A Selection of Possible Pitfalls on the Usage of Empirical Models in the Rational Seal Design Method of South Africa

Abstract:

A large portion of surfaced roads in Zambia have asphalt as part of their pavement structure. Most of these surfaces and to some extent base layers are in a deplorable state. This situation, coupled with unfavorable economic conditions, leaves highway authorities with a huge backlog on highways sustainability. The past practice of “worst-first” is still a common principle other than maintaining pavements earlier in their service life to reduce life cycle costs. In order to include pavement preservation as a pavement network strategy, road surface sealing is adopted. This paper is focused on a selection of possible pitfalls on the usage of empirical models in the rational flexible road surfacing seal design of South Africa, which is commonly used in Zambia. The aggregates, fillers (dust) and bitumen used in surface seal coats vary to a large extent and with the availability of good quality natural materials becoming less, the challenges in providing good quality seal coats are increasing. Since the emphasis is based on failures rather than successes, few answers are provided on the number of questions that usually arise from seal coat design and the aim is to create awareness on some possible pitfalls for using the rational seal design method. The paper emphasizes on design aspects that are not addressed in the Interim guidelines for the design and construction of seal coats in South Africa (Technical Recommendations for Highways (TRH3, 2007)). A few case studies from recent projects in Zambia are also included and evaluated.

• Periodical: Advanced Materials Research (Volumes 450-451)
• Pages: 1336-1339
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.450-451.1336
• Online since: January 2012
• Authors: Aaron D. Mwanza, Pei Wen Hao, Mike H. White
• Keywords: Aggregates, Ball Penetration, Bitumen, Rational, Rehabilitation, Surface Seal

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