Treesearch

Dip-treatment of wood packing materials is often used instead of pressure treatment mainly because of issues relating to simplicity and cost. Packaging boxes fabricated for the United States Army are required to be dip-treated for at least one minute in an approved preservative solution prior to use. These boxes are expected to have a service life of up to 20 years in a wide variety of environments. Recently, there is interest in using laser markings on these boxes, which can result in a breach of the preservative shell, potentially increasing susceptibility of the wood to termites and...

Two important wood properties are stiffness (modulus of elasticity, MOE) and bending strength (modulus of rupture, MOR). In the past, MOE has often been modeled as a Gaussian and MOR as a lognormal or a two- or threeparameter Weibull. It is well known that MOE and MOR are positively correlated. To model the simultaneous behavior of MOE and MOR for the purposes of wood system reliability calculations, a 2012 paper by Verrill, Evans, Kretschmann, and Hatfield introduced a bivariate Gaussian–Weibull distribution and the associated pseudo-truncated Weibull. In that paper, they obtained an...

Chemical modification of wood increases decay resistance but the exact mechanisms remain poorly understood. Recently, Ringman and coauthors examined established theories addressing why modified wood has increased decay resistance and concluded that the most probable cause of inhibition and/or delay of initiation of brown-rot decay is lowering the equilibrium moisture content. In another recent study, Jakes and coauthors examined moisture-induced wood damage mechanisms, including decay and fastener corrosion, and observed that these mechanisms require chemical transport through wood cell...

Wood species that exhibit innate tolerance to wood destroying organisms such as termites are considered to be naturally durable. This durability can, in part, be due to the complex chemical compounds in the heartwood of naturally durable wood species. We examined the effects of varying concentrations of heartwood extractives on the subterranean termite, Reticulitermes flavipes from four wood species from Pakistan (Dalbergia sissoo, Cedrus deodara, Morus alba and Pinus roxburghii) as well as Teak (Tectona grandis). Termites showed increasing levels of mortality with increasing concentration...

Natural durable wood species are those which exhibit innate tolerance to wood decay organisms such as fungi and termites. The goal of this study was to evaluate 4 wood species (Dalbergia sissoo, Cedrus deodara, Morus alba and Pinus roxburghii) from Pakistan in order to determine their resistance to both a model brown (Postia placenta) and white (Trametes versicolor) rot fungus compared to a durable reference species (Tectonis grandis). In a 12 week soil bottle test, C. deodara and M. alba were found to be resistant to decay, D. sissoo was moderately resistant and P. roxbughii was non-resist...

Seasonal cambial activity was investigated in one- to three-year-old branch modules (branch constructional units) of ten woody species from cerrado sensu stricto, a savanna-like ecosystem, of southernBrazil. Relationships between cambial activity and environmental factors (precipitation, temperature,day length) and leaf production were tested using generalized linear mixed model. Regardless the planthabit and leaf shedding patterns, cambial activity (about 5 months) corresponded to the core of the rainyseason (when at least 66% of the annual precipitation had been reached), even though...

After exposure in the field and laboratory soil block culture testing, the void content of wood–plastic composite (WPC) decking boards was compared to unexposed samples. A void volume analysis was conducted based on calculations of sample density and from micro-computed tomography (microCT) data. It was found that reference WPC contains voids of different sizes from the micrometer range up to several cubic millimeters. Large voids were unevenly distributed within the composite sample. Void size and volume increased after conditioning the WPC in water at 70°C. Depending on the effect of...

Several nondestructive evaluation (NDE) technologies were studied to determine their efficacy as scanning devices to detect internal moisture and artificial decay pockets. Large bridge-sized test specimens, including sawn timber and glued-laminated timber members, were fabricated with various internal defects. NDE Technologies evaluated in this research were ground penetrating radar (GPR), microwave scanning, ultrasonic pulse velocity, ultrasonic shear wave tomography, and impact echo methods. Each NDE technology was used to evaluate a set of seven test specimens over a 2-day period and...

Shisham (Dalbergia sissoo) heartwood extractives were investigated for antitermitic activities against Heterotermes indicola and Reticulitermes flavipes. Heartwood extractives were removed from wood shavings by soxhlet extraction using (2:1) ethanol: toluene as the solvent system. Filter paper bioassays were conducted against both species to observe concentration dependent feeding response and mortality of termites. Results indicated that the highest termite mortality occurred at 10 mg/ml with a LC50 at 5.54 and 3.89 mg/ml against H. indicola and R. flavipes, respectively. Shisham extractiv...

The dynamic viscoelasticity of full-size wood composite panels (WCPs) under the free-free vibrational state were determined by a vibration testing method. Vibration detection tests were performed on 194 pieces of three types of full-size WCPs (particleboard, medium density fiberboard, and plywood (PW)). The dynamic viscoelasticity from smaller specimens cut from the panels was measured using a cantilever beam vibration test apparatus, and the two data sets were compared. A strong linear relationship was discovered between the dynamic viscoelasticity values measured by the vibration...