool is intended to reduce the subjectivity of the assessment of reuse potential of RC components. This report then describes the steps to carry out the complete resource assessment of reinforced concrete structures and their components. The resource assessment collects all information needed to evaluate and plan the future reuse of the components: classification and quantification of the components, grading of their pre-existing damages, investigations on their geometrical and material properties and evaluation of their qualities (aesthetics, accessibility, resistance, environmental impact). This systematic methodology aims at reducing the subjectivity of such an assessment. The methods and protocols described herein allow planning the deconstruction of an obsolete RC structure using methods that will subsequently facilitate the reuse of the components with the most potential. They also give the information for preliminary designs of a receiver structure. In later design stages, additional investigations on the stock might be required., See also German version. DOI: 10.5281/zenodo.7457954

The Lagerhalle Erlenmatt Ost is a 3-story building (basement, ground floor and two upper floors) used for food storage, located in Erlenmatt district in Basel and erected in 1975. Cast-in-place reinforced concrete (RC) slabs, walls, and mushroom columns form the main load-bearing structure of the building. The self-supporting facade is made of lightweight expanded clay aggregate (LECA) concrete panels. The deconstruction of this building is planned, thus making available a large amount of RC components composing the structure and the facades. Little-known and rarely implemented, the reuse of concrete components from obsolete buildings in new projects is a sustainable approach that promotes a circular economy. When reusing, the components of obsolete buildings are carefully dismantled without being crushed. They are then cleaned, possibly repaired or trimmed, and reassembled with little transformation in a new project, maintaining their shapes and structural properties. In addition to maintaining the embodied energy and history of the reused components, reuse allows the construction industry to reduce demolition waste, greenhouse gas emissions, and material consumption. This report is a preliminary resource assessment and aims at inventorying and assessing all structural components of the Lagerhalle Erlenmatt Ost, focusing on their potential value for reuse. Interest is mainly in the precast LECA concrete facade panels, but cast-in-place RC components are briefly included. The assessment methodology, detailed in a complementary report, allows identifying all properties needed to evaluate the potential for reuse of a RC component: geometry, material properties, resistance, current condition, accessibility, future durability, aesthetics and environmental impacts. After reviewing available reports and drawings on the building, onsite visits are carried out to complete the information and visually inspect the structural components. During the inspection, the components are assessed with regards to their suitability for reuse and their condition is classified into a five-grade scale. The building is made up of approximately 4 700 m3 of material constituting the load-bearing system, with approximately 450 m3 of precast LECA concrete and 4 250 m3 of cast-in-place concrete. The LECA panels are damaged and are assessed as unsuitable for structural reuse. The other components of the building load-bearing structure are considered in good condition by a first preliminary visual inspection. However, they would require further detailed investigations to gather all data needed to plan a potential future reuse. The inventoried components are divided into 5 categories: (1) facade components; (2) slab components; (3) wall components; (4) column components; and (5) staircases. For each of these categories a complete factsheet is prepared, including pictures, drawings and useful information on their condition. The volume and weight of each component types are given, as well as their share of the total material volume. The embodied global warming potential (in kgCO2eq and kWhoil-eq) for fabrication and demolition of the components is also calculated. This document should serve as a base for designing and planning future reuse applications for the concrete components extracted when deconstructing the Lagerhalle Erlenmatt Ost. The information presented here will help planners to prioritize the reuse strategy on the components in the best conditions, with the largest volume share and thus with the largest embodied global warming potential.

Concrete accounts for the largest share of worldwide building material use and waste generation, with cement production being responsible for approximately 9% of global anthropogenic CO2 emissions. A currently untapped strategy to significantly reduce these environmental impacts consists in reusing reinforced concrete (RC) elements in new load-bearing applications. This paper presents a new design-and-build concept to reuse cast-in-place RC wall and slab elements sourced from obsolete buildings. The applicability of the proposed paradigm is demonstrated through a prototype: a 10-m spanning post-tensioned segmental arch made of 25 reclaimed concrete blocks. The paper illustrates the complete workflow, including the sourcing of the blocks through sawing and the prototype assembly. A comparative Life Cycle Assessment shows that the prototype structure has a significantly lower environmental impact than equivalent designs made of new material.

The Triemli Personalh��user are three equal 15-story buildings located on the Z��rich Triemli Stadtspital campus and erected between 1964 and 1969. Cast-in-place reinforced concrete (RC) slabs and walls form the building cores and their surrounding corridors. The rooms are arranged around these cores. The load-bearing intermediate walls, made of prefabricated masonry, support thin precast slabs used as permanent forms. A RC layer is cast over these precast slabs and connects the room slabs with the cast-in-place slabs of the corridors and cores. The self-supporting facade consists of precast RC panels. The City of Z��rich plans the deconstruction of these three buildings, thus making available a large amount of RC elements composing the structure and the facades of these buildings. Little-known and rarely implemented, the reuse of concrete elements from obsolete buildings in new projects is a sustainable approach that promotes a circular economy. When reusing, the components of obsolete buildings are carefully dismantled without being crushed. They are then cleaned, possibly repaired or trimmed, and reused without many transformations in a new project, maintaining their shapes, technologies, and mechanical properties. In addition to maintaining the embodied energy and history of the reused components, reuse allows the construction industry to reduce demolition waste, greenhouse gas emissions, and material consumption. This report is a preliminary resource assessment and aims at inventorying and assessing all structural elements of the Triemli Personalh��user, focusing on their potential value for reuse. Both precast and cast-in-place RC elements are included. They are part of the load-bearing structure or are self-supporting such as the precast facade elements. The proposed methodology allows identifying all properties needed to evaluate the potential for reuse of an element: geometry, material properties, current condition, aesthetics, accessibility, resistance, future durability and environmental impacts. After reviewing available reports and drawings on the buildings, onsite visits are carried out to complete the information and visually inspect the structural elements. During the inspection, the elements are assessed with regards to their suitability for reuse and their condition is classified into a five-grade scale. The investigations are completed with destructive and non-destructive testing of the material properties. Together, Buildings A, B and C are made up of approximately 7 000 m3 of materials constituting their load-bearing system, with approximately 2 500 m3 of precast concrete, 3 400 m3 of cast-in-place concrete and 1 100 m3 of masonry. Of this total, approximately 4% of the volume is dropped from the analysis due to the bad condition of the elements, namely the balcony slabs, the roof slab, and the external stairs. The other elements are in a good or acceptable condition and ae inventoried and analysed in detail. The inventoried elements are divided into 5 categories: (1) facade elements; (2) slab elements; (3) wall elements; (4) column elements; and (5) staircases. Each of these categories are subdivided into a certain number of element types for which a complete factsheet is prepared, including pictures, drawings and useful information on their condition. The volume and weight of each element types are given, as well as their share of the total material volume. The embodied global warming potential (in kgCO2eq) for fabrication and demolition of the elements is also calculated. The results of the investigation on material properties confirm sufficient compressive strength for all elements. The carbonation depths measured on the cores are lower than the cover thickness of the reinforcement. Thus, the concrete is not carbonated in the reinforcement areas and the risk of corrosion is kept low, insuring a good durability of the elements. This document should serve as a base for designing and planning future reuse applications for the concrete elements extracted when deconstructing the Triemli Personalh��user. The information presented here will help the planners to prioritize the reuse strategy on the elements in the best conditions, with the largest volume share and thus with the largest embodied global warming potential.

The Triemli Personalhäuser are three equal 15-story buildings located on the Zürich Triemli Stadtspital campus and erected between 1964 and 1969. Cast-in-place reinforced concrete (RC) slabs and walls form the building cores and their surrounding corridors. The rooms are arranged around these cores. The load-bearing intermediate walls, made of prefabricated masonry, support thin precast slabs used as permanent forms. A RC layer is cast over these precast slabs and connects the room slabs with the cast-in-place slabs of the corridors and cores. The self-supporting facade consists of precast RC panels. The City of Zürich plans the deconstruction of these three buildings, thus making available a large amount of RC elements composing the structure and the facades of these buildings. Little-known and rarely implemented, the reuse of concrete elements from obsolete buildings in new projects is a sustainable approach that promotes a circular economy. When reusing, the components of obsolete buildings are carefully dismantled without being crushed. They are then cleaned, possibly repaired or trimmed, and reused without many transformations in a new project, maintaining their shapes, technologies, and mechanical properties. In addition to maintaining the embodied energy and history of the reused components, reuse allows the construction industry to reduce demolition waste, greenhouse gas emissions, and material consumption. This report is a preliminary resource assessment and aims at inventorying and assessing all structural elements of the Triemli Personalhäuser, focusing on their potential value for reuse. Both precast and cast-in-place RC elements are included. They are part of the load-bearing structure or are self-supporting such as the precast facade elements. The proposed methodology allows identifying all properties needed to evaluate the potential for reuse of an element: geometry, material properties, current condition, aesthetics, accessibility, resistance, future durability and environmental impacts. After reviewing available reports and drawings on the buildings, onsite visits are carried out to complete the information and visually inspect the structural elements. During the inspection, the elements are assessed with regards to their suitability for reuse and their condition is classified into a five-grade scale. The investigations are completed with destructive and non-destructive testing of the material properties. Together, Buildings A, B and C are made up of approximately 7 000 m3 of materials constituting their load-bearing system, with approximately 2 500 m3 of precast concrete, 3 400 m3 of cast-in-place concrete and 1 100 m3 of masonry. Of this total, approximately 4% of the volume is dropped from the analysis due to the bad condition of the elements, namely the balcony slabs, the roof slab, and the external stairs. The other elements are in a good or acceptable condition and ae inventoried and analysed in detail. The inventoried elements are divided into 5 categories: (1) facade elements; (2) slab elements; (3) wall elements; (4) column elements; and (5) staircases. Each of these categories are subdivided into a certain number of element types for which a complete factsheet is prepared, including pictures, drawings and useful information on their condition. The volume and weight of each element types are given, as well as their share of the total material volume. The embodied global warming potential (in kgCO2eq) for fabrication and demolition of the elements is also calculated. The results of the investigation on material properties confirm sufficient compressive strength for all elements. The carbonation depths measured on the cores are lower than the cover thickness of the reinforcement. Thus, the concrete is not carbonated in the reinforcement areas and the risk of corrosion is kept low, insuring a good durability of the elements. This document should serve as a base for designing and planning future reuse applications for the concrete elements extracted when deconstructing the Triemli Personalhäuser. The information presented here will help the planners to prioritize the reuse strategy on the elements in the best conditions, with the largest volume share and thus with the largest embodied global warming potential.

A travers une revue de la littérature, ainsi que 32 études de cas et des entretiens avec des praticiens, ce recueil: › synthétise les principes fondamentaux des deux approches; › documente et diffuse les retours d’expériences et les bonnes pratiques; › apporte aux entrepreneurs/entrepreneuses, concepteurs/conceptrices et maîtrises d’ouvrage des références techniques; › procure aux parties prenantes un bagage théorique à la pointe et détaillé ainsi qu’une série de référence pour aller plus loin; › esquisse les perspectives d’évolution et opportunités applicables au bâti suisse.

As the most widely used construction material worldwide, concrete is the main cause of greenhouse gas emissions, material depletion, and waste generation by the construction industry. Typically, concrete waste is crushed and, at best, reclaimed into recycled aggregate or used as gravel. This process is energy-intensive and results in a reduction in material properties. In contrast, the direct reuse of concrete elements from obsolete structures offers great potential for significantly reducing the environmental impact of new constructions. To be reused, concrete elements are carefully sawn out of soon-to-be-demolished buildings. Elements are then used without other major transformations for another service cycle in a new assembly. This paper analyses two recent projects in Switzerland that showcase innovative applications of concrete reuse: a post-tensioned segmented arch footbridge and a parking pavement. Both projects reuse blocks extracted from cast-in-place concrete buildings undergoing transformation or demolition. In this paper, environmental and economic analyses provide a comprehensive understanding of the alleviations and costs involved. Results are compared to those of alternatives with conventional construction methods. The two projects reusing concrete globally showcase a drastically lower environmental impacts for comparable or higher construction costs, hence calling for future developments of such new circular construction strategies.