TY - CONF A1 - Klimek, André A1 - Stelzner, Ludwig T1 - Screening-tests on the susceptibility to spalling of two ordinary concretes N2 - Investigating the spalling behaviour of a concrete mixture using large scale members is complex and expensive. Thus, the susceptibility of concrete to spalling is investigated by means of fire tests on small scale specimens. However, the reduction of the fire exposed surface increases the influence of boundary effects. Macrocracking and the water loss via the lateral surfaces reduce the impact of the thermomechanical and thermohydraulic damage mechanisms and therefore, lower the risk of spalling. Thus, the influence of different restraints on the spalling behaviour of intermediate scaled specimens (Ø0.47 m; h=0.29 m) was investigated for two ordinary concrete mixtures. Both mixtures had the same composition except the type of aggregate. One mixture contained only quartzitic aggregates, whereas the other mixture was made with basalt grit as coarse aggregates. Applied steel rings restrained the thermal expansion of the specimen and prevented the loss of water, whereas applied steel sheet primarily reduced the loss of water during the fire test. Additionally, the fire exposed surface of one specimen of each mixture was pre-dried under controlled climate conditions and fire tested with applied steel rings. The results show a higher spalling volume for the ring restrained specimens compared to the other covering types. Further, the pre-dried boundary zone leads to delayed and decreased occurrence of spalling compared to the non-dried specimens for the concrete with quartzitic aggregates and to a prevention of spalling for the mixture with basalt aggregates. Additionally, the results show that the influence of the thermomechanical behaviour of the coarse aggregates increases with increasing restraint. The restrained conditions of the specimens with applied steel ring are comparable to the conditions in the centre of a large scale member. This test series is a further step for possible concept of steel ring restraint concrete specimens as “screening-tests” in upcoming projects. T2 - 7th International Workshop on Concrete Spalling due to Fire Exposure CY - Berlin, Germany DA - 12.10.2022 KW - Spalling KW - Fire test KW - Concrete KW - Restraint PY - 2022 AN - OPUS4-56023 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Klimek, André A1 - Stelzner, Ludwig A1 - Hothan, Sascha T1 - Auswirkung von passivem Zwang auf das Abplatzverhalten von Beton im Brandfall N2 - Beschreibung des Abplatzverhaltens von vier Prüfkörpertypen in Abhängigkeit der Ummantelungsart und Lagerungsbedingungen für zwei Betonrezepturen T2 - 8th Symposium Structural Fire Engineering CY - Brunswick, Germany DA - 13.09.2022 KW - Brand KW - Beton KW - Abplatzen KW - Zwang PY - 2022 AN - OPUS4-55734 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -