ABSTRACT
This chapter describes the mechanisms and techniques for evaluating corrosion in steel and iron materials in relation to the long-term performance and degradation of reinforcement and support systems and provides site examples. First the background of iron corrosion due to chemical or electrochemical action of water in the presence of oxygen and hydrogen is explained. Then factors affecting corrosion rate such as environment, pH concentration of dissolved oxygen, and temperature are presented. Some laboratory experiments and in-situ observations on the corrosion rate of iron and steel are described and results of measurements and observations are tabulated. In addition, the possibility of evaluating corrosion state using non-destructive testing such as electrical resistivity, p-wave velocity and X-Ray CT scanning technique is discussed through some actual measurements. These techniques clearly showed some potential to determine the state of corrosion and its rate. Furthermore, a finite element modeling of corrosion problem is presented and applied to some practical situations. Some methods are also proposed to evaluate the failure time of rockanchors subjected to prestresses.
