Civil Engineering Reference
In-Depth Information
Table 11.2
Corrosion strategy checklist for monolithic concrete tunnel elements (
Continued
)
Structural element
Risk
Mitigation
Criteria and design consideration
Steel
membrane
Leakage through
welds
Appropriate weld types,
speciication and testing
Test procedures to recognized standards
Undertake 100% testing during fabrication
Pitting or general
corrosion
Coating
Select appropriate coating material and design life
Combine with CP
Sacriicial thickness
Identify minimum thickness and add based on predicted corrosion
rates. Not recommended approach for general corrosion.
Cathodic protection
Initial provision of SACP or ICCP system:
Design type and location of anodes
Decide on design life
Detail for robust connections to structure
Include monitoring system
Future provision of ICCP system:
Speciication for cast-in connection plates and electrical
continuity of reinforcement
Monitoring for initiation of corrosion
Bacterial corrosion
Coating
Select appropriate material and application coating design life to be as
long as possible
Sacriicial thickness
Determine minimum thickness
Stray current
corrosion
Earthing and bonding
Design to standards
Applied
membrane
Leakage at defects
Material selection
Durable, lexible material needed, with good adhesion properties not
susceptible to workmanship defects
Prevent damage during
placing
Coating thickness typically
>
2 mm and material to have high
resistance to abrasion and impact and able to bridge cracks
Thickness testing
For sprayed membranes; to manufacturer's or recognized standards
Adhesion testing
For sheet membranes; to manufacturer's or recognized standards
