Browsing by Author "Alexander, M G"

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    Cradle-to-gate environmental impacts of the concrete industry in South Africa
    (2013) Muigai, R; Alexander, M G; Moyo, P
    The objective of the paper is to provide an understanding of the South African concrete industry's environmental burden in terms of natural resource consumption and carbon dioxide equivalent emissions (CO2-e). The review covers current practices in the concrete construction field in South Africa (SA) and their implications for the environment. Elaboration in terms of detail and quantification is given for the environmental burden generated during the manufacture of raw materials for concrete and their transportation to site. Four-year average (2005-2008) data is provided for resources consumed and wastes emitted during the quarrying and manufacture of raw materials for concrete. Carbon dioxide-equivalent emissions data per unit of material produced was obtained from the InEnergy Report produced for the Cement and Concrete Institute (C&CI) of South Africa. The study determined that, on average, 39.7 Mt of raw materials are consumed per year and 4.92 x 109 kg CO2-e emissions are emitted per year to produce cement and aggregates for concrete production in South Africa.
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    Performance of concrete made with commercially produced recycled coarse and fine aggregates in the Cape Peninsula
    (2004) Kutegeza, Benjamin; Alexander, M G
    [pg129,130 missing] Properties and performance of concrete made with laboratory-crushed recycled aggregate have been extensively investigated and reported by various researchers. However, only limited data are available on commercially produced recycled aggregates (RA). In this study, the properties of RA and the performance of concrete made with RA were analysed and compared with the properties of natural aggregate and normal concrete respectively. The results obtained from this study show the material to be within allowable limits suggested by various concrete Standards and specifications. Both recycled coarse aggregate (RCA) and fine aggregate (RFA) were continuously graded. Stone content was the main component in the RA, with mass fraction of about 58%. Stone/mortar conglomerate (concrete) comprised about 21 %, mortar comprised 12% and bricks comprised 8%. Other impurities such as wood, chipboards, and tiles to mention a few totalled about 1 %.