Resistance of some hardwoods used in marine structures against marine borers attacks in South and North coasts of Iran

Wood samples of Teak (Tectona grandis), Keruing (Dipterocarpus alatus), Yellow Balau (Shorea laevis) and Chengal (Balanocarpus heimii) were treated by Creosote, using Ruping method. The dimension of samples were 200 x 75 x 20 mm and the retention of Creosote were 188, 186, 331, 40 kg /m3 respectively. Both treated and untreated samples were installed in seawater (Chabahar in Oman Sea, Bandar Abbas, Boshehr and Mahshar in Persian Gulf and Bandar Torkman and Noshahr in Caspian sea coasts) according to recommendation of IRG/WP-4432 (1985). After 6, 9, 21, 23, 28, 46 months exposure in sea water in south coasts and in Caspian sea coasts every 6 months and after 11 years, wood samples dislodged and evaluated according to IRG/WP-4432 (1985) and ASTM D-2481. In order to examine the test material, each of the supporting frames was removed from the water and the panels carefully scraped to remove the surface of the marine organism. According to results of this research, Natural durability of Teak wood against marine borers in south coasts of Iran is less than one year and also it is not resistant against soft rot organism. Creosote treated of Teak samples after more than 2 years exposures in seawater were sound. Rates of marine borers activity in coasts of Iran are different and in Boshehr coasts are harder than others. At coastal zones of Mahshar, less damage were found, as compared to other points. Wooden structures in north coasts, as compared to south cost of Iran, were affected more intensively by fungi damages. In Caspian seacoasts, expect soft rot on the samples surfaces, both treated and untreated samples after 11years installation were sound. It is concluded that there are no marine borers in south coasts of Caspian Sea.

Keywords:

marine borers , wood , impregnation , Creosote , durability , Ruping method