Treesearch

The presence of slope of grain (SoG) in wood can severely reduce the bending strength in wood. Failure to recognize the degree to which SoG can reduce strength can be catastrophic if wood is in single member use. In the United States, a growing concern in the sport of baseball relates to the high frequency of multi-piece broken wood bats. It was observed that hard maple bats tended to break explosively, whereas white ash bats were more likely to stay intact. An examination of bats collected during the last three months of the 2008 baseball season indicated that for that time period the...

The United States recently completed its transition from the allowable stress design code to the load and resistance factor design (LRFD) reliability-based code for the design of most highway bridges. For an international perspective on the LRFD-based bridge codes, a comparative analysis is presented: a study addressed national codes of the United States, Canada, and Europe. The study focused on codes related to timber bridges and involved the following parameters: organization format, superstructure types, loads, materials, design for bending, design for shear, deflection criteria, and...

Eastern red cedar (Juniperus virginiana L.) is an abundant renewable resource and represents a vast potential source of valuable natural products that may serve as natural biocides. Both the wood and needles from J. virginiana were extracted using liquid carbon dioxide (L-CO2) as well as ethanol (EtOH) and the yields determined.Woodblocks were vacuum impregnated with the extracts and subsequently tested for resistance against eastern subterranean termites (Reticulitermes flavipes) and two species of brown-rot fungi (Gloeophyllum trabeum and Postia placenta). Cedarwood oil (CWO) yields...

It is well documented in the literature that temperature and humidity can influence formaldehyde emissions from composite panels that are produced using urea-formaldehyde (UF) adhesives. This work investigates the effect of temperature and humidity on newer, ultra-low emitting formaldehyde urea formaldehyde (ULEF-UF) and no-added formaldehyde (NAF) adhesives. A modified version of the EN 717-3 method to collect formaldehyde coupled with the acetyl-acetone method to quantify formaldehyde emissions was used. Formaldehyde emissions from a commercial CARB phase II compliant hardwood-plywood...

The goal of this study was to gain an understanding of the environmental impact of hardwood lumber production through a gate-to-gate life-cycle inventory (LCI) of hardwood sawmills in the Southeastern United States (SE). Primary mill data were collected per Consortium on Research for Renewable Industrial Materials (CORRIM) Research Guidelines. Life-cycle impact assessment is beyond the scope of the study.

A 22-month field investigation of nine different north-and south-oriented wood-framed wall assemblies was conducted to determine the moisture performance of various wall construction types, most of which incorporated absorptive cladding. The study was conducted on the campus of the National Association of Home Builders (NAHB) Research Center, in Upper Marlboro, MD, 20 miles east of Washington, DC, in a mixed humid climate. Moisture content of the sheathing and wall cavity temperatures were measured at various points in each wall section. The primary performance measure was moisture content...

Proper management of indoor humidity in buildings is an essential aspect of durability. Following dissipation of moisture from construction materials, humidity levels during normal operation are generally assumed to primarily depend on the building volume, the number of building occupants and their behavior, the air exchange rate, and the water vapor content of outdoor air. A potentially large additional source of indoor humidity that often is not considered is the building foundation, which is in contact with earth that commonly damp. Recent work has suggested that the rate of water vapor...

In flood-prone areas, elevating a building’s floor system above the anticipated flood level can significantly limit the extent of property damage associated with flooding. In hot and humid climates, such as the Gulf Coast region, raised floor systems may, however, be at risk for seasonal moisture accumulation, as the majority of residential buildings in such climates are now mechanically cooled. Conditions were monitored over a one-year period in a sample of 12 houses with insulated raised floors, eight in New Orleans and four in Baton Rouge, Louisiana. Eleven of the 12 houses were located...

Although organic, lipophilic acids, such as acetic, propionic, sorbic and benzoic, have a long history as preservatives in the food industry, relatively high concentrations are required and their bioactivities generally pertain to retarding microbial growth rather than eliminating pathogens. Moreover, exclusive use of organic acids such as lactic or citric acid, alone, as broad-spectrum biocides, is generally not sufficient for long term control of mold fungi. However, specific organic acids (i.e., glycolic and L-lactic), even at low concentrations, are now known to be potent synergists...

Biobased adhesives fall into several major classes based upon their chemical structures. Starches are used in large volume, especially in the paper products industries, but cellulosics generally do not have the strength and water resistance needed for most wood products. Several authors have covered cellulosics adhesives (Baumann and Conner 2002, Pizzi 2006). However carbohydrate adhesives have not been used in wood bonding and they will not be discussed further here. Biobased adhesive bonding methods covered in this section, include proteins, lignins, tannins, as well as no added adhesive...