Behaviour of masonry systems incorporating waste plastic subjected to fire

Thesis (MEng)--Stellenbosch University, 2022.ENGLISH ABSTRACT: Plastic waste within the built environment is a global concern, with proportions of waste plastic produced in municipal solid waste being more than 10% by the beginning of the millennium. Within the engineering community, the use of construction materials implementing waste plastics has been a recent development that aims to minimise the effect of plastic waste on the environment. One major concern, however, is that addition of plastics has an unknown impact on the fire response and behaviour of recycled construction products. All structures are required to have a fire rating to quantify the resistance of the structure to a fire event. The unknown response of recycled construction materials to fire has resulted in the investigation of several recycled construction systems within this thesis. Systems that were analysed include Ecobricks (a building block made of a plastic bottle that is filled with plastic infill material), adobe bricks (building units made from natural in-situ soils) and RESIN8 bricks (concrete masonry units with added plastic aggregate replacement). The exposure of each of these systems to a heat source representing a small fire allowed their respective response to fire to be examined, both qualitatively and quantitively, and for observed behaviour to be captured. The adaptation of a newly developed system for fire response testing (Heat Transfer Rate Inducing System or H-TRIS) was employed for the experimentation carried out in this thesis. The system used involved the use of electric radiant panels for means of heating experiments (coined as the eH-TRIS). Samples were subjected to constant heat fluxes of up to 35 kW/m² imparted purely by means of radiative heat transfer, without the effect of the convective zone heating the sample. A qualitative assessment of the behaviour of exposed Ecobricks with the use of video and photographic data was performed, as well as quantitative thermal assessment of the associated adobe protection system. A quantitative analysis of the RESIN8 samples was carried out to determine total mass losses, release of energy as well as total heat release rates for samples of increasing replacement plastic content. In addition, the pre- and post-fire compressive strengths of the RESIN8 samples were determined to quantify the effect of fire on the capacity of brick strength. The use of exposed Ecobricks was found to lead to undesirable fire behaviour, including the presence of flaming droplets, high smoke production and sustained burning immediately after ignition. A significant improvement was observed with the use of adobe, with minimal effects of heat transfer impacting on the system. The replacement content of the RESIN8 samples influenced both smoke production and heat transfer, with high volumes of smoke observed for the highest replacement group. Capacity of the RESIN8 units was also found to drop up to 34.7% of original compressive strength, with heat releases ranging from 291 to 3075 kW with an increase in RESIN8 replacement. The research in this paper aims to act as a spearhead into the topic of these systems, as further research will be required into the many other facets (and additional construction materials) that remain.AFRIKAANSE OPSOMMING: Plastiekafval is 'n wêreldwye bekommernis, met betrekking tot plastiekafval wat in munisipale afval geproduseer word en wat meer as 10% gestyg het van die begin van die millennium. Binne die ingenieursgemeenskap is die gebruik van konstruksiemateriaal, wat afvalplastiek implementeer, 'n onlangse ontwikkeling wat daarop gemik is om die effek van plastiekafval op die omgewing te verminder. Een groot bekommernis is egter dat byvoeging van plastiek 'n onbekende impak op die brandreaksie en gedrag van herwonne konstruksieprodukte het. Alle strukture moet 'n brandgradering hê om die weerstand van die struktuur teen 'n brandgebeurtenis te kwantifiseer. Die onbekende reaksie van herwonne konstruksiemateriaal op brand het gelei tot die ondersoek van verskeie herwonne konstruksiestelsels binne hierdie tesis. Stelsels wat ontleed is, sluit in ‘Ecobricks’ ('n boublok gemaak van 'n plastiekbottel wat met plastiekvulmateriaal gevul is), adobe-stene (bou-eenhede gemaak van natuurlike in-situ grond) en RESIN8-stene (betonmesseleenhede met bygevoegde plastiek-aggregaatvervanging). Die blootstelling van elk van hierdie stelsels aan 'n hittebron, wat 'n klein brand verteenwoordig, het toegelaat dat hul onderskeie reaksies kon ondersoek, beide kwalitatief en kwantitief en waargenome gedrag kon vasgelê word. Die aanpassing van 'n nuwe ontwikkelde stelsel vir brandreaksietoetsing (‘Heat Transfer Rate Inducing System of H-TRIS’) is aangewend vir die eksperimentering wat in hierdie tesis uitgevoer is. Die stelsel wat gebruik is, behels die gebruik van elektriese stralingspanele vir middele van verhittingseksperimente (ontgin as die eH-TRIS). Monsters is blootgestel aan konstante hittevloede van tot 35 kW/m² wat deur middel van radiatiewe hitte-oordrag oorgedra is, sonder dat die effek van die konvektiewe sone die monster verhit. 'n Kwalitatiewe assessering van die gedrag van blootgestelde ‘Ecobricks’ met die gebruik van video en fotografiese data is uitgevoer, sowel as kwantitatiewe termiese assessering van die gepaardgaande adobe-beskermingstelsel. 'n Kwantitatiewe ontleding van die RESIN8-monsters is uitgevoer om totale massaverliese, vrystelling van energie sowel as totale hittevrystellingtempo's vir monsters met toenemende vervangingsplastiekinhoud te bepaal. Daarbenewens is die voor- en na-vuur druksterktes van die RESIN8 monsters bepaal om die effek van vuur op die kapasiteit van baksteensterkte te kwantifiseer. Daar is gevind dat die gebruik van blootgestelde Ecobricks tot ongewenste brandgedrag lei, insluitend die teenwoordigheid van vlammende druppels, hoë rookproduksie en volgehoue brand onmiddellik na ontsteking. 'n Beduidende verbetering is waargeneem met die gebruik van Adobe, met minimale effekte van hitte-oordrag wat 'n impak op die stelsel het. Die vervangingsinhoud van die RESIN8- monsters het beide rookproduksie en hitte-oordrag beïnvloed, met hoë volumes rook waargeneem vir die hoogste vervangingsgroep. Daar is ook gevind dat die kapasiteit van die RESIN8-eenhede tot 34.7% van oorspronklike druksterkte daal, met hittevrystellings wat wissel van 291 tot 3075 kW met 'n toename in RESIN8-vervanging. Die navorsing in hierdie tesis het ten doel om as 'n begin-punt in die onderwerp van hierdie stelsels op te tree, aangesien verdere navorsing vereis sal word na die vele ander fasette (en bykomende konstruksiemateriaal) wat oorbly.Master