Effect of Freezing-treatment on Estimating Free Water Distribution in Wood by Ultrasonic Wave
Soma T., Shida S., Arima T. Dept of Biomaterial Sci., University of Tokyo, 1-1-1 yayoi, bunkyo-ku, Tokyo, JAPAN, 113-8657.
ABSTRACT
A simple equation, which gives the ratio of air-dried part to water-saturated part as length. was proposed for estimating moisture distribution in wood by ultrasonic waves. In the region of five water, the ultrasonic velocity is known to change slightly with moisture content It was examined how freeze-treatment, which changes free-water from liquid state to solid state effects on ultrasonic velocity. It was confirmed that ultrasonic velocity was higher in freeze-treated specimens than in non-treated specimens at any moisture contents in the L, P, and T directions. With increasing moisture content the ultrasonic velocity of non-treated specimen was approaching to the liquid water value (1.50km/s) on the other hand, that of freeze-treated was approaching to the solid water value (3.23km/s). In the R and T directions, the velocity difference between the non-treated specimens and the freezing-treated was significant in the region of fee water, on the contrary, it was not in the region of bound water These facts show that the velocity difference caused by freezing-treatment may indicate free water quantity m wood. In the verification of the proposed equation by, model specimens, the calculated values with frozen specimens were closer to the pre-determined fixed values as a model than with non-treated specimens. The freeze-treatment is considered to be, therefore effective on evaluating free water distribution in wood.
Publication Source: Proceedings of the 12th International Symposium on Nondestructive Testing of Wood University of Western Hungary, Sopron, 13-15 September 2000, ISBN 963 7180 88 5 Publisher: University of Western Hungary, H 9400 Sopron, P.O.Box 132, FAX: +36 99 311 103
