Civil Engineering Reference
In-Depth Information
densities, the chloride content could be reduced by more than 90% within
a few days, but some drawbacks such as high temperatures, cracks and an
increased permeability were caused in the concrete. Thus, the following ECE
applications were done at reduced voltages and over several weeks.
In Norway, an application system that was developed and introduced in
1986 (Noteby, 1986) has gained the biggest portion of ECE applications and
uses sprayed, wet cellulose fibres as an electrolyte reservoir, which provides
an excellent connection between anode and concrete (see
Figures 8.2
and
8.3)
. It is also known as NORCURE and can be used on large surfaces.
A very intensive research on ECE in laboratory and field scale was done
within the Strategic Highway Research Program (SHRP) of the US Federal
Highway Administration (FHWA) from 1988 to 1993 (Bennett et al., 1993b),
which led to detailed recommendations and several practical applications in
North America.
Generally, for an ECE the following components are needed:
• a dimensionally stable anode (DSA), usually activated titanium mesh
• an electrolyte reservoir that embeds and attaches the anode to the
concrete surface
• a high power supply that establishes an electrical field between anode
and reinforcement
• measuring and control units for recording and controlling voltage,
current and - if present - the signals from installed reference electrodes.
a column of Burlington Skyway, Ontario, Canada in 1989. Photo courtesy John B.
Miller.
