sustainability Article Building the Future on Lessons of Historic Reinforced Concrete Maria Bostenaru Dan Department of Urban and Landscape Design, Faculty of Urbanism, “Ion Mincu” University of Architecture and Urbanism, 010014 Bucharest, Romania; [email protected] Received: 12 May 2020; Accepted: 20 July 2020; Published: 23 July 2020 Abstract: This contribution presents the way the construction material reinforced concrete was introduced at the beginning of the 20th century, from both the technical (Hennebique system) and the philosophical points of view. The philosophy underlying the use of this material is evident in the theories on finding a language of form corresponding to tectonics, and its dialogue with timber, formulated by certain notable practicing architects of the time across Europe. Not to be neglected are aspects relating to the conservation of material and to interventions carried out over time. In Modernist times, this meant a change from the artistic expression of Art Nouveau. Today, it means technical adaptation. The paper addresses thus sustainability of intervention versus conservation. Keywords: 20th century architecture; historic concrete; conservation 1. Introduction Concrete had existed since the Roman times, but it was Joseph Monier (8 November 1823 Saint-Quentin-La-Poterie–12 March 1906, Paris) who conceived the idea of reinforcing it, showing the idea at the Paris Exhibition 1867. Although reinforced concrete was a new material which spread during the heyday of Modernism, its language of form was sought after during the Art Nouveau period. The new material introduced at the time of Art Nouveau was iron, but the discussion on finding new forms for new materials applied equally to reinforced concrete. In many parts of Europe, unlike older buildings which are doubtless recognized as heritage, buildings from the 20th century still struggle to get this status, not being considered old enough. Also, the innovative material concrete was seen in that time as technological revolution, as we will see in this paper, but proved in history not to be an everlasting material. At that time, the material was suitable for industrial production and was also employed in industrial buildings, since the challenge of early 20th century was related to economic efficiency and industrialization. The challenges of the beginning of the century were connected to the mass movement of the population to cities, in search of work places in the context of industrialization, and this was highlighted also in the discussions (conference, films, exhibitions) of Bauhaus 100th anniversary last year (1919–2019). Today’s challenges are different and related to environmental protection. Sustainability is an issue we have to take into account when thinking today of future generations, since resources are limited. The city cannot expand anymore, and these environmental issues are building a mostly invisible fortification around the city, sometimes visible as a green belt. Intensive construction replaces extensive construction. As such, the reuse of the materials they are made of or of the whole buildings of early 20th century is one of the challenges of today, especially since concrete aged and security requirements also evolved since and are not met today anymore. The sustainability of concrete as production material was addressed in [1]. Today, some buildings present challenges of security [2] against earthquake. According to the Brundtland report in 1987, 33 years ago now, the sustainability of concrete has to be put into question. Mindes and Aitcin [3] built on this affirmation when thinking of the material included in concrete, but concentrated Sustainability 2020, 12, 5925; doi:10.3390/su12155925 www.mdpi.com/journal/sustainability Sustainability 2020, 12, 5925 2 of 26 Sustainability 2020, 12, x FOR PEER REVIEW 2 of 27 materialon contemporary is only sparsely concrete. produced. However, Hence the reuse the ofnece existingssity for buildings reuse and satisfies restoration the criteria touched set, sincein case new of somematerial of these is only buildings. sparsely In produced. case of demolitions, Hence the so necessityme examples for reuse with and material restoration reuse touchedhave been in shown. case of Sakaisome ofand these Noguchi buildings. 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Life cyclecycle assessmentassessment is is needed, needed, and and there there are earefforts efforts to network to network internationally internationally for this, for for examplethis, for examplein the COST in the (European COST (European Cooperation Cooperation in Science andin Science Technology) and RESTORETechnology) “Rethink RESTORE Sustainability “Rethink Sustainabilitytowards a Regenerative towards a Economy”Regenerative network, Economy” including network, the circularincluding economy. the circular Historic economy. constructions Historic constructionsshall satisfy today’s shall satisfy safety today’s and energy safety regulations and energy and regulations be upgraded and be accordingly, upgraded accordingly, while maintaining while maintainingoriginal substance original in substance order to complyin order with to comply monument with protectionmonument regulationsprotection regulations but also because but also of becausematerial of sustainability material sustainability issues. In Karlsruhe issues. 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Further to the BrundtlandBrundtland report,report, thethe EXPO EXPO (World (World exhibition) exhibition) 2000 2000 Hannover Hannover was was also also bound bound to tosustainability sustainability principles, principles, containing containing issues issues regarding regarding the usethe of use local of materialslocal materials and water. and water. The author The authorvisited thevisited EXPO the and EXPO saw and in the saw Netherlands in the Netherla pavilionnds anpavilion innovative an innovative employment employment of the principles of the principlesregarding regarding the basement-body-roof the basement-b principleody-roof principle of a building, of a building, also in concretealso in concrete [6]. Examples [6]. Examples of the ofconservation the conservation of early of buildingsearly buildings in reinforced in reinforced concrete concrete are given are given here here in more in more detail detail for Italy. for Italy. In this In thisseismically seismically prone prone country, country, it is not it is only not the only aging the ofag theing materialof the material that poses that a poses problem, a problem, but also but the loadalso thebearing load characteristics.bearing characteristics. Several studies Several on studies such characteristics on such characteristics of historic of reinforced historic reinforced concrete structures concrete structureswere carried were out carried by the out University by the University of Genoa [ 2of], Ge fornoa example, [2], for related example, to therelated restoration to the restoration and functional and functionalconversion conversion of the former of the Hotel former Colombia Hotel (1921–1926)Colombia (1921–1926) to a university to a un library,iversity or library, to the Stock or to Exchangethe Stock Exchangebuilding (1909–1912) building (1909–1912)(Figure (Figure1)[ 7] and the1) [7] Grand and Hotelthe Grand Miramare Hotel (1906–1908). Miramare (1906–1908). Although Porcheddu, Although Porcheddu,the agent of the Hennebique agent of Hennebique in Italy was basedin Italy in was the based North, in in the Turin, North, and in most Turin, works and were most concentrated works were concentratedthere, buildings there, made buildings of early made reinforced of early concrete reinforced which concrete need which repair need and repair maintenance and maintenance are found arethroughout found throughout the country, the also country, in the South,also in like the the So Risorgimentouth, like the Risorgimento bridge