PULLMAN, Wash. — The 1970s ushered in a new era of energy efficiency in housing construction. A generation later, following dramatic changes in both building construction and materials, a multidisciplinary team of researchers, including researchers in Washington State University’s Wood Materials and Engineering Laboratory, is trying to identify problematic areas of durability in wood structures and possible material-based solutions.

The Office of Naval Research this month awarded an approximately $4 million, two-year contract to the group of university, industry and government researchers to study the condition of wood timber structures owned by the U.S. Navy in coastal areas. The group also will assess the feasibility of using new materials like thermoplastic/wood composites to increase the structures’ durability. In addition to WSU, other entities involved in the project include the University of Maine, Pennsylvania State University, U.S. Forest Service, Naval Research Laboratory, Naval Facilities Engineering Service Center, Honeywell Corp. and Strandex Corp.

“Since the 1970s, there have been many changes in building practices and materials, particularly in how buildings are sealed in order to increase energy efficiency,” said Mike Wolcott, WMEL program coordinator and associate professor. “At the same time, there has been a rapid change in durability. We are helping the Navy assess how big a problem they have with durability.”

Wolcott suspects that about 50 to 70 percent of the durability problems will show up in one or two areas of the wood structures. The researchers hope to increase durability in the areas and thereby decrease structure maintenance costs for the Navy through the use of recently developed thermoplastic/wood composites and by evaluating technologies to control moisture movement in conventional wood in the structures.

Plastic/wood composites are a combination of wood fiber and plastic , like that used in milk jugs. The new materials can be processed into very complicated shapes to facilitate installation and performance. They were developed in the past decade and have become popular in the commercial market for such light-load applications as doors, windows, siding, flooring and decking. They are being used in outdoor, moist environments because they resist moisture damage well.

In the past three years, WMEL researchers have worked to develop such composites to support heavy loads. The lab is completing a $7.5 million Navy contract to develop a durable and ecologically friendly replacement for creosote-treated piers in harbors. The plastic/wood composite prototypes are scheduled to be installed for demonstration this spring in naval facilities.

In addition to assessing damage, researchers working on the new contract will study important factors for leaders in the contracting, architecture and engineering business to begin adopting new technologies like plastic/wood composites. The researchers will evaluate critical aspects of material design and processing that contribute to durability in both wood and hybrid materials. Specifically, they will work to better understand the interface region in the plastic/wood composites, where the materials bond together. They also will study how the addition of moisture affects the way that energy is dissipated through the materials. Once researchers better understand where and how the Navy structures are suffering moisture damage, they hope to better tailor the plastic/wood materials to fit those needs.

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