Unlocking durability enhancement in intact cylindrical Moso bamboo (Phyllostachys edulis) via pilot-scale steam heat treatment

초록

Bamboo is a sustainable material with rapid growth and excellent mechanical properties; however, its susceptibility to biological degradation and surface deterioration under outdoor conditions limits its applications. Although steam heat treatment has been widely studied to improve bamboo durability, most previous studies have relied on strip and small-sized specimens, limiting their industrial applicability. In this study, steam heat treatment was applied to full-length cylindrical Moso bamboo (Phyllostachys edulis) using a large-scale industrial facility (1.8 & times; 1.8 & times; 8 m3), highlighting the feasibility of the process under practical manufacturing conditions at 120-180 degrees C. This approach enabled direct evaluation of circumferential and diameter changes in intact bamboo under realistic processing conditions. With increasing temperature, moisture content decreased while specific gravity increased, accompanied by progressive shrinkage and densification. However, at 180 degrees C, pronounced cracking and splitting were observed, associated with significant hemicellulose degradation. In terms of mechanical performance, the modulus of rupture (MOR) increased with temperature and reached its maximum at 140 degrees C, showing a 38.9% improvement compared to the untreated control, followed by a decline at higher temperatures. At >= 160 degrees C, durability against fungal decay and termite attack was markedly improved. These results indicate that heat treatment at 140-160 degrees C provides an optimal balance between mechanical performance, dimensional stability, and durability for cylindrical bamboo, highlighting its distinction from conventional studies using processed specimens.

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