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Vielleicht nannten es die Berliner „Puppen putzen“, wenn in den 1880er Jahren die Marmorstatuen auf der Schlossbrücke vor dem Berliner Stadtschloss mit Bürste, Wasser und Seife von Staub, Ruß und Taubendreck befreit wurden. Soviel Pflege wurde diesen Göttinnen aus der griechischen Mythologie nicht immer zuteil. So haben Klima, Luftverschmutzung und der 2. Weltkrieg, wie bei anderen Kunstwerken auch, tiefe Spuren hinterlassen. Der Erhalt dieser zwischen 1847 und 1857 aufgestellten Skulpturen und vieler vergleichbarer Objekte im Stadtbild ist durch die auch heute weiter fortschreitende Schädigung des Marmors gefährdet. In den Jahren 2006 bis 2010 förderte die Deutsche Bundesstiftung Umwelt (DBU) ein Projekt zur „Entwicklung und Überprüfung von Einhausungssystemen zur Reduzierung umweltbedingter Schädigungen von außenexponierten Marmorobjekten mit dem Ziel des langfristigen Erhalts in situ an einem national bedeutenden Objektkomplex, den Schlossbrückenfiguren unter den Linden, Berlin“. Geleitet und restauratorisch betreut wurde das Projekt durch das Landesdenkmalamt (LDA) Berlin. Durch die Abteilung Strukturgeologie und Geodynamik (GZG) der Georg-August Universität Göttinnen wurden die Verwitterungsmechanismen des Marmors untersucht und auf dieser Basis Anforderungen an das Schutzsystem formuliert. Anhand von numerischen Simulationen des Instituts für Bauklimatik der Technischen Universität Dresden (TUD) wurde das bauphysikalische Konzept des Einhausungssystems optimiert. Die konstruktive Gestaltung eines Prototyps und des finalen Entwurfs erfolgte durch das Fachgebiet Konstruktives Entwerfen und Tragwerkslehre der Universität der Künste Berlin. Durch den Fachbereich Baustoffe der BAM erfolgten die Realisierung des Prototyps der Einhausung sowie ein umfangreiches Klimamonitoring an den Skulpturen. Anhand dieses interdisziplinären Projektes und ergänzt durch weitere Messungen wird gezeigt, mit welchen Methoden die für die Degradation von Marmor relevanten Mechanismen untersucht werden können. Die Erkenntnisse aus dem Projekt sind die Grundlage für die Entwicklung nachhaltiger Pflege- und Schutzkonzepte für die kulturhistorisch wertvollen Skulpturen. Nur mit solchen modernen konservatorischen Programmen können die Originalskulpturen im Berliner Stadtraum erlebbar bleiben.
The project has developed a variety of new multifunctional and flexible building components for a healthier indoor environment. [H] house solutions are durable, energy efficient, safe and affordable. They are suitable for use in new buildings and for renovation. [H] house solutions cover aspects of long service life, reduced maintenance and long-term improvement of energy efficiency.
For the damage assessment of reinforced concrete structures the quantified ingress profiles of harmful species like chlorides, sulfates and alkali need to be determined. In order to provide on-site analysis of concrete a fast and reliable method is necessary. Low transition probabilities as well as the high ionization energies for chlorine and sulfur in the near-infrared range makes the detection of Cl I and S I in low concentrations a difficult task. For the on-site analysis a mobile LIBS-system (k = 1064 nm, Epulse ≤ 3 mJ, t = 1.5 ns) with an automated scanner has been developed at BAM. Weak chlorine and sulfur signal intensities do not allow classical univariate analysis for process data derived from the mobile system. In order to improve the analytical performance multivariate analysis like PLS-R will be presented in this work. A comparison to standard univariate analysis will be carried out and results covering important parameters like detection and quantification limits (LOD, LOQ) as well as processing variances will be discussed (Allegrini and Olivieri, 2014 [1]; Ostra et al., 2008 [2]). It will be shown that for the first time a low cost mobile system is capable of providing reproducible chlorine and sulfur analysis on concrete by using a low sensitive system in combination with multivariate evaluation.
This paper presents the development of ultra-high performance concrete (UHPC) for façade elements with self-cleaning properties. For creating self-cleaning surfaces two different approaches are proposed. One approach is based on the photocatalytic activation of the external UHPC shell by incorporation of TiO2 particles. The second approach consists of the modification of the UHPC surface by micro structuring in combination with the application of hydrophobic agents to create durable super hydrophobicity. In the framework of the H-HOUSE Project funded by the European Commission the experimental investigations were performed with UHPC based on Dyckerhoff Nanodur® technology. The special properties of this material enable the precise reproduction of any micro structure without flaws. The current results obtained from laboratory and outdoor weathering tests are promising and demonstrate the feasibility of the approaches.
Earth, timber, fibre boards and insulation materials based on wooden and other natural fibres offer a variety of properties beneficial for eco innovative constructions that are able to improve the energy and resource efficiency of buildings.
Due to their porosity, natural building materials are vapour active and are able to buffer moisture. In combination with highly insulated and airtight but vapour permeable building envelopes, modern earth-timber constructions provide stable indoor humidity levels and can therefore be naturally ventilated while achieving highest energy efficiency standards. Experimental evidence suggests that monitored pilot buildings in Berlin do show healthy indoor air humidity levels (around 50%) in wintertime, while mechanically ventilated buildings demonstrate significantly lower values (around 25%), which have to be considered as uncomfortable and unhealthy.
The application of building materials being poor in chemical emissions, particularly volatile organic compounds (VOC) and radon, improves the indoor air quality further, so that intermittent ventilation twice a day will be sufficient to provide healthy indoor air quality. The air quality in critical rooms (e.g. small bedrooms), demonstrating a smaller air volume, should be monitored if appropriate ratios of room size to occupancy level cannot be realised.
Through night time ventilation in summer, vapour active earth-timber constructions provide evaporative cooling (humidity adsorption at night time and desorption during the day). As a result, indoor temperatures of earth-timber buildings range around 8 °C below the outside temperature peak, when an appropriate glazing ratio is reflected. The EU funded research project H-house is investigating various construction materials regarding water vapour adsorption as well as emission and absorption of harmful substances. Based on this investigation new wall constructions are designed to provide a healthier indoor environment.
The paper presents a comparison between two different numerical modelling approaches aimed to simulate the in-plain behaviour of rammed earth walls, namely under axial, diagonal and cyclic shearcompression loading. In the first part of the study the mechanical characterisation of wallets tested under uniaxial compression and diagonal compression and walls tested under in-plane cyclic shear-compression loading is presented. The results were used to implement and validate the finite element simulations.
The numerical modelling of the rammed earth samples tested is then discussed in the second part. A non-linear constitutive law based on the total strain rotating crack model (TSRCM) was employed as implemented in the DIANA® software. The aim of the numerical analyses presented here is to simulate the behaviour of rammed earth under different inplane loading conditions. For the wallets, tests under static loading both macro- and micro-modelling
approaches were considered for the simulation of the experimental tests. For the walls subjected to cyclic loading only the micro-modelling approach was applied for the simulation of the experimental tests.
The respective FEM model was calibrated with the experimental results. The rammed earth layers were represented by continuum elements, the contact surfaces between layers by interface elements. This approach allowed assessing the influence of the apparent weakness of the interfaces between layers on the shear behaviour of rammed earth.
The goal of the numerical simulation of the cyclic tests was to establish the adequacy of common analytical methods (e. g. used for masonry) applied to the analysis of rammed earth. Rammed earth exhibits brittle characteristics similar to masonry materials and is used in geometrical typologies, such as walls, common in masonry construction.
The repair of earthen structures is not an easy task. Earth as a construction material has comparatively weak mechanical properties. It is also susceptible towards liquid water, were it can lose cohesion very quickly if certain moisture contents are exceeded. Repair concepts of structures built with such materials are therefore challenging. Historical earthen structures often exhibit damages in form of extensive cracking, which may have been caused by static or dynamic loads. Frequently these cracks are insufficiently or inappropriately repaired because of lack of knowledge and / or technology. In particular, the behaviour of crack repair by grouting poses a challenge in earthen materials and demands specific requirements for the grouting mortar, such as low water content, good water retention, low shrinkage. Grouting materials require additional specifications such as compatible strengths and Young’s modulus as well as good adhesion to the earthen substrates. In addition, grouts have to be sufficiently flowable to fill small cracks and voids without segregation or bleeding. Therefore, the rheological behaviour has to be well understood and controlled to gain the desired effects.The repair of cracks in earthen buildings is traditionally done by stuffing manually mortar into the gap. Naturally, this method is only usable for cracks with large widths. Another disadvantage is that cracks going through thicker walls cannot be completely reached by the tools used for stuffing the mortar into the crack. Lime based grouts for earthen materials were usually used for re-attachment of plasters but less for structural reasons.Due to the nature of earthen materials grouts based on formulated or hydraulic lime (according to the definition in EN 459-1) have to meet considerable demands on a variety of properties, which are related to compatibility, durability and in particular to the ability of being injected. The goal of this study was to create a grout, which can be used to re-establish structural continuity in cracked earthen masonry or other massive earth walls (rammed earth and cob) with the focus on grouting cracks. The grout material was based on hydrated lime (calcium hydroxide) with additions of pozzolana and lime stone filler.
The paper presents a comparison between two different numerical modelling approaches aimed to simulate the in-plain behaviour of rammed earth walls, namely under axial, diagonal and cyclic shearcompression loading. In the first part of the study the mechanical characterisation of wallets tested under uniaxial compression and diagonal compression and walls tested under in-plane cyclic shear-compression loading is presented. The results were used to implement and validate the finite element simulations. The numerical modelling of the rammed earth samples tested is then discussed in the second part. A non-linear constitutive law based on the total strain rotating crack model (TSRCM) was employed as implemented in the DIANA® software [1]. The aim of the numerical analyses presented here is to simulate the behaviour of rammed earth under different inplane loading conditions. For the wallets, tests under static loading both macro- and micro-modelling approaches were considered for the simulation of the experimental tests. For the walls subjected to cyclic loading only the micro-modelling approach was applied for the simulation of the experimental tests. The respective FEM model was calibrated with the experimental results. The rammed earth layers were represented by continuum elements, the contact surfaces between layers by interface elements. This approach allowed assessing the influence of the apparent weakness of the interfaces between layers on the shear behaviour of rammed earth. The goal of the numerical simulation of the cyclic tests was to establish the adequacy of common analytical methods (e. g. used for masonry) applied to the analysis of rammed earth. Rammed earth exhibits brittle characteristics similar to masonry materials and is used in geometrical typologies, such as walls, common in masonry construction.
Die Instandsetzung von Lehmbauwerken ist keine einfache Aufgabe. Der Baustoff Lehm hat vergleichsweise schwache mechanische Eigenschaften. Er ist außerdem anfällig gegenüber eindringendem Wasser, wobei er sehr schnell seinen Zusammenhalt verlieren kann, wenn gewisse Feuchtegehalte überschritten werden. Instandsetzungskonzepte für Bauwerke aus solchen Materialien stellen deshalb eine Herausforderung dar. Historische Lehmbauwerke zeigen oft Schäden in Form von starker Rissbildung, die durch statische oder dynamische Lasten hervorgerufen sein kann. Häufig werden solche Risse wegen mangelnder Fachkenntnis und / oder fehlender Techniken nur ungenügend instandgesetzt. Die Rissinstandsetzung mit Einpressmörteln birgt insbesondere für Lehmbaustoffe eine Herausforderung und erfordert spezifische Anforderungen an den Einpressmörtel, wie z. B. niedriger Wassergehalt, gutes Wasserrückhaltevermögen, niedriges Schwindmaß, an das instandzusetzende Material angepasste Festigkeit und E-Modul sowie eine gute Haftung am Lehmuntergrund. Zusätzlich müssen Einpressmörtel eine ausreichende Fließfähigkeit aufweisen, um kleine Risse und Hohlräume ohne Entmischung zu füllen. Deshalb muss das rheologische Verhalten des Einpressmörtels gut untersucht und kontrolliert werden, um die gewünschte Wirkung zu erzielen. Die Rissinstandsetzung bei Lehmbauwerken erfolgt traditionell durch manuelles Stopfen mit einem Mörtel. Natürlich können auf diese Weise nur Risse mit einer großen Breite verfüllt werden. Ein weiterer Nachteil ist, dass Risse, die durch dickere Wände verlaufen, nicht vollständig mit den für das Stopfen verwendeten Werkzeugen erreicht werden können. Kalkgebundene Einpressmörtel für Lehmbaustoffe werden gewöhnlich für die Wiederbefestigung von Putzen und weniger aus statisch-konstruktiven Gründen eingesetzt.
Aufgrund der Eigenschaften von Lehm, müssen Einpressmörtel auf Basis von hydraulischem Kalk nach EN 459-1 [4] wesentliche Anforderungen an eine Reihe von Eigenschaften erfüllen, die sich auf die Verträglichkeit, die Dauerhaftigkeit und insbesondere die Injektionsfähigkeit beziehen. Das Ziel der vorgestellten Untersuchungen war einen Einpressmörtel zu herzustellen, mit dem die strukturelle Kontinuität in Lehmmauerwerk oder anderen massiven Lehmwänden (Stampf- und Wellerlehm) durch Rissverpressung wiederhergestellt werden kann. Das Material bestand aus Kalkhydrat mit Zusätzen von Puzzolanen und Kalksteinfüller.