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Die in den Abschlussberichten zu den Vorhaben zur Ermittlung der Prüffestigkeit von Flachglas (BAM-161) und zur Tragfähigkeit großer Glasscheiben (BAM-162) dokumentierten Ergebnisse von durchgeführten Balken-Siegeversuchen und Doppelring-Biegeversuchen in Anlehnung an DIN 52303 Teil 1 bzw. DIN 52292 Teile 1 und 2 sowie Biegebruchversuchen an zweiseitig und vierseitig aufgelagerten Scheiben aus vorgespanntem und nicht vorgespanntem Spiegelglas (abkürzend als ESG bzw. Floatglas) werden zusammenfassend ausgewertet.
Es wurden Doppelring-Biegeversuche an quadratischen Proben mit 30 cm Seitenlänge, Biegeversuche bei zweiseitiger Auflagerung nach DIN 52303 Teil 1 und Doppelring- Biegeversuche nach DIN 5229 Teil 2 an 6 mm und 10 mm dickem, vorgespanntem und nicht vorgespanntem Flachglas durchgeführt, Die statistische Auswertung aller Prüfserien erfolgte nach üblichen Verteilungsfunktionen wie Normal-, Lognormal- und Weibullverteilung.
In Germany, about 60 million tons of demolition waste are generated annually. Approximately 70% of the demolition waste is currently recycled. Most recycling applications, for example in roadbed substructures, can be seen as a kind of downcycling. However, there are also some high-level applications for demolition waste. For instance, crushed and sieved concrete demolition waste can be used as concrete aggregate instead of natural materials. Depending on the crushing process, about a third of the broken concrete is currently concrete sand. At present, concrete sand fraction (0-4 mm) is rarely reused as a concrete aggregate. This is due to the fact that some important characteristics of crushed concrete sand are different from those of natural sand. As a result, it does not reach the standards required for aggregates. Concrete containing such aggregate is of lower quality than concrete made of natural aggregate. This paper describes an experimental investigation on the treatment of concrete sand gained from demolition waste by wet processing using a jig whereby the sand is separated by grain size and, more importantly, by density. Concrete produced with concrete sand which has been treated in this manner should have the same quality as concrete prepared with natural aggregate. Recycled sand used as aggregate substitutes natural resources and avoids disposal of waste. It has all the characteristics of an Ecomaterial. (author abst.)
On the background of the need for reuse of building rubble and the saving of natural resources, a European Union research project was performed covering concrete technology and durability aspects. A very special precondition was the use of large-scale processed building rubble with unknown origin and the total replacement of aggregates above 2 mm. Comprehensive tests were carried out on the properties of the starting material from different processing plants and fresh concrete, particularly the interdependence of water addition and wor ability. Investigations on hardened concrete properties included strength devel-opment, creep and shrinkage, modulus of elasticity, capillary absorption, freezing and thawing resistance, and carbonation behavior over a long period. The results demonstrate that the industrial production of a high-grade, durable concrete is possible. The project is a promising contribution for sustainable development.