WHY USE WOOD? Many reasons for using wood are obvious, but perhaps a brief review will be informative. For one thing, a wide range in properties allows the user to choose the kind of wood that will suit his particular purposes. For example, in windows, doors, and trim, strength is not particularly important, but dimensional stability and good machining characteristics are. In flooring, dimensional stability, good appearance, and hardness are critical. For structural members, good strength and stiffness are highly important, although appearance may be of no concern. In certain uses a high resistance to decay is necessary. And so the demands go through many uses. The large number of species available in this country and their wide range of properties permit the choice of the best materials for specific end uses. Wood is widely available in quantity in all areas of the country. This availability is not limited to lumber, the form we are most likely to think of, but as plywood, fiberboard, paper, laminated timbers, and chemical products as well. Longtime usage and wide availability have developed a countrywide group of craftsmen skilled in the use of wood. It is probable that carpenters are more generally available in most areas than are skilled steelworkers, cement finishers, or similar artisans. This is an important consideration in planning construction in certain areas. Wood has long been used to support loads in buildings, bridges, aircraft, and ladders. In large part, this is a recognition of its high ratio of strength to weight. In part, also, this reflects the ability of wood to absorb considerable overloads for short periods without failure-impact loads on railroad bridges, earthquake shocks, and hurricane winds, among others. The performance of wood structures in earthquake and hurricane areas has been outstanding. Contrary to the popular conception, wood in large sizes has excellent resistance to fire. While the surface may burn, the good thermal insulation of wood and of the char formed in burning prevents fire from penetrating rapidly into the interior. Wood beams and arches of large cross section, therefore, perform well in fire. TECHNICAL DEVELOPMENT AND WOOD USE Forest products research at the Forest Products Laboratory and forest experiment stations of the Forest Service, at various laboratories of State or other universities, and at the laboratories of the wood industries has played an important role in diversifying the products available from wood and in making them serve more efficiently and economically. Basic studies of the inner structure of wood have defined more accurately those things that determine quality in wood and have served a dual objective of pointing forest management in the direction of growing trees with these qualities and of helping us do a better job of selecting wood for specific uses. Research has given us both better saws and sawing methods, so that sawmills can turn out a higher quality product in better yield than ever before. Gluing research has developed adhesives and techniques that led to such new products as weatherproof plywood and overlaid lumber, as well as the laminated structures that have taken away our age-old limitation of size as related to the pieces which can be cut from a tree. Improved preservative chemicals and processes, new paints and other finishes have vastly improved wood's resistance o weather, fire, decay, and insects. Engineering research has given us not only a more detailed knowledge of the physical and mechanical properties of wood and its products, but also the ability to design more effectively. It has solved the problems of dealing with such complex combinations of materials as sandwich construction. Pulp and paper research has given us a wide variety of pulp-based products at increasingly high yields from an increasingly broad species base. It has given us papers and boards with a range of properties to fit specific uses. Chemical research has given us a range of products from better preservative chemicals through improved woods to chemicals for soil stabilization. It has taught us how to make use of sawmill residues and pulpmill effluent. In spite of significant developments from forest products research, many problems still require solution to use our forest resources more effectively and more efficiently. Thus, research in this field must continue and will become increasingly important in the future utilization of this resource. THE REPORT This report is designed to give an insight into the current and potential use in public works of wood and of products from wood. To that end, the report is divided into three parts. The first of these is a partial listing of wood products and the various uses to which they can be put in bridges, buildings, highway construction, waterfront structures, and the like. Wood use in these applications is so varied that we can hope to give only typical examples rather than an exhaustive listing. Such examples will serve, however, to indicate the important role of wood. Since many public works planners may not be fully aware of the potentials for the use of wood and wood products that have been developed through research and technological development, the second section describes some of these developments. Wood is a more technologically advanced material than is generally realized. The final section is something of a look ahead, an attempt to fire the imagination of the planners of public works projects to think beyond conventional uses of wood. A few items are described to indicate some of the potentialities. These are intriguing, but they are only examples of the horizons possible in the use of wood and wood products. 85963 0-62——— -3 SECTION I WOOD AND WOOD PRODUCTS USED IN PUBLIC WORKS The following list outlines some of the present and potential uses of wood in public works. Of necessity, the list is not complete. In many instances only broad fields of use are indicated. The list is confined to those materials used directly in construction or incorporated into the final structure. There are, however, many indirect uses. For example, equipment to be installed into the structure, from lighting fixtures to air conditioners, reaches the job in wood crates or fiberboard containers. During construction, materials are handled on wood pallets. Desks, chairs, and other furniture are commonly of wood. Cement, lime, and other materials are delivered to the construction site in paper sacks. Such indirect uses are not included in the list. WOOD PRODUCTS A. Round wood products (products used in round form with a mini mum of manufacture; used untreated or treated with preserva tives): 2. Poles: Dams. (d) Railroad and highway bridges and trestles. (e) Marine structures. (2) Crossarms for braced frames. (b) Pole buildings. (c) Log-type buildings. (d) Railroad and highway bridges and trestles. (e) Retaining walls. (f) Scaffolds and temporary structures. (g) Lighting standards. (h) Highway signs. (i) Flagpoles. (j) Cribs. |