Treesearch

The voluntary withdrawal of chromated copper arsenate (CCA)-treated wood from most residential applications has increased the use of non-arsenical copper-based organic wood preservatives. Because the arsenic component of CCA controlled copper tolerant fungi, scientists have renewed interest in and concern about the decay capacity in the important copper-tolerant group of brown-rot fungi. We have demonstrated that the primary means of inactivating copper in preservatives is by excess production of oxalic acid (OA). Oxalic acid production is a key metabolic indicator of brown- rot decay, and...

A study was conducted to evaluate environmental accumulation and mobility of total copper, chromium, and arsenic adjacent to a chromated-copper-arsenate-(CCA-C-) treated wetland boardwalk. The study was considered a severe test because it included a large volume of treated wood in a site with high annual rainfall. Soil and sediment samples were collected before construction and 0.5, 2, 5.5, 11, 24, and 60 months after construction. Increased concentrations of copper, chromium, and arsenic were detected in some soil and sediment samples. The environmental concentrations varied with time,...

This study involved the evaluation of ponderosa pine glulam made from lumber that was sawn from a small-diameter timber resource. Two different glulam beam depths were evaluated: 8 and 13 laminations. A comprehensive glulam test program was conducted to evaluate edgewise and flat-wise bending, shear, and tensile strength. Beam deflection was measured and a variety of glulam MOE values were determined. The calculated design values for various me-chanical properties of this new ponderosa pine glulam beam combination were compared to the published design values of the L3 glulam combination....

Heat sterilization of lumber, timbers, and pallets is currently used to kill insects, thus preventing their transfer between countries in international trade. An important factor in this treatment is the time required for the center of any wood configuration to reach the temperature necessary to kill the insect. This study explored the effect of size (1-, 1.5-, and 2.0-in.-thick by 6-in.-wide boards, and 3- by 3-, 4- by 4-, and 6- by 6-in. timbers), hardwood species (red maple, sugar maple, red oak, basswood, and aspen), and two wet-bulb depressions (nominal 2°F and 8–10°) at a nominal...

This paper describes an effort to develop a global dynamic testing technique for evaluating the overall stiffness of timber bridge superstructures. A forced vibration method was used to measure the natural frequency of single-span timber bridges in the laboratory and field. An analytical model based on simple beam theory was proposed to represent the relationship between the first bending mode frequency and bridge stiffness (characterized as EI product). The results indicated that the forced vibration method has potential for quickly assessing the stiffness of the timber bridge superstructu...

A considerable amount of small-diameter, branched, or curved timber is currently left standing, bucked and left on the ground, chipped, or burned after logging or thinning operations. Most North American mills are not equipped to handle this low-value material. In many areas of the western United States, such forest residue does not decompose and becomes susceptible to forest insects or disease, especially if the material is partially damaged or injured during logging. The USDA Forest Service Forest Products Laboratory is conducting a comprehensive research program to add value to biomass...

Wood poles have been used to support utility distribution lines for well over 100 years. Over that time, specifications for a “wood utility pole” have evolved from the closest available tree stem more than 15 ft in length to straight, durable timbers of lengths ranging up 125 ft and base diameters of as much as 27 in. The continued success of wood poles in this application is due in part to the development of consensus standards. These standards define the phrase “minimum acceptable” to the satisfaction of both users and producers. They also encourage more competitive pricing by relaxing...

The spread of Formosan subterranean termites (FSTs) in the southern United States has increased public interest in finding a preservative treatment to protect framing lumber from termite attack. This study evaluated the use of a borax-based preservative to protect wood from FST attack. Southern Pine and Douglas-fir specimens were pressure-treated with three concentrations of a borax–copper (BC) preservative composed of 93% borax (sodium tetraborate decahydrate) and 7% technical copper hydroxide. Untreated specimens and specimens pressure-treated with disodium octaborate tetrahydrate (DOT)...

Simple and cost-effective protocols were developed for removing particulates from samples prior to analysis by high performance liquid chromatography and gas chromatography. A filter and vial holder were developed for use with a 96-well filtration plate. The device saves preparation time and costs.

To use small-diameter trees effectively as square timbers, we need to be able to estimate the amount of time it takes for these timbers to air-dry. Since experimental data on estimating air-drying time for small-diameter logs have been developed, this study looked at a way to relate that method to square timbers. Drying times were determined for a group of round cross-section ponderosa pine logs and a group of square timbers. With regression analysis used to relate the two groups, it was shown that there is a square cross section ofdimension S that results in the same drying time as around...