Treesearch

Stress-wave-based nondestructive evaluation methods were used to evaluate the potential quality and modulus of elasticity (MOE) of wood in used preservative-treated Douglas-fir and southern pine piles. Stress wave measurements were conducted on each pile section. Stress wave propagation speeds in the piles were then obtained to estimate their MOE. This was followed by a sequence of tests conducted on octagon-shaped cants, on boards, and on small, clear wood specimens obtained from the piles. Statistical regression analyses revealed a strong correlation between the stress-wave-based MOE...

In a previous study on the strength and durability of a new class of wood adhesives called one-part polyurethanes, four commercial one-part polyurethanes, along with a resorcinol-formaldehyde adhesive representing a standard of performance, were compared in bonds to yellow birch and Douglas-fir in a series of industry-accepted tests (7). The polyurethanes all performed essentially the same: high in dry and wet strength but low in wet wood failure and resistance to delamination. In the study described in this paper, we look at improving the durability of polyurethane bonds to wood by...

Several spans of a 60-year-old open-deck timber railroad bridge on the Southern Pacific Railroad Line (now the Union Pacific) in Southwest Texas were field tested. The tests were conducted with the sponsorship and cooperation of the Association of American Railroads to determine the vertical live load distribution characteristics of the superstructure. The bridge was originally constructed with Douglas-fir larch solid sawn stringers but was rehabilitated on several occasions to allow comparisons to be made with respect to different rehabilitation options, including the use of a helper...

Forest managers have identified forest stands overstocked with small-diameter trees as a critical forest health issue. Overstocked stands are subject to attack by insects and disease and, as a result of the heavy fuel load, risk total destruction by fire. Prescribed burning is an economic tool for suppressing the growth of brush and tree seedlings, but its use is often restricted for environmental reasons. Forests that contain a heavy fuel load extending into the canopy must be thinned to reduce the fuel load before prescribed burning can be used to avoid future loss caused by fire,...

Three species of small-diameter logs from the Klamath/Siskiyou Mountains and the Cascade Range in southwest Oregon were tested for their potential for value-added structural applications. The logs were tested in bending and compression parallel to the grain. Strength and stiffness values were correlated to possible nondestructive evaluation grading parameters and compared to values derived from published values based on tests of small-diameter clear wood of the test species. For the test sample, specific gravity and static bending modulus of elasticity were good indicators of strength....

Wood is a biological material that has widely different properties depending on species, geographic area where the tree grew, the growth conditions, size of the tree at harvest, sawing, and other manufacturing processes. Some of the more important wood properties as they relate to wood finishing are discussed, e.g., growth rate, density, knots, extractives, juvenile wood, grain orientation, and weathering characteristics.

Because of performance problems with hardboard siding in southern Florida, the U.S. Department of Housing and Urban Development (HUD) proposed a local standard requiring prefinishing of siding and priming of all siding surfaces, including the back. However, the effectiveness of these practices was questioned. To determine if back-priming or factory finishing improves durability and performance of hardboard siding, we installed factory-finished and factory-primed siding on two buildings in southern Florida. The buildings were identical except that one had gutters and no overhangs and the...

Drying Hardwood Lumber focuses on common methods for drying lumber of different thickness, with minimal drying defects, for high quality applications. This manual also includes predrying treatments that, when part of an overall quality-oriented drying system, reduce defects and improve drying quality, especially of oak lumber. Special attention is given to drying white wood, such as hard maple and ash, without sticker shadow or other discoloration. Several special drying methods, such as solar drying, are described, and proper techniques for storing dried lumber are discussed. Suggestions...

To promote more efficient use of small-diameter timber, research efforts are being focused on the development and evaluation of connection methods that can be easily applied to non-standard round wood profiles. This report summarizes an evaluation of a bdowel-nut connectionc as an option for the use of Douglas-fir peeler cores in three-dimensional truss or bspace-framec structural applications. Joint details were selected on the basis of ease of fabrication, joint strength, failure mode, and cost. It was concluded that the cores should be dried close to expected ambient conditions prior to...

The productivity of U.S. wood and paper product output in terms of wood input is computed and displayed in graphs. Background tables provide supporting data. The productivity trend parallels trends in the recovered paper utilization rate. Recycling and wood residue use are key factors in productivity gains.