Effect of locality and axial position on the properties of iron bamboo (Guadua angustifolia kunt.) and solid bamboo [Dendrocalamus strictus (Roxb.) Nees] grown in the Philippines

This study investigated the effect of locality and axial position on the morphological, physical, and mechanical properties of iron bamboo (Guadua angustifolia Kunt.) and solid bamboo [Dendrocalamus strictus (Roxb.) Nees] from three locations in the Philippines: Laguna, Baguio City, and Nueva Vizcaya. Morphological properties were assessed by measuring culm height, internode length (IL), culm diameter (CD), and culm wall thickness (CWT), whereas physical and mechanical properties were determined using ASTM D143-2019 and ISO 22157-2019. Results showed significant differences in properties based on localities and axial position. Laguna's iron bamboo had 75.29 and 11.87% higher CD and CWT than Baguio's, respectively. Laguna's solid bamboo CD exceeded Nueva Vizcaya's by 38.76%, but Nueva Vizcaya's solid bamboo had a 9.13% higher CWT than Laguna's. Iron bamboo's CD increased by 62.66%, and solid bamboo by 24.41% from bottom to top. Conversely, their CWTs decreased by 47.70 and 55.18%, respectively. Baguio City's iron bamboo exhibited greater relative density (RD), radial (RS), tangential (TS), longitudinal (LS), and volumetric shrinkage (VS) surpassing Laguna's by 30.50, 42.58, 15.40, 33.96, and 29.31% respectively. However, its moisture content (MC) was 27.04% lower. Meanwhile, Laguna's solid bamboo had an 8.00% higher RD but an 18.46% lower MC compared to Nueva Vizcaya. Notably, solid bamboo from Nueva Vizcaya recorded the highest shrinkage properties. Both bamboo species showed an increasing trend in RD from the bottom to the top but a decreasing trend in MC, RS, TS, and VS. LS was highest in the top portion of iron bamboo and in the bottom portion of solid bamboo. Baguio City and Nueva Vizcaya bamboo exhibited the highest static bending strength than the bamboo from Laguna. In contrast, Laguna's culms showed significantly higher shear (SS) and maximum compression strength (MCS) 46.09 and 97.09% higher for iron bamboo, and 100 and 123.29% higher for solid bamboo, respectively. The presence of nodes did not significantly affect SS and MCS in either species, but samples without nodes had higher strength than those with nodes. The result indicates that iron and solid bamboo from Laguna is suitable for construction and engineered bamboo applications, whereas bamboo from Baguio City and Nueva Vizcaya is recommended for structural applications that require high strength but not necessarily large culms. The findings highlight the versatility of Philippine-grown iron and solid bamboo as eco-friendly and sustainable raw materials for the bamboo industry in green building practices.