Mechanical Properties of Low-Stiffness Out-of-Grade Hybrid Pine — Effects of Knots, Resin and Pith

Cherry, Rebecca and Karunasena, Warna ORCID: https://orcid.org/0000-0003-3636-3068 and Manalo, Allan ORCID: https://orcid.org/0000-0003-0493-433X (2022) Mechanical Properties of Low-Stiffness Out-of-Grade Hybrid Pine — Effects of Knots, Resin and Pith. Forests, 13 (927). pp. 1-32.

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Abstract

Out‐of‐grade pine timber is an abundant material resource that is underutilised because its mechanical properties are not well understood. Increasing trends toward shorter rotation times and fast‐grown plantation pines around the world such as Pinus elliottii x P. caribaea var. hondurensis hybrid (PEExPCH) mean low‐stiffness corewood is becoming a larger portion of this out‐of‐grade population. This study characterised the modulus and strength properties in bending, compression parallel to grain (CParG) and compression perpendicular to grain (CPerpG), shear and tension strength of low‐stiffness out‐of‐grade PEExPCH. The effect of resin, knots and pith on these properties were also investigated. The results show that in clear wood, the MOE in bending, CParG, CPerpG and shear modulus are 6.9 GPa, 5.78 GPa, 0.27 GPa and 0.59 GPa, respectively, while strengths are 45.8 MPa, 29.4 MPa, 6.7 MPa, 5.7 MPa, respectively. The tensile strength is 32.4 MPa. Resin significantly increased density 45% higher than clear, but performed similar with the excep-tion of CPerpG MOE and strength which were significantly different. Resin area ratio (RAR) has a moderate correlation with density with an R2 of 0.659 but low to no correlation for mechanical prop-erties. Knots were significantly different to clear for all test types and within a range of 48% to 196%. Knots were high in CPerpG MOE and strength but lower for all other properties and had the largest negative impact on tensile strength. Knot area ratio (KAR) had low to moderate correlation with tension strength and CPerpG MOE with R2 of 0.48 and 0.35, respectively. Pith was within the range of 76% to 121% of non‐pith samples for structural performance, some of which were significantly different, and pith samples were higher in density than non‐pith. This new information is crucial for the effective establishment of grading rules, design optimisation and utilisation of low‐stiffness out‐of‐grade PEExPCH as a new material resource in civil engineering applications.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Future Materials (1 Jan 2017 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Future Materials (1 Jan 2017 -)
Date Deposited: 05 Sep 2022 23:18
Last Modified: 23 Sep 2022 02:26
Uncontrolled Keywords: bending; compression; corewood; juvenile wood; knots; low‐grade; out‐of‐grade; PEExPCH hybrid pine; pith; resin
Fields of Research (2020): 40 ENGINEERING > 4005 Civil engineering > 400511 Timber engineering
40 ENGINEERING > 4005 Civil engineering > 400510 Structural engineering
40 ENGINEERING > 4016 Materials engineering > 401610 Timber, pulp and paper
Socio-Economic Objectives (2020): 24 MANUFACTURING > 2417 Wood, wood products and paper > 241799 Wood, wood products and paper not elsewhere classified
26 PLANT PRODUCTION AND PLANT PRIMARY PRODUCTS > 2602 Forestry > 260205 Softwood plantations
24 MANUFACTURING > 2417 Wood, wood products and paper > 241704 Wood products
Identification Number or DOI: https://doi.org/10.3390/f13060927
URI: http://eprints.usq.edu.au/id/eprint/51098

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