Some Mechanical Properties of Aspen Wetwood

Green wetwood samples from five quaking aspen trees cut at the Cloquet Forest Research Center were tested in compression parallel to the grain and in bending. The compression specimen size was l/2 by 1/2 by 3 inches, that of the bending specimen was 1/2 by 1/2 by 8 inches with a load span of 6 inches. Smaller than normal specimens were used in order to obtain samples consisting entirely of wetwood. A matched sample of green normal sapwood cut from an area immediately adjacent to the location of each wetwood specimen was used for control purposes. Moisture content of the sapwood was 40 to 50 percent lower than the wetwood. In both the bending and compression tests a speed of loading was used which produced a strain rate comparable to the prescribed rate in ASTM D – 143. For all tests the wetwood was significantly weaker than the normal sapwood in close proximity to it. The strength properties of the wetwood averaged from 18 to 28 percent less than normal sapwood while the modulus of elasticity averaged 52 percent less. The sapwood was found to have a slightly higher specific gravity and a lower volumetric shrinkage than the wetwood. In the wetwood there was a weak, nonsignificant correlation between modulus of elasticity, modulus of rupture, fiber stress at proportional limit, and specific gravity. The specific gravity range was 0.29 to 0.47. Maximum crushing strength did exhibit a significant correlation with specific gravity.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member