The specific gravity ofbamboo varies between 0.4 and 0.8 depending on its anatomi­cal structure. The specific gravity of 1-year-old bamboo is very low as compared to

3- or 5-year-old bamboo culms. The average specific gravity increases about 58 % from 1 to 3 years of age. The specific gravity value of outer layer of bamboo is observed to be twice than that of inner layer (Li 2004). The specific gravity of bam­boo fiber reinforced plastic composite is measured as 0.924 (Jain et al. 1993).

2.4.4 Specific Strength

Bamboo fiber extracted by steam explosion method has a very high specific strength. The specific strength of steam exploded bamboo fiber is equivalent to conventional glass fiber (Okubo et al. 2004). The specific strength of bamboo fibers is higher than plastics, which makes them a very good choice for preparation of many substances including furniture (Lakkad and Patel 1981). Bamboo fiber’s specific strength when compared with specific strength of mild steel is 3-4 times higher. Bamboo fiber reinforced plastic composites possess a very high specific strength (Jindal 1986). The specific strength of bamboo fibers can be increased by making a composite with maleic anhydride grafted polyethylene (Mohanty and Nayak 2010). A remarkable increase in specific strength of bamboo fibers is observed when they are reinforced with aluminum alloy sheets (Li et al. 1994).

The specific strength ofbamboo decreases with increase in age. The best strength is observed in the bamboos of 3-6 years (Li 2004). The strength is also observed to increase with height. The strength increases from central to outer part (Li 2004). BZB is seen to have a higher specific strength than many of the commercially avail­able wood fibers (Nugroho and Ando 2000).