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Browsing Books by browse.metadata.type "Article"

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    Correlating the asphalt-binder MSCR test results to the HMA HWTT and field rutting performance
    (2022-09) Walubita, LF; Ling, M; Fuentes, L; Komba, Julius J; Mabrouk, GM
    Asphalt binder is one of the key constitutive components of hot-mix asphalt (HMA) that considerably affects its rutting performance. In particular, the high-temperature rheological properties measured from the multiple stress creep and recovery (MSCR) test are critical for correlating to the HMA rutting resistance. In this study, the Texas flexible pavements and overlays database was used as the data source to investigate the effect of asphalt-binder high-temperature rheological properties on the HMA rutting resistance. The study methodology was based on correlating the results of the MSCR test and the Hamburg wheel-tracking test (HWTT) to HMA field rutting performance. The data matrix for the study included asphalt binder (PG 64-22) from three different sources, three widely used Texas HMA mixes (fine gradation to coarse gradation), and five in-service highway test sections constructed using the same asphalt binders and HMA mixes. In general, the MSCR nonrecoverable creep compliance parameter, Jnrdiff, showed fairly strong correlations with the HMA rutting performance in the laboratory and field. The percent recovery parameter (R), on the other hand, exhibited the potential to ascertain and quantify the presence of modifiers in the asphalt binders. Furthermore, the test results indicated that material source/supplier has an impact on the rheological properties of the asphalt binders with the same performance grade (PG). Overall, the use of the MSCR test to quantify the asphalt-binder high-temperature rheological properties indicated the potential to compliment the laboratory HWTT test for correlating with the field HMA rutting performance in terms of the effects of asphalt binder.
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    Enhanced methodology for visual bridge inspections in South Africa
    (2022-09) Kemp, Lana; Steyn, W; Roux, Michael P
    This paper introduces the application of technology solutions into the realm of bridge inspection methodologies in South Africa, aiming to enhance the current visual bridge inspection methodology. Unmanned Aerial Vehicles (UAVs) can be used as an alternative to collect bridge image data, and point cloud models can be created from captured images by using photogrammetry software. For this study, accredited bridge inspectors were approached to complete TMH 19 inspection sheets of bridge structures using only the point cloud models and captured images, as a proposed new inspection methodology. This paper compares historic inspection ratings and the point cloud inspection ratings to investigate the effectiveness and practicality of the new proposed inspection methodology. The study concluded that bridge inspectors could identify and rate critical defects of bridge structures using the new inspection methodology, but there are limitations and specific use cases that need to be identified.
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    Polymer Science in South Africa
    (2024-07) Pfukwa, R; Ray, Suprakas S
    Polymer science and technology now impact all spheres of this age's everyday life, from packaging, water purification materials, health, agriculture, transport and electronics. The wide applicability of polymers leverages the unique physicochemical properties of these macromolecules, the vast array of available building blocks and a stocked synthetic toolbox for accessing polymers with differing functionalities, topologies and architectures. Polymer science is a mature field, with a unique balance between fundamental research and applied science, and a significant involvement of commercial companies. The polymer industry is an important cornerstone of South Africa's highly diverse and complex chemical industry.[1] In addition, South Africa has fairly comprehensive polymer science teaching and research programs.[2] This special issue, “Polymer Science in South Africa” comprises 16 open access research articles, i.e., 10 experimental papers and 6 review articles from the South African polymer science community. Research areas covered include polymer analysis, polymer engineering, materials for health and biotechnology, degradable polymers and environmental impacts of polymers materials; these contributions are summarized below.