The effect of structural changes on the compressive strength of LVL
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The effect of structural changes on the compressive strength of LVL Wanzhao Li1,2 · Zheng Zhang2 · Guoqiang Zhou2 · Pierre Kibleur3 · Changtong Mei1,2 · Jiangtao Shi2 · Joris Van Acker2,3 · Jan Van den Bulcke3 Received: 28 January 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Laminated veneer lumber (LVL) is an important engineered wood product. Internal structural changes have a substantial influence on the mechanical performance of LVL. To investigate the relationship between the internal structural changes and the compressive strength, poplar LVL layering is manufactured by taking into account the veneer lathe checks, namely lathe checks both facing inwards (TLLT), lathe checks both oriented outwards (LTTL) and lathe checks in one layer facing outwards (LTLT). Macroscopic compressive strength of the samples is measured using a universal testing machine. Microscopic internal structural changes are periodically recorded with X-ray CT when the samples are compressed using a load cell. The results show that the compressive strength of LTLT is significantly higher than that of LTTL and TLLT types of LVL. During the compression test, density increase in the samples is non-homogenous. There is a minor increase in density of the glue line, while this is larger in regions with a low density. Density increase is mainly induced by collapse of large vessels. However, the presence of phenol formaldehyde resin can enhance the resistance of vessels against collapse. Structural changes, i.e., vessels collapse and collapse propagation, are likely to occur in locally heterogeneous regions. Propagation of collapsed vessels is more frequently observed in regions where large vessels are contiguous.
* Changtong Mei [email protected] 1
Co‑Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, China
2
College of Materials Science and Engineering, Nanjing Forestry University, Longpan Road 159, Nanjing 210037, China
3
UGCT‑UGent‑Woodlab, Laboratory of Wood Technology, Department of Environment, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
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Wood Science and Technology
Introduction Wood-based composites, such as plywood, oriented strand board (OSB) and laminated veneer lumber (LVL), are important construction materials given their high strength/weight ratio and ease of processing (Zhan et al. 2018a, b; Singh et al. 2019). LVL is a particularly high-performance type of engineered wood, made of several wood veneers bonded in the grain direction under hot-pressing conditions. The mechanical performance of LVL depends on many factors, such as wood species, glue type and quantities, hot pressing techniques and wood veneer treatment. Wei et al. (2019) found that fibrosis veneers can increase the mechanical properties and water resistance of LVL. Jin et al. (2014) indicated that the mechanical properties of thermally modified LVL samples are better than those of untre
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