Biological durability and moisture dynamics of untreated and thermally modified poplar

Cross laminated timber (CLT) and glue laminated timber (glulam or GLT) are gaining attention given their use in high-rise buildings as climate mitigation concept. In most cases softwood is used to manufacture these engineered wood products, yet fast-growing and widespread hardwood species such as hybrid poplar have potential to meet the increasing demand. In addition to the mechanical performance, it is also key to investigate the fungal susceptibility and moisture dynamics of poplar, to gain insight into the service life of engineered poplar products. This paper therefore investigates the fungal decay resistance, as well as the moisture sorption properties of (thermally modified) hybrid poplar clones and Norway spruce. Fungal decay resistance was tested using the mini-block test. Moisture dynamics were evaluated using a floating test and dynamic vapor sorption (DVS). A higher fungal decay resistance and a significant decrease of moisture sorption was observed for thermally modified poplar. Our results show that the overall moisture properties of poplar and spruce are similar and that differences among the poplar clones are negligible, demonstrating the potential of poplar wood for engineered wood products. Together with findings on the mechanical properties in the literature, these results on durability and moisture performance give extra support for the potential utilization of poplar CLT in constructions.