IN-GRADE CLT FROM UNGRADED PINUS RADIATA BOARDS

Within the feasibility analysis for a Cross Laminated Timber (CLT) plant, the possibility to produce in-grade panels from boards that were not strength-graded according to the applicable standard was demonstrated by tests on panels produced in industrial conditions. The “cross-lamination effect” that explains this result was observed, and an innovative CLT lay-up with inner boards at 45deg angles was tested for the first time on Pinus Radiata. A set of scans and sorting feedback information, executed by Microtec on a sub-sample of the boards, provided a very useful insight and allowed significant resource optimization, particularly in the case of knotty boards. The comparison with a benchmark of C24 Spruce CLT, produced and tested in identical conditions, showed that higher in-plane shear resistance and modulus were achievable with ungraded Radiata Pine; this is a desirable performance for mid-rise construction (buildings of at least 4-storey high), which is a growing market trend, able to generate more value for the fraction of this fast-grown plantation timber which is currently not meeting the stud framing market specifications.