The Canadian lumber industry has identified, as a high priority, the establishment of a multi-year Lumber Properties Program that pulls together a number of urgent initiatives currently underway to establish and/or maintain Canadian lumber design values. The desire is to have an overall program that emphasizes the proper development of a longer-term strategic plan and process to deal with current and future initiatives. Combining the current industry resources with Federal Government contributions through Natural Resources Canada (NRCan), the first step in the Program has been completed: to gather the various initiatives now underway and to begin the formal development of pan-Canadian policies to guide the development, implementation and on-going maintenance of such initiatives.
The key activities in 2006-07 were:
Launching of the pilot phase of the on-going monitoring program, and development of a simulation model to assist in determining what sort of trends can be reliably detected and which cannot;
Completion of the in-grade testing program on Canadian Norway spruce;
Analysis of the No.2 2x4 Hem-Fir (N) monitoring study and confirmation of the appropriateness of assigned design values;
Identification of an alternative species grouping procedure for further study;
Starting of a process under the ASTM Committee on Wood to address gaps in the Grade Quality Index provisions in ASTM Practice D1990, and
Establishing a forum for engaging the US in discussions on lumber properties issues.
Lumber properties issues crucial to maintaining the competitiveness of Canadian lumber continue to be the same as in previous years: tests and means to adjust for sample representativeness using the Grade Quality Index (GQI), species grouping and re-grouping procedures, and on-going lumber monitoring. As a result, discussion on a pan-Canadian strategy and supporting policies necessary to support Canadian lumber initiatives tend to focus on these three issues. The challenge is to ensure that these issues are dealt with in a way that balances both short and longer-term needs and provides a net overall benefit to the Canadian industry.
Forintek has completed a two-year investigation of the NLGA SPS 6 Standard, Special Products Standard for Structural Face-Glued Lumber. The NLGA SPS 6 Standard prescribes product specifications and qualification and quality control requirements for structural products created by edge-gluing and/or fingerjoining lumber segments. Under the NLGA SPS 6 Standard, the design values assigned are based on the visual grade and the stress level achieved in qualification tests on the glue joints.
The project assessed the effect of the following three factors on strength of the NLGA SPS 6 product:
1. Tension proof-loading;
2. Relative location of fingerjoints in adjacent members when fingerjoined material is edge-glued;
3. Strength of the material used to make the NLGA SPS 6 product.
Results showed a positive effect of proof-loading, a minor effect of staggering of fingerjoints, and a highly significant effect of density of raw material on tensile stress of edge-glued specimens. It was confirmed that SPS6 products of greater commercial value can be obtained from lower grade lumber. However, visual grading of SPS 6 products proved to be more difficult than visual grading of lumber, because grade-determining wood characteristics were sometimes hidden in the bond line, and could not be properly identified.
The findings of this project can be used to fine tune the NLGA SPS 6 standard and the other NLGA fingerjoint and face-glued lumber product standards. The project will help the wood industry maximize the utilization of their raw material resource, resulting in increased profitability.
Five fungal species were used to modify and activate natural binding agents from wood fibres for manufacturing MDF panels. Two different methods of the bio-treatment were carried out using these five different fungal species. In the first method, the fungi were inoculated to black spruce (Picea mariana) sawdust, incubated for 20 days at 25ºC, and then refined into wood fibres, with the UF resin loadings of 0% and 8%, respectively. The second method was carried out using normal fibres refined from fresh black spruce sawdust. The fibres were blended with the fungal filtrates in the rotary blender and incubated for 12 hours. MDF panels were made from these different fibres. The mechanical and physical properties were evaluated and compared with the normal MDF panels made of UF resin. Preliminary test results indicate that:
To some extent, the experimental work showed that the self-bonding ability existed after the bio-treatment of wood fibres using the fungal species studied in the project;
All the fungal treated fibres showed the improved bond quality in MDF. The fibres treated with Type-4 fungus yielded the highest bonding strength in the panels with the first treatment method while that with Type-3 had the best result using the second method;
The internal bond strength of all trialed panels without urea-formaldehyde (UF) resin was lower than that of the normal MDF with 8% or 12% UF resin and below the requirement of ANSI standard;
The results suggest that the fungal species studied behave different and no obvious correlation between IB and thickness swell or water absorption can be established;
No obvious consistent trend in MOR and MOE of the panels made with five bio-treatments between two different methods was observed;
Similar MOE and MOR were obtained in the second method among different treatments except T1. The MOE and MOR of T1 panels were lower than those of the rest panels and all of them were significantly lower than those of the control MDF;
This preliminary experiment showed that it is possible to produce MDF using bio-treated fibres with reduced UF resin content in the fibres and it was feasible to use crude extracts of fungi to replace high pure laccase. However, the experimental work was preliminary and further work is required to identify more suitable fungal species and better treatment and process conditions to substantially reduce the time of incubation and process cost to be compatible with the current resin systems used in the manufacture of MDF.
Norway spruce is a highly productive exotic species that has been planted in Eastern Canada since the beginning of 1900. In Quebec and the Maritimes, many plantations have now reached merchantable sizes or will reach it in the near future. As part of these plantations need to be thinned, forest owners have to decide on what to do with their wood. As a result, the question arises on how the Norway spruce resource compares to commercial Canadian species and Norway spruce grown in Europe in terms of lumber structural properties. The present work summarizes published literature on the lumber mechanical properties of Norway spruce with respect to bending stiffness (modulus of elasticity, MOE) and bending strength (modulus of rupture, MOR). The report also addresses major wood characteristics that affect the mechanical properties of Norway spruce lumber, and softwoods in general.
As expected, the European literature on the structural properties of Norway spruce is far more abundant than that in Canada. As summarized in Table 10, the published MOE values ranged between 6100 MPa to 13 800 MPa in Europe and between 5 844 MPa to 9 357 MPa in Eastern Canada. However, it should be pointed out that different testing methods were used to assess lumber MOE and MOR, which makes them not always directly comparable. Hence, the reader should consider Table 10 as indicative, providing a general idea of the range of variation in lumber mechanical properties for Norway spruce as affected by different growth conditions and rotations ages. MOE and MOR values for Norway spruce lumber correlate positively to wood density, which in turn, is influenced by tree age and growth conditions. Several studies have demonstrated that fast-grown Norway spruce generally decreases wood density, which has a negative impact on lumber structural properties. When trees grow fast at young tree, wood density is even lower because of the increased proportion of juvenile wood that significantly lowers lumber MOE and MOR.
The following general trends are observed for Norway spruce: 1) mature trees (> 70 yrs) have generally higher strength properties than young juvenile trees (< 40 yrs); 2) the faster the growth rate (whether it is caused by large tree spacings and/or better site conditions), the lower the wood density and thereby the structural properties; 3) European Norway spruce tends to show higher lumber MOE. However, it should be understood that: 1) European Norway spruce is generally harvested at maturity (80 years or older); 2) genetically superior trees have been planted over a last century and 3) intensive silviculture (through several thinnings) has contributed to improving the general quality of the forests by a systematically removal of low quality trees. In Eastern Canada, Norway spruce has been mainly planted on productive sites such as agricultural land where trees growth is generally faster than that of natural forests, producing larger volumes of low-strength juvenile wood. Moreover, these trees are often harvested at a younger age than in Europe, which even worsen their mechanical properties. In Eastern Canada, Norway spruce trees could show comparable lumber mechanical properties that in Europe if they were allowed to grow at slower rates than today and were cut at maturity (> 70 years).
European authors generally agree that it is difficult to produce short-rotation wood with good structural properties. The selection of genetically superior trees with high-density juvenile wood could solve the problem of short-rotation forestry by reducing the negative impact of juvenile wood on wood mechanical properties. Until a good balance between volume production and wood quality is found, and until the species is accepted by the National Lumber Grading Authority and included in the S-P-F group, Canadian fast-grown wood from young Norway spruce plantations should be used preferably in non-structural applications. For example, it could be used in appearance products (furniture, mouldings) in a similar way as white pine is being used in Eastern Canada, or incorporated in some part of engineered or composites wood products where stiffness and strength specifications are lower than that of structural lumber.