17 NACE INTERNATIONAL: VOL. 56, NO. 11 MATERIALS PERFORMANCE NOVEMBER 2017
Information on corrosion control and prevention
The failed segment at Pier 22. Photo courtesy of Ali Abu-Yosef, Pivot
Engineers.
Tier 2 for further monitoring; and the
remainder were tagged as Tier 3, which
required no further action. Tier 1 pier
repairs included installing new concrete
drill-shaft foundations connected to the
existing piers, which WisDOT says will
provide adequate corrosion protection
with a design service life of 75 years.
"Only f ive [piers] were exposed to the
corrosive f ly ash layer," Abu-Yosef says.
"The repair engineer, Michael Baker
International [Coraopolis, Pennsylvania],
decided wisely not to rely anymore on
steel piles, and instead installed concrete
drill shafts. That transferred the loads
from the pile caps to the concrete drill
shafts. Because concrete is susceptible to
premature distress in high-sulfate soils,
they have installed inert sleeves around
the drill shafts to isolate the concrete
from the f ly ash soil."
Tier 2 piers had monitoring probes
and steel coupons
installed in 2014. Data
are collected from the
probes during ty pical
biannual bridge main-
tenance inspections,
and the probe data are
supplemented by sec-
tion loss measure-
ments from the
coupons.
"What we did was
install monitoring sen-
sors to gauge corrosion
rates using electrical
resistance probes,"
Abu-Yosef says. "The
probes contain a sacrif icial piece of
metal. If it corrodes, a change in voltage is
detected. That will tell you the corrosion
rate over time. After three, f ive, and 10
years, it should give us an indication of
how fast the corrosion is actually
happening."
The bridge reopened on January 5,
2014, just over three months after the
Continued on page 18
NO SALT. NO RUST. ONE STEP.