The purpose of this study was to determine if stress wave analysis could be used to monitor the degradation of wood specimens exposed to the brown-rot decay fungi (Gloeophyllum trabeum) and of wood specimens subjected to attack by subterranean termites. One hundred fifty 3/4 by 3/4 by 12 in. Southern pine specimens were used for exposure to brown-rot decay fungi and two hundred twenty-five 3/4 by 3/4 by 12 in. Southern pine specimens were used for attack by subterranean termites. Lots containing twenty five specimens each were subjected to either brown-rot decay fungi or monocultures of subterranean termites for various lengths of time in order to produce a gradient series of wood degradation. The specimens were then stress waved and statically tested to failure in compression. Stress wave modulus of elasticity and stress wave time provided useful correlation coefficients when used to estimate the ultimate compression stress of the degraded wood specimens. For the brown-rot decay specimens, a correlation coefficient of 0.892 was achieved using stress wave modulus of elasticity, as calculated with original specific gravity and exposed stress wave time values, to predict ultimate compression stress. Stress wave time by itself provided a correlation coefficient of 0.729. For the termite attacked specimens, correlation coefficients ranged from r = 0.90 for the control specimens, to r = 0.79 for the attacked specimens. In this case however, stress wave time by itself was not affected by the degradation of the wood due to the fact that the termites devoured the early wood but not the late wood of each annual ring. Changes in stress wave modulus of elasticity and stress wave time values reflected changes in ultimate compression stress values during early periods of decay. From the results it appears that stress wave analysis can be used to accurately monitor the strength degradation of wood specimens exposed to brown-rot decay fungi. Similar results were found in the termite attacked specimens with stress wave modulus of elasticity but not with stress wave time alone.

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