Introduction

I.I General Serviceability and safety of concrete structures have been the main concern of structural engineers and currently required performance is generally assessed by conducting structural analyses based on nonlinear solid mechanics. Another issue of great engineering importance is how to retain performance during the expected life of buildings and infrastructures. The length of time serviceability and safety of structures remain is generally referred to as durability, which has also been a long-term topic of interest to engineers with extensive study in the past. The serviceability limit of concrete structures is primarily governed by the extent of damage resulting from daily service loads and various deterioration processes, which might be active throughout the structure's life. These deterioration processes can be physical, chemical or mechanical, and their net effect is to weaken the integrity and tightness of the complex internal microstructural building blocks of concrete. Figure 1.1 shows a hypothetical concrete structure exposed to some of the typical and most common types of deterioration processes which may be active over the lifespan of structures. These deterioration processes may be due to weathering, occurrence of extreme temperatures, abrasion, electrolytic action, repeated fatigue loads and possible attack by natural or industrial liquids and gases assisted by moisture ingress.