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Evaluation of sawmilling and cross-laminated timber processing value chain integration

dc.contributor.advisorWessels, Branden_ZA
dc.contributor.advisorMuller, Barryen_ZA
dc.contributor.authorChatukuta, Sylvesteren_ZA
dc.contributor.otherStellenbosch University. Faculty of AgriScience. Dept. of Forest and Wood Science.en_ZA
dc.date.accessioned2022-03-10T21:06:12Z
dc.date.accessioned2022-04-29T09:43:11Z
dc.date.available2022-03-10T21:06:12Z
dc.date.available2022-04-29T09:43:11Z
dc.date.issued2022-04
dc.identifier.urihttp://hdl.handle.net/10019.1/124952
dc.descriptionThesis (MScFor)--Stellenbosch University, 2022.en_ZA
dc.description.abstractENGLISH ABSTRACT: Current high prices for CLT in South Africa are a deterrent to its adoption as a construction material. This prospect is further exacerbated by the predicted lumber shortages in the coming years. As such it is imperative to consider development of innovative, lower cost CLT manufacturing processes, underpinned by raw material optimization. This research investigated the integration of manufacturing of lumber and CLT with the aim of reducing the unit cost of CLT as a product. Arguably the best potential for cost reduction of lumber is the increase of volume recovery during the sawmilling process. Two ways in which volume recovery increases can be achieved include the production of random width boards and increasing the wane allowance on boards. The objectives of this study were: (1) To evaluate the potential increase in volume recovery when an SA Pine sawmill include random widths and increased wane allowance in its sawing strategy (both random widths and increased wane products can potentially be used as raw materials for CLT manufacture), and (2) to investigate the effect of increased wane allowance on SA Pine CLT strength and stiffness performance. To achieve the objectives; the research branched into three separate studies. Firstly, benchmarking of the Simsaw 6 sawmill software was performed to quantify the difference between simulated volume recovery and real-world volume recovery. Secondly, structured random widths (RW) and increased wane (IW) allowance scenarios were simulated to evaluate increase in volume recovery possible. Lastly, ten CLT panels of varying crosswise lamella wane surface area were manufactured and tested to destruction according to the American National Standards Institutes (ANSI) (2018) PRG-320 and EN 16351 (2015) specifications. This was done to determine whether increased wane allowance had an effect on CLT bending performance. Preparation of the panels closely mirrored commercial CLT fabrication. Results from the sawmill benchmarking trial show that Simsaw 6 predicted real world sawmill yields. For small logs, the software overestimated log volume recovery by between 1,4% to 2,4% with a mean of 2,01% volume recovery overestimation. The software overestimated the real-world sawn logs volume recovery with between 1,3 to 3,7%, with a mean of 2,13% for large logs. For the small and large logs combined, the simulation results were on average 2,07% higher than real sawn results. Increased wane allowance (IW) and increased wane allowance combined with random widths (IW+RW) showed significantly improved volume recoveries in all log classes. Using the maximum wane permitting scenario of (thickness =75%, width =50% and length =100%), the simulated volume recovery was interpolated to real-world sawmill volume recovery, as a weighted average of simulated yields. Maximum mean weighted volume recovery for a typical small-log sawmill was 63.5% for the increased wane combined with random widths scenario (IW+RW), followed closely by increased wane (IW) scenario at 61.5 % respectively. These volume recovery results indicate very high improvements compared to the current volume recoveries attained in typical sawmills in South Africa. Ten sample CLT panels were manufactured and tested to failure and mechanical bending properties were determined. Prominent failure mode of the bending tests was the brittle tension failure, ensuing from the CLT bottom longitudinal layer. The measured knot properties on the middle section of the CLT panels were correlated with the MOE and MOE values; however, no significant correlation was noted. The experimental bending stiffness of each CLT panel was then compared with its predicted mechanical properties based on the shear analogy method for loads perpendicular to plane based on the global stiffness measurements. The comparisons between predicted and experimental results for the three wane groups, despite small sample size, show close similarity. Results from the severe wane category demonstrated that the inclusion of substantial wane percentage in CLT within the crosswise lamellas did not influence the bending stiffness of the CLT panel. A comparison between the experimental bending moment of the sample CLT panels and predicted bending moment of manufactured CLT panel was performed. The calculated experimental bending moment (FbS) results varied between 7.2 and 12.5 N. mm whilst the predicted bending moment for S5 CLT (FbSeff) was 2.2 N.mm. Of the five severe wane panels, two had an FbS value lower than 10 N.mm/m. Of the five moderate and no-wane panels, none had values lower than 10 N.mm/m. It, therefore, seems as if the severe wane might have resulted in lower FbS values. If present, the magnitude of this effect still seems to be fairly small. It is likely that the lower bonding area due to gaps caused by wane was responsible for the perceived lower FbS values. Overall, the results show a good indication of the potential use of wane edged boards in CLT production. CLT manufacturing with increased wane allowance boards resulted in high utilization of lower value lumber, therefore increased value extraction per single log. As attested by the successful design, testing and validation of the experimental work undertaken in this research, value chain integration seems to hold much potential to reduce the cost of CLT in South Africa.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Huidige hoë pryse vir CLT in Suid-Afrika is 'n afskrikmiddel vir die aanvaarding daarvan as 'n konstruksiemateriaal. Hierdie vooruitsig word verder vererger deur die voorspelde houttekorte in die komende jare. As sodanig is dit noodsaaklik om die ontwikkeling van innoverende, laerkoste CLT-vervaardigingsprosesse te oorweeg, ondersteun deur grondstofoptimalisering. Hierdie navorsing het die integrasie van vervaardiging van hout en CLT ondersoek met die doel om die eenheidskoste van CLT as 'n produk te verminder. Waarskynlik die beste potensiaal vir kostevermindering van hout is die toename in volumeherwinning tydens die saagmeulproses. Twee maniere waarop volumeherwinnings- verhogings bewerkstellig kan word, sluit in die produksie van enige-breedte planke en die verhoging van die bastoelaag op planke. Die doelwitte van hierdie studie was: (1) Om die potensiële toename in volumeherwinning te evalueer wanneer 'n SA Dennesaagmeule enige breedtes en verhoogde bastoelaag in sy saagstrategie insluit (beide enige-breedtes en verhoogde basprodukte kan moontlik as grondstowwe vir CLT-vervaardiging dien), en (2) om die effek van verhoogde bastoelae op SA Den CLT-sterkte en styfheidsprestasie te ondersoek. Om die doelwitte te bereik het die navorsing in drie afsonderlike studies vertak. Eerstens is ‘n vergelykende studie van die Simsaw 6-saagmeulsagteware uitgevoer om die verskil tussen gesimuleerde volumeherwinning en werklike volumeherwinning te kwantifiseer. Tweedens is gestruktureerde enige-breedte (RW) en verhoogde bastoelae (IW) scenario's gesimuleer om toename in volumeherwinning moontlik te evalueer. Laastens, is tien CLT-panele met verskillende dwarslamella-oppervlakte vervaardig en getoets volgens die American National Standards Institutes (ANSI) (2018) PRG-320 en EN 16351 (2015) spesifikasies. Dit is gedoen om te bepaal of verhoogde bastoelae 'n effek op CLT-buigprestasie gehad het. Voorbereiding van die panele het die kommersiële CLT-vervaardiging weerspieël. Resultate van die saagmeul vergelykingstoest toon dat Simsaw 6 werklike saagmeule- opbrengste goed voorspel het. Vir klein stompe het die sagteware stompvolume-herwinning met 1,4% tot 2,4% oorskat met 'n gemiddelde van 2,01% volume-herwinning-oorskatting. Die sagteware het die werklike herwinning oorskat met tussen 1,3 tot 3,7%, met 'n gemiddelde van 2,13% vir groot stompe. Vir die klein en groot stompe gekombineer was die simulasieresultate gemiddeld 2,07% hoër as werklike gesaagde resultate. Huidige hoë pryse vir CLT in Suid-Afrika is 'n afskrikmiddel vir die aanvaarding daarvan as 'n konstruksiemateriaal. Hierdie vooruitsig word verder vererger deur die voorspelde houttekorte in die komende jare. As sodanig is dit noodsaaklik om die ontwikkeling van innoverende, laerkoste CLT-vervaardigingsprosesse te oorweeg, ondersteun deur grondstofoptimalisering. Hierdie navorsing het die integrasie van vervaardiging van hout en CLT ondersoek met die doel om die eenheidskoste van CLT as 'n produk te verminder. Verhoogde bastoelaag (IW) en verhoogde bastoelaag gekombineer met enige-breedtes (IW+RW) het aansienlik verbeterde volume-herwinnings in alle blokklasse getoon. Deur die maksimum bastoelaag-scenario van (dikte =75%, breedte =50% en lengte =100%), is die gesimuleerde volume herwinning geïnterpoleer na werklike saagmeul volume herstel, as 'n geweegde gemiddelde van gesimuleerde opbrengste. Maksimum gemiddelde geweegde volume-herwinning vir 'n tipiese klein-hout-saagmeul was 63.5% vir die verhoogde bastoelaag gekombineer met enige-breedtes scenario (IW+RW), nou gevolg deur verhoogde bastoelaag (IW) scenario op 61.5% onderskeidelik. Hierdie volume-herwinningsresultate dui op baie hoë verbeterings in vergelyking met die huidige volume-herwinnings wat in tipiese saagmeulens in Suid-Afrika behaal word. Tien CLT panele is vervaardig en getoets tot faling en meganiese buigeienskappe is bepaal. Prominente falingsmodus van die buigtoetse was die bros spanningsfaling, wat voortgespruit het uit die CLT onderste longitudinale laag. Die gemete kwaseienskappe van die middelste gedeelte van die CLT panele het geen beduidende korrelasie met MOE gehad nie. Die eksperimentele buigstyfheid van elke CLT-paneel is dan vergelyk met sy voorspelde meganiese eienskappe gebaseer op die skuif-analogie-metode vir ladings loodreg op vlak gebaseer op die globale styfheidsmetings. Die vergelykings tussen voorspelde en eksperimentele resultate vir die drie bas-toelaaggroepe, ten spyte van klein steekproefgrootte, toon noue ooreenkomste. Resultate van die hoë bas-kategorie het getoon dat die insluiting van 'n aansienlike baspersentasie in CLT binne die kruislamellas nie die buigstyfheid van die CLT-paneel beïnvloed het nie. 'n Vergelyking tussen die eksperimentele buigmoment van die monster CLT panele en voorspelde buigmoment van vervaardigde CLT paneel is uitgevoer. Die berekende eksperimentele buigmoment (FbS) resultate het tussen 7.2 en 12.5 N. mm gewissel terwyl die voorspelde buigmoment vir S5 CLT (FbSeff) 2.2 N.mm was. Van die vyf panele wat erge bas gehad het, het twee 'n FbS-waarde laer as 10 N.mm/m gehad. Van die vyf matige en lae-bas panele het geen waardes laer as 10 N.mm/m gehad nie. Dit wil dus voorkom asof die hoë bastoelaag tot laer FbS-waardes kon gelei het. As dit teenwoordig is, blyk die omvang van hierdie effek nog redelik klein te wees. Dit is waarskynlik dat die laer bindingsarea as gevolg van gapings veroorsaak deur bas verantwoordelik was vir die waargenome laer FbS waardes. Oor die algemeen toon die resultate 'n goeie aanduiding van die potensiële gebruik van basplanke in CLT-produksie. CLT-vervaardiging met verhoogde bastoelae-planke het gelei tot 'n hoë benutting van laerwaarde-hout, dus verhoogde waarde-onttrekking per enkele stomp. Soos getuig deur die suksesvolle ontwerp, toetsing en validering van die eksperimentele werk wat in hierdie navorsing onderneem is, blyk dit dat waardekettingintegrasie baie potensiaal inhou om die koste van CLT in Suid-Afrika te verminder.af_ZA
dc.format.extentxiv, 91 pages : illustrations (some color)en_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.subjectSawmills -- Yields -- South Africaen_ZA
dc.subjectShear analogy modelen_ZA
dc.subjectSimulation -- Optimization integrationen_ZA
dc.subjectValue chainen_ZA
dc.subjectIncreased waneen_ZA
dc.subjectWood products -- South Africaen_ZA
dc.subjectTimber -- Economic aspects -- South Africaen_ZA
dc.subjectCross laminated timberen_ZA
dc.subjectUCTDen_ZA
dc.titleEvaluation of sawmilling and cross-laminated timber processing value chain integrationen_ZA
dc.typeThesisen_ZA
dc.description.versionMastersen_ZA
dc.rights.holderStellenbosch Universityen_ZA


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