Treesearch

This is the third in a series of reports on the erosion rates of wood exposed outdoors near Madison, Wisconsin. The specimens were exposed at an orientation of 90* or 45* facing south or horizontally (0*) for 10 years. Erosion was measured annually for the first 8 years and after 10 years. The erosion rates of earlywood (springwood) and latewood (summerwood) were determined for smooth-planed vertical-grained and flat-grained lumber (radial and tangential surfaces, respectively). Wood species included Douglas-fir, loblolly pine, southern pine, western redcedar, northern red oak, and yellow...

Increased use of pressure sensitive adhesives for labels and stamps has introduced another contaminant into the office paper stream: silicone- coated release liners. This study examines methods and conditions for removal of contaminants, including these liners, from a typical batch of discarded office papers. Removal of contaminants contained in the furnish were compared using alkaline and near neutral pH repulping conditions. Residual contaminants were measured by image analysis, and the number and size of the contaminants were compared on handsheets that were prepared from samples...

The strength and stability of any structure depends heavily on the fasteners that hold its parts together. One prime advantage of wood as a structural material is the ease with which wood structural parts can be joined together using a wide variety of fasteners: nails, staples, screws, lag screws, bolts, and various types of metal connectors. For the utmost rigidity, strength, and service each fastener type requires careful design. General requirements for moisture content, location, spacing, and fabrication in the design of joints should be checked with design manuals (American Forest and...

A sampling of nominal 6- by 8-inch (standard 140- by 184-mm) Douglas-fir timbers was obtained from an industrial military building in Minnesota. Thirty selected timbers had heart checks (boxed heart splits), which are characteristic of most old timbers installed in dry locations. Sixty selected timbers did not have heart checks. Most of the beams would grade as Select Structural Beams and Stringers by current grading rules. The modulus of elasticity (MOE) of the unchecked beams was greater than the allowable values given in the National Design Specification, but the modulus of rupture...

This paper presents a review of more than 10 years of research on the effects of fire-retardant treatments on wood properties and the potential of these treatments for in-service degradation when exposed to elevated temperatures. It presents an in-depth discussion of the findings and implications of a major wood engineering research program to assess the current condition, extend service life, and predict residual serviceability of fire-retardant-treated plywood when used as structural roof sheathing.

This paper documents the development of procedures in American Society for Testing and Materials standards for adjusting the allowable properties of lumber for changes in moisture content. The paper discusses the historical context of efforts to establish allowable properties on a consensus basis, beginning in the 19th century. Where possible, the reasons for proposed changes in the standards are presented. The goal of this work is to foster a better understanding of how current standards have evolved and to promote reconciliation of conflicting property assignment procedures between...

The designated fiber stress values published in the American National Standards Institute Standard for Poles, ANSI 05.1, no longer reflect the state of the knowledge. These values are based on a combination of test data from small clear wood samples and small poles (

To satisfy the increasing demand for forest products, much of the future timber supply will be from improved trees grown on managed plantations. This fast-grown resource will tend to be harvested in short age rotations and will contain higher proportions of juvenile wood than that of current harvests. In anticipation of this resource, definitive information is needed on the influence of juvenile wood on lumber properties so that grading rules and the associated allowable design stresses can be modified as needed. This document reports the results of an extensive review of the literature on...

Preservative-treated wood is often used for construction of highway and foot bridges, wetland boardwalks, and other structures in or over water or sensitive environments. In these applications it is important that release of preservative from the wood into the environment is minimized. This publication addresses this concern by describing the various types of pressure-treated wood, reviewing recent research on the environmental impacts of pressure-treated wood, and discussing methods of minimizing potential environmental impacts. Recent research indicates that wood treated with these...

To enhance long-term timber bridge performance, timber material must be protected from moisture. Wearing surfaces made of asphalt pavement with and without a waterproof membrane have been used to provide protection from moisture on timber decks. This type of wearing surface also protects the deck from other damage while providing a smooth, skid-resistant surface. However, the long-term performance of timber bridges has often not been satisfactory as a result of cracking of the wearing surface or separation of the asphalt or membrane from the deck. Cracking or separation allows moisture...