Investigating a new green edge laminating process for CLT manufacturing from twist-prone SA pine sawn timber

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dc.contributor.advisorWessels, Brand C.en_ZA
dc.contributor.authorFavis, Jesseen_ZA
dc.contributor.otherStellenbosch University. Faculty of AgriSciences. Dept. of Forest and Wood Science.en_ZA
dc.date.accessioned2023-03-07T15:14:44Zen_ZA
dc.date.accessioned2023-05-18T07:15:05Zen_ZA
dc.date.available2023-03-07T15:14:44Zen_ZA
dc.date.available2023-05-18T07:15:05Zen_ZA
dc.date.issued2023-03en_ZA
dc.descriptionThesis (MScFor)--Stellenbosch University, 2023. en_ZA
dc.description.abstractENGLISH ABSTRACT: There is potential for fast-grown, low quality raw material to produce high-value cross laminated timber (CLT). South African Pine plantations are harvested in shorter-age rotations to increase productivity, which results in greater proportions of corewood in the timber. Corewood tends to have a lower density and highly variable physical properties, leading to severe deformation after the timber is dried. Twist is the drying defect that causes the most rejection of dried wood for structural applications in South Africa. It is increasingly necessary for the sawmill industry to recognise the importance of conversion efficiency as it increases profits, reduces waste and extends the supply of standing timber. Twist in sawn timber can have a large effect on the conversion efficiency of logs, affecting both the volume and value recovery. The processor can manage twist in two ways: first, by predicting twist propensity in sawn timber from specific log resources, and second, by devising strategies to reduce the twist in the sawn timber from these resources. This study investigated both the prediction of twist and the use of an alternative processing method to reduce twist. In the first sub-study, the relationship between grain angle (spiral grain) and twist deformation of fast-grown South African Pine was evaluated. The highly significant p value (2.77 x 10⁻¹⁵) association identified between grain angle and twist had a relatively low coefficient of determination (R² = 0.28). Grain angle alone could not predict this deformation; other influential properties, including variation in density, microfibril angle and curvature of growth rings should be investigated further, to be able to model twist in seasoned boards accurately. In the second study, timber boards for CLT panel layers were green-edge bonded with a one-component polyurethane adhesive (1C-PUR), before seasoning, to reduce twist deformation. The potential of this manufacturing process to improve the conversion efficiency of low-quality South African Pine wood into CLT was investigated. The new manufacturing process reduced twist by 60.1% and increased volume recovery by 7% compared with the conventional manufacturing method of manufacturing. The perfectly flat panel layers would require less pressure to be made into CLT, which would ultimately reduce the cost of the mass timber material.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Daar is potensiaal vir vinnig-groeiende, lae kwaliteit, hout-roumateriale om hoëwaarde kruisgelamineerde hout (CLT) te produseer. Suid-Afrikaanse denneplantasies word in korter rotasies geoes om produktiwiteit te verhoog, wat lei tot groter proporsies kernhout in die hout. Kernhout is geneig om 'n laer digtheid en hoogs veranderlike fisiese eienskappe te hê, wat lei tot ernstige vervorming nadat die hout gedroog is. Draaitrek is die droogdefek wat die meeste verwerping van gedroogde hout vir strukturele toepassings in Suid-Afrika veroorsaak. Dit is toenemend nodig vir die saagmeulbedryf om die belangrikheid van omskakelingsdoeltreffendheid te erken aangesien dit wins verhoog, vermorsing verminder en die aanbod van staande hout vergroot. Draaitrek in gesaagde hout kan 'n groot uitwerking op die omskakelingsdoeltreffendheid van stompe hê, wat beide die volume en waardeherwinning beïnvloed. Die verwerker kan draaitrek op twee maniere bestuur: eerstens deur die draai-geneigdheid in gesaagde hout uit spesifieke houtbronne te voorspel, en tweedens deur strategieë te bedink om die draaitrek in die gesaagde hout uit hierdie hulpbronne te verminder. Hierdie studie het beide die voorspelling van draaitrek en die gebruik van 'n alternatiewe verwerkingsmetode om draaitrek te verminder ondersoek. In die eerste substudie is die verband tussen spiraalgrein en draaitrek van vinnig-groeiende Suid-Afrikaanse denne geëvalueer. Die hoogs betekenisvolle p-waarde (2.77 x 10-15) wat tussen spiraalgrein en draaitrek geïdentifiseer is, het 'n relatief lae bepalingskoëffisiënt (R2 = 0.28) gehad. Spiraalgrein alleen kon nie hierdie vervorming voorspel nie; ander invloedryke eienskappe, insluitend variasie in digtheid, mikrofibrielhoek en kromming van groeiringe moet verder ondersoek word, om die draaitrek in gedroogde planke akkuraat te modelleer. In die tweede studie is houtplanke vir CLT-paneellae met 'n een-komponent poli-uretaan kleefmiddel (1C-PUR) gelym terwyl dit nat of groen was, om draaitrek te verminder. Die potensiaal van hierdie vervaardigingsproses om die omskakelingsdoeltreffendheid van laegehalte Suid-Afrikaanse dennehout in CLT te verbeter, is ondersoek. Die nuwe vervaardigingsproses het die draaitrek met 60,1% verminder en volumeherwinning met 7% verhoog in vergelyking met die konvensionele vervaardigingsmetode van vervaardiging. Die perfek plat paneel lae sal vereis dat minder druk in CLT vereis word, wat uiteindelik die koste van die massa houtmateriaal sal verminder.af_ZA
dc.description.versionMastersen_ZA
dc.format.extent100 pages : illustrations (some color)en_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/127304
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subjectGreen edge bonding, edge lamination, green edge gluing, one component polyurethane adhesive, drying defects, twist deformation, warp, corewood, Cross Laminated Timber (CLT), grain angle, spiral grain, fast-grown South African Pine, Pinus elliottiien_ZA
dc.subject.lcshCross laminated timber -- South Africaen_ZA
dc.subject.lcshLaminated wooden_ZA
dc.subject.lcshPine -- Quality -- South Africaen_ZA
dc.subject.lcshPine -- Evaluationen_ZA
dc.subject.lcshPine -- South Africa -- Growthen_ZA
dc.subject.lcshFast growing treesen_ZA
dc.subject.lcshSawmills -- South Africaen_ZA
dc.subject.nameUCTDen_ZA
dc.titleInvestigating a new green edge laminating process for CLT manufacturing from twist-prone SA pine sawn timberen_ZA
dc.typeThesisen_ZA
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