In the construction of buildings, the timber-concrete (TCC) system can be a cost-competitive solution for floors with longer spans, since the mechanical properties of the two materials are used efficiently. Furthermore, the additional mass from the concrete improves the acoustic performance compared to a timber floor system alone. Nevertheless, TCC floors are not commonly used in buildings in Canada, due to the absence of technical guidelines for such types of structural systems in this country.
An above-ground field test of glulam and laminated veneer test samples protected by a combination of coating and treatment with borate by two alternative processes was initiated. Assessment of coating and sample preparation are described.
The project objective is to provide key data on the laminating properties of Canadian wood species to assist the secondary manufacturing industry to meet domestic and international customer expectations. This is a progress report to March 31, 1999.
A review of delamination/durability tests was conducted, and tests were selected for comparative study. Reduced catalyst levels affected phenol-resorcinol formaldehyde (PRF) and catalyzed polyvinyl acetate (PVA) bond durability. Wood moisture content (MC) at the time of bonding affected PVA durability, but not PRF. Growth rate and density affected Douglas-fir bond durability. Density did not affect the results of slow-growth lodgepole pine.
In laminated wood, although all five delamination tests accepted conforming and rejected non-conforming PRF, only two tests rejected both non-conforming PRF and PVA. In fingerjoined lumber, delamination was sensitive to the final MC. Specimen length affected specimen-drying time, but its effect on delamination was not consistent. The NLGA delamination suggested lower bond durability than the WWPA durability-bending test.
The susceptibility of non-veneered composite panel products to decay is greater than solid timber when exposed to high moisture contents and severe decay hazard conditions. Preservative chemicals incorporated into these products at various stages of manufacture generally improve the decay resistance of these materials but certain strength properties, especially internal bond, are adversely affected. It appears from the literature survey that treatment of the composite panel products with ACA type preservative system could provide adequate protection with acceptable loss in the strength properties of the panels.