Civil Engineering Reference
In-Depth Information
electrode system. Photo courtesy John B. Miller.
Simple tap water can be used as an electrolyte. In order to prevent
acidification of the electrolyte and of the concrete surface, frequently an
alkaline solution made of Ca(OH)2 or of NaOH is used. Also from the SHRP
comes the recommendation to take a lithium borate solution as electrolyte
for a better alkaline buffering effect and to counteract expansive effects of
ASR (Mietz, 1998).
Other application systems use geotextile blanket anodes with circulating
electrolyte or tanks that contain the anode and an aqueous electrolyte
(Broomfield, 2007). They can be mounted either horizontally or vertically.
A different technical solution was developed in 2001 in Germany by
CITec and is designed for the focused treatment of smaller corrosion 'hot
spots'. The basic layout can be seen in
Figure 8.4
and has the following key
features:
• The electrodes used for the ECE have a size of 60 × 60 cm, are
pre-manufactured, re-usable and have an ion exchanger for binding
chloride
• Accordingto the configuration (rebar spacing, concrete cover, chloride
content, concrete permeability etc) the electrodes can be combined in
groups (max 10 m²).
