This research investigated the feasibility of using framing softwood, recovered from building deconstruction, as a feedstock for structural glulam manufacture. It covered the sourcing of timber from a demolition site; the methods of its processing and characterization; its manufacture into six glued laminated beams as if in a commercial process; and the testing of these glulams. The work was part of the “Circular Construction In Regenerative Cities” (CIRCuIT) project [1], which received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 821201.
Previous research has shown the potential for using secondary timber as feedstock for laminated structural timber, including also cross-laminated timber (CLT) [e.g. 2], as these products can nullify some of the issues with this resource. Short lengths can be finger jointed, and the connection of multiple lamella together to form a much larger cross-section reduces the impact of localised defects and material properties uncertainty. Additionally, this can make use of lower-grade softwood (often found in modern concealed internal structures such as partitions, raised floors, and false ceilings) which otherwise has limited alternative uses where aesthetic qualities of the timber are important. However, there are several special concerns that require attention. These include assessment (“grading”) of those shorter available element lengths; damage caused during building removal processes; potential chemical contamination; processing limitations due to embedded metal fasteners; lack of knowledge about the secondary timber mechanical properties; and lack of an obvious formal route for product certification.
Keywords: recycled, reuse, glulam, circular economy
Authors
Philip Isaac
Simple Works, United Kingdom
Dan Bergsagel
Schlaich Bergermann Partner, USA
Annabel Koeck
Grimshaw Architects, United Kingdom
Hassell, Australia
Dan Ridley-Ellis
Edinburgh Napier University, United Kingdom
Marlene Cramer
Edinburgh Napier University, United Kingdom
Colin Rose
ReLondon, United Kingdom
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