Journal of the Korean Wood Science and Technology

The Korean Society of Wood Science & Technology (한국목재공학회)
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Effects of Density, Temperature, Size, Grain Angle of Wood Materials on Nondestructive Moisture Meters

  • Pang, Sung-Jun (Department of Wood Science and Engineering, Chonnam National University) ;
  • Jeong, Gi Young (Department of Wood Science and Engineering, Chonnam National University)
  • Received : 2018.10.01
  • Accepted : 2018.12.21
  • Published : 2019.01.25
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Abstract

The aim of this study was to investigate the effects of density, temperature, size, and grain direction on measurement of moisture contents (MC) of wood materials non-destructively. The MC of different sizes of solid wood, glulam, and CLT from larch (larix kaempferi, $560kg/m^3$) and pine (pinus koraiensis, $430kg/m^3$) were measured using the dielectric type and resistance type meters. The specimens were conditioned in the environmental chamber to be equilibrium moisture content (EMC) of 12 % and 19 %. When density setting in dielectric type meter was increased from $400kg/m^3$ to $600kg/m^3$, the MCs of specimen (S-L-100-E) were decreased from 13.4 % to 11.3 %. However, when wood group (WG) setting in resistance type meter was changed from WG1 to WG4, the measured MCs were increased from 9.2 % to 12.3 %. When temperature setting in resistance type meters was changed from 0 to $35^{\circ}C$, the MC was decreased from 17.0 % to 13.0 %. The MCs measured by dielectric type meter for larger specimens (S-L-100-E_11.3 %, G-L-240-E_11.7 % and C-L-120-E_12.8 %) were higher than those of small size specimens (S-L-30-E_8.7 %, G-L-150-E_10.3 %, and C-L-90-E_9.7 %). The MCs measured by resistance type meter for larger specimens (G-L-240-E_11.6 % and C-L-120-E_13.3 %) were also higher than those of small size specimens (G-L-150-E_10.4 %, and C-L-90-E_11.8 %). The resistance type meter was not affected by the grain direction but the dielectric type meter were affected by the grain direction. The MC measured by resistance type meter for G-L-120-E perpendicular to grain direction was 11.5 % and the measured MC parallel to grain direction was 11.3 %. The MC measured by dielectric type meter parallel to grain direction (12.1 %) was higher than that measured perpendicular to grain direction (10.7 %).

Keywords

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Fig. 1. Types and orientations of specimens.

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Fig. 2. Procedures for conditioning and measuring of moisture contents of specimens.

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Fig. 3. Schematic diagram to measure the moisture contents of specimens by using portable moisture meters.

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Fig. 4. Combinations of specimens for evaluating the detectable depth of meters.

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Fig. 5. Moisture contents depending on the contacted grain direction and species, as well as the wood group options in MC-380XCA (Condition of environmental chamber: EMC 12 % Temperature of testing room:20 ℃).

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Fig. 6. Moisture contents depending on the contacted surface and grain direction of specimen, as well as the wood group options in MC-460 (G-L-120-E specimen, Condition of environmental chamber: EMC 12 %, Condition of temperature setting of the meter: 20 ℃, Temperature of testing room: 20 ℃).

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Fig. 7. Moisture contents of wood materials depending on the temperature option in MC-460 (Condition of environmental chamber: EMC 12 %, Condition of wood group setting: WG3, Temperature of testing room: 20 ℃).

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Fig. 8. Moisture contents depending on the specimen volume (Condition of environmental chamber: EMC 12 %, Conditions of density setting for MC-380XCA:500kg/m3, Conditions of wood group and temperature setting for MC-460: WG3 and 20 ℃, Temperature of testing room: 20 ℃).

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Fig. 9. Moisture contents detected by dielectric type meters (MC-380XCA) for combinations of specimens which have different moisture content (Conditions of density setting: 500kg/m3, Temperature of testing room: 20 ℃).

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Fig. 10. Comparisons of moisture contents depending on measuring methods (Conditions of density setting for MC-160SA and MC-380XCA: 500kg/m3, Conditions of wood group and temperature setting for MC-460:WG3 and 20 ℃, Temperature of testing room: 20 ℃).

Table 1. Nomenclatures of specimens depending on the specimen conditions

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References

  1. ASTM D 4442. 2007. Standard test methods for direct moisture content measurement of wood and woodbase materials In: Annual book of ASTM standard, sect 4, vol 04.10 Wood. American Society for Testing and Materials (ASTM), West Conshohocken, PA.
  2. Exotek. 2013a. User's manual for MC-160SA. Exoteck instruments. www.exotek-instrucments.com.
  3. Exotek. 2013b. User's manual for MC-380XCA. Exoteck instruments. www.exotek-instrucments.com.
  4. Exotek. 2013c. User's manual for MC-460. Exoteck instruments. www.exotek-instrucments.com.
  5. Fredriksson, M., Claesson, J., Wadso, L. 2015. The influence of specimen size and distance to a surface on resistive moisture content measurements in wood. Mathematical Problems in Engineering, Mathematical Problems in Engineering, Article ID 215758: 1-7. http://dx.doi.org/10.1155/2015/215758
  6. Jung, H.S., Smith, W.B. 1994. Comparison of equilibrium moisture contents for conventional kiln dried- and high temperature dried softwood lumber by moisture content determination. Journal of the Korean Wood Science and Technology 22(4): 37-42.
  7. Kang, C.W., Jang, E.S., Jang, S., Kang, H.Y., Li, C., Choi, I.G. 2018. Changes of air permeability and moisture absorption capability of the wood by organosolv pretreatment. Journal of the Korean Wood Science and Technology 46(6): 637-644. https://doi.org/10.5658/WOOD.2018.46.6.637
  8. Kang, C.W., Lim, H.M., Kang, H.Y. 2017. Estimation of wood oven-dry density by using a portable dielectric moisture meter. Journal of the Korean Wood Science and Technology 45(5): 629-639. https://doi.org/10.5658/WOOD.2017.45.5.629
  9. Kazemi, S.M., Dickinson, D.J., Murphy, R.J. 2001. Effects of initial moisture content on wood decay at different levels of gaseous oxygen concentrations. Journal of Agricultural Science and Technology 3:293-304.
  10. Kim, H.B., Han, Y., Park, Y., Yang, S.Y., Chung, H., Eom, C.D., Lee, H.M., Yeo, H. 2017. Finite difference evaluation of moisture profile in boxed-heart large-cross-section square timber of pinus densiflora during high temperature derying. Journal of the Korean Wood Science and Technology 45(6): 762-771. https://doi.org/10.5658/WOOD.2017.45.6.762
  11. Lee, C.J., Lee, N.H., Oh, S.W. 2016a. Effects of the knife-incising and kerfing pretreatment on moisture content and surface check occurrence of douglas-fir heavy timber. Journal of the Korean Wood Science and Technology 44(3): 302-314. https://doi.org/10.5658/WOOD.2016.44.3.302
  12. Lee, M., Park, S.B., Lee, S.M. 2016b. Comparison of moisture absorption/desorption properties of carbonized boards made from wood-based panels. Journal of the Korean Wood Science and Technology 44(3): 424-429. https://doi.org/10.5658/WOOD.2016.44.3.424
  13. Niemz, P., Mannes, D. 2012. Non-destructive testing of wood and wood-based materials. Journal of Cultural Heritage 13(3): S26-S34. https://doi.org/10.1016/j.culher.2012.04.001
  14. Oh, S.W. 2016. Electrical properties and far-infrared ray emission of ceramics manufactured with sawdust and rice husk. Journal of the Korean Wood Science and Technology 44(1): 106-112. https://doi.org/10.5658/WOOD.2016.44.1.106
  15. Ra, J.B. 2014. Determination of equilibrium moisture content of outdoor woods by using hailwoodhorrobin equation in Korea. Journal of the Korean Wood Science and Technology 42(6): 653-658. https://doi.org/10.5658/WOOD.2014.42.6.653
  16. Ra, J.B. 2018. Determination of moisture index in Korea. Journal of the Korean Wood Science and Technology 46(4): 301-308. https://doi.org/10.5658/WOOD.2018.46.4.301
  17. Son, D.W., Lee, D.H. 2004. Wood decay detection by non-destructive methods. Journal of the Korean Wood Science and Technology 32(4): 74-81.
  18. Yang, I., Kim, S.H., Han, G.S. 2017. Effect of moisture content of sawdust and length to diameter ratio of a hole in flat-die pelletizer on the fuel characteristics of wood pellets produced with quercus mongolica, pinus densiflora, pinus rigida and larix kaempferi. Journal of the Korean Wood Science and Technology 45(4): 382-398. https://doi.org/10.5658/WOOD.2017.45.4.382