Effects of pre-steaming treatment on high-temperature and low-humidity drying characteristics of super-heavy timber with boxed-heart of Korean red pine and Douglas-fir

Abstract

This study aimed to investigate how pre-steaming affects the drying times, final moisture contents (final MCs), and prevention of checking during the high-temperature and low-humidity drying process of boxed-heartwood Korean red pine (Pinus densiflora S. et Z.) and Douglas-fir (Pseudotsuga menziesii) with 20 × 20 cm and with 30 × 30 cm cross sections. Although average final MCs of the larger cross sections were slightly higher than those of smaller cross sections, all were over-dried between 3.3% and 8.1% MC, compared to the in-use moisture content for outdoor building materials. All the pre-steamed samples were only slightly defected by surface checks of 5 mm or less in width. The sample timbers with the 20 × 20 cm cross-sectional size were slightly defected by internal checking, whereas those with the 30 × 30 cm cross-sectional size were severely defected. However, there was no clear impact of pre-steaming time on the prevention of internal checking.

Keywords:

• Final moisture content
• moisture gradient
• surface checks
• internal checks

Authors’ contributions

N-H L designed this study and was a major contributor to the writing of the manuscript. C L prepared the experimental equipment and materials, and collected and analyzed the experimental data. All authors have read and approved the final version of the manuscript.

Additional information

Funding

This study was supported by research funds of Jeonbuk National University in 2019.