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Assessment of alkali-silica reaction damage in mortars with nonlinear ultrasonic techniques
In this work, a nonlinear ultrasonic modulation technique is employed to assess the damage state of Portland cement mortar samples induced by alkali-silica reaction (ASR). Due to the nonlinear interaction of propagating waves caused by distributed microcracks that are agitated from its equilibrium state, the ultrasonic responses of samples produce sideband frequencies around the frequency of propagating waves. The amplitude of the sidebands depends on the amplitude of the input signals and is particularly sensitive to the state of damage evolved in the sample. Therefore, the development of internal microcracks with increasing duration of exposure to aggressive conditions can be quantitatively related to the variation of external ultrasonic measurements. The ultrasonic results are compared with results from standard ASR expansion measurements (ASTM C 1260), and a proportionally increasing relation was found in the early stages. In addition, aggregates with different alkali-reactivity (i.e., low reactivity or high reactivity) were examined in a similar manner. The results indicate that the nonlinear parameter obtained from ultrasonic tests directly reflects the difference of aggregate reactivity. This clearly indicates that the developed nonlinear ultrasonic method is potentially a good alternative for a more rapid and still reliable assessment of aggregate alkalireactivity.
Assessment of alkali-silica reaction damage in mortars with nonlinear ultrasonic techniques
In this work, a nonlinear ultrasonic modulation technique is employed to assess the damage state of Portland cement mortar samples induced by alkali-silica reaction (ASR). Due to the nonlinear interaction of propagating waves caused by distributed microcracks that are agitated from its equilibrium state, the ultrasonic responses of samples produce sideband frequencies around the frequency of propagating waves. The amplitude of the sidebands depends on the amplitude of the input signals and is particularly sensitive to the state of damage evolved in the sample. Therefore, the development of internal microcracks with increasing duration of exposure to aggressive conditions can be quantitatively related to the variation of external ultrasonic measurements. The ultrasonic results are compared with results from standard ASR expansion measurements (ASTM C 1260), and a proportionally increasing relation was found in the early stages. In addition, aggregates with different alkali-reactivity (i.e., low reactivity or high reactivity) were examined in a similar manner. The results indicate that the nonlinear parameter obtained from ultrasonic tests directly reflects the difference of aggregate reactivity. This clearly indicates that the developed nonlinear ultrasonic method is potentially a good alternative for a more rapid and still reliable assessment of aggregate alkalireactivity.
Assessment of alkali-silica reaction damage in mortars with nonlinear ultrasonic techniques
Bewertung von Alkali-Silika Reaktionsschäden in Mörtel mittels nichtlinearer Ultraschallverfahren
Chen, J. (author) / Jayapalan, A.R. (author) / Kurtis, K.E. (author) / Kim, J.Y. (author) / Jacobs, L.J. (author)
2008
8 Seiten, 10 Bilder, 10 Quellen
Conference paper
Storage medium
English
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