Wood is a material formed from water and carbon dioxide by solar energy, and its use is expected to expand in the transition to a sound material-cycle society. Wood used in the seawater as piers of a jetty, etc. is damaged by marine borers, and wood used outdoors as windbreak fences, etc. is gradually weathered. The purpose of this study is to investigate the resistance of various wood materials against marine borers and weathering.
　In the experiments, various wood samples were installed in the seawater circulation pool, seawater shower field and air exposure field in the laboratory, and the dry mass or bending rigidity was measured regularly to evaluate the deterioration. As a result, the marine borer resistance of untreated wood differed depending on the wood species, and some samples were remaining after the seawater immersion period of 12 years, but no wood species were undamaged. Some heat-treated wood samples were undamaged after 13 years of immersion in the seawater, and acetylated wood samples were undamaged after 2 and a half years of immersion. Carbon fiber sheet-coated wood samples maintained the flexural rigidities of 50% or more of the initial values at 15 years of immersion. Measurement results of 100 untreated wood species exposed in the air with seawater spray for 3 years and exposed in the air without seawater spray for 4 years showed larger decreases in mass and flexural rigidity of non-tropical broadleaf wood than those of conifer and tropical broadleaf wood.

Key Words: wood, durability, marine borer, weathering