Semester

Summer

Date of Graduation

2023

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Division of Forestry and Natural Resources

Committee Chair

Joseph F. McNeel

Committee Co-Chair

Curt C. Hassler

Committee Member

Levente Denes

Committee Member

Gloria Oporto

Abstract

The use of cross-laminated timber (CLT) has significantly grown in North America, but hardwood species have not yet been deemed a viable material to manufacture CLT panels, whereas, softwood species continue to serve as the only approved material for CLT in structural applications according to ANSI/APA PRG-320. In order to introduce hardwoods into the CLT market, we must develop non-structural CLT products that utilize low grade lumber from hardwood species. This allows hardwood manufacturers to enter the CLT market without certification, while also displaying the strength and beauty of the hardwood resources found within this region.

Of the hardwood species located within Appalachia, northern red oak (Quercus rubra) is readily available. The main purpose of this research was to develop hardwood cross-laminated timber (HCLT) mats utilizing low grade red oak lumber. In order to manufacture HCLT mats, the best adhesive and bonding parameters had to be identified. Overall, sample CLT panels were made using three adhesives with nine different setups for each adhesive. The sample panels were processed into smaller blocks and separated for cyclic delamination and shear-block tests.

The results of this research found that a phenol-resorcinol formaldehyde (PRF) adhesive produced the lowest percentage of delamination, satisfying the delamination requirement for ANSI/APA PRG-320. The PRF adhesive also produced the largest percentage of wood failure in shear-block testing, however, the results fell short of meeting the requirements of ANSI/APA PRG-320. Through the use of a Taguchi analysis, the results for each adhesive have the potential to be improved, as it determines the optimal bonding parameters for each adhesive. The optimized bonding parameters for the polyurethane (PUR) adhesive produced favorable results as well, indicating that the delamination results have the potential to nearly meet the standard requirements, while the predicted shear results would exceed the requirements of ANSI/APA PRG-320.

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