Developing high-mass laminated flooring products from fibre-managed plantation hardwood

Australia had about 960,000 ha of hardwood plantations in 2013 and the majority of these were planted and are grown in unthinned and unpruned estates for pulpwood. As these plantations are reaching their commercial maturity, estate owners are seeking to diversify their product options by exploring means to convert this resource into viable solid wood products. This study investigated the structural performance of nail laminated (NLT) and glue laminated (GLT) commodity-based high mass timber floor products assembled from pulpmanaged plantation Eucalyptus nitens and E. globulus.

The hardwood resources used in this project were 15 years old E. nitens and 26 years old E. globulus. Industrial standardised hardwood seasoning procedures were applied for the conversion of logs into boards. The logs were milled into 38mm thick hardwood boards using a back sawing strategy for volume recovery. Based on the small end diameters of the logs, the cutting pattern was confined to a limited number of sizes to create an adequate volume of timber in sizes for laminating end sections. The sapwood and log heart were retained.

The seasoned timber boards were nail or glue laminated to form floor panels. Bending tests were conducted to determine the MOE and MOR of the single boards and the laminated panels. All panels were formed with randomly selected boards with scattered MOE and MOR values. Test results revealed that although the wood has a F7 performance if used in a scantling product limited by MOR, the overall structural performance of the species was improved when the wood was used as laminated panels through nail or glue lamination method. The E. nitens and E. globulus panels could be classified as F8 and F11 respectively. The structural performance of the wood was further enhanced by forming timber-concrete composite panels. The composite panels showed structural properties equivalent to timber boards with a F14 performance.

The results proved that the current eucalypt plantations targeted at pulpwood production can be used as laminated floor panels to provide additional options in the building sector.