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Organisationseinheit der BAM
Weltweit besteht einen hoher, stetig wachsender Bedarf an Natursteininstandsetzung im Bereich des denkmalgeschützten Kulturguts. Das Ausbessem beschädigter Elemente mit sogenannten Steinersatzmassen ist dabei eine etablierte Technik. Hierfür werden Mörtel unterschiedlichster Zusammensetzung verwendet. Die Schwierigkeit für den Restaurator liegt in der Wahl, bzw. der Verfügbarkeit des optimalen Produkts, um im individuellen Fall sowohl den mechanischen und bauphysikalischen Anforderungen als auch den gestalterischen und denkmalpflegerischen Belangen gerecht zu werden. Anhand der im Beitrag an Fallbeispielen erläuterten häufig auftretenden Probleme und der daraus abgeleiteten Anforderungen an Natursteininstandsetzung, lässt sich die Komplexität dieser Aufgabe erkennen. An der BAM wird derzeit im Rahmen eines Forschungsprojekts ein modulares Steinersatzsystem entwickelt. Ziel der Entwicklung ist es dem Restaurator die größtmögliche Freiheit in der Anpassung des Mörtels an die Originalsubstanz zu geben. Erste Ergebnisse aus Parameterstudien zur Bindemittel- und Sandvariation sowie zu Polymermodifikationen werden vorgestellt.
For several years, optical measuring techniques play an ever increasing role in various areas of construction. Applications ränge from simple laser-based distance measurements up to the use of advanced camera Systems to assess shape changes of components. The advantages of such Systems lie in the ränge of non-contact respectively in non-destructive measurement and in the high required accuracy and reproducibility. The continuous improvement and development of sensors and laser sources also opens constantly new applications and areas of applications. Already established measurement methods and technologies can be further developed and adapted to modern requirements. At BAM it is a laser-based measurement System has been developed that is capable to measure the roughness of component surfaces in equal to already established methods.
Since its invention in the early 1990’s, self-consolidating concrete has never become well established in the ready-mix sectors worldwide. The reason for this can be mainly found in the fact that the sophisticated compositions are sensitive against changing environments. This lack of robustness can be attributed to the interaction between cement hydration reaction and high range water reducing agent (HRWRA). Understanding the relevant mechanisms that control the initial flow performance as well as the flow retention helps optimizing SCC mixtures that perform either steadily in one specific environment or that perform largely similarly at steadily changing environments.
This paper depicts how HRWRAs interact with clinker and hydration phases and discusses the important role of the charge density of a polycarboxylic HRWRA in the way the rheology is affected. Based on rheometric results and observations of the Vicat setting times, it is shown that increasing charge densities of the HRWRA and decreasing water to powder ratios (w/p) reduce the flow retention and have lesser retarding effect on the setting. Based on the discussion, optimization procedures for the mixture composition and the HRWRA modification are suggested to achieve optimized performance for varying environmental situations or highest robustness for specific conditions.
The present article gives an insight into the research project BEGLARES. Main topics are the restoration “Dalles de Verre” Windows and the development of repair mortars and techniques. This project is executed in cooperation between Glasmalerei Peters GmbH, the University of York, and the BAM Federal Institute for Materials Research and Testing. It is funded by the Federal Ministry of Economics and Technology. The main mechanism of damage, Standards for protection and repair of concrete structures, and the development of repair mortar and special test specimens are presented.
Repair mortars for the restoration and reprofiling of natural stone elements in cultural heritage
(2011)
For the protection of the world's cultural heritage the restoration of listed buildings and monuments is an important task. In many cases the need to repair and reprofile natural stone elements occurs. Repair mortars for such applications have to match historicocultural interests as well as durability related and constructive interests. Currently a research project dealing with the development and optimisation of such mortars is set up at the BAM. Special focus is laid on the possibility of a modular adaption to match a vast variety of stone properties. Besides the development and lab scale testing of the mortar system, an in-situ application will be planned and executed.