ABSTRACT
From the point of view of limiting crack width, only the first four exposure classes are considered as shown in Table 10.1.
10.3 RECOMMENDED VALUES OF MAXIMUM CRACK WIDTH
Table 10.2 shows the permitted maximum crack width for various exposure classes
Exposure class Frequent load combination
Quasi permanent load combination
X0, XC1 0.2 mm
XC2 – XC4 0.2 mm Check decompression
XD1, XD2, XS1−XS3 Check decompression
Class designation
Description of the environment Examples of where exposure classes might occur
No risk of corrosion or attack
X0 For concrete without reinforcement or with reinforcement in very dry
environment
Concrete inside buildings with very low humidity
Corrosion induced by carbonation
XC1 Dry or permanently wet Concrete inside buildings with very low humidity. Concrete permanently submerged in water
XC2 Wet, rarely dry Concrete surfaces subjected to long-term water contact. Many foundations
XC3 Moderate humidity Concrete inside buildings with moderate or high air humidity. External concrete sheltered from rain
XC4 Cyclic wet and dry Concrete surfaces subjected to water contact, not within exposure class XC2
Corrosion induced by chlorides.
