Browsing by Author "Le Roux, Franel"
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- ItemStructural, economic and environmental feasibility of plastic load-bearing walling and roofing system for low-income housing(Stellenbosch : Stellenbosch University, 2014-12) Le Roux, Franel; De Villiers, Wibke; Stellenbosch University. Faculty of Engineering. Department of Civil Engineering.ENGLISH ABSTRACT: The lack of adequate housing becomes an increasing concern as the human population increases, which is not only restricted to Africa, but worldwide. With the world becoming more environmentally aware, the aim towards more sustainable development has become more essential. This results in alternative building technologies (ABT’s) being investigated to address the backlog in housing. This study investigates plastic materials as structural elements in low-income housing to address the housing backlog in a structurally stable, cost efficient and environmentally sustainable manner. The viable plastic materials that were identified are FFC (foam-fibre composite) and WPC (wood-plastic composite) as structural elements and EPS (expanded polystyrene) as a core infill panel. Material parameters were obtained experimentally which were used in a numerical analysis to validate the structural stability of a modular WPC housing unit. The experimental work includes a direct compression, direct tension, compressive creep and a four-point bending test for the WPC. With the sandwich panels a push-though shear and four-point bending test were done. The compressive strength of the EPS as well as a relative bond strength of the selected adhesives was also tested. Furthermore, a comparative study was conducted on the fire performance (fire rating), cost efficiency as well as the environmental sustainability of three housing units constructed of FFC, WPC and block and mortar, respectively. In terms of structural stability, a modular plastic housing unit was devised and validated by both experimental work and plastic material investigations which showed that WPC can be used for load-bearing walling (with EPS as core infill panel), roofing and flooring systems. From the comparative study, it was found that the fire rating of the block and mortar housing unit met the requirements of 20 and 30 minutes for the internal and external walls, respectively, prescribed by SANS 10400-T (2011). The fire rating of the block and mortar housing unit was met in terms of integrity, insulation and stability. The two modular plastic housing units, however, only met the fire rating in terms of integrity and insulation, but failed to meet the requirements in terms of stability. The approach used to determine the fire behaviour of a housing unit is not as accurate as the physical fire test, since assumptions are made in terms of the fire properties. However, the approach gives an indication of the fire performance of a housing unit. FFC and WPC are laminated with PVC (polyvinyl chloride) which emits hydrochloride acid (HCl), when burning. Hydrochloride acid is a toxic gas. Thus, according to one of the minimum norms, stipulated by the NHBRC Home Building Manual and Agrément, an adequate housing unit should not emit harmful gasses. Although these regulations are not mandatory, in terms of this, WPC and FFC are not viable building materials for an adequate housing unit, especially when human behaviour and smoke control are considered. However, this aspect can be improved by adding additives to control, and in some cases prevent, smoke production. The comparative study also indicated that the cost efficiency of the FFC housing unit is comparable to that of the block and mortar design. The modular WPC housing unit has a cost which is substantially greater than that of the FFC as well as the block and mortar housing units. The modular plastic housing units, FFC as well as WPC, typically utilise unskilled labour to construct a housing unit, which can lead to the socioeconomic conditions of a community being improved by means of job creation. Due to the relative ease of construction of a modular plastic housing unit as well as a construction period of approximately three days, the demand for housing can be reached at a more rapid pace than by using conventional methods. In terms of the environmental sustainability, the plastic materials showed less negative environmental impacts as well as improved energy efficiency compared to the block and mortar unit.