An investigation of the potential for fire-resistance improvement of pinus patula cross-laminated timber.

Thesis (MSc)--Stellenbosch University, 2024.

ENGLISH ABSTRACT: Recent architectural trends include the design and construction of tall or multi-storey buildings using woodbased materials. Cross-laminated timber (CLT) is one of the engineered timber materials with potential for being used in the construction of multi-storey buildings. The interest in using CLT is based on its suitability as a renewable and sustainable material and its potential to provide cost-effective building solutions. There is, however, a concern regarding the use of CLT as a structural material in tall buildings. This is due to the combustible nature of timber and the perception that it might not be safe in fire. Therefore, the fire performance of CLT needs to be addressed in order to develop reliable strategies to improve the fire performance. A recently completed study found that CLT made from South African pine and eucalypt wood has higher charring rates than many other wood species that have been studied. In this study the effect of adhesives, edge-bonding and fire-retardant treatment were evaluated for possible improvement of the fire performance of Pinus patula CLT. The study was conducted by focusing on structural fire resistance tests in accordance with the SANS 10177-2 standard in a furnace test and a radiant heat panel test method. The objectives of this study were: • To investigate the effect of adhesive systems (polyurethane vs. melamine urea formaldehyde) on fire resistance performance of CLT; • To investigate the effect of boron-phosphate based fire-retardant treatment (treated vs. untreated) on fire resistance performance of CLT; • To investigate the effect of CLT bonding-configuration (edge vs. non-edge bonding) on fire resistance performance of CLT. The experimental design for this study consisted of a 2 3 -factorial design of eight groups. Four 300 x 300 x 90 mm CLT specimens were prepared in each group with one from each group tested in the furnace and three from each group tested using a radiant heat panel, making a total of 32 CLT specimens. Eventually, eight CLT specimens were tested in a furnace test and 24 CLT specimens were tested using a radiant heat source test respectively. Charring rate and burn-through time were parameters measured to determine the fire resistance of CLT panels. CLT specimens bonded with a melamine urea formaldehyde (MUF) adhesive showed better fire resistance compared to CLT specimens bonded with a polyurethane (PUR) adhesive. The charring rate and burn-through time in both test methods was better for MUF bonded specimens than PUR specimens. The improved fire resistance of MUF bonded specimens was mainly due to the higher degree of delamination observed in PUR bonded specimens during testing. The resultsto assess the effect of a boron based fire-retardant preservative chemical on the fire resistance of CLT specimens was inconclusive since the different test methods produced different results. Edge-bonding did improve the fire-resistance of Pinus patula CLT panels. Although the charring rate of edge-bonded and non-edge-bonded specimens were similar, the burn-through time of edgebonded specimens were better in both test methods. Based on observations in this study, edge bonding reduced the degree of fire-induced delamination. It is recommended that follow-up studies should be conducted where higher sample numbers are used in a furnace test setup. The single specimen per treatment used in this study’s furnace tests leave a degree of uncertainty in the results.

AFRIKAANSE OPSOMMING: Onlangse argitektoniese neigings sluit in die ontwerp en konstruksie van hoë of meerverdiepinggeboue wat houtgebaseerde materiale gebruik. Kruisgelamineerde hout (CLT) is een van die vervaardigde houtmateriale met potensiaal om in die konstruksie van meerverdiepinggeboue gebruik te word. Die belangstelling in die gebruik van CLT is gebaseer op die geskiktheid daarvan as 'n hernubare en volhoubare materiaal en sy potensiaal om kostedoeltreffende bouoplossings te verskaf. Daar is egter 'n kommer oor die gebruik van CLT as 'n strukturele materiaal in hoë geboue. Dit is te wyte aan die brandbare aard van hout en die persepsie dat dit dalk nie veilig in brand is nie. Daarom moet die brandprestasie van CLT aangespreek word om betroubare strategieë te ontwikkel om die brandprestasie te verbeter. ’n Studie wat onlangs voltooi is, het bevind dat CLT gemaak van Suid-Afrikaanse denne- en bloekomhout hoër verkooltempo het as baie ander houtsoorte wat bestudeer is. In hierdie studie is die effek van kleefmiddels, randbinding (“edge-bonding”) en brandvertragende behandeling geëvalueer vir moontlike verbetering van die brandprestasie van Pinus patula CLT. Die studie is uitgevoer deur te fokus op strukturele toetse in ooreenstemming met die SANS 10177-2-standaard in 'n oondtoets en 'n stralingshittepaneeltoetsmetode. Die doelwitte van hierdie studie was: • Om die effek van kleefmiddelstelsels (poliuretaan vs. melamien ureum formaldehied) op brandweerstandsprestasie van CLT te ondersoek; • Om die effek van boor-fosfaat-gebaseerde brandvertragende behandeling (behandel vs. onbehandeld) op brandweerstandsprestasie van CLT te ondersoek; • Om die effek van CLT binding-konfigurasie (rand vs. nie-rand binding) op brandweerstand prestasie van CLT te ondersoek. Die eksperimentele ontwerp vir hierdie studie het bestaan uit 'n 23 faktoriële ontwerp van agt groepe. Vier 300 x 300 x 90 mm CLT-monsters is in elke groep voorberei met een uit elke groep wat in die oond getoets is en drie uit elke groep wat met 'n stralingshittepaneel getoets is, wat 'n totaal van 32 CLT-monsters maak. Uiteindelik is agt CLT-monsters in 'n oondtoets getoets en 24 CLT-monsters is getoets met 'n stralingshittebrontoets onderskeidelik. Verkooltempo en deurbrandtyd was parameters wat gemeet is om die brandweerstand van CLT-panele te bepaal. CLT monsters gebind met 'n melamien ureum formaldehied (MUF) kleefmiddel het beter brandweerstand getoon in vergelyking met CLT monsters gebind met 'n poliuretaan (PUR) kleefmiddel. Die verkooltempo en deurbrandtyd in beide toetsmetodes was beter vir MUF monsters as PUR monsters. Die verbeterde brandweerstand van MUF monsters was hoofsaaklik te wyte aan die hoër graad van delaminering wat in PUR monsters tydens toetsing waargeneem is. Die toetsresultate om die effek van 'n boor-gebaseerde brandvertragende preserveermiddel op die brandweerstand van CLT-monsters te bepaal, was onoortuigend aangesien die verskillende toetsmetodes verskillende resultate opgelewer het. Randbinding het wel die brandweerstand van Pinus patula CLT-panele verbeter. Alhoewel die verkooltempo van rand-gebinde en nierand-gebinde monsters soortgelyk was, was die deurbrandtyd van randgebinde monsters beter in beide toetsmetodes. Gebaseer op waarnemings in hierdie studie, het randbinding die graad van brandgeïnduseerde delaminering verminder. Dit word aanbeveel dat opvolgstudies uitgevoer moet word waar hoër monstergetalle in 'n oondtoetsopstelling gebruik word. Die enkele monster per behandeling wat in hierdie studie se oondtoetse gebruik is, laat 'n mate van onsekerheid as gevolg van die lae monstergetal.

Masters