An investigation into the structural suitability of standard grade Expanded Polystyrene (EPS) as an innovative building material
Authors:   , Mncwango Bonke 
Published: July 2021

Rapid urbanization has brought numerous economic, cultural and political development in South Africa; however, it has also led to some parts of the country turning into slums. The spread of slums is mainly driven by the lack of adequate housing provision by the Government. Although it has been twenty-five years since South Africa had its first democratic elections, millions of citizens still continue to live under squalid conditions as a result of lack of housing. The South African government cites numerous reasons for not being able to eradicate the housing backlog, including insufficient housing budget allocation as well as the worsening global economic climate. It is evident from the current housing backlogs that more building solutions that can reduce cost and construction time are needed. Further, new building materials should be explored in order to alleviate the environmental pressures that conventional building materials cause on the environment. This research investigates the properties of standard grade Expanded Polystyrene (EPS) as a potential contributor in low-cost housing provision. Currently the construction of EPS dome houses using modified EPS is only occurring outside of South Africa and it requires the possession of intricate moulding equipment. Existing suppliers require a minimum order, for instance, Japan Dome House Company supplies dome houses at a minimum order of three-hundred units. This research examines the potential of carving standard grade EPS into a form of dwelling using a hot-wire tool to re-create a model similar to a commercially produced EPS dome house. EPS components were assembled and left exposed to the elements since the main method of analyses of the live model was through exposure, particularly against rain and wind experienced within the jurisdiction of Pietermaritzburg, South Africa. Analyses of the live model was supplemented by testing of compression, flexural and thermal qualities of EPS under laboratory conditions. With wind speeds of thirty-nine km/hr and a rainfall intensity of twenty-eight mm, the model was found to still be in its original state of composure after six-months even without having been permanently anchored to the ground. Existing industry models such as Moladi, Khaya ReadyKit and Fischer Housing were examined to provide a standard of comparison for this investigation. This was done in order to distinguish how EPS dome houses differ to current existing alternative building technologies within the sector of low-cost housing. Observation of the model revealed that it is possible to successfully re-create an EPS dome house without complex moulding equipment. Some of the main findings from the laboratory analysis were that, contrary to expectations, thermo-gravimetric analyses of three different densities (fifteen kg/m3, twenty kg/m3 and thirty kg/m3) revealed that as the density of EPS increases, the maximum degradation value decreases. A study of the interaction of the polystyrene beads through microscopic analysis revealed that in higher EPS densities beads can rupture, leading to a compromise in both structural integrity and form. A water absorption test on EPS revealed that the percentage of water absorbed by EPS is similar to that absorbed by clay bricks over a 24-hour period, which makes the materials comparable in this regard. In terms of the outcomes of the study, the researcher has already published articles in three journals and two conference proceedings. This research will be of value to design professionals in alleviating the environmental impacts of commonly used conventional materials through the inclusion of EPS where low compressive loads are permissible.