TY - CONF A1 - Krütt, Enno T1 - Online monitoring of the expansion of ASR-affected concrete prisms implemented to the accelerated concrete prism test at 60 °C N2 - The susceptibility of concrete structures due to alkali–silica reaction (ASR) can be assessed by means of ASR concrete prism testing at 60 °C, according to RILEM AAR 4.1. There, expansion of concrete prisms indicates alkali-reactivity of the examined concrete mix. This work applies in situ expansion measurement to accelerated concrete prism testing. Automated measuring facilitates both storage without the usually necessary interruptions for manual measurement and acquisition of quasi-continuous expansion data. A comparative experimental programme showed that conventional testing resulted in stronger expansion and leaching of alkalis than automated testing. Experimental simulation of interruptions, typically associated with manual measurements in conventional testing, could prove the influence of these cooling–heating cycles. Auxiliary measurement of acoustic emissions and ultrasonic velocity helped characterising mechanisms such as hydration and cracking, which also influence prism expansion. The proposed modification of the measurement procedure provides an extended basis to analyse expansion mechanisms. T2 - 10th Meeting of RILEM TC 258-AAA CY - Zurich, Switzerland DA - 01.11.2018 KW - ASR KW - Expansion Measurement PY - 2018 AN - OPUS4-46480 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krütt, Enno T1 - Fatigue-induced degradation in pavement concrete and its effect on alkali-silica reaction N2 - In recent years the German motorway network has seen an increase in the occurrence of damage to concrete road surfaces that can be attributed to the alkali-silica reaction (ASR). The effects of mechanically-induced damage resulting from cyclic traffic and climatic loading have previously not been taken into consideration while developing ASR test procedures. Therefore this contribution investigates the influence of fatigue mechanical loading on the ASR. T2 - SLD 4 CY - Delft, The Netherlands DA - 26.08.2018 KW - Fatigue KW - Pavement KW - ASR PY - 2018 AN - OPUS4-45729 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krütt, Enno T1 - Ermüdungsbedingte Degradation von Fahrbahndeckenbeton - Einfluss auf den Stofftransport - N2 - In den letzten 15 Jahren hat im deutschen Autobahnnetz die Anzahl von Schäden an Betonfahrbahnen, die vor 2005 er-richtet wurden zugenommen. Dies führt oft zu einer Vermin-derung der Lebensdauer von 30 auf 10 bis 15 Jahre. Trotz umfassender Untersuchungen wurde die Ursache bis jetzt nicht eindeutig geklärt, jedoch scheint die Alkali-Kieselsäure-Reaktion (AKR) hierbei eine Rolle zu spielen. Vor diesem Hintergrund wurden AKR-Performance-Tests entwickelt, die jedoch die mechanischen Einwirkungen aus Klima und Ver-kehr nicht berücksichtigen. Aus diesem Grund wurde eine AKR-Forschergruppe von der Deutschen Forschungsgemein-schaft ins Leben gerufen, welche sich experimentell und auf Simulationsebene mit diesem Thema befasst. Inhalt dieses Beitrages sind ausgewählte Ergebnisse des an der BAM bear-beiteten experimentellen Projektteils, welche in eine auf die Auswirkung einer mechanischen Degradation fokussierte Promotionsarbeit einfließen. T2 - DFG Workshop CY - Karlsruhe, Germany DA - 15.03.2017 KW - Fatigue KW - Pavement KW - ASR PY - 2017 AN - OPUS4-45975 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krütt, Enno A1 - Weise, Frank A1 - Meng, Birgit ED - Ye, G. ED - Yuan, Y. ED - Romero Rodriguez, C. ED - Zhang, H. ED - Savija, B. T1 - Fatigue induced degradation in pavement concrete and its effect on the alkali-silica reaction N2 - In recent years the German motorway network has seen an increase in the occurrence of damage to concrete road surfaces that can be attributed to the alkali-silica reaction (ASR). In view of the often drastically reduced service life of road surfaces due to ASR, research activity in this field has notably increased. Alongside preventative measures in concrete technology i.e. the usage of low-alkali cements, the main research focus up to now has been on the development of performance-oriented testing procedures for ASR prevention. The effects of mechanicallyinduced damage resulting from cyclic traffic and climatic loading have previously not been taken into consideration. The assessment of the myriad degradation and transport processes necessary for an understanding of these effects requires close interaction between experiments and corresponding multi-scale models. This contribution is focused on the experiments utilizing innovative testing techniques. The research is founded on a series of fatigue tests performed on large-scale beams with simultaneous tracking of the degradation process using non-destructive evaluation methods. Subsequently, smaller test specimens were extracted from the predamaged beams for further experiments. These experiments included investigation of the influence of fatigue-induced cracks on moisture and alkali transport. Subsequent storage of the small-scale test specimens, with and without cyclic pre-damage, in an ASR-conducive environment then provided initial findings on the influence of fatigue-induced degradation on the ASR. The results show that the degradation process can be well observed with the test Setup developed for the fatigue experiments. Further, a small but noticeable increase of mass Transport due to fatigue-induced degradation was measured, which correspondingly indicated an increased ASR damage potential. T2 - 4th International Conference on Service Life Design for Infrastructures (SLD4) CY - Delft, The Netherlands DA - 27.08.2018 KW - Fatigue KW - Pavement KW - ASR KW - Concrete PY - 2018 SN - 978-2-35158-213-8 SP - 112 EP - 121 PB - RILEM Publication S.A.R.L. CY - Paris, France AN - OPUS4-46197 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krütt, Enno T1 - Fatigue induced degradation in pavement concrete and its effect on the alkali-silica-reaction N2 - In recent years the German motorway network has seen an increase in the occurrence of damage to concrete road surfaces that can be attributed to the alkali-silica reaction (ASR). In view of the often drastically reduced service life of road surfaces due to ASR, research activity in this field has notably increased. Alongside preventative measures in concrete technology i.e. the usage of low-alkali cements, the main research focus up to now has been on the development of performance-oriented testing procedures for ASR prevention. The effects of mechanicallyinduced damage resulting from cyclic traffic and climatic loading have previously not been taken into consideration. The assessment of the myriad degradation and transport processes necessary for an understanding of these effects requires close interaction between experiments and corresponding multi-scale models. This contribution is focused on the experiments utilizing innovative testing techniques. The research is founded on a series of fatigue tests performed on large-scale beams with simultaneous tracking of the degradation process using non-destructive evaluation methods. Subsequently, smaller test specimens were extracted from the predamaged beams for further experiments. These experiments included investigation of the influence of fatigue-induced cracks on moisture and alkali transport. Subsequent storage of the small-scale test specimens, with and without cyclic pre-damage, in an ASR-conducive environment then provided initial findings on the influence of fatigue-induced degradation on the ASR. The results show that the degradation process can be well observed with the test Setup developed for the fatigue experiments. Further, a small but noticeable increase of mass Transport due to fatigue-induced degradation was measured, which correspondingly indicated an increased ASR damage potential. T2 - 4th International Conference on Service Life Design for Infrastructures (SLD4) CY - Delft, The Netherlands DA - 27.08.2018 KW - Fatigue KW - Pavement KW - ASR KW - Concrete PY - 2018 AN - OPUS4-46199 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krütt, Enno A1 - Wallau, Wilma A1 - Meng, Birgit A1 - Greim, M. A1 - Pirskawetz, Stephan T1 - Automatisierte AKR-Prüfung im 60 °C-Betonversuch T1 - Automated ASR Concrete Prism Testing at 60 degrees C N2 - Der 60 °C-Betonversuch ist eine in Deutschland und international verbreitete Methode um die Empfindlichkeit von Gesteinskörnungen und Betonen hinsichtlich einer Alkali-Kieselsäure Reaktion (AKR) zu prüfen. Dieser Beitrag stellt eine neuentwickelte automatisierte Variante der Prüfmethode in einem Minireaktor vor. Dabei werden die Dehnungen von Betonprismen nicht, wie beim konventionellen Test manuell, sondern automatisch in entsprechend ausgerüsteten Prüfbehältern gemessen. Neben einer Reduzierung des Messaufwands bringt die automatisierte Prüfung im Minireaktor weitere Vorteile. Die Dehnungssignale werden, anders als bei der konventionellen Messung, quasi-kontinuierlich aufgezeichnet und bilden das Expansionsverhalten der Prismen detailliert ab. Außerdem bleiben Unterbrechungen der AKR-provozierenden Lagerung aus, die bei der konventionellen Prüfung notwendig sind. Im Beitrag werden die automatisierte und konventionelle Prüfung anhand der Dehnungen von Prismen zweier Gesteinskörnungen verglichen. In Übereinstimmung mit vorhergehenden Untersuchungen sind im Minireaktor gemessene Dehnungen systematisch kleiner als manuell gemessene. Als mögliche Ursache werden Unterschiede im Auslaugverhalten experimentell untersucht. Zur Überprüfung der Einstufung der zwei Gesteinskörnungen erfolgen außerdem Referenzprüfungen in der Nebelkammerlagerung bei 40 °C. N2 - The Concrete Prism Test at 60 °C (60 °C-CPT) is a common method to evaluate the susceptibility of concrete and aggregates to the Alkali-Silica Reaction (ASR). This paper presents a new device for an automated version of the 60 °C-CPT. The system monitors the expansion of concrete prism automatically. Compared to the conventional test method, effort and time consumption are notably reduced. The nearly continuous recording of expansion signals allows for studying of ASR-mechanisms in more detail than the conventional test. In addition, the interruptions of ASR-provoking storage, necessary for manual measurements, are avoided. The presented study compares results of conventional and automated testing of two types of aggregate. In accordance with previous findings, continuously stored prisms generally expand less than the conventionally tested prisms. To find a possible explanation, differences in leaching of alkali from the concrete prisms were quantified. For verifying the alkali-reactivity of the two aggregates, they were also classified in the fog chamber test at 40 °C, the German reference method. KW - Baustoffe KW - AKR KW - 60 °C-Betonversuch KW - Automatische Dehnungsmessung KW - Auslaugung KW - Building Materials KW - ASR KW - Concrete Prism Test at 60 °C KW - Automated expansion measurement KW - Leaching of alkalis PY - 2019 DO - https://doi.org/10.1002/best.201900040 SN - 1437-1006 SN - 0005-9900 VL - 114. Jahrgang IS - 12 SP - 911 EP - 918 PB - Ernst & Sohn AN - OPUS4-50062 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -