Service life and durability design of RC structures: general considerations and selected Southern African perspectives and experiences

ABSTRACT

There is a growing trend to include service life (SL) and durability considerations in the design of reinforced concrete structures. This is partially a consequence of increasing deterioration of ageing concrete infrastructure worldwide and associated financial burdens and structural failures. Against this trend, this contribution critically explores the principles of SL and durability design and highlights the differences between SL modelling, SL prediction, SL design, and performance-based design, focussing on aspects related to reinforcement corrosion in concrete. Based on extensive research and practical experience, the Southern African perspective on concrete durability is then explored in more detail, in particular the South African performance-based design methods, associated SL modelling, and deterioration prevention methods. Based on chloride ingress measurements in-situ, a critique of design exposure classes for marine environments is presented, highlighting the need not only to consider chloride ingress, but also the various factors promoting reinforcement corrosion.

KEYWORDS:

• Service life design
• service life modelling
• durability design
• performance-based approach
• reinforced concrete structures
• durability indexes

Acknowledgments

The authors wish to acknowledge with gratitude the financial support over the period of this work (2008–2019) received from: CoMSIRU, The University of Cape Town, The Concrete Institute, The National Research Foundation (NRF), Sika (SA) Pty Ltd., PPC Ltd, AfriSam, Haw & Inglis Civil Engineering (Pty) Ltd, Aveng Grinaker-LTA Ltd, The Tertiary Education Support Programme (TESP) of ESKOM, and the Water Research Commission (WRC).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1. Certain review material in this paper is adapted from other publications of the authors on similar topics. In particular, the following publications were drawn upon in preparing this review: (Alexander et al., 2017; Alexander & Beushausen, 2019; Beushausen & Fernandez-Luco, 2015; Beushausen et al., 2019a, 2019b).

Additional information

Notes on contributors

Mark Alexander

Emeritus Prof Mark Alexander is an Emeritus Professor and a Senior Research Scholar in the University of Cape Town. He has a PhD from the University of the Witwatersrand, and is a Fellow of the University of Cape Town and of RILEM. He co-authored “Aggregates in Concrete” (2005), “Alkali-Aggregate Reaction and Structural Damage to Concrete” (2011), and “Durability of concrete – design and construction” (2017) (CRC Press) and was Editor of “Marine concrete structures. Design, durability and performance” (Woodhead Publishers (2016). He is involved in CoMSIRU at UCT, which focuses on infrastructure performance and renewal research.

Hans Beushausen

Hans Beushausen is a Professor of Structural and Materials Engineering at the University of Cape Town (UCT). He holds a first degree in Structural Engineering from the University of Applied Sciences in Hamburg, Germany, and MSc and PhD degrees from UCT. He has more than 20 years of research experience in concrete technology, durability modelling of concrete structures, concrete repair technology, and reinforcement corrosion. He is currently the Director of the Concrete Materials and Structural Integrity Research Unit at UCT. Hans is a specialist industry consultant for condition assessment and repair of concrete structures, and he is also actively involved in RILEM and fib and other national and international organizations.

Mike Otieno

Mike Otieno is an associate professor of civil engineering at the University of the Witwatersrand, Johannesburg. His teaching covers both undergraduate and postgraduate courses in construction materials, including strength and mechanics of materials. His research interests include concrete durability, service life prediction, steel corrosion in reinforced concrete structures and repair and rehabilitation of concrete structures. He also acts as a consultant to industry on concrete materials problems.