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Authors = Victor Akpan ORCID = 0000-0002-0101-4071

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24 pages, 16145 KiB  
Review
Ballast Contamination Mechanisms: A Criterial Review of Characterisation and Performance Indicators
by Daniel Bassey, Ben Ngene, Isaac Akinwumi, Victor Akpan and Gideon Bamigboye
Infrastructures 2020, 5(11), 94; https://doi.org/10.3390/infrastructures5110094 - 2 Nov 2020
Cited by 17 | Viewed by 13416
Abstract
Across the world, ballasted railway tracks are utilised extensively due to their cost efficiency, ease of drainage, and capacity to withstand cyclic imposed loadings from heavy trains. In spite of these benefits, the ballast is often considered as a flexible medium; as such, [...] Read more.
Across the world, ballasted railway tracks are utilised extensively due to their cost efficiency, ease of drainage, and capacity to withstand cyclic imposed loadings from heavy trains. In spite of these benefits, the ballast is often considered as a flexible medium; as such, its continuous deterioration is largely disregarded. Geotechnical challenges such as ballast contamination in the form of particle fragmentation, deposition of weathered materials, upward pumping of clay and fines from underlayers, and coal intrusion have led to differential settlements and reduced drainability of tracks, thereby exacerbating track maintenance costs. This study reviews existing works of literature to expound on the mechanisms for ballast contamination and to highlight the fundamental parameters that guide the characterisation and performance evaluation of railway ballasts. The study shows that ballast fragmentation accounts for about 76% of commonly recorded contaminations, while it is also observed as the most critical to track stability. As such, a variety of indices and specifications for ballast gradation have been established worldwide to guide practice in ballast characterisation and performance evaluation. However, the mechanisms of ballast fragmentation and deterioration require further research to guide the improvement of contemporary guidelines, and mitigate the risk of abrupt track failures, especially in developing countries. Full article
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28 pages, 3931 KiB  
Review
Hazardous Waste Management: An African Overview
by Victor E. Akpan and David O. Olukanni
Recycling 2020, 5(3), 15; https://doi.org/10.3390/recycling5030015 - 2 Jul 2020
Cited by 47 | Viewed by 25632
Abstract
Hazardous waste materials and their management are of prime importance to society. This article gives an overview of the current practices that relate to hazardous waste management. It looks at issues concerning the transboundary or international movement of harmful materials from industrialized nations [...] Read more.
Hazardous waste materials and their management are of prime importance to society. This article gives an overview of the current practices that relate to hazardous waste management. It looks at issues concerning the transboundary or international movement of harmful materials from industrialized nations to the developing and emerging world. This study has shown that Africa, most notably Nigeria, has become a dumping ground for hazardous waste materials as a result of the high importation of scrap computers and electronic devices into the country. The public health hazards, such as birth deficiencies, cancers, and even infectious diseases such as human immunodeficiency virus (HIV) and Hepatitis B and C, respectively, have been traced to the improper management of these waste materials. The review highlights a few models on hazardous waste management as developed by previous literature, which gives a hierarchy, ranging from source reduction, recycling, and landfill options. Studies reveal that hazardous waste management in Africa must revolve around wealth creation, economic, and environmental sustainability. The study provided evidence that the recycling option has high potentials in the areas of energy recovery. The data collected show South Africa to be the most advanced in the African continent in the field of hazardous waste management. For a sustainable environment, keen attention must be paid to hazardous waste management globally. Full article
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