Treesearch

Among the most abundant of our undervalued hardwoods are the soft maples. However, other species that are also underutilized include some species of birch and some lower grades of the hard maples. This chapter covers physical, mechanical, and other important properties of different soft maples, hard maples, and yellow birch and compares them with the properties of benchmark species. The benchmark values are taken to be average values for eight species of southern yellow pine.

This chapter evaluates the performance of red maple glulam beams made from two distinctly different lumber resources: 1. logs sawn using practices normally used for hardwood appearance lumber recovery; and 2. lower-grade, smaller-dimension lumber primarily obtained from residual log cants.

Structural lumber markets have traditionally been dominated by softwood species. Historically, however, hardwood species have been extensively used for certain structural products such as timbers for railway and highway bridges, railway ties, mine timbers, and for pallets and containers. In the 1920s, when uniform procedures were first developed for structural grading, allowable properties were assigned to both hardwood and softwood species (Appendix D of Green and Evans 2001). In 1922, the National Lumber Manufacturers' Association (currently the American Forest & Paper Association)...

Prefabricated wood I-joists and headers are widely used in wood construction throughout the world. They are used in roof and floor systems in both residential and commercial applications. These structural members consist of flanges, which are made from either solid-sawn or laminated veneer lumber, that are adhesively bonded to a web that is made of plywood or oriented strandboard (OSB). Approximately 1 billion linear feet of wood I-joists and headers are manufactured annually. Currently, softwood species are predominately used for flanges. The work presented in this chapter was conducted...

As the cost of quality waste paper continues to escalate in response to an increased global demand for this finite resource, loss of saleable fiber within flotation rejects becomes both environmentally and economically unacceptable. The ability of surfactant spray technology to reduce fiber loss without detriment to pulp brightness gains has been demonstrated during both laboratory and pilot-scale flotation deinking investigations. This paper documents the successful transfer of this technology to a single flotation unit within the deinking line of a mill production newsprint from 100%...

Over the last 50 years many changes have roiled lumber markets. On the positive side, treated lumber has created major opportunities for lumber use in outdoor applications. But some negative developments underscore the mature status of lumber as a commodity. Sheathing had been lost long ago to panels. Likewise, roof rafters and joists have been supplanted by less wood-intensive trusses. More recently, lumber use in floor joists has been shrinking due to replacement by wood I-Joists, while in the girder, beam and header segment, LVL has been taking large shares. Similarly, in outdoor...

An important aspect of any adhesive bond is that the bond maintains its integrity during its end use. Epoxies form highly durable bonds with many substrates but are usually not considered capable of forming completely durable bonds with wood by standard accelerated tests. However, epoxies are sold for wood boat construction, and some data have indicated that epoxies can have sufficient exterior durability for general use in wood products. This conflicting information raises an important question. Are the reported discrepancies caused by changes in epoxy–wood bond formulations or in the use...

An important aspect of any adhesive bond is that the bond maintains its integrity during its end use. Epoxies form highly durable bonds with many substrates but are usually not considered capable of forming completely durable bonds with wood by standard accelerated tests. However, epoxies are sold for wood boat construction, and some data have indicated that epoxies can have sufficient exterior durability for general use in wood products. This conflicting information raises an important question. Are the reported discrepancies caused by changes in epoxy–wood bond formulations or in the use...

X-ray photoelectron spectroscopy (XPS) is one of a set of tools that have been used to characterize wood surfaces. Among the advantages of XPS are surface sensitivity, identification of nearly all elements, and frequently, discrimination of bonding states. For these reasons, XPS seemed to be an appropriate tool to help explain the differences in bond strength under wet conditions for planed and unplaned acetylated wood bonded with epoxies. Some care needs to be taken to ensure correct analysis of the high-resolution XPS spectra. The XPS, in conjunction with labeling with trifluoroacetic...

Is the hydroxymethylated resorcinol (HMR) primer unique or can a melamine- based primer also increase the wet wood strength of epoxy bonds? Although the exact reason for poor durability with some wood adhesives is not known, the HMR priming agent was found to facilitate durable bonds in most cases tested. A model of cell wall stabilization that is believed to be the mechanism of HMR has led to the consideration of melamine-based primers. Previous studies have shown that melamine resins can increase the hardness of wood cell walls and lower the amount of swelling from water impregnation....