TY - CONF A1 - Wallau, Wilma A1 - Pirskawetz, Stephan A1 - Voland, K. A1 - Weise, Frank A1 - Meng, Birgit 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 - 14th International Conference on Durability of Building Materials and Components CY - Gent, Belgium DA - 29.05.2017 KW - Building Materials KW - Alkali-silica reaction KW - Accelerated Concrete Prism Test KW - Continuous monitoring KW - Expansion modelling PY - 2017 AN - OPUS4-40495 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 -