TY - JOUR A1 - Giebson, C. A1 - Voland, K. A1 - Ludwig, H.-M. A1 - Meng, Birgit T1 - Alkali-silica reaction performance testing of concrete considering external alkalis and preexisting microcrack N2 - In concrete elements, simultaneously subjected to cyclic loadings and external alkalis, the risk for damage caused by or under participation of an alkali-silica reaction (ASR) is particularly high. This is of particular concern for concrete pavements due to the increasing heavy vehicle traffic and the application of sodium chloride (NaCl) de-icer during winter. Since 2004, the climate simulation concrete prism test (CS-CPT) has been used successfully to evaluate job mixtures for pavements by considering the impact of alkali-containing de-icers. However, the role of mechanical predamage on ASR is largely unclear. In a joint research project, the CS-CPT has been used to investigate the influence of preexisting microcracks on ASR. It was evident that an ASR initiated earlier in the predamaged concrete prisms due to the more rapid ingress of NaCl solution through the microcracks. KW - Alkali-silica reaction KW - Climate simulation concrete prism test KW - External alkalis KW - Laser-induced breakdown spectroscopy KW - Microcracks KW - Pavement concrete PY - 2017 U6 - https://doi.org/10.1002/suco.201600173 SN - 1464-4177 SN - 1751-7648 VL - 18 IS - 4 SP - 528 EP - 538 PB - Ernst & Sohn AN - OPUS4-42574 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Meng, Birgit A1 - Weise, Frank A1 - Voland, K. A1 - Krütt, Enno T1 - Ermüdungsbedingte Degradation und ihre Auswirkungen auf den Stofftransport in Fahrbahndeckenbeton N2 - Im Rahmen des Beitrags soll aufgezeigt werden, welchen Einfluss eine mechanisch induzierte Vorschädigung (Ermüdungsbeanspruchung) auf den Ablauf und die Intensität des AKR-Schädigungsprozesses hat. Dies erfordert eine ausführliche Beschreibung der vielfältigen interagierenden Schädigungs- und Transportprozesse und aufbauend eine enge Verknüpfung von Experimenten mit einer mehrskaligen Modellierung. Die experimentelle Basis bildete die mechanische Vorschädigung (Ermüdungsbeansprochung) großformatiger Balken aus einem Fahrbahndeckenbeton bei Einsatz alkaliempfindlicher Gesteinskörnungen. Aus diesen großformatigen Balken wurden nach erfolgter Ermüdungsbeanspruchung kleinformatige Probekörper gewonnen. An diesen wurde detailliert untersucht wie sich die mechanische Vorschädigung auf das Betongefüge und die daraus resultierenden Transport- und Schädigungsprozesse auswirkt. Von der mechanisch induzierten Vorschädigung bis zum AKR Schädigungsprozess sollten in diesem Kontext die Rissbildungsprozesse und der interagierende Eintrag bzw. die Auslaugung der Alkalien ganzheitlich betrachtet werden. Der Beitrag fokussiert auf die Charakterisierung der infolge der mechanischen Vorschädigung induzierten Rissbildungsprozesse. Ferner wird detailliert auf die Auswirkungen der mechanischen Rissbildung auf den Stofftransport eingegangen. KW - Baustoffe KW - Beton KW - Dauerhaftigkeit KW - Ermüdung KW - Alkali-Kieselsäure-Reaktion KW - AKR PY - 2017 SN - 978-3-00-056692-9 SP - 416 EP - 427 CY - Bochum AN - OPUS4-42970 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Voland, K. A1 - Meng, Birgit A1 - Weise, Frank T1 - Alkali-silica reaction in concrete pavements N2 - A significant number of German concrete motorway pavements have shown damage only a few years after construction. The alkali-silica-reaction (ASR) is often one of the reasons for this damage. German guidelines and regulations focus on the optimisation of the concrete composition to avoid damage due to ASR. Moreover, diverse research projects have dealt with the development and optimisation of ASR performance test methods with and without external alkali supply. However, the influence of other parameters on the occurrence and intensity of a damaging ASR had not yet been taken into account. Such parameters include, e.g., insufficient curing and the modifications of concrete’s porosity due to the use of slip form pavers. Likewise, the increased traffic loading had not yet been considered. The Federal Institute for Materials Research and Testing (BAM) assesses these parameters and processes in a number of projects. These projects aim primarily to increase the durability of the concrete pavements, in particular by improving preventive measures that may be taken before or after the construction of concrete pavements. This paper gives a short overview of BAM’s projects concerning ASR in concrete pavements. Furthermore, results regarding the influence of the cyclic traffic loading on ASR are presented. T2 - 8th International conference on concrete under severe conditions - environment & loading (ConSec) CY - Lecco, Italy DA - 13.09.2016 KW - Building materials KW - ASR KW - Concrete KW - Damage PY - 2016 AN - OPUS4-39104 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voland, K. A1 - Weise, Frank A1 - Meng, Birgit T1 - Alkali-silica reaction in concrete pavements N2 - A significant number of German concrete motorway pavements have shown damage only a few years after construction. The alkali-silica-reaction (ASR) is often one of the reasons for this damage. German guidelines and regulations focus on the optimisation of the concrete composition to avoid damage due to ASR. Moreover, diverse research projects have dealt with the development and optimisation of ASR performance test methods with and without external alkali supply. However, the influence of other parameters on the occurrence and intensity of a damaging ASR had not yet been taken into account. Such parameters include, e.g., insufficient curing and the modifications of concrete’s porosity due to the use of slip form pavers. Likewise, the increased traffic loading had not yet been considered. The Federal Institute for Materials Research and Testing (BAM) assesses these parameters and processes in a number of projects. These projects aim primarily to increase the durability of the concrete pavements, in particular by improving preventive measures that may be taken before or after the construction of concrete pavements. This paper gives a short overview of BAM’s projects concerning ASR in concrete pavements. Furthermore, results regarding the influence of the cyclic traffic loading on ASR are presented. T2 - 8th International conference on concrete under severe conditions - environment and loading (ConSec) CY - Lecco, Italy DA - 13.09.2016 KW - Alkali-silica-reaction KW - ASR KW - Concrete pavements KW - Durability KW - Concrete's porosity KW - Cyclic traffic loading and mechanical pre-damage PY - 2016 U6 - https://doi.org/10.4028/www.scientific.net/KEM.711.714 SN - 1662-9795 VL - 711 SP - 714 EP - 721 PB - Trans Tech Publications CY - Switzerland AN - OPUS4-39106 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wallau, Wilma A1 - Pirskawetz, Stephan A1 - Voland, K. A1 - Meng, Birgit T1 - Continuous expansion measurement in accelerated concrete prism testing for verifying ASR-expansion models 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-continuousexpansion 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. Two phenomenological approaches, frequently used for describing reaction kinetics of ASR by linking it to expansion results from ASR-testing, were validated with continuous expansion data of three types of aggregate. Experimental expansion depicted s-shaped curves similar to them of the modelling approaches. However, strong swelling recorded in the beginning of the test was not covered by the model curves. 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. Regarding data for validation of ASR-expansion models, continuous expansion results are preferable to conventional test results. KW - Alkali–silica reaction KW - Accelerated concrete prism test KW - Automated expansion measurement KW - ASR modelling PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-455959 SN - 1359-5997 SN - 1871-6873 VL - 51 IS - 3 SP - 51 EP - 79 PB - Springer AN - OPUS4-45595 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wallau, Wilma A1 - Pirskawetz, Stephan A1 - Voland, K. A1 - Weise, Frank A1 - Meng, Birgit ED - De Schutter, G. ED - De Belie, N. ED - Janssens, A. ED - Van Den Bossche, N. T1 - Online monitoring of the expansion of alkali-silica reaction affected concrete prisms implemented to the accelerated concrete prism test at 60 °C N2 - The accelerated concrete prism test (ACPT-60 °C) facilitates testing of alkali-silica reactivity of aggregates within five months. Manual measurement is usually conducted to determine expansion of test specimen every 28 days. This conventional procedure gives only limited insight to expansion behaviour of ASR-affected prisms. Due to the large time intervals, expansion exceeding the critical value of 0.3 mm/m is likely to be noticed late. Continuous recording resolves this problem and delivers beneficial information on the shape of the expansion curve. Displacement transducers integrated into a special testing equipment developed at BAM put continuous measurement into practice. Additionally, ultrasonic velocity and acoustic emissions are measured in-situ and provide deeper insights into hydration and crack formation processes during the test. Aiming for an automated testing method close to the German guideline, the following technical and methodical challenges arise. Changing of the vertical orientation of the prisms with every manual measurement as standardised cannot be implemented. Furthermore, preliminary results already proved true that cooling and heating cycles, as necessarily associated with each manual measurement, can evoke additional expansion. Therefore, interrupted and continuously measured expansions reveal systematic differences, indicating the necessity to adjust the threshold expansion value for automated testing. Results presented in the paper: Different types of reactive aggregate have been tested applying continuous and manual expansion measurement to the concrete specimens. Development of continuously measured ultrasonic velocity and acoustic emissions of the aggregates tested diverge significantly while the expansion curves vary in shape and maximum strain. Prisms produced from a slowly reacting aggregate do not exhibit noticeable crack formation. It shows that comprehensive measuring helps describing and distinguishing ASR-damage mechanisms. Models of ASR-induced expansion, available in the open literature, so far are validated with discontinuous data hardly tracing the modelled curve. Continuous measurement improves validation and further model development. T2 - XIV DBMC - 14th International Conference on Durability of Building Materials and Components CY - Gent, Belgium DA - 29.05.2017 KW - Alkali-silica reaction KW - Accelerated concrete prism test KW - Continuous monitoring KW - Expansion modelling PY - 2017 SN - 978-2-35158-159-9 VL - PRO 107 SP - 1 EP - 11 PB - RILEM Publications S.A.R.L. AN - OPUS4-40499 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weise, Frank A1 - Meng, Birgit A1 - Pirskawetz, Stephan A1 - Voland, K. T1 - Influence of simultaneous cyclic loading and external alkali supply on the alkali-silica reaction in concrete pavements N2 - In recent years the German motorway network has seen an increase in the occurrence of damage to concrete road surfaces which can be attributed to the alkali-silica reaction (ASR). In view of the often drastically reduced life expectancy of road surfaces due to ASR, research activity in this field has notably increased. Alongside preventative measures in concrete technology, the main research focus up to now has been the development of performance-oriented testing procedures for ASR prevention. This included more specifically the accelerated simulation of climatic effects and external alkali penetration on road surfaces. The effects of mechanical pre-damage resulting from cyclic traffic loading and climatic impact had previously not been taken into consideration. Since 2011, the five-partner research group 1498 sponsored by the German Research Foundation (DFG) has been pursuing research on how simultaneous cyclic loading and external alkali penetration impacts destructive ASR in road surface concretes. The depiction of the myriad degradation and transport processes necessary for an understanding of these effects requires close interaction between experiments and their multi-scale modelling. This paper aims to focus on the aforementioned experiments by means of innovative testing techniques. The research is founded on a series of cyclic fatigue tests performed on large-format beams, both with and without previous application of a sodium chloride (NaCl) solution, with simultaneous tracking of crack development. Subsequently, smaller test specimens were extracted from the pre-damaged beams for further experiments. These included the spatial visualization and quantification of fatigue-induced cracks using micro X-ray 3D-computed tomography (3D-CT). Additionally, the effects of fatigue-induced cracks on alkali transport were investigated using Laser-Induced Breakdown Spectroscopy (LIBS). Subsequent storage of the small-format test specimens, with and without cyclic pre-damage, in an ASR-conducive environment then provided initial findings on the influence of fatigue-induced predamage on the ASR. T2 - 15th International Conference on Alkali-Aggregate reaction (ICAAR 2016) CY - Sao Paulo, Brazil DA - 03.07.2016 KW - concrete pavements KW - alkali-silica-reaction KW - fatigue KW - damage monitoring PY - 2016 SP - Paper 191 AN - OPUS4-37142 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -