Browsing by Author "Collis, Vernon"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Open Access
    The suitability of rammed earth for construction in the Cape Town metropolitan area
    (2012) Thuysbaert, John; Alexander, Mark Gavin; Collis, Vernon
    The purpose of this thesis was to explore the suitability for Rammed Earth construction in the Cape Town metropolitan area. This would ultimately lead to drawing up a guideline for building of Rammed Earth housing and structures. The research involved collecting sixteen soil samples from strategically selected sites in Cape Town. The suitability of a soil was established through a variety of tests, varying between relatively simple field tests and rigorous laboratory analysis. These tests were undertaken to assess soil grading, organic matter content, plasticity and Optimum Moisture Content (OMC). Grading gave an indication of fines present and plasticity indicated the cohesive nature of the fines. More detailed tests were undertaken to determine type and level of soluble salts and mineralogical composition.
  • Thumbnail Image
    Item
    Open Access
    The use of construction and demolition waste in concrete in Cape Town
    (2013) Wickins, Kyle; Alexander, Mark Gavin; Collis, Vernon
    Incorporating recycled aggregates in concrete, despite the fact that effective technologies are available, is being adopted at a slow rate. These shortcomings have been associated with poor quality recycled aggregate (RA) products, lack of guidelines facilitating the use of RAs in various applications, and little incentive to incorporate these materials into civil engineering projects in Cape Town. In order to promote the use of RAs, a construction and demolition waste (C&DW) recycling culture has to be developed. Analysis of municipal waste data over the past 10 years shows that the commercial aggregate industry and market has not grown. A major contributor to the excess C&DW in the City, is the discarded C&DW once used to manage landfill sites with regard to activities such as cell creation, road building etc. This has resulted in 195 000 tons of the estimated 680 000 tons per annum (2012) of C&DW being disposed in Cape Town. The approach of the City and the construction industry to waste management is characterised by quality control issues, resource inefficiencies, economic and social burdens and environmental impacts. The realisation of C&DW as a resource and the development of on-site recycling procedures are seen as the key to creating more sustainable C&DW management systems. This is achieved internationally through detailed integrated waste management plans (IWMPs) that require waste generators to identify and separate a variety of C&DWs, as well as specify their proposed uses for these materials. This creates an environment where a specialist waste-processing sector can develop and practices such as the re-use and recycling of multiple C&DWs can flourish. It is important that the management and handling of C&DWs is carried out in a manner such that the technical requirements of this resource are understood. This study analyses two major C&D materials in clay and concrete masonry (CMA) materials and waste concrete (RCA). Greywacke stone is used as the control coarse aggregate. A 100% replacement ratio of coarse RA is used in all RA concrete mixes. A 50% Klipheiwel and 50% Dune sand mix is used in all concrete mixes respectively. C&D materials in this study were processed through simulated, on-site procedures to produce 19 mm coarse aggregate for concrete.
  • Thumbnail Image
    Item
    Open Access
    The use of natural site derived materials as concrete aggregate.
    (2012) O'Neill-Williams, Barrie; Alexander, Mark Gavin; Collis, Vernon
    This thesis focuses on the use of site-derived fine material, in its natural form, as aggregate in concrete construction. It is proposed that the utilisation of this type of concrete aggregate will lead to; the preservation of natural materials that would otherwise have to be beneficiated off site, the reduction of waste material produced on a construction site, and an overall energy saving.