Efficacy of Preservative Treatment and Physical Barriers in Preventing Biodeterioration of Rubber Wood under Estuarine Environment

Abstract

Among the prospective non conventional boat building materials, rubber wood has gained accep- tance for being an easily available agricultural by- product. It is highly vulnerable to biodeterioration. The service life of rubber wood under estuarine conditions is estimated to be about six months. Present investigation is focused on the assessment of extent of protection imparted to rubber wood by preservatives like Chromated Copper Arsenate (CCA), dual preservative and physical barriers like paint and Fibreglass Reinforced Plastic (FRP). Eighteen months study showed that untreated rubber wood failed to prevent marine borer attack in six months of exposure to estuarine waters. Among the three retentions of CCA studied, 16 and 29 kg m-3 showed susceptibility to attack by Sphaeroma spp. and Teredo spp. on prolonged exposure. Higher retention of CCA viz., 42 kg m-3 and dual treatment imparted higher degree of protection to rubber wood. Physical barriers that were applied on CCA treated panels accorded a 100% protection to rubber wood. Commercially available CCA treated marine grade plywood samples showed moderate attack in twelve months of exposure and failed after eighteen months.