Lightweight sandwich panels using small-diameter timber wood-strands and recycled newsprint cores

Christopher Ray Voth

As the natural resources of this planet are being stretched to the limit, it is necessary to look towards effective utilization of undervalued raw materials for production of structural building materials with reduced impact on the Earth's environment. Small-diameter timber is often used for production of structural panels for building construction, but new value-added products using this timber need to be developed to pay for fuel reduction treatments in our national forests for their removal. A lightweight sandwich panel construction with a thin-walled core provides a system to use these undervalued lignocellulosic based materials for production of structural and non-structural panels. Analysis of the core design was investigated to determine a process that can be utilized for engineering design of future sandwich panel cores. The most crucial design parameter for the core is to ensure sufficient width of the corrugated ribs so that flexural failure of the sandwich panel occurs in the face plies as opposed to failure at the interfaces between the core and faces due to shear or crushing/buckling of the walls. Small-diameter Ponderosa Pine wood-strands were utilized in fabrication of a lightweight sandwich panel that has a specific bending stiffness (D, lb-in2/in) 88% stiffer than commercial OSB. The sandwich panels designed within this study utilize 60% less wood-strands and resin by weight compared to OSB panels of equivalent thickness. A case study was performed on the wood-strand sandwich panels to determine their potential in structural flooring as an alternative for OSB. The sandwich panel can support a 40 psf live load and a 20 psf dead load without exceeding IBC (2006) deflection limits. Sandwich panels consisting of old newsprint (ONP) cores were designed for non-structural applications such as shelving units, doors, furniture, etc. The newspapers were shredded into strips and hot-pressed using a powdered phenol formaldehyde resin. ONP strips were oriented to take advantage of the 4:1 ratio in strength and 7:1 ratio in Young's Modulus due to their directional dependent properties. The ONP sandwich panels have a bending stiffness (D, lb-in2/in) 83% stiffer than particle board and over 125% stiffer than a medium density fiberboard.

Lightweight sandwich panels using small-diameter timber wood-strands and recycled newsprint cores

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