Laminated Veneer Lumber Products Research Articles

Optimizacija parametara proizvodnje ugušćene lamelirane furnirske građe proizvedene upotrebom urea-formaldehidne smole

This research aims to optimize densified laminated veneer lumber production parameters of compression ratio, press temperature, press time, and adhesive spread rate to maximize their mechanical properties. In the manufacturing process of densified laminated veneer lumber, I-77/51 American poplar clone (Populus deltoides) veneers and urea formaldehyde adhesive are used. The results showed that the compression rate and press time had the most significant impact on the mechanical properties of densified laminated veneer lumber. The optimal production conditions were determined as follows: 38 % compression, press temperature of 170 °C, press time of (10±3) minutes, and spread rate of 150 g/m2. Modulus of rupture, modulus of elasticity, tensile shear strength, and tensile strength perpendicular to panels surface of densified laminated veneer lumbers produced under these conditions increased by 49 %, 8 %, 71 %, and 23 %, respectively, compared to the control group of laminated veneer lumber. So, it can be said that the production parameters of densified laminated veneer lumbers can be optimized safely and effectively using Taguchi method-based grey relational analysis.

Impact of Facility Location on the Financial Performance of Integrated and Distributed LVL Production in Subtropical Eastern Australia

In subtropical eastern Australia, the declining availability of traditional, large hardwood native forest logs has motivated hardwood sawmills to explore potentially utilising small logs in the manufacture of veneer-based engineered wood products (EWPs), such as laminated veneer lumber (LVL). An aspatial mathematical model that maximises net present value (NPV) over a 30-year project life has been applied to estimate the financial performance of LVL manufacture in this region. Of particular interest was how facility location affected financial performance, and whether distributed production of veneer (close to the log resource) and LVL (distant from the log resource) may be more profitable than integrated production under some circumstances. While integrated production of veneer and LVL near the resource maximised NPV, distributed production was found to be more profitable than integrated production in situations where the LVL manufacturing facility had to be located relatively far from the resource. Nevertheless, the level of value-adding and processing scale had a greater impact on financial performance than facility location. The analysis also highlighted that log procurement strategy substantially affected financial performance. Encouragingly for forest growers and wood processors, utilising large volumes of small diameter logs, was important for maximisation of NPV of larger-scale LVL facilities.

KIZILAĞAÇ VE KAVAKTAN ÜRETİLEN TABAKALI KAPLAMA KERESTELERİN MEKANİK VE FİZİKSEL ÖZELLİKLERİ ÜZERİNE TABAKA KOMBİNASYONUNUN ETKİSİ

Laminated veneer lumber (LVL) is an engineering product material used as girders, beams, joist, headers, panels, etc. in construction. In this study, the effect of ply combination on oven-dry specific gravity, equilibrium moisture content, thickness swelling and water absorption, tensile-shear strength, modulus of rupture, modulus of elasticity and compression strength parallel to grain of LVL manufactured from alder and poplar was investigated. Alder veneer, poplar veneer and urea formaldehyde glue were used in LVL production. LVLs were produced in a total of 10 different combinations. Oven-dry specific gravity, equilibrium moisture content, thickness swelling and water absorption, tensile-shear strength, modulus of rupture, modulus of elasticity and compression strength parallel to grain of test samples were determined according to TS 2472, TS 2471, TS EN 317, EN 314-1, TS 2474 and TS 2595, respectively. Based on this study, the highest modulus of rupture, modulus of elasticity, compression strength and oven dry specific gravity values were obtained with alder veneers used in all plies. On the other hand, the highest tensile-shear strength values were obtained with poplar veneers used in all plies. With the rising in the use of poplar veneer in LVL production, an increase in the amount of thickness swelling and water absorption was observed. It was also observed that as contribution rate of alder veneer in lamination increases, oven dry specific gravity, modulus of rupture, modulus of elasticity and compression strength values were increased.

Application of holistic and integrated LCSA: Case study on laminated veneer lumber production in Central Germany

PurposeWe have to transform our societies and economic systems towards social, ecological, and economic (holistic) sustainability. Bioeconomy (BE) can contribute to sustainable development by substituting fossil-based products with renewable ones; however, sustainability is not intrinsic to BE.MethodsTherefore, we developed a holistic and integrated life cycle sustainability assessment (HILCSA) method containing 91 indicators, implemented in openLCA, using the Ecoinvent and SoCa database, and addressing 15 out of 17 Sustainable Development Goals. We applied it for the first time to show its capabilities by assessing the holistic sustainability of laminated veneer lumber (LVL) relative to hot-rolled steel beams.Results, discussionOur results indicate that renewable bio-based construction materials can have a better holistic sustainability than fossil-based products for nearly all indicators, by less stressing the environment, having a less negative impact on society and being economically more efficient. However, fossil-based components of LVL such as phenolic resin are main contributors of negative impacts and should be reduced and replaced. Renewable resources from agriculture and forestry have significant impacts on land use (change).ConclusionsHILCSA demonstrates to be able to provide comprehensive sustainability assessments as well as aggregated results. BE substitutes indeed can improve sustainability; however, sustainability assessments and HILCSA need to be further developed to allow conclusions to be drawn about absolute sustainability of BE.

Interfacial properties of windmill palm (Trachycarpus fortunei) fiber reinforced laminated veneer lumber (LVL) composites under high voltage electrostatic field (HVEF)

The acid/alkali pretreatment of windmill palm fiber (WPF) and the application of high voltage electrostatic force (HVEF) technology were used to prepare WPF-reinforced laminated veneer lumber (LVL). The effects of acid/alkali pretreatment on the surface morphology, chemical composition, crystallinity and mechanical properties of WPF were investigated. Moreover, the effects of intensity of HVEF on chemical composition and wettability of WPF were analyzed. Based on the mechanical experiment of WPF reinforced LVL composites, the mechanism of acid/alkali pretreatment and HVEF for the reinforcement of the composite was systematically clarified. The results showed alkali treatment efficiently removed silica particles and cuticles on the fiber surface and produced windmill palm fiber with relatively high Young’s modulus and tensile strength (increased by 167.07% and 26.52%, respectively). After HVEF treatment, the increase of surface-active groups (- OH and - CHO) led to the increase of surface oxidation degree and water contact angle of WPF. Under the synergistic effect of acid/alkali pretreatment and HVEF, the interfacial properties between the adhesive and WPF were improved. This study showed that the synergistic effect of acid/alkali pretreatment and HVEF not only broaden the application scope of WPF, but also provide insights into the engineering of LVL production.

Calibration of Electrical Resistance to Moisture Content for Beech Laminated Veneer Lumber “BauBuche S” and “BauBuche Q”

Electrical resistance measurements are often employed for the purpose of nondestructive long-term monitoring of wood moisture content (MC) in timber structures. As a structural material for high-performance load-bearing applications in such structures, beech laminated veneer lumber (LVL) enjoys a growing popularity. However, due to the processing of beech LVL affecting physical properties, calibration curves for bulk beech wood cannot be used. In this study, resistance was measured on 160 beech LVL samples equilibrated in four different relative humidity (RH) climates. The results show a difference not only between the beech LVL products “BauBuche S” and “BauBuche Q”, but also between measurements at two different depths. For each data set, parameters for calibration models using two and using three model parameters were determined by regression analysis to MC determined by the gravimetric method.

Laminated veneer lumber from spindleless rotary-peeled veneers produced from short rotation, small Hevea plantation logs: Effects of lamination pressure

The invention of spindleless lathe technology has enabled veneers to be produced from small logs, such as logs from short rotation Hevea plantations, with low recovery loss. However, for structural laminated products, such as laminated veneer lumber (LVL), manufacturers are highly selective regarding the veneers for their conventional production. During the peeling process of small logs (< 18 cm), deeper and higher frequency of lathe checks were induced on veneer surface compared to the common log size used (> 30 cm). In this study, spindleless rotary-peeled veneers made from small rubber logs were processed into LVL using different lamination pressures: 7, 8, 9, and 10 kgf/cm2. The effects of lamination pressures on the physical and mechanical properties of the produced LVL were evaluated. Based on the findings, the specific gravity increased from 0.73 to 0.83 with increased lamination pressure. In terms of mechanical properties, all the values increased with lamination pressure, but with a sudden drop with 10 kgf/cm2. Understanding the effect of lamination pressure on the physical and mechanical properties can shed light on optimizing the usage of spindleless rotary-peeled veneers from small logs for the production LVL and other lamination products.

A comparative study on the mechanical properties of laminated veneer lumber (LVL) produced from blending various wood veneers

Rotary veneers from spotted gum (Corymbia citriodora) and white cypress pine logs (Callitris glaucophylla) recovered from the native forest in Queensland, as well as Queensland plantation hoop pine (Araucaria cunninghamii) logs were used to manufacture LVL products following six different lay-up strategies including blended species LVL. The different lay-up strategies were to determine the opportunities for improving the mechanical performance of plantation softwood LVL by including native forest veneers. The manufactured products were evaluated for their bending performance, tension, bearing strength perpendicular to the grain, and longitudinal-tangential shear strength. The all-spotted gum LVL showed superior performance in all testing compared to other construction strategies. Blending even a small amount of spotted gum veneer with plantation hoop pine veneer resulted in improved mechanical performance, especially in flatwise bending. Opportunities exist to develop more optimised construction strategies that target specific product performances while optimising the use of the variable veneer qualities generated from log processing.

Using acoustic wave velocity to select fibre-managed plantation Eucalyptus nitens logs for laminated veneer lumber products

The aims and objectives of this study were to investigate the potential to predict laminated veneer lumber (LVL) stiffness from wood properties measured on trees and logs, and determine variation in log, wood and veneer properties as a function of tree height and age. Log selections were made from trees in three stands that were planned for harvesting at 14, 20 and 21 years of age. Rotary peeled veneer recovery from the logs was on average 65%. After drying, Metriguard testing showed over 50% of the veneer had an estimated dynamic modulus of elasticity (MOEdyn) above 12 GPa, with 20% above 14 GPa, and that veneer from the second log by tree height had higher MOEdyn values. In visual assessment to the AS/NZS 2269.0:2012 Standard, no veneer could be utilised in a panels face or subface positions and the older-age stand provided almost four times the volume of usable veneer. Standing-tree acoustic wave velocity (AWV) explained a moderate amount of variance in log MOEdyn and Pearson correlation coefficients between the (Metriguard) veneer MOEdyn, log AWV, log MOEdyn and disc basic density were significant, positive and strong, with log AWV explaining most of the observed variance in log stiffness. A moderately strong and positive linear regression existed between log AWV and veneer MOEdyn, supporting the use of log AWV tools for the ranking of stiffness in fibre-grown plantation E. nitens logs. Mechanical strength testing of LVL studs extracted from panels manufactured from the trial’s veneer indicated they equalled, and for some tested parameters exceeded, the characteristic design strength values previously published by commercial LVL manufacturers for equivalent size pine products.

The potential use of wood waste ash nanofiller for improvement of laminated veneer lumber production made from Jabon (Anthocephalus cadamba)

The objective of this research was to improve the bonding properties of laminated veneer lumber (LVL) and its strength made from Jabon (Anthocephalus cadamba) wood bonded using phenol formaldehyde (PF) adhesive mixed with nanofiller made from wood waste ash as substitution material of industrial filler produced from wheat flour. Wood waste ash (WWA) produced from boiler installation of plywood mill was converted into nanoparticle using conventional ball milling for 144 h. WWA nanoparticle was characterized to analyze its particle size, morphology, chemical components and thermal properties. The WWA nanoparticle then added to PF adhesive as a nanofiller under various compositions based on weight: (A) PF 100% + hardener 8%; (B) PF 100% + hardener 8% + wheat flour filler 8%; (C) PF 100% + hardener 8% + WWA nanofiller 2.5% and (D) PF 100% + hardener 8% + WWA nanofiller 8%. These compositions of PF adhesive are then used to produce the LVL from Jabon wood and evaluated its bonding and mechanical properties. Compared to wheat flour filler, PF adhesive filled using nanofiller of 2.5% exhibited the improvement in LVL bonding and strength properties, and the increased values of horizontal shear strength on flat and edge direction were 94% and 107%, respectively. Additionally, the increased values of modulus of rupture (MOR) on flat and edge direction were 62% and 32%, respectively, and modulus of elasticity (MOE) on flat and edge direction was 39% and 16%, respectively.

Properties of red maple laminated veneer lumber impregnated with waterborne micronized and two soluble copper formulations

ABSTRACTCertain important quality parameters of red maple (Acer rubrum) laminated veneer lumber (LVL) impregnated with three waterborne formulations: copper azole (CA-B), micronized copper azole (MicroCA or MCA) and alkaline copper quaternary (ACQ-D) bonded with phenol formaldehyde or cross-linked polyvinyl acetate (XPVAc) adhesives were evaluated. Pre-dipping of veneers before LVL production and two post-manufacturing procedures, viz., vacuum-pressure and post-dipping of LVL, were applied. Maximum copper retention in pre-dip-treated, vacuum-pressure and post-dip-treated LVL was 1.4, 9.7 and 1.7 kg/m3, respectively. Copper retention in MCA-treated LVL was relatively lower than soluble formulations. Various physical, mechanical and bonding properties of treated LVL such as density, water absorption, swelling, flexural properties, hardness, tensile shear strength, delamination and wood failure (%) were studied and compared with untreated LVL. Little to negligible deleterious effect was observed on properties of LVL due to these chemical treatments. Analysis of variance results showed that most of properties of red maple LVL were not significantly different compared with those of untreated LVL. Therefore, vacuum-pressure impregnation process can be used to treat the red maple LVL with novel micronized copper formulations for increasing the service life of such products against biodegradation without affecting techno-mechanical quality parameters.

Laminated Veneer Lumber (LVL) Sengon: An Innovative Sustainable Building Material in Indonesia

Laminated Veneer Lumber (LVL) is recently available in Indonesian markets. The veneers are majority from Sengon wood (Paraserianthes falcataria), which is a fast-growing timber species native to Indonesia. Sengon trees are planted in many community forests so that they are sustainable in term of its availability. Their use in practice is limited to non-structural components since Sengon wood species has low engineering properties and less resistance to termite attacks. The LVL production introduced few years ago has significantly improved both mechanical properties and durability as well as has expanded its utilization into various structural components. This remarkable improvement has made LVL Sengon wood as an innovative sustainable building materials in Indonesia. This paper summarized a series of authors’ work conducted since couple years ago to initiate the utilization of LVL Sengon in structural components such as shear walls, connections, and floor systems as parts of a project to develop its design standard. In addition, creep behavior of this LVL is also highlihgted here as this phenomenon is essential for designers and engineers to anticipate their designs within their service life.

Calculation model to assess the structural behavior of LVL-concrete composite members with ductile notched connection

This paper presents an analytical model of timber-concrete composite slabs made of laminated veneer lumber (LVL) with notched connection. Timber-concrete composite slabs could be used as alternative to timber slabs or conventional reinforced concrete slabs and represent an interesting solution due to ecologic, economic and structural advantages. The use of LVL products guarantees for controllable and homogeneous properties of the timber part of the composite member and allows taking advantage of the high mechanical properties of hardwood (e.g. beech). The advantages of the notch as timber-concrete connection system are its high stiffness and the possibility to achieve a ductile compressive failure of timber. The presented analytical model is based on simple equilibrium formulations and allows the development of a ductile and reliable design procedure based on notch yielding. Because of the difference between the material properties of LVL and concrete, local LVL deformations within the notches may compromise the shear-carrying mechanism in concrete, leading to premature failure of the composite member. This problem can be solved by installing vertical reinforcement. The model has been validated by means of full scale bending tests on timber-concrete composite members made of beech LVL plates.

A comparative life cycle study of alternative materials for Australian multi-storey apartment building frame constructions: Environmental and economic perspective

The building construction sector contributes to a quarter of the total Australian Greenhouse gas emissions. These emissions are mainly attributed to the use of energy intensive materials. To achieve better environmental benefits and cost saving, the utilisation of wood-based construction materials is currently attracting attention. However, the manufacturing of engineered wood products consumes large quantities of chemicals and energy, which may have adverse environmental impacts. Therefore, a life cycle study was conducted to compare various materials for constructing the structural frame of a 4-storey apartment building compliant with the Australian building codes. Five alternatives were assessed: Laminated Veneer Lumber (LVL) manufactured from early to mid-rotation hardwood plantation logs (LVLm), LVL manufactured from mature hardwood plantations (LVLh), LVL manufactured from mature softwood plantations (LVLs), concrete and steel. The functional unit was defined as the whole building structural frame. Global Warming Potential (GWP), Acidification, Eutrophication, Fossil Depletion, Human-toxicity Potential (HTP) and Life Cycle Cost (LCC) were evaluated. The LVL generally performed better than concrete and steel structural products. Particularly, LVLm had the lowest GWP (2.84E4±233 kg-CO2-eq) and LCC ($128,855 ± 2797), which were less than a quarter of the concrete option. However, the usage of chemical preservatives and phenol-formaldehyde adhesive during the LVL production and treatment caused the HTP impact to be higher than the steel option. Monte Carlo Analysis showed that while the LVL options presented a higher sensitivity to the combined uncertainties, the overall ranking of the five options remained the same. Therefore, the inclusion of wood-based material in structural elements may significantly contribute to reduce the environmental impacts and the LCC of the construction sector.

Variation of Density and Dynamic Modulus of Elasticity of Poplar Veneer and Its Impact on Grade Yield

To maximize the value of poplar wood in manufacturing of laminated veneer lumber (LVL), its radial (from pith to bark) and longitudinal (from bottom to top) variations were examined in terms of the density and dynamic modulus of elasticity (ED) of veneer. The veneer sheets were rotary-peeled from seven representative poplar butt bolts (the bottom part of a stem) and seven representative poplar second bolts (the middle part of a stem). A grading strategy for selecting veneer was proposed based on the requirements of LVL products. In this study, the ED value of each poplar veneer sheet was non-destructively measured by the ultrasonic method. The results showed that there was a weak correlation between veneer density and ultrasonic wave velocity. The bolt class (butt or second bolt) did not significantly influence the variation of veneer density and ED. However, the among-bolt variation played a significant role in the variability. A large difference in diameter between two ends of a bolt (i.e. the within-bolt variation) resulted in a low veneer ED. According to the sorting criteria of Chinese Standard “Laminated Veneer Lumber”, the estimated grade yields of the poplar veneer studied were 45.2% for G1, 39.3% for G2, 13.1% for G3, and 2.4% for G4.

Cradle-to-Gate Life-Cycle Assessment of Laminated Veneer Lumber Production in the United States*

Abstract To keep environmental product declarations current, the underlying life-cycle inventory (LCI) data and subsequent life-cycle assessment data for structural wood products must be updated. Primary data collected from the industry for the year 2012 were analyzed using the weighted-average to update LCIs for laminated veneer lumber (LVL) production on a 1-m3 basis in the Southeast (SE) and Pacific Northwest (PNW) regions of the United States. In addition, cradle-to-gate life-cycle impact assessments (LCIAs) were performed to assess the environmental impacts associated with LVL production for both regions. The cradle-to-gate LCIAs included three life-cycle stages: forestry operations, dry veneer production, and LVL production. The LCIs revealed that the dry veneer life-cycle stage dominated overall primary energy consumption for both the SE and the PNW at 6.83 (68.5%) and 6.75 GJ/m3 (75.3%), respectively. Energy consumption at the veneer stage was based primarily on renewable sources, especially wood ...

Modelling the effects of wood cambial age on the effective modulus of elasticity of poplar laminated veneer lumber

A modelling method is proposed to highlight the effect of cambial age on the effective modulus of elasticity of laminated veneer lumber (LVL) according to bending direction and veneer thickness. This approach is relevant for industrial purposes in order to optimize the performance of LVL products. LVL is used increasingly in structural applications. It is obtained from a peeling process, where product’s properties depend on cambial age, hence depend on radial position in the log. This study aims to highlight how radial variations of properties and cambial age impact the mechanical behaviour of LVL panels. An analytical mechanical model has been designed to predict the modulus of elasticity of samples made from poplar LVL panels. The originality of the model resides in the integration of different data from the literature dealing with the variation in wood properties along the radius of the log. The simulation of the peeling process leads to veneers with different mechanical properties, which are randomly assembled in LVL panels. The model shows a correct mechanical behaviour prediction in comparison with experimental results of the literature, in particular with the decrease in MOE in LVL made of juvenile wood. It highlights that the bending direction and veneer thickness have no influence on the average MOE, but affect MOE dispersion. This paper proposed an adequate model to predict mechanical behaviour in the elastic domain of LVL panels based on the properties of raw wood material.

Effects of Veneer Treatment with Copper-Based Preservatives on the Decay Resistance and Mechanical Properties of Poplar LVL

To improve the durability of poplar laminated veneer lumber (LVL), the veneers were impregnated with alkaline copper quaternary (ACQ) and copper azole (CA) at four retention levels, and the effects of the treatments on the LVL properties were examined. The results demonstrated that the treatments substantially improved the decay resistance of LVLs, with the decreases in mass losses ranging from 42.6% to 87.3%. However, retention levels greater than the specified standard values for Use Category C4.1 might be required for sufficient protection of poplar LVL against decay fungi. The bending and shear properties of all treated LVLs met the requirements for high-grade products specified in the LVL standard GB/T 20241. No significant effects of the treatments were observed on the mechanical properties of LVLs, and the LVLs did not display any visible delamination after boil-dry treatment. These results imply that the treatments significantly improved the decay resistance of poplar LVL products and had no appreciable impact on their mechanical and physical properties.

Effects of grading of veneers on properties of LVL made from Schizolobium amazonicum Huber ex. Ducke

The work aimed at evaluating the influence of pre-classification of veneer made from parica (Schizolobium amazonicum Huber ex. Ducke) plantation trees on Laminated Veneer Lumber (LVL) properties. This species is native to the Amazonian and is fast growing with low density. For LVL production, veneers were separated into four classes according to the density or dynamic modulus of elasticity. LVL was produced considering three different strategies of assembly—random veneers assembly; assembly using veneers with greater EMd placed at the surface layer with gradual reduction up to the center of the panels; assembly using veneers with greater density placed at the surface layer and gradual reduction into the center of the panels. The following mechanical and physical properties were then evaluated: static bending modulus of elasticity (EM), modulus of rupture (fM), compression strength parallel to grain (fc0), shear strength parallel to glue-line (fv0), shear strength perpendicular to glue-line (fv90), water absorption and thickness swelling for 2 and 24 h of water immersion. Physical properties of LVL were not found to be influenced by different pre-classification strategies, while for mechanical properties only bending strength at flatwise position was influenced by pre-classifying veneers.

Acoustic Testing and Sorting of Chinese Poplar Logs for Structural LVL Products

The purpose of this study was to investigate the feasibility of using resonance-based acoustic technologies for sorting Chinese poplar logs for laminated veneer lumber (LVL) products. Representative poplar logs were sampled. Each log was first tested for acoustic velocity and then peeled into veneer. Each veneer sheet was subsequently dried and measured with a production-line veneer tester. LVL beams were made, and their stiffness was non-destructively measured by both time-of-flight (TOF) acoustic method and free-beam vibration methods. Based on the LVL dynamic modulus of elasticity (MOE) values, logs were sorted into several grades with known grade outturns. The results showed that there was a strong correlation between resonance-based acoustic velocities of logs and dynamic MOE of veneer and LVL. Thus, it is feasible to predict the stiffness of LVL products based on log resonance-based acoustic velocity measured. The resonance-based acoustic measurement is easy to use and reliable, which can help increase the grade outturn and in turn value recovery of Chinese poplar logs. It was estimated that the log grade outturns were approximately 31.1% for LVL grade 1, 38.6% for LVL grade 2, and 26.1% for LVL grade 3.