Decking markets in Canada lack options of hybrid designs and are generally limited to smooth 5/4” or 2x6” of either pressure treated wood, cedar, tropical hardwoods or wood plastic composites. Profiled decking has been unsuccessful in entering the Canadian market on a large scale even though globally it is more prevalent. This report looks to leverage FPInnovations’ expertise to identify opportunities to improve the stability, durability, performance and competitiveness of wood decking by combining profiling and treatment with additional non-wood materials. This information will be used to develop prototypes of novel wood-based decking products that would suit the needs of Canadian consumers as well as maintaining or expanding the solid wood decking market for Canadian producers. Six hybrid decking models were conceptualized to address market concerns about wood decking.
In this project, the main objective was to evaluate the “best bet” experimental mat structure design previously identified by FPInnovations in 2018/19. This mat structure was comprised of three strand size classes incorporated into six equal weight mat layers. Both experimental and control panels were prepared at 39lb/ft³ and 35lb/ft³ densities and tested for dry static bending, single cycle bending (D4), concentrated static load, thickness swell, and internal bond strength.
The findings of recent studies from both eastern and western Canada have shown that the drying behaviour of subalpine fir (A. lasiocarpa) and balsam fir (A. balsamea) is similar, which allows common solutions to be applied based on research conducted on one species of fir or the other. This article summarizes previous research findings and good practices that can be adopted in the short term to improve the drying of fir.
Des travaux récents tant dans l’est que dans l’ouest du Canada ont montré que le comportement au séchage du sapin subalpin (A. lasiocarpa) et du sapin baumier (A. balsamea) est similaire, ce qui permet une application de solutions communes à partir de travaux effectués sur l’une ou l’autre variété de sapin. Le présent
document se veut une revue sommaire de résultats de travaux antérieurs et de bonnes pratiques pouvant être adoptées à court terme pour améliorer le séchage de cette essence.
Fifteen structural composite lumber (SCL) products including laminated-veneer lumber (LVL), laminated strand lumber (LSL), oriented strand lumber (OSL), and parallel strand lumber (PSL) provided by Boise Cascade, LP, West Fraser, and Weyerhaeuser were tested for moisture-related properties in this study, also covering four reference materials: 16-mm Oriented Strand Board (OSB), 19-mm Canadian Softwood Plywood (plywood), 38-mm Douglas-fir and lodgepole pine solid wood. Water absorption, vapour permeance, vapour sorption, and dimensional stability were measured with limited replication by following relevant standards for a purpose of assisting in improving building design and construction, such as hygrothermal modelling of building envelope assemblies, design for vertical differential movement, and on-site moisture management.
Continuous drying is still in its relatively early stages and mills are currently dealing with process adjustments to obtain desired throughput and quality of the final product. Field measurement carried out in 2015-16 illustrated a number of opportunities for process optimization involving each of the three main stages of current continuous kilns. Simulations of industrial continuous drying at laboratory level performed in 2016-17 were successful and allowed the evaluation of each of the drying stages to be fully characterized (lumber temperatures, drying schedule conditions of dry and wet bulb temperatures). Thus, different drying schedules provided an excellent opportunity to examine the impact of schedule conditions on drying defects, drying rates and kiln residence times.
The main objectives of the project for 2017-18 were to simulate continuous drying in laboratory conditions for different products, products mix, species and green sort groups. In addition, a detailed evaluation of potential technologies was carried out to explore the concept of dynamically adjusting speed (push rates), based on drying rates and moisture content.
Piecewise regression was used to identify the optimum push rate and suggest design modifications of continuous kilns. This method proved to be efficient in identifying potential reductions in drying time for different sorts of sprue/pine (SP) lumber without compromising the quality of the final product. Simulations also allowed identifying the push rate of 2 feet/h to satisfactorily dry green hem-fir 2-inch lumber.
Initial tests showed that mid-sort sub-alpine (moisture content below approximately 70%) could not be mixed with wet sort SP in a continuous kiln operating at push rate of 4.2 feet/hr because only 73% of the sub-alpine sort dried below 21%. Decreases in push rate will reduce the percentage of sub-alpine fir wets but will also increase the amount of over-dried lumber. Changes in kiln configuration may reduce the drying time but increase the percentage of over-dried lumber.
The results indicated that additional laboratory tests are required to develop drying schedules and temperature profiles in the main drying zone of continuous kilns, drying times and final moisture content distribution.
To support the implementation of biomass procurement practices, a formal, rigorous, consistent, science-based biomass quality control (QC) program is needed. This program should be designed to determine customer needs, the sources of product variation, and ways of eliminating or minimizing product variation as soon as it occurs. The program should also include a well-designed QC plan and sampling protocol, statistical process control methodologies and tools, formal QC teams, and regular training.
This report describes various statistical QC tools and demonstrates those using examples of biomass moisture content data. These tools can be developed in-house or be purchased, but their integration with existing databases (e.g., LIMS) is recommended. FPInnovations experts can assist in developing customized QC programs for companies and for specific biomass products, and can train QC teams to develop and use the tools presented here.
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Interior partition walls for non-residential and high-rise residential construction are an US$8 billion market opportunity in Canada and the United States (Crespell and Poon, 2014). They represent 1.6 billion ft² (150 million m²) of wall area where wood currently has less than 10% market share. To approach this market a new system would be needed to compete against the incumbent system (wood/steel stud plus gypsum). The system would need to have an installed cost before finishing of approximately US$5 per ft² or lower. The system would also need to meet several code requirements for strength, sound transmission and fire resistance (flame spread and burn through). Crespell and Poon further concluded that to be truly transformative, the system would also need to address major trends impacting the building industry including reducing labor, reducing skilled labor, reducing onsite waste, reducing call-backs, and easily recyclable with low environmental impact. A likely market entry point for wood-based interior partition systems may be in taller and larger wood buildings.
Work described in this report investigated the fabrication, installation, acoustic and combustion properties of prototype interior partition wall designs.
Two types of non-structural prototype interior wall panels designated Type A and Type C were installed between two offices in the FPInnovations Vancouver laboratory. Wood sill plates for mounting the prototype panels were fastened to the concrete floor, sides and top of the opening between the two offices to produce a frame for mounting the test panels. Panels were fastened to the frame using dry wall screws. This same method of installation is envisioned in practice. The installation method makes it easy and fast to both install and remove the wall panels.
Acoustic tests showed the difference in ASTC rating measured between a double wall composed of Type A and Type C prototype panels compared with a double wood stud wall with gypsum board faces was approximately 6 ASTC points. A 6 point difference would be clearly noticeable. Although the results of this study are largely qualitative, they suggest that the prototype interior partition panels would have an acoustic advantage compared to stud wall designs.
In a related study summarized in this report, the combustion properties of three prototype interior panel constructions, including Types A and C evaluated in this report, indicated that any of the three types of partition constructions could be used in combustible construction in accordance with Division B of the National Building Code of Canada.
A second related study, also summarized in this report, estimated an installed cost of US$4.07 per ft² including overhead and profit for unfinished panel partitions comparable to panel construction Type C (gypsum/OSB/wood fibre insulation) as evaluated in this study. Thus, there would appear to be potential installed and finished cost advantages for the wood-based panel partitions compared to steel or wood stud walls with gypsum faces.
Other potential advantages of the prototype interior partition panels compared with the most common, currently-used systems (wood/steel stud plus gypsum) include ease and speed of installation, ease and speed of removal, design flexibility, prefabrication including pre-finishing, and easy installation of services.
Based on the positive results of these exploratory studies, further development of wood-based interior partition systems including design, fabrication, installation and in-service performance would appear justified. Knowledge of the products and testing methods developed in these studies would be expected to speed further development.
This report covers our involvement in phytosanitary-related issues and research in the financial year 2016/17. It addresses actions planned in the 2016/17 project statement of the CFS-funded project entitled: Phytosanitary Measures and deliverables for Codes and Standards work related to phytosanitary issues. It captures our ongoing engagement with CFS, CFIA, and industry, and participation in the key phytosanitary forums including the International Forestry Quarantine Research Group (IFQRG) and the Canadian Forest Phytosanitary Working Group (CFPWG) as these two forums provide guidance to our research in the area.
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A total of 48 peeler blocks and 256 mini-billets were sampled from mills to investigate the effects of yard storage time, and artificial yard drying and sprinkling on residual moisture contents (MCs) and veneer quality. MC in fresh and stored log inventories varied greatly across mills according to geographic location of their wood supply zones, bark damage and loss, and storage time and conditions. The main findings were as follows:
1. DF logs supplied by three BC mills from the Cariboo, Thompson Okanagan, or Kootenay regions were highly variable in wood MC.
2. Winter-cut DF logs with high sapwood MC stored had good bark retention and high moisture retention over 6 and 9 winter-spring months. No effects on veneer peeling roughness from longer-term winter storage up to 9 months.
3. Summer-cut logs had little or no residual bark, or the bark slipped off very easily during debarking. Exposed, bark-free summer-cut logs can dry and crack on edges and ends very quickly, within a few weeks.
4. A marked decline in veneer quality with piling time in Summer for spruce and DF, suggesting an optimum window of processing of such exposed logs of about two weeks. Veneer quality and recovery suffered markedly once the logs had fully air dried mainly because of edge splits creating natural fragmentation of the ribbon.
5. Mills receiving dry-zone logs with much lower MC have a very limited storage window, especially over winter. As little as 2-3 weeks if bark is damaged or missing.
6. Veneer quality could not be definitively tied to log residual MC. Under the controlled laboratory conditions used here it was observed that peeling quality could still be good at low sapwood MC (35-40%) and or very high (MC>100%). Whether this is still the case in mill production is unknown.
7. Logs must never be allowed to fall below FSP and develop edge-checks or deep end checks.
8. Wax emulsion end sealants were effective at hampering drying and end checking on high MC logs, but not effective on low MC logs.
9. Sprinkling retained log freshness and peel quality in high MC DF for several months and prevented log drying and end splitting as well as inner log staining. Ends absorbed considerable extra moisture. Some variability in peel quality was noted.
10. The prototype EM1000 Ground Penetrating Radar could only be reliably used in log edge mode in DF. The unit would also require re-calibration for the very high sapwood MC in spruce and wet-zone DF logs.
Pour différentes raisons, les moisissures représentent un défi constant lors de la production de bois résineux et feuillus : santé, environnement, qualité et stratégies de production. Elles sont aussi une préoccupation constante pour les consommateurs et à l’origine de réclamations qui peuvent être très coûteuses pour les producteurs. Un sondage en 2014 dans l’Est du Canada révélait qu’en moyenne les coûts annuels liés à la détérioration biologique étaient de 60 000 $ par usine. Dans le cas d’une usine intégrée, spécialisée en transformation primaire et secondaire de feuillus et résineux, ces coûts avaient atteint près de 475 000 $ pour cette même année. Ces coûts sont liés à un ensemble de facteurs : modification du procédé, perte de productivité, réclamations, pertes de ventes (Gignac, 2015).
Plusieurs facteurs peuvent contribuer au développement de moisissures dont la teneur en humidité du bois, les conditions climatiques et la durabilité naturelle propre à l’essence de bois. Avec les années, FPInnovations a acquis beaucoup de connaissances, accumulé beaucoup d’information, de données et de savoir-faire à travers ses projets de recherche et son soutien technique à l’industrie. En combinaison avec d’autres données disponibles dans la communauté scientifique, nous proposons de résumer l’information pertinente pour l’industrie et de la présenter sous forme de document de vulgarisation. Ce document se veut un outil simple et pratique pour le personnel de l’industrie de la transformation du bois afin de les soutenir dans la prise de décision concernant les stratégies d’entreposage, de séchage à l’air, séchage au séchoir, gestion du bois sec et transport jusqu’à sa destination finale, le consommateur. Ce document de référence regroupe les connaissances générales en lien avec les problématiques de moisissures.
Transformative Technologies - Development of "Green" Wood Adhesives for Wood Composite Products
Project no.301006168
E-4956
Localisation
Québec, Québec
Langue
English
Résumé
Chitosan is an amino polysaccharide obtained from the deacetylation of chitin, which is naturally occurring in the shells of a large number of marine crustaceans. Chitosan is soluble in weakly acidic aqueous solutions and possesses adhesive properties. Chitosan has received much attention for medical and industrial applications; however, only limited studies have been conducted on the application of chitosan as a wood adhesive, because its bonding properties on wood are poor. To improve the adhesive quality of chitosan resin, an innovative study on chitosan adhesives has been conducted to use selected fungal species to modify chitosan and improve its bonding properties, to synthesize non-formaldehyde resins with the fungus-modified chitosan, and to enhance urea-formaldehyde (UF) and phenol-formaldehyde (PF) resin performance with the fungus-modified chitosan.
The bonding properties of wood composites made with these chitosan-based green wood adhesives were significantly improved, in terms of lap-shear strength. Unmodified chitosan solution was not compatible with ammonium lignosulfonate, liquid PF resin, soybean resin, powder PF resin, or soybean flour, but was compatible with UF resin, polyvinyl acetate (PVA) resin, and phenol. With the addition of chitosan in UF and PVA resins, both the dry and wet shear strengths of plywood panels were improved, compared with those of panels bonded with the control UF and PVA resins, i.e. without chitosan. A number of chitosan and chitosan-reinforced UF resins were prepared as a binder for particleboard panel manufacturing. Six (6) types of particleboard panels with different levels of resin loadings and press conditions were manufactured. The resulting boards were tested to evaluate the bond quality of the chitosan and chitosan-reinforced UF resins. The test results showed that particleboard panels with good visual quality could be produced with all formulations of chitosan-UF adhesives, even with resin systems made with 1% of chitosan resin only. All chitosan resins used alone or added to UF resins yielded panels with better internal bond (IB) strength than those made with the UF control resin. The panels made with 1% chitosan resin plus 66% UF resin in a 1:1 ratio yielded panels with the highest IB strength and the best overall mechanical properties.
Des pièces de bois sont régulièrement rejetées à l’entrée de la raboteuse en raison de courbures excessives. Elles proviennent en majorité des rangs du haut des chargements de séchoirs. À cet endroit, les pièces ne sont pas contraintes, et les conditions de séchage sont souvent plus sévères. Dans une étude antérieure de Forintek Canada Corp., Garrahan (1997) a démontré l’impact du poids de chacune des rangées sur le déclassement du bois en fonction de la hauteur du chargement. La figure 1 montre que les pertes en valeur diminuent du haut du chargement jusqu’au bas. Le poids exercé par les rangées supérieures est de plus en plus important et permet de contraindre le bois en place en cours de séchage.
La technologie de séchage par haute fréquence en continu développée par FPInnovations et Hydro-Québec a récemment été démontrée à l’échelle semi-industrielle (précommerciale) (Lavoie et al. 2015). Les essais de séchage ont porté principalement sur des applications de produits à valeur ajoutée. La technologie est viable techniquement et peut répondre à des besoins de séchage de précision pour des applications spécifiques. La technologie a également le potentiel de resécher des pièces demeurées humides (volontairement ou involontairement) lors de la production de bois d’œuvre.
BC Coastal mills will need to diversify the drying technologies currently used and consider new approaches in order to improve productivity, reduce drying costs, regain competiveness and continue to play a significant role in the increasingly stringent quality market for forest products. New demands for drying are related to energy efficiency, low environmental impact and of course, quality of the final product.
The specific objectives of the project were: (1) to improve the conventional drying of 4.5” x 4.5” Douglas-fir lumber, (2) to evaluate the superheated steam/vacuum (SS/V) drying of 4.5” x 4.5” Douglas-fir lumber, (3) to develop a green sorting strategy for hem-fir lumber and (4) to determine the time required to reach 56°C in the core of 5¼ x 5¼ lumber using the requirements of CFIA PI-07 Heat Treatment schedule Option D - Generic Phytosanitary Heat Treatment Schedule, Heat Treatment with Moisture Reduction.
The results showed that the drying time in conventional drying of 4.5” x 4.5” Douglas-fir lumber can be reduced by up to 25% without compromising the quality of the lumber. This can be achieved by increasing the temperature in the final drying stages and using lower relative humidity at the beginning of the drying process. In addition, final moisture content (MC) variation was reduced from 6.2% to 3.9%.
Reductions of drying times from 26% to 41% were observed when drying 4.5” x 4.5” Douglas-fir under SS/V drying. Quality of the lumber at the end of drying was better when compared to the quality of the lumber at the end of conventional drying. In addition, specimens exhibited less final MC variation.
Based on drying rate measurements of green hem-fir lumber dried to 9.0% MC, a new database was developed which in turn was incorporated into OASiS 2.0 software to evaluate different pre-sorting scenarios. Pre-sorting simulations allow end users to estimate the impact of kiln productivity, final MC distribution and drying degrade. The results showed that different correlations between the time to reach 19.0% MC and initial weight or initial MC could be established. The best correlation with an R square of 0.77 was made between initial weight and MC. After performing several simulations with the new database an optimum cut-off point of 65% yielded the best results in terms of potential increase of productivity and quality of the final product.
Wood heating rate test results showed that CFIA Option D may be extended for 5¼ x 5¼ lumber as long as the dry-bulb = 71°C (= 160°F) for 36 hours at the end of the heat treatment. Total heat treatment time required, including the time required to reach 71°C (160°F), is 72 hours.
FPInnovations launched a multi-year research project to measure mid- to high-rise wood buildings’ natural frequencies and damping ratios to expand the database and validate or adapt the existing equations to estimate the natural frequencies. Two high-rise wood buildings equipped with an anemometer and accelerometers are also being constantly monitored to study how the wind excites the building.
There is a need to demonstrate how novel timber-concrete composite floors can span long distances and be a practical alternative to other traditional structural systems. Better understanding of the fire behaviour of these hybrid systems is essential. To achieve this, the fire-resistance of a timber-concrete composite floor assembly, using BC wood products, will be evaluated in accordance with
CAN/ULC-S101 [2]. A 2 hr fire resistance rating will be targeted, as this is the current requirement in high-rise buildings for floor separations between occupancies.
The structural behaviour of this type of system will also be assessed from conducting pull-out tests of the shear connectors.
In conjunction with previous test data, the results of this test will be used to develop an analytical model to assess the structural and fire-resistance of timber-concrete composite floors. 301010618
This study develops and tests a simple model for the effect of knots on MOR: assuming that a knot is hole in the cross-section of a board a strength ratio is calculated and the MOR is the product of the strength ratio and the strength (MOR) of clear wood. This knot model is based on the stresses being in the elastic range and ignores the effect of grain angle and the orthotropic properties of wood and so should not accurately predict either loads for initial failure or the loads at final failure, on which MOR is based. However, the predicted values of MOR for SPF and Douglas fir compare well to measured values. This lead to the conclusion that while the model is physically wrong, the results imply that the strength ratio of the knot model are related to the strength ratio at final failure, which usually occurs at the end of a crack that starts at the knot but propagates some distance along the board. A model for the strength of the remaining section at the end of the crack was developed and tested on six boards. Not only were the strength ratios for the remaining section model similar to those of the knot model, but the remaining section model predicted MOR values closer to the measured values than the knot model did. The task of future work is to predict the location of the initial crack, the path that it propagates and the strength of the clear wood.
Effective preservative treatments for Canadian glulam products are needed to maintain markets for mass timber on building facades, access markets with significant termite hazards, and expand markets for wood bridges. For all three applications, borate-treatment of lamina before gluing would be preferred as it would lead to maximum preservative penetration. However, the need to plane after treatment and prior to gluing removes the best-treated part of the wood, and creates a disposal issue for treated planer shavings. The present research evaluates the block shear resistance of glulam prepared from untreated and borate-treated lamina with a polyurethane adhesive. Borate treatment was associated with a small but statistically significant loss in median shear strength when evaluated dry; however, there was no difference between the performance of untreated and borate-treated samples when exposed to the vacuum-pressure soak/dry or the boil-dry-freeze/dry procedures. Further work is needed to modify the composition or application of the resin to improve shear strength for glulam applications and ensure consistent performance. However, overall, these data indicate that samples prepared from borate-treated lamina perform similarly in terms of block shear resistance to those prepared from untreated lamina.
Softwood lumber producers have been using conventional drying systems (batch drying) for many years. The original premise of those systems was to design kilns that could dry large quantities of lumber at relatively low costs. Based on the evidence throughout the industry across Canada, those
requirements have been historically met and the industry has greatly benefitted from the existing system for decades. Currently, however, due to environmental pressures, increased processing costs, more stringent quality and moisture content requirements and the need to improve productivity, softwood lumber producers must consider alternative ways to dry lumber to ensure their competiveness in traditional markets and to explore opportunities for entering new markets. Drying faster without compromising the quality of the final product will position Canadian lumber producers to achieve the
aforementioned goals.
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