Civil Engineering Reference
In-Depth Information
titanium wires to form a zone.
electrical discontinuity between bars is unlikely to lead to significant stray
current induced corrosion as the currents and potentials are low.
Table 4.2
summarises the different anodes and their characteristics:
•
Thermal sprayed zinc - Zinc is flame or electric arc sprayed onto the
concrete surface and a direct connection made to the reinforcement. It
can be used as sprayed on marine splash or tidal applications. In dryer
locations a humectant solution of hygroscopic salts can be applied. Over
50,000 m
2
has been applied, mainly in Florida.
•
Thermal sprayed aluminium/zinc/indium - A proprietary variation on
thermal sprayed zinc that uses an alloy to enhance the current rather
than a humectant. A 300 micrometre thick coating is applied by arc
spray. Over 35,000 m
2
has been applied.
•
Adhesive zinc sheet - A proprietary system consisting of rolls of zinc
0.25 mm thick, 25 mm wide with a conductive gel adhesive on one side.
The installed system can be painted. The edges must be sealed against
water ingress as the gel can swell and leak.
•
Encasement system - A proprietary system initially developed by Florida
DoT consisting of expanded zinc mesh in a permanent form, grouted
onto concrete piles or columns. Several hundred piles and columns have
been protected with this system. It is for marine splash and tidal zone
applications.
•
Probe anodes in patch repairs - Proprietary anodes approximately 65
mm diameter by 30 mm high with four wires protruding for attachment
to exposed reinforcing steel in the patch. Anodes are installed on a
