A product characterization of glulam made from secondary timber – from wood collection to structural testing

Engineered wood products can reduce the carbon emissions involved in constructing our built environment. To realize the benefits of this reduction we must ensure long-term carbon storage within the wood products, such as by applying circular economy principles that extend the life cycle of timber components and avoid the release of carbon dioxide during decomposition or incineration. This product characterization study elevated the material value of secondary timber as a feedstock for structural glulam. The study discusses material sourcing from a demolition site, methods of processing and characterization, and manufacture into six glue-laminated beams. The results of acoustic resonance testing and four-point bending tests of the manufactured glulam beams determined a mean strength of 36 N/mm2, a mean dynamic elastic modulus of 13 kN/mm2, and a mean local pseudo-static modulus of elasticity of 12.2 kN/mm2; all within the range of the glulam GL24 classification manufactured from primary timber feedstock. A modified glue line test demonstrated shear strengths greater than 6 N/mm2 with a wood failure percentage surpassing the minimum requirement in the European standard. The small sample size of six beams precludes the calculation of 5th percentile characteristic values from this study, and further testing on a larger sample of specimens is recommended.