Incising is an essential preprocessing method to ensure lumber from difficult-to-treat wood species can achieve chemical loadings during pressure treatment that will allow commodities to perform in ground contact or critical infrastructure applications. National Design Specifications in the United States require engineers to include a strength reduction for incised lumber, but these reductions are based on data collected on 2-in (51-mm) nominal-thickness lumber. Little work has been done to measure the impact of incising on lumber with a larger cross-section. This exploratory study measured the effect of incising on modulus of rupture (MOR) and modulus of elasticity (MOE) of nominal 4 by 6-in (102 by 152-mm) Douglas-fir lumber. Lumber pieces ranked and matched by vibrationally measured MOE were tested edgewise by a four-point bending test according to ASTM D4761. A total of 48 incised and nonincised test specimens were included in the final analysis. Incised MOR values were 11.5 percent lower than nonincised pieces ( P < 0.05 analysis of variance). MOE values were 2.5 percent lower for incised pieces compared with nonincised pieces, but the difference was not statistically significant ( P > 0.05). Ranking paired incised and nonincised specimens showed that the divergence between the two categories was greatest in specimens with lower MOR values. The coefficient of variation for MOR values was high for both incised (32.4%) and nonincised (26.6%) samples and a more uniform data set would provide better confidence for resolving differences between them. This work provides a useful preliminary comparison in structural performance of incised and nonincised lumber.

In wood, longitudinal fluid flow is several orders of magnitude greater than in radial or tangential directions. Incising of difficult-to-treat (i.e. refractory) wood species is a critical step in achieving adequate preservative penetration. Incising, as broadly defined, involves creating holes, incisions or fluid pathways to varying depths into the timber to increase longitudinal fluid flow and penetration into the wood. Incising has been used globally with early development occurring in the U.S., Canada, U.K. and Germany. It has been most heavily adopted in North America where it is required for treatment of thin sapwood lumber species in both the Canadian and U.S. treatment and engineering design standards. Incising can be either physical or biological. Physical incising uses teeth, knives, drills, needles, lasers, or high-pressure water jets to create pathways in the wood to the depth of the desired preservative treatment in a pattern that ensures uniform treatment. Biological incising uses bacteria or fungi to increase permeability. This review outlines the development, processes, applications and effects of incising technology. It specifically discusses their effects on treatability and strength properties, and reviews recent developments for modeling incising-related strength effects.

Fast growing Eucalyptus grandis W. Hill ex Maiden (EG), E. amplifolia Naudin (EA), Corymbia torelliana (F.Muell.) K.D.Hill & L.A.S.Johnson (CT), and Populus deltoides W.Bartram ex Marshall (PD) may be deployed in Short Rotation Woody Crop (SRWC) systems in the lower Southeastern USA, especially in Florida. To evaluate these species for possible use as medium density fiberboard (MDF) and other composites, 2.5 m logs of three EG clones, three PD clones, six EA progenies, four CT trees, and one P. tremuloides Michx. (PT) tree from northern Wisconsin as a control were characterized for basic wood properties before being chipped, pulped, and pressed into MDF. The chips were thermomechanically pulped (TMP) for a two-phase study of the factors expected to influence suitability for MDF production: wood characteristics, refining system, resin system, and MDF formation. Phase I used TMP and 4% phenol-formaldehyde (PF) resin to produce 17 MDF species/genotype batches (S/GB). Thickness Swell (TS), Water Absorption (WA), Internal Bonding (IB), Modulus of Elasticity (MOE), and Modulus of Rupture (MOR) were evaluated to: (1) assess within species and within tree variation, (2) relate basic wood properties to MDF potential, and (3) examine repeatability of MDF-making. There was considerable variation among and within species, but only minor within tree variation. Six of the seventeen S/GBs had superior physical and mechanical MDF properties. In Phase II, two of the six better performing Phase I S/GBs were evaluated, along with three average Phase I S/GBs. Phase II compared the effects on IB from using tube and drum blenders for resin application, the influence of using unscreened versus screened fibers, and the differences of using PF resin at 4% or 6% versus urea-formaldehyde (UF) resin at 8% or 12%. Overall, genetic variation among species, and particularly within these species, affected their potential for commercial MDF. Log specific gravity (SG), fines, MDF SG, and fiber length influenced MDF properties, as did refining and MDF-processing variables. Further study of specific processing requirements can optimize the potential of young EG, EA, PD, and CT genotypes for MDF and other composites.

Wood is increasingly viewed as a more environmentally sustainable material owing to its low embodied energy, workability, and renewability, but its two major drawbacks are susceptibility to biological degradation and fire. Biodegradation is typically addressed through effective designs to exclude moisture or, where that is not possible, the use of either naturally durable or chemically protected timber. Naturally durable timbers are widely used globally while preservative treatments are increasingly used to protect less durable timbers. These practices have markedly extended the use and service life of timber in harsher environments. However, these treatments do not improve the fire performance of the timber and there is increasing interest in the use of fire resistive coatings or impregnation with fire retardants to allow use in bushfire prone areas. This review provides background on the problems associated with increased building and construction in the wildland-urban interface. It summarizes the codes, standards and state of the art practices needed for adequate fire safety in timber construction.

Southern pine lumber is often treated with preservatives, but issues related to initial kiln-drying conditions and geographic source across the wide southern pine growth range have been suspected to negatively affect subsequent permeability and treatability. These effects remain poorly understood. In this series of exploratory studies, southern pine from across part of the growing range subjected to different kiln-drying regimes was evaluated in three phases exploring the effects of geographic source and initial kiln-drying conditions on permeability, pit structure and eventual preservative treatment of southern pine lumber. The results suggest that elevated temperatures coupled with poor humidity control at the start of the kiln drying process may negatively influence permeability and preservative penetration, but had only negligible effects on several other wood properties.

The utility sector has been employing ultrasonic-based nondestructive evaluation (NDE) to determine the cross-sectional groundline integrity of wooden utility poles. While it is far less invasive than other methods, its efficacy has not been thoroughly studied. This study aims to fill this technical gap by analyzing the correlation between the propagational characteristics of the ultrasonic stress wave using a novel embedded waveguide technique and the existing destructive testing methods. The proposed embedded waveguide technique excites diffusive Rayleigh mode (AW2) propagating in the shell region of the cross-sectional plane. This discovery allows a direct examination of the shell region condition through stress wave analysis. By employing the Gabor wavelet transformation and the model-based arrival region identification, this proposed technique extracts the propagation velocity and the associated spectral response of AW2. This study uses the static break assessment per ASTM 1036 Standard Test Methods And The longitudinal compression test per ASTM D143-14 "secondary method" to quantify the cross-sectional strength of the test specimen. This work performs a comprehensive correlation analysis between the extracted AW2 features and the associated destructive test. An overall correlation R2 from 0.2 to 0.5 is achieved between the AW2 features and the static break test results. An overall correlation of R2 of 0.4 is achieved for 30-35 ft poles in the longitudinal compression test.

Incising is required in Canadian and US national standards for the treatment of many timber species, especially those from western North America. Incising increases the amount of end-grain exposed to fluid flow, but it also decreases the cross-sectional area and, thus, has the potential to affect mechanical properties. Models have been developed to predict the effects of incising on flexural properties, but correlative data for engineering design adjustment factor(s) for incised and preservative treated lumber and timber are lacking. Current engineering design adjustment factors are primarily based on nominal 2x (38-mm, 1.5-in)-thick lumber tests. In 2018, this fact was recognized and the new design standard allowed for theoretical models to be used for larger materials where appropriate test data were not currently available. This article reports the results of mechanical tests evaluating the effects of incising on flexural properties of nominal 3x and 4x (64- and 89-mm)-thick by 184-mm (7.25-in)-wide Douglas fir and western hemlock lumber. It uses these data to develop potential engineering design adjustment factor(s) for incised nominal 2x (64- and 89-mm)-thick lumber and discusses theoretical modeling to predict those factors.

Wood durability researchers have long described fungal decay of timber using the starkly simple terms of white, brown and soft rot, along with the less destructive mold and stain fungi. These terms have taken on an almost iconic meaning but are only based upon the outward appearance of the damaged timber. Long-term deterioration studies, as well as the emerging genetic tools, are showing the fallacy of simplifying the decay process into such broad groups. This paper briefly reviews the fundamentals of fungal decay, staining and mold processes, then uses these fundamentals as the basis for a discussion of fungal attack of wood in light of current knowledge about these processes. Biotechnological applications of decay fungi are reviewed, and an overview is presented on how fungi surmount the protective barriers that coatings provide on surfaces. Advances in biochemical analyses have, in some cases, radically altered our perceptions of how wood is degraded, and even the relationships between fungal species, while other new findings have reinforced traditional perspectives. Suggestions for future research needs in the coatings field relative to enhanced fungal and environmental protection are presented.

To achieve a sustainable future, our evolving global society needs to embrace the concept of Integrated Biomass Technologies.Such a systematic use of renewable bio-resources to meet our needs could promote resource sustainability while at the same time maximizing feedstock values, product performance, and increased total profitability in either or both the agriculture and forest products industries.The fundamental principles of Integrated Biomass Technologies include biorefining to produce biofuels, bio-based chemical feedstocks, bioenergy, and cellulose nano-fibers, using problematic, waste or under-valued biomass as a direct source of electrical energy, and for developing advanced wood and biocomposite materials to engineer advanced structures.These fundamental principles provide a global roadmap to biobased economies based on the systematic use of many under-valued lignocellulosic resources to produce liquid biofuels, energy, chemical feedstocks, and advanced materials.Implementation of Integrated Biomass Technologies could lead to a more sustainable global society.

In Part I of this series, the relationship between physical properties and chemistry and anatomy of wood were reviewed (Winandy 2016). This Part II article explores a fundamental relationship between the mechanical properties and the chemical composition of wood and how degradation of its individual chemical components affects strength loss. It then presents a proposal for a universal theory as to the fundamental mechanism between wood strength loss and changing wood chemistry. That theory purports that the desequencing of the complex lignocellulosic structure of woody materials involves the same systematic series of processes during either biological, chemical, or thermal deterioration. The goal of this article is to create a better understanding of how changes in wood chemistry fundamentally influence wood strength.

Investigations have continued for production of high performance agrobased composites using environmentally acceptable approaches. The possibility of preparing high performance agro-based composites using non toxic rice bran-modified urea formaldehyde (RB-based UF) adhesive systems is evaluated in comparison with that synthesized from starch- based modified UF adhesive system (St-based UF). This chapter focuses on the research of incorporating rice bran into urea-formaldehyde using denaturalized RB in either a slurry (wet) or dry form. It also investigates optimizing the nitrogen content of modified starch systems. The evaluations include assessment of the role of RB- and modified starch-based adhesives 180in reducing emissions of free-HCHO content and its effect on viscosity and gel time of modified UF adhesives. It also includes investigations of the physical, mechanical and water resistance properties of sugarcane bagasse particleboard composites. The results obtained show that both adhesive systems exhibit improved environmental performance (reduction in HCHO emission is ~ 53%) over a commercially HCHO-based adhesive (UF). Further, they provided particleboards that meet the requirements of grade H-3 per particle board grade requirements from NPA (ANSI A208, 1999).

Key message This paper briefly reviews the state of the art in various types of wood- and bio-based composites, summarizes recent advances, and then discusses future possibilities for improving the durability of wood- and bio-based composites.Context Wood can be processed and reformed into a number of different biocomposites.Aims We aimed at reviewing the state of the art in various types of wood- and bio-based composites.Methods Review of utility, performance and durability of wood- and bio-based composites.Results The advanced biocomposites will: Combine wood, natural biofibers, and non-biomaterials to create synergistic hybrid materials that far exceed performance capabilities of current biocomposites Be renewable, recyclable, and totally sustainable Provide superior performance and serviceability exceeding performance of current biocomposites Bemore durable, dimensionally stable, moisture proof, and fire resistant Be less expensive to produce and use (over the life cycle of use) than the materials they replaceConclusion The next generation of advanced wood- and bio-based composites must provide high-performance construction and specialty products that simultaneously promote resource and environmental sustainability and provide advanced performance, long-term performance, enhanced durability, and value.

This research investigated the effects of specimen width on the flexural properties of laboratory manufactured, fire retardant treated strandboard. In this study, fire retardant-treated and untreated 864- by 864- by 10.5-mm strandboard panels were manufactured in the laboratory. Each panel was edge trimmed and cut into five specimens of various widths. Each specimen was then tested in four-point flexure across a 648-mm span. We assessed the effect of strandboard specimen width on the stability of mean and variance estimates. It is critical to recognize specimen width as an important experimental factor because the size and orientation of individual flakes and strands in narrow-width strandboard test specimens can influence the magnitude and variability of test results. The bending properties of 305-mm-wide strandboard specimens, and to a lesser extent those of 203-mm-wide specimens, were consistently greater than the 102- and 152-mm-wide treated groups. Variability of flexure results, based on coefficient of variation, was for the most part uniform. The internal bond strength was consistent at all widths tested.

This research investigated the mechanical properties of laboratory-manufactured, fire retardant-treated (FRT) strandboard in an effort to establish laboratory testing protocols for these types of composite products. This study evaluates both the initial effects of fire retardant treatment and the effects of extended high-temperature exposure. Two sets of FRT and untreated strandboard panels were manufactured and tested. Preliminary work had assessed the effect of strandboard specimen width on the stability of mean and variance estimates obtained when testing matched treated and untreated specimens with four different widths. Those results indicated that use of >= 200-mm-wide strandboard specimens decreased both variation and error associated in mean estimates compared with testing narrower-width strandboard specimens. The findings in this study show that the testing protocols developed for laboratory-manufactured, FRT strandboard were both reproducible and adequately severe. These laboratory test methods successfully identified the potential initial strength effects on strandboard performance and their potential for secondary strength loss when exposed for an extended time in a high-temperature environment minimizing the costs of using large commercial production facilities.

Our understanding of how to relate laboratory-induced degradation data to real-world in-service performance of fire-retardant (FR) systems is currently limited because we are unable to correlate laboratory steady-state experiments with actual in-service field performance. Current studies have generally been limited to isothermal rate studies with selected model FR chemicals. Currently, no known direct comparison exists of matched sets of samples with one set exposed to high-temperature laboratory conditions and the other exposed for an extended period of time as traditionally used in North American light-framed construction. The objective of this study was to determine the relationship for FR model compounds between laboratory and field results based on strength-temperature-RH (moisture content)-FR chemical interactions. Two previous studies evaluated the effects of various exposures on bending strength properties and directly compared matched laboratory- and field-exposure samples. This study presents an empirical model to relate the differential effects of laboratory and field exposures on changes in mechanical properties for matched samples.

Wood strength is affected by many factors. Mois­ ture content (MC) and temperature both affect mechan­ ical properties; these effects are exaggerated when wood is treated with preservatives or fire-retardant (FR) chemicals. Treated wood usually has a high MC, well in excess of the fiber saturation point, and is conse­ quently dried after treatment to improve dimensional stability and reduce shipping weight. This report re­ views the technical literature on the interactive re­ lationship between treatment with preservatives or FRs and post-treatment drying and its effect on wood strength. Strength and stiffness of untreated wood increase as wood is dried from the green condition to MCs be­ low the fiber saturation point. These properties de­ crease as MC increases. In the absence of decay, the effects of MC are reversible. This paper discusses the interactive relationship between treatment and mois­ ture effects; the independent effects of MC are more thoroughly discussed in the Wood Handbook (40). Temperature also affects mechanical properties of untreated wood. Strength and stiffness decrease when wood is heated and increase when it is cooled. The temperature effect is immediate and, for the most part, recoverable for short heating durations. However, if wood is exposed to elevated temperatures for an ex­ tended time, strength is permanently reduced because of degradation of wood substance with a correspond­ ing loss in weight. The magnitude of this permanent effect depends upon MC, heating medium, tempera­ ture, exposure period, and to a lesser extent, species and specimen size. This paper will examine the inter­ active relationship between treatment and temperature effects; the independent effects of temperature (both immediate and permanent) are more thoroughly dis­ cussed in the Wood Handbook (40).

Wood as a material has unique properties that make it ideal for above ground exposure in a wide range of structural and non-strucutral applications. However, no material is without limitations. Wood is a bio-polymer which is subject to degradative processes, both abiotic and biotic. This chapter is a general summary of the abiotic and biotic factors that impact service life of wood in above ground exposures, and briefly discusses test methodologies commonly used in North America to determine the durability of wood and wood based materials in above ground exposure. Current efforts to improve service life estimates for wood and wood based materials are also discussed.

Public health awareness has increased in the past few years regarding the disposal of chromated copper arsenate (CCA) preservative-treated wood wastes. This study demonstrates the potential for using remediated CCA lumber and alternative fiber sources, such as sugar cane bagasse, to produce medium density fiberboard (MDF). The role of both remediated CCA loaded spruce wood and substitution of a part of it with sugar-cane bagasse fibers on the performance of MDF produced were evaluated. The remediation conditions were optimized from examining the FTIR-spectra and TGA analyses of the treated wood fibers resulted from changing the remediated pH (1.4-7.0) and temperature (20-80 degrees C) together with the efficiencies of removing the preservative metals. The results showed that CCA-remediated spruce fiber provided MDF with 59% and 75.5% reduction in water absorption and thickness swelling, respectively, and 93% increase in IB, compared to panels made from untreated wood. Blending both bagasse fibers with either untreated or remediated fibers had a positive impact on MDF properties. Compared to boards made with untreated control spruce fibers, boards made with up to 30% bagasse had up to 79% reduction in water absorption, 62% reduction in thickness swell, 38% increase in modulus of rupture (MOR), and 244% increase in internal bond (IB) strength. According to ANSI Standard for interior MDF, the remediated CCA-treated spruce was suitable for the manufacture of MDF, either individually or in blends with sugar cane bagasse.

Wood is an environmentally desirable material for fiber and structural use. It is efficient in both economic and environmental costs to the user. Sometimes wood is treated with chemicals to extend its utility into new markets. In North America, fire retardant-treated lumber and plywood are sometimes permitted as alternatives to noncombustible materials in structures that require increased fire safety. The history of the development of fire-retardant chemicals and their adaptation as wood treatments in standards and building codes is beyond the scope of this review, but it has been comprehensively documented (Barnes 1993, 1994). This review focuses on the effects of fire-retardant chemicals and their treatment processes on the physical and mechanical performance of fire retardanttreated wood (FRTW). It also deals with how the conditions of the use environment further affect those performance properties.