Civil Engineering Reference
In-Depth Information
chloride-induced corrosion
Rob B. Polder
15.1 Introduction
Since the mid-1990s, service-life modelling of concrete structures has become
feasible and, subsequently, increasingly popular. Today many owners require
service lives of 100 or even 200 years for important concrete infrastructure.
Acknowledging previous work on modelling since the 1970s (Siemes et
al., 1985), a major breakthrough was due to European Research project
DuraCrete (DuraCrete, 2000; Siemes et al., 2000). DuraCrete successfully
combined mathematical modelling of degradation processes with structural
design philosophy, in particular reliability analysis. Since then, similar
approaches and extensions have been worked out, additional field work
has been done and particular subjects have been refined (Polder and Rooij,
2005; Gehlen, 2000; Li et al., 2008; FIB, 2006). Over the last five years,
a simplified version has been developed in the Netherlands for chloride-
induced corrosion (CUR, 2009). In principle, the approach is aimed at
service-life design of new structures. However, modelling the remaining
life of existing structures could be just as important for maintaining our
infrastructure. Some work on degradation modelling was extended in that
sense (Polder and Rooij, 2005; Rooij and Polder, 2005) but the subject is
definitely underdeveloped. The main body of this chapter is devoted to
describing the simplified model for chloride-induced corrosion related
service-life design. However, in the final sections, possible application to
existing structures is discussed.
15.2 Modelling for design of long service life
Until recently, design codes did not give quantified guidance for designing
concrete structures for service life, in particular not for periods of 100 or
more years. Another drawback of existing regulations is that no distinction
is made between cement types (EN 1992-1-1, 2004). In particular, blending
Portland cement with blast furnace slag, fly ash or silica fume has been
found to substantially increase the resistance against chloride penetration
