Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
A study on wave dispersion and attenuation in fresh cementitious material
Concrete is the most widely used construction material. Its behavior is timedependent since, just after mixing, it starts as a liquid suspension of particles, i.e. cement, sand grains, aggregates and air bubbles, suspended in water, while the hydration reaction transforms it into a porous solid medium with considerable load bearing capacity provided that mixture proportions are adequate. Therefore, the importance of assessing quality of concrete even when it is still fresh is undoubted. Many different approaches have been followed towards fresh concrete w/c determination. As to wave propagation, several studies concerning examination of fresh cementitious material have been reported. The present work includes results from an experimental series of ultrasonic measurements in fresh mortar. The study concerned a wide range of frequencies, namely between 20 kHz and 1 MHz. This is because, the influence of the individual phases present in the material, due to different characteristic size and physical properties, is expected to be pronounced at different frequencies. Additionally, a theoretical investigation of the mechanisms being responsible for the obtained experimental phase velocity dispersion and attenuation is undertaken through multiple scattering theory. To this end, the simple multiple scattering theory proposed by Waterman and Truell (1961) is employed to facilitate the solution of the scattering problem on sand grains and air bubbles.
A study on wave dispersion and attenuation in fresh cementitious material
Concrete is the most widely used construction material. Its behavior is timedependent since, just after mixing, it starts as a liquid suspension of particles, i.e. cement, sand grains, aggregates and air bubbles, suspended in water, while the hydration reaction transforms it into a porous solid medium with considerable load bearing capacity provided that mixture proportions are adequate. Therefore, the importance of assessing quality of concrete even when it is still fresh is undoubted. Many different approaches have been followed towards fresh concrete w/c determination. As to wave propagation, several studies concerning examination of fresh cementitious material have been reported. The present work includes results from an experimental series of ultrasonic measurements in fresh mortar. The study concerned a wide range of frequencies, namely between 20 kHz and 1 MHz. This is because, the influence of the individual phases present in the material, due to different characteristic size and physical properties, is expected to be pronounced at different frequencies. Additionally, a theoretical investigation of the mechanisms being responsible for the obtained experimental phase velocity dispersion and attenuation is undertaken through multiple scattering theory. To this end, the simple multiple scattering theory proposed by Waterman and Truell (1961) is employed to facilitate the solution of the scattering problem on sand grains and air bubbles.
A study on wave dispersion and attenuation in fresh cementitious material
Eine Studie zur Wellendispersion und Schwächung in frischen zementösen Werkstoffen
Aggelis, D.G. (Autor:in) / Shiotani, T. (Autor:in) / Philippidis, T.P. (Autor:in) / Polyzos, D. (Autor:in)
2006
9 Seiten, 5 Bilder, 24 Quellen
Aufsatz (Konferenz)
Datenträger
Englisch
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