Durability treated wood

Fujimura, T., Ryu, J.Y., Imamura, Y., Furuno, T. and Jodai, S. (1993a). Improvement of the durability of wood with acryl-high-polymer VII. Biological resistance of acrylic-copolymer treated wood. Mokuzai Gakkaishi, 39(9), 1042-1048. 

Kamden, D.P., Pizzi, A. Guyonnet, R. and Jermannaud, A. (1999). Durability of heat-treated wood. International Research Group on Wood Preservation, Doc. No. IRG/WP 99-40145. 

Fire-retardant-treated wood is durable and stable under normal exposure conditions. Treatments using inorganic water-soluble salts, however, are not recommended for exterior exposures to rain and weathering unless the treatment can be adequately protected by water-repellent coating. Exterior-type treatments in which the chemicals are "fixed" in the wood in some manner are leach resistant and nonhygroscopic. 

Needless to say, the fixation of inorganic chemicals in wood by interaction with the wood substrate and extractives is beneficial and greatly improves the durability of these preservatives. Contrarily, other interactions provide less desirable reactions. For example, under certain circumstances copper and zinc can become so tightly bound to the wood that their efficacy as wood preservatives is reduced. This result occurs when copper acetate and zinc acetate are used to treat wood (53). In this form, these elements are salts of acetic acid and they form ion-exchange bonds with the wood components that are stable in the weak acid environment and cannot be ionized readily by water. Conversely, this reduction in efficacy does not occur when copper sulfate and zinc chloride are used because they are salts of strong acids and the pH of the environment prevents insolubilization of these elements by the wood. 

The coating durability of organolead-treated southern pine in exterior exposure was reported (144), Significant improvement in the durability of a vinyl-acrylic latex and an alkyd paint on treated wood was demonstrated. Improved durability appeared to be independent of the type or concentration of the organolead-treated compounds. 

The cardinal rules for proper use of wood can be stated simply keep wood dry, and, if you can t keep it dry, use naturally durable or preservative-treated wood. The first rule is based on a simple biological principle liquid water is needed in wood cells to provide a medium for diffusion of the enzymes or other metabolites by which wood-decomposing organisms digest the wood substance. If there is no liquid water present inside the wood cells, there will be no medium for diffusion, and therefore no biological decomposition except for certain insects of relatively minor importance. Thus, as long as wood is kept below its fiber-saturation point (about 27% of its dry weight), it will never decay. 

PCP was first introduced in the 1940s as a substitute for ereosote. The aetive ingredient, a chlorinated phenol, is a crystalline solid that dissolves in a variety of organic solvents. The performanee of PCP and the properties of the treated wood are influenced by the ehoiee of solvent. A heavy oil solvent is preferred where treated wood is to be used in ground eontact - wood treated with lighter solvents is not as durable. PCP treated wood has many characteristics and properties that mimic those of creosote, except that it is ineffeetive against marine borers. 

Researehers have demonstrated that wood treated with heavy metals ean be chipped or flaked and reused to form durable panel produets or wood-cement composites. However, this type of reuse has not gained commercial acceptance beeause of eoneems with processing the treated wood, with the introduction of pesticides into the panel fabrication process, and with the leaching or environmental impacts from the final product (Kartal and Clausen, 2001). 

Building Research EstablishmenL MTP Construction, 3-66 Lebow ST, Brooks KM and Simonsen J (2002) Environmental impact of treated wood in service. In Enhancing the durability of lumber and engineered wood products. Forest Products Society, Madison, Wisconsin, 205-15... 

Pressure-treated lumber has a significantly higher static coefficient of friction compared with WPCs. This is a remarkable feature of wood, along with it unsurpassable strength and stiffness compared to WPG materials. If not a relatively low durability of wood, its sensitivity to biodegradation, and an increasing scarcity of wood of a good quality, appropriate for deck materials, composite materials would hardly be competitive to real wood. 

In general, properties such as colour, natural durability and dimensional stability of thermal treated wood differ from those of untreated wood. Depending on the duration and the power of the process, thermally treated wood shows improved rot-resistance properties and also demonstrates increased resistance to both fungi and climatic influences.To warrant the natural durability it must be ensured, however, that the TMT products have no contact to the ground. Furthermore, its dimensional stability can be improved as well as its adhesion property against hydrophobic materials. 

Tascioglu, C., et al. (2003). Bond durability characterization of preservative treated wood and E-glass/phenolic composite interfaces. Composites Science and Technology, 63, 979-991. 

European Standard EN 351-1, 1996. Durability of wood and wood-based products - Preservative treated solid wood - Part 1 Classification of preservative penetration and retention. 

Durability of wood and wood-based products. Performance of preventive wood preservatives as determined by biological tests. Part 1. Specification according to hazard class Methods of analysis of wood preservatives and treated timber. Part 3. Quantitative analysis of preservatives and treated timber containing copper/chromium/arsenic formulations Specification for wood preservation by means of copper/chrome/arsenic compositions Standards for waterborne preservatives... 

Studies are currently being conducted on smoke development and heat release rate from treated and untreated wood and wood products (52,56). An evaluation of the available treatment systems for wood shingles and shakes was completed using artificial weathering (11). A further development from this work was a new ASTM Standard Method D2898 (67,68) for testing durability of fire-retardant treatment of wood. 

Little is understood of the mechanism involved in the improvement of a wood surface after treating with chromium-containing chemicals and the subsequent durability of applied finishes (5). The data in Table II show that the reduction of the rate of weathering (as measured by loss of springwood) is directly related to chromium concentration. 

Hakkou M, Petrissans M, Gerardin P, Zoulalian A. Investigations of the reasons for fungal durability of heat-treated beech wood. Polymer Degradation Stability. 2006 91 393-7. 

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