Durability of Concrete Structures

Abstract

As recently as 1976 textbooks on the design of reinforced concrete structures contained remarks such as ‘compared with other building materials, reinforced concrete is distinguished for its very long service life. With proper service conditions reinforced concrete members can last an indefinite time without reduction of their load-carrying capacity. This arises from the fact that the strength of concrete does not decrease with time but, on the contrary, increases, and the steel embedded in it is protected against corrosion.’ Although today such statements appear somewhat naive, they are in fact essentially true. However, they need to be qualified, and as long ago as 1954 a survey showed that ‘even on a moderately exposed site, the trouble-free life of reinforced concrete is likely to be short if the cover to the reinforcement is meagre, if binding wire projects towards the surface, or if for any reason the concrete is pervious to moisture’. In the rapid expansion of the construction industry during the 1960s such lessons were often forgotten and today in the UK we are seeing the result—a £500 million per annum programme of concrete repair. In this book I have attempted to bring together experts from the field of concrete durability, repair and protection to provide a state-of-the-art report on current thinking, materials and techniques. The basic deterioration mechanisms and methods for the site investigation of distressed concrete structures are discussed first. Materials and techniques for repair are critically reviewed and relatively novel ideas for protection are discussed. The second part of the book consists of a series of case studies for various structure types. They are written by those who have immediate experience of both the technical and financial difficulties of concrete repair and maintenance programmes. Of necessity the information is presented for particular circumstances only and I cannot claim that the case studies are exhaustive. For example, low-rise housing has been consciously omitted, as has alkalisilica reaction where the solution is likely to be unique in every case. I wish to thank all my contributory authors for their painstaking efforts amidst the pressures of modern life in the construction industry. Particular thanks, however, go to Jan Price who typed the complete manuscript for this book