Changes in Physical Characteristics of Bamboo in Response to Its Degradation in Water and Soil Environments

抄録

The utilization rate of bamboo in Japan is still very low, leading to the formation of abandoned bamboo forests. To reduce the area of abandoned bamboo forests, the use of bamboo as a construction material has been gaining attention in recent years. To use bamboo as a construction material, its physical characteristics (e.g., bending and compressive strengths) and chemical (e.g., degradation and organic matter) characteristics must be understood. Previously, the compressive strength and degradation of bamboo had been reported. To the best of our knowledge, the relation between the physical and chemical characteristics is still unclear. The first objective of this study is to clarify the degradation characteristics of bamboo in water and soil environments. Another objective of the study is to examine changes in the physical characteristics of bamboo, i.e., compressive strength, in response to its degradation in water and soil environments. Regarding the experiments performed in the laboratory, the bamboo samples with and without creosote oil treatment were placed in deionized water, soil, and ultraviolet light environments. Then, the temporal changes in mass loss on ignition, water content, and compressive strength of each sample were examined. Soil organisms were observed at the end of the experiments. The degradation of bamboo seemed to be higher in soil and UV light environments compared with its degradation in deionized water. Soil organisms and the destruction of cell walls of bamboo due to UV light may partly contribute to the higher degradation of bamboo in soil and UV light environments. It is noteworthy that the compressive strength seemed to decrease with the bamboo degradation. Fortunately, treating bamboo with creosote oil could reduce the rate of reduction in compressive strength of bamboo due to degradation. From the observation made on soil organisms, bamboo degradation could activate heterotrophic bacteria in soils, and treating bamboo with creosote oil had no negative effects on soil organisms.