9
Steel Structures 8 (2008) 73-81 www.ijoss.org
Estimation of Quantity of Cl− from Deicing Salts on
Weathering Steel Used for Bridges
Masamichi Takebe1,*, Makoto Ohya1, Shota Ajiki2, Takashi Furukawa3, Ryo Adachi1,
Rumiko Gan-ei4, Naoki Kitagawa1, Junya Ota1, Yasuhiko Matsuzaki5 and Toshihiko Aso6
1Matsue College of Technology 14-4, Nishi-ikuma-cho, Matsue, Shimane, 690-8518, Japan2Izucon Co. Ltd. 1778-1, Ohtsu-cho, Izumo, Shimane, 693-0021, Japan
3Furukawa consultant, 1612-1, Enya-cho, Izumo, Shimane, 693-0021, Japan4West Japan Rallway Company, 5-1-39, Noda, Okayama, 700-0971, Japan5WESCO Inc. 16-1 Yomeshima-cho, Matsue, Shimane, 690-0047, Japan6Graduate School of Science and Engineering, Yamaguchi University,
2-16-1 Tokiwadai, Ube, 755-8611, Japan
Abstract
To estimate the contribution of Cl− from deicing salt (CaCl2) on weathering steel on a bridge in southwestern Japan, therelationship among the quantities of Cl−, SO4
2− and Ca2+ on girders is examined. The composition of the ions on girder showsseasonal variation, and the Ca2+ and Cl− on the western second girder are enriched with a ratio corresponding to CaCl2 in winter,suggesting that CaCl2 from deicing salt had been accumulating in winter. The contribution of CaCl2 is more 50 % of totalchlorine ion and the corrosion is more enhanced on the second girder.
Keywords: weathering steel bridge, accumulating slat, deicing salt, corrosion
1. Introduction
To reduce life cycle costs, weathering steels are widely
used for infrastructure. In Japan, the conventional
weathering steel specified as Japan Industrial Standard G
3114 SMA (JIS-SMA weathering Steel) is considered to
be appropriate for bridges in environments where corrosion
loss on one side of a girder is within 0.5 mm during 100
years of exposure (Public Work Research Institute-
Ministry of Construction, 1993; Japan Road Association,
2002). Since corrosion loss is related to deposition rates
of air-born salts, the Japanese Roads and Bridges Policy
Manual specifies that JIS-SMA weathering steel can be
used without any rust controlling surface treatment for
bridges in regions where the deposition rate of air-born
salts is less than 0.05 mg NaCl/dm2/day (mdd) (Japan
Road Association, 2002). When a steel bridge is planned,
the rate of salt deposition at the site should be measured
by the method described in JIS Z 2381 to assess the
applicability of using weathering steel (Japan Road
Association, 2002). The measurement can be omitted at
sites distant from the sea (Japan Road Association, 2002),
because the quantity of air-borne salts derived from
seawater may be expected to decrease with distance. The
manual also specifies the standard distances for which
monitoring can be omitted (Japan Road Association, 2002).
In addition to air-bone salt from the ocean, deicing salt
often causes corrosion problems on weathering steel
bridges (Miki and Ichikawa, 2004). In Japan, the mass of
deicing salt applied to roadways increased after 1991,
when studded tires were prohibited (Miki and Ichikawa,
2004). Therefore the corrosive effects of deicing salts
should also be examined, during the planning stage for
bridges. Although the manual briefly mentions the effect
of deicing salts on corrosion (Japan Road Association,
2002), there is no standard method for estimating this
factor. The purpose of this study is to describe the method
for evaluating the quantities of salt on girder from deicing
salt.
Typical components of deicing salt that causes corrosion
of steel are NaCl and CaCl2 (Hara et al., 2005). The
corrosive influence on bridge girders of deicing salt
composed mostly of NaCl is hard to be distinguished
from that of NaCl from sea-salt, because supplies of both
increase in winter. However, there is the possibility that
the influence of deicing salt composed of CaCl2 is
distinguished from that of sea-salt, by comparing the
This manuscript for this paper was submitted for review and possiblepublication on November 20, 2007; approved on June 13, 2008.
*Corresponding authorTel/Fax: +81-852-36-5182E-mail: [email protected]
74 Masamichi Takebe et al.
quantities of accumulating Na+, Cl−, and Ca2+. To estimate
the quantities of deicing salt on girders and reveal the
influence of deicing salt on corrosion, we discuss the
seasonal variation in ions and the corrosion state of
weathering steel on an a bridge, where CaCl2 was applied
to prevent freezing.
2. The Studied Bridge and Analytical Methods
2.1. The studied bridge and weathering condition
The bridge examined for this study is located in Izumo,
Shimane, which is in southwestern Japan and adjoining
the Japan Sea. Averaged temperature and annual precipitation
of Shimane are 15oC and 1700 mm, respectively (Japanese
meteorological agency). Matsuzaki et al. (2007) reported
that climate of Shimane is characterized by high
humidity. The average humidity is up to 85% in a
summer and is about 70% even in winter, which is dry
season in Japan. Matsuzaki et al. (2007) also reported that
rate of air born salt in Shimane is high in winter, in which
the westerly wind are generally dominant.
It is known that air-borne salt from the sea is
abundantly supplied to the area adjoining the Japan Sea
due to prevailing westerly winds (Miki and Ichikawa,
2004). In the southwestern Japan adjoining the Japan Sea,
excepting Okinawa, the Japan Road Association has
determined that analysis of deposition rate of air-born
salts can be omitted when a planned weathering steel
bridge will be located at a distance of more than 5 km
from sea (Japan Road Association, 2002). The distance of
the examined bridge and the Japan Sea is 10 km (Fig. 1).
The bridge examined for this study is made of weathering
steels with supplementary surface treatment (Fig. 2A) for
rust control and has been in use since 1983. The bridge
spans north to south across the prevailing wind, which
blows from the west or east.
In this study, the girders of the bridge are numbered
from west to east, for example, girder 1 and 2 (G1 and
G2) correspond to the first and second girders from west
respectively (Fig. 1B). These two westernmost girders
(G1 and G2) were examined. Between G1 and G2, there
is a drainpipe on slab (Fig. 2B). The drainage from the
drainpipe may occasionally splash on G2 due to westerly.
In the following discussion, the term ‘salt’ is used for
‘chemical compounds comprising cations and anions’.
Fig. 1 shows the sampling points. Salt samples were
collected in August and November 2005, and February,
May and August 2006 by wiping with gauze. Salt of part
“e” in August 2006 was not obtained due to mistakes
during sampling. The sampling method is described in
Takebe et al. (2007). The sample site on the girder was
wiped 9 times using three gauze squares during each
sampling set. There is a possibility that the sampling
procedure did not collect all salt on girders because the
girder surfaces are roughened due to corrosion. The
analyzed quantities of ions correspond to the lower limits
of quantities of ions on girders. However, we can discuss
how much deicing salt accounts for salt on the girder, on
the basis of the relative quantities of analyzed ions.
Quantities of Na+, K+, Mg2+, Ca2+, Cl−, SO42− and NO3
−
on the girders were measured using ion-exchange
chromatography (IC7000M) at Matsue College of
Technology. Analytical error is estimated to be less than
3%. The ionic species measured are those commonly
contained in rain, sea, and river water (Mason and Moore,
1982; Krauskopf and Gird, 1995), and so salt on girders
of bridges generally consists of these ions (Takebe et al.,
2007). To express the composition of salt on girders, stiff
diagram (Stiff, 1951) with the unit of electrochemical
equivalent (meq) is used. The stiff diagram is generally
used to express the composition of rain, stream water and
ground water [Carreón-Diazconti et al., 2003; Anderson
et al., 2006; Hefting et al., 2006; Lipfert et al., 2006;
Tsujimura et al., 2007]. The stiff diagram with electrochemical
equivalent is convenient to depict the quantities of ions
and to estimate the chemical compound. In this paper,
unit of meq/m2 is used in stiff diagrams to express the
quantity of ions.
The level of rust at the sampling sites was ranked by
visual inspection and thickness of rust, following the
method of Kihira (2005; 2007). The rust thickness was
measured by an electro-magnetic coating thickness meter.
In general, weathering steel with surface treatment on
bridges shows variable corrosion rates even within an
area of several tenths of a square centimeter (Matsuzaki
et al., 2006; Takebe et al., 2007). As a result, the
Fig. 1. Locality of the bridge examined (A) and samplingpoints on the bridge (B).
Estimation of Quantity of Cl− from Deicing Salts on Weathering Steel used for Bridges 75
measured thickness of rust varies considerably. Therefore,
the measured thickness was used as supplementary
information for visual inspection.
3. Resut
3.1. Rank of rust states
Table 1 shows thickness of rust and rank of corrosion
state in examined sites. The outside ward surface on web
of G1 shows the color change of supplemental coatings
(Fig. 2A) and thickness of rust is too thin (57 µm). The
outside web of G1 is considered to be Rank-B. There are
many spots of rusts with a few centimeters in diameter on
the inside-ward surface web of G1 (Fig. 2C). Some spots
of rust are clumped. Supplementary coatings showing
initial state are still remained among the spots of rust. The
rusts make up about 75 percents of the surface. The
average rust thickness is about 200 µm. Considering the
thickness of rust and remains of the initial state of the
supplementary coatings, the rust state of the inside web of
G1 is classed into Rank-5. On westward surface of web
in G2, the supplementary coatings have been mostly
converted to rust (Fig. 2B and D). The surface is full of
rust with several millimeters in diameter, and the
thickness of rust is higher than 400 µm. Therefore Rank-
2 is assigned to the web of G2. On the upper surface of
lower flange of G1, rusts with about 1 mm in diameter
cover the surface (Fig. 2E). On the flange, there are
several detachments of scab-like patches of rusts, which
were converted from the supplementary coating (Fig. 2E).
The scab-like patches are several centimeters in diameter
and can be easily removed from the girder by hand. The
thickness of rust other than scab-like patches is less than
400 µm. Considering the scab-like detachment and
thinness of rust, the upper surface of the lower flange in
G1 is classed into Rank-3. On the upper surface of the
lower flange of G2, there is detachment of rust plate
converted from supplementary coatings (Fig. 2F and G).
The detachment is several centimeters in width and is
beyond several tenth centimeters in length. The electro-
magnetic coating thickness meter gave thicknesses of
higher than 1000 µm on the surface. In addition to rust,
pore space between the rust plate and steel is possibly
responsible for the high value. Rank-2 was assigned to
the upper surface of the lower flange of G2. The under
surface of the lower flange of G2 is covered by rough
rusts (Fig. 2H), which detach when touched by the hand.
Corrosion has progressed especially on the under surface
close to the edge, in which there are the detachments of
rust converted from supplementary coating (Fig. 2G). The
thickness of rust is up to 1300 µm at best. Rank-2 is
assigned to the under surface of lower flange of G2.
3.2. Composition of salt on girders
Table 2 shows quantities of salts on girders. Compositions
of ions sampled in August 2005 are shown as stiff
diagrams in Fig. 3. The outside web of G1 has very low
quantities of ions, less than 4 mg/m2. The ions on the
other examined sections consist mainly of Na+, Ca2+, Cl−,
and SO4
2−, which range from 40 to 300 mg/m2. In terms
of electrochemical equivalent units, the quantities of Ca2+
and SO4
2− on the inside web of G1 and G2 are higher than
those of Na+ and Cl−, respectively (Fig. 3). The web of
G2 is enriched in Ca2+ and Cl− relative to that of G1. On
the upper surface of the lower flanges, quantities of Na+
Table 1. Thickness of rust and rank of corrosion state
examined sitesthickness of rust (µm)
corrosion
rank
a: outside-ward surface on web of G1 57 B
b: under surface of lower flange of G2 1328 2
c: inside-ward surface on web of G1 209 5
d: westward surface of web of G2 479 2
e: upper surface of lower flange of G1 365 3
f: upper surface of lower flange of G2 1244 2
Fig. 2. Photos of girders of the bridge. “W” and “E” witharrow in photos refer to West and East. A: Outside wardsurface of G1. B: Westward surface of G2. C: Eastwardsurface of G1 web. D: Westward surface of G2 web. E:Eastward upper surface of G1 lower flange. F: Westwardupper surface of G2 lower flange. G: Westward edge ofG2 lower flange. H: Under surface of G2 lower flange.
76 Masamichi Takebe et al.
and Cl− are higher than those of Ca2+ and SO4
2−,
respectively. The quantities of Na+ and Cl− on the upper
surface of the flanges range from 200 to 400 mg/m2,
which is approximately twice as high as those on the
webs. The upper surface of the lower flange of G2 is rich
in Ca2+ and poor in SO4
2− relative to those of G1. The
quantity of Na+, Ca2+, Cl−, and SO4
2− on the under surface
of the lower flanges in G2 ranges 70 to 100 mg/m2.
Fig. 4 shows the composition of salt at November 2005
and February, May, and August 2006. The outside web of
G1 did not show significant quantities throughout the
year. The highest quantities of ions on the outside web are
found in February 2006. The quantities of Na+, Ca2+ and
SO4
2− are less than 10 mg/m2, and that of Cl− is 15 mg/
m2. The quantities of Na+, Ca2+, Cl−, and SO4
2- on the
other webs range from 8 to 112 mg/m2, and are high in
February and May 2006 and low in November 2005 and
August 2006. The quantities of Ca2+ and SO4
2− on the
webs are similar to, or lower than, those of Na+ and Cl−,
while quantities of Na+ on the inside web of G1 are
always higher than those on the web of G2. In terms of
electrochemical equivalent units, the inside web surface
of G1 is enriched in Na+ and Cl−, while the web surface
of G2 is enriched in Ca2+ as well as Na+ and Cl− (Fig. 4).
Ca2+ and Cl− on the G2 web surface are especially
enriched in February 2006. In contrast to the other
examined parts, relative composition of ions on the upper
surface of the lower flange in G1 shows little variation
and is similar to that sampled at August 2006 (Figs. 3 and
4). The quantities of Na+, Cl−, and SO4
2− are several
hundred mg/m2 and the quantity of Ca2+ ranges from 39
to 130 mg/m2. These quantities decrease from August
2005 to May 2006. The quantities of Na+, Ca2+, Cl−, and
SO4
2− on the upper surface of the lower flange in G2
range from 10 to 100 mg/m2, which is slightly lower than
those in G1. The quantities of ions on the flange of G2
are high in February 2006 and low in August 2006, and
show distinctive seasonal variation (Fig. 4). The quantity
of Ca2+ on the surface is significantly higher and lower
than that of Na+ at February and August 2006, respectively.
Table 2. Quantities of ions on surface of girders (mg/m2)
Na+ K+ Ca2+ Mg2+ Cl− SO42− NO3
−
a 2.9 0.5 2.0 0.5 1.2 3.5 2.3
b 73.8 5.0 69.0 5.3 103 114 14.0
2005.8c 69.1 4.2 87.4 5.9 104 166 20.6
d 44.6 2.4 152 7.7 162 248 15.2
e 243 18.0 131 26.0 394 249 34.0
f 214 16.5 134 12.5 258 114 14.5
a 3.4 0.3 2.0 0.5 4.7 3.0 2.0
b 29.5 2.3 17.8 1.8 34.8 17.5 3.3
2005.11c 21.4 1.0 19.3 1.5 25.8 27.4 4.5
d 9.6 1.2 17.3 4.1 46.9 14.6 4.0
e 224 19.0 131 17.0 321 258 38.5
f 96.5 7.5 61.0 6.0 70.5 44.5 5.0
a 9.5 0.0 4.1 1.1 15.4 8.0 4.7
b 43.5 0.0 44.8 2.0 76.0 49.5 6.3
2006.2c 44.5 0.0 27.9 2.3 57.5 66.8 8.7
d 39.3 0.0 35.1 3.3 112 43.4 10.5
e 179 0.0 93.0 15.0 234 211 36.0
f 78.5 5.0 123 3.5 163 62.0 9.0
a 3.1 0.1 2.0 0.5 2.8 4.5 3.6
b 23.8 1.0 13.7 1.5 39.1 21.8 4.2
2006.5c 39.4 2.5 22.6 2.2 47.8 38.8 7.9
d 29.4 1.3 25.8 1.7 80.2 32.4 6.3
e 118 6.0 45.5 7.0 142 97.0 37.0
f 34.8 2.5 42.0 2.7 34.1 13.4 1.8
a 2.0 0.0 1.8 0.2 0.8 1.8 1.7
b 15.9 0.0 7.9 0.8 21.7 9.6 3.3
2006.8c 23.9 0.0 14.2 0.9 23.6 27.6 6.6
d 8.0 0.6 8.7 0.7 15.4 9.8 2.6
e
f 16 1.6 19.0 1.6 12.7 7.7 2.7
Estimation of Quantity of Cl− from Deicing Salts on Weathering Steel used for Bridges 77
The Cl− is always the dominant anion on the surfaces.
The quantity of Cl− relative to the other anions is highest
in February 2006.
4. Discussion
4.1. Quantities of salt accumulating over twenty-two
years and over one year
Fig. 5 compares quantities of ions at August 2005 to
the sum of those from November 2005 and February,
May and August 2006. The quantities of ions at August
2005 may result from accumulation of ions over twenty-
two years since construction of the bridge. Ions sampled
at other times had accumulated during the 3 months
between sampling dates, and the sum corresponds to
quantities of ions accumulating over the year from
August 2005 to August 2006. As shown in Fig. 5, the
total values are higher than the quantities at August 2005
Fig. 3. Composition of salts sampled in August 2005. Upper-right case letters refer to the sampling sites (Figure 1B).
Fig. 4. Composition of salt sampled in November 2005, and February, May and August 2006. Upper-right case lettersrefer to the sampling sites (Figure 1B).
78 Masamichi Takebe et al.
in some cases. Considering the period that ions accumulated,
the quantities of ions at August 2005 are so small
compared with the sum. Therefore quantities of ions are
not considered to proportionally increase with the age of
the bridge. The quantity of salt on a girder is considered
to result not only from precipitation of air-born salt but
also from removal of salt from girder. Takebe et al.
(2007; 2008) reported the possibility that rain and dew
remove ions on girders.
4.2. Influence of deicing salt on corrosion
In Izumo, Shimane, Japan, air-born salt from sea
increases in winter (Matsuzaki et al. 2006). In addition,
deicing salts have been sprinkled in this area during
winter. These circumstances are probably the cause of the
high quantities of ions on the bridge in winter (Fig. 4). In
contrast to other parts, the upper surface on the lower
flange of G1 shows a gradual decrease without seasonal
variation. This is potentially because high quantities of
ions and the rough corroded surface caused incomplete
sampling of ions on the surface. Hence, analytical data
from on the lower flange of G1 is omitted in the
following discussions.
The enrichment of Ca2+ and Cl− relative to the other
ions in G2 during winter infers the accumulation of CaCl2of deicing salt on the girder. Cl− is a typical ion affecting
corrosion, therefore researching the origin and quantities
of Cl− on bridges is important to estimate the circumstances
for corrosion of weathering steel. To distinguish between
the contributions of Cl− from sea-salt and deicing-salt on
the girders, we examine the relation between quantities of
Cl− and other ions, such as, Na+, Ca2+, and SO42−.
The proportion of Cl− from sea-salt is potentially
estimated from the quantity of Na+ in the situation where
the deicing salt used in a bridge consists mainly of CaCl2,
because seawater consists mainly of NaCl (Krauskpf and
Gird, 1995). However, the Cl−/Na+ ratio of salts on
bridges in Shimane is generally low relative to seawater,
though quantities of Na+ and Cl− on bridges are positively
correlated (Fig. 6A; Takebe et al., 2005; 2007). Na+
probably originates not only from NaCl of seawater but
also from other compound, for example Na2CO3. Hence,
it is hard to estimate the quantity of Cl− originating from
seawater by Cl−/Na+ ratio of the salt on girders in the
studied area.
While, Takebe et al. (2005; 2007) reported a distinctively
Fig. 5. Comparison of quantities of ions in August 2005 and sum of those in November 2005 and February, May andAugust 2006.
Estimation of Quantity of Cl− from Deicing Salts on Weathering Steel used for Bridges 79
positive correlation between quantities of Ca2+ and SO42−
on bridges on the Izumo plain located more than 2 km
from sea. The correlation line has an inclination close to
a SO42-/Ca2+ ratio of CaSO4 (Fig. 6B; Takebe et al. 2005;
2007), suggesting that Ca2+ and SO42− are present mainly
as CaSO4 on the bridges. Considering that the bridge
examined in this study is located in the center of Izumo
plain, SO42− on the bridge is also attributed mainly to
CaSO4. Assuming that SO42− entirely accumulates as
CaSO4, Ca2+ is present as CaSO4 (Ca2+CaSO4) on the
bridges can be calculated. Fig. 7A shows the correlation
diagram of Cl− and “total- Ca2+ minus Ca2+CaSO4 (Ca2+non-
CaSO4)”. In Fig. 7A, plots of the ion for each examined part
are connected linearly in order of sampling date.
Quantities of Cl− and Ca2+non-CaSO4 on the upper and under
surface of the lower flange of G2 are enriched at February
2006. The enrichment of Cl− and Ca2+non-CaSO4 in February
2006 relative to other sampling dates corresponds to a
Cl−/Ca2+ ratio of CaCl2, suggesting that Ca2+non-CaSO4accumulating on the lower flange of G2 during winter is
ascribed to CaCl2. Considering that CaCl2 is applied
around the bridge in winter as a deicing salt, deicing salt
Fig. 6. Correlation diagrams of accumulating ions on bridgesin Shimane, Southwestern Japan. A: Correlation diagram of
Cl− and Na+ on bridges in Shimane. B: Correlation diagram
of SO42− and Ca2+ on bridges on Izumo Plain and at a
distance of more than 2 km from sea.
Fig. 7. Correlation diagram of Cl- and Ca2+non-CaSO4. A:Diagram for ions from sampling in November 2005, andFebruary, May and August 2006. Plots of the ions fromthe same sampling position are connected linearly in orderof sampling date. B: Diagram for ions sampled at August2005.
80 Masamichi Takebe et al.
is considered to play an important role in quantities of Cl−
on the flange. On the webs of G1 and G2, Cl− is more
enriched than Ca2+non-CaSO4 in February 2006, suggesting
that salt other than CaCl2 also contributes to the
enrichment of Cl− on the webs. Increase in air-born salt
from the sea during winter may be the cause of the
enrichment of Cl− of sea salt on the webs.
In Fig. 7B, quantities of ions sampled at August 2005
are plotted in a correlation diagram of Cl− and Ca2+non-
CaSO4. Except for the samples from the outside web of G1,
the quantities of ions plot along the line with inclination
corresponding to CaCl2, and the web and the upper
surface of the lower flange of G2 are enriched in Ca2+non-
CaSO4 and Cl−. The enrichment in Cl− on the web and
lower flange of G2 is associated with the enrichment in
Ca2+non-CaSO4, suggesting that the accumulation of CaCl2from deicing salt on G2.
Contribution of CaCl2 to the total Cl− is estimated,
assuming that SO42- and Ca2+non-CaSO4 are attributed to
CaSO4 and CaCl2, respectively. The Cl− of CaCl2 Cl−CaCl2accounts for several tens of percents of total Cl− (Fig. 8).
Contributions of CaCl2 to total Cl− on the web and lower
flange of G2 are more than 50 %. The high contributions
of CaCl2 on G2 relative to G1 probably explain why the
rust condition of G2 is more serious than that of G1. The
CaCl2 of deicing salt is probably supplied as droplets
from drainpipe on the slab, and the droplets may splash
G2 by westerly.
In this study, we can evaluate the influence of deicing
salt on the bridge according to the abundance of Cl−
relative to those of the other ions on girders. The method
used in this study can be applicable for other bridges. In
case the bridge that CaCl2 is used as deicing salt, seasonal
variation of the abundance of Cl− relative to those of the
other ions gives us information about the influence of
deicing salt. Knowledge about the general feature of the
composition of salt on bridges around the focused bridge
is also need, in order to depict the feature of the
composition of salt on the bridge precisely. In the case of
this study, the knowledge is Fig. 6.
For the case of a bridge where NaCl is generally
applied to prevent freezing, following method can be
proposed. The method is that CaCl2 instead for NaCl is
tentatively applied to prevent freezing during a winter
season and the seasonal variation of composition of salt
on girders are analyzed. Considering that accumulating
salt is not remained on the girders for many years, even
the tentative approach probably gives us information
about whether the sprinkled deicing salt during winter
accumulates on girders or not (Fig. 5).
5. Summary
The quantities of Cl− from deicing salt on a weathering
steel bridge in southwestern Japan is estimated from the
quantities of Cl− and the other ions on the girders. The
examined bridge is located at a distance of 10 km from
the Sea of Japan. Around the bridge, CaCl2 is applied as
deicing salt during winter. The quantity of ions
accumulating during the twenty-two years since the
construction is less than twenty-two times of the
accumulating quantity during one year, suggesting that
quantities of ions on girders are not proportional to the
number of years since bridges constructed. Composition of
ions on the bridge shows seasonal variation. Larger
quantities of Na+, Ca2+ and Cl− tend to accumulate during
winter. Ca2+ and Cl− on the lower flange of G2 during
winter are enriched by a ratio corresponding to CaCl2,
suggesting that CaCl2 as deicing salt accumulates
abundantly on G2 during winter. The Cl−CaCl2 accounts for
several tens of percent of total Cl−. In particular,
contributions of Cl−CaCl2 to total Cl− on the web and lower
flange of G2 are in excess of 50 %. The greater influence
of deicing salt is reflected by the fact that corrosion is
more enhanced in G2. The method used in this study can
be applicable for other bridges.
Acknowledgments
We thank Mr. K. Shimizu, Dr. H. Kihira, Mr. Y. Fujii,
and Dr. H. Ushioda, Nippon Steel Corporation for
instructive information for starting this study. The quantities
of ions were measured by ion-exchange chromatography,
which was presented by the Geochemistry Laboratory,
division of Earth and Environmental Sciences, Graduate
School of Environmental Studies, Nagoya University. We
express the special thank for researchers in the laboratory.
We especially wish to express gratitude to Ms. P. J. Murrow,
Matsue College of Technology for her patience in
revising the English version of this paper. In Fig. 1A,
Kashmir 3d was used.
Fig. 8. Column chart of quantities of Cl− sampled in August
2005. Contribution of Cl− of CaCl2 to total Cl− is expressed
in each column.
Estimation of Quantity of Cl− from Deicing Salts on Weathering Steel used for Bridges 81
References
Anderson, K., Nelson, S., Mayo, A. and Tingey, D. (2006).
“Interbasin from recited: The contribution of local
recharge to high-discharge springs, Death Valley, CA.”
Journal of Hydrology, 323, pp. 276-302.
Carreón-Diazconti, C., Nelson, S. T., Mayo, A. L. Tingey, D.
G. and Smith, M. (2003). “A mixed ground water system
at midway, UT: discriminating superimposed local and
regional discharge.” Journal of Hydrology, 273, pp. 119-
138.
Hara, S., Miura, M., Uchiumi, Y., Fujiwara, T. and Yamamoto,
M. (2005). “Suppression of deicing salt corrosion of
weathering steel bridges by washing.” Corrosion Science,
47, pp. 2419-2430.
Hefting, M., Beltman, B., Karssesnberg, D., Rebel, K., van
Riessen, M. and Spijker, M. (2006). “Water quality
dynamics and hydrology in nitrate loaded riparian zones
in the Netherlands.” Environmental Pollution, 139, pp.
143-156.
Japan Road Association (2002). Specification for Highway
Bridges, I and II ,Steel Bridge, Maruzen, Tokyo, Japan.
(in Japanese)
Kihira, H. (2005). “Weathering Steel bridge technologies for
eco-conscious future -A frame work and modules of
durability engineering toward risk based minimum
maintenance system-.” Kyoryo-to-Kiso, 8, pp. 441-48. (in
Japanese)
Kihira, H. (2007) “Systematic approaches toward minimum
maintenance risk management methods for weathering
steel infrastructures.” Corrosion Science, 49, pp. 112-119.
Krauskopf, K. B. and Gird, D. K. (1995). Introduction to
geochemistry, McGraw-Hill, Inc. New York, N.Y., USA.
Lipfert, G., Reeve, A. S., Sidle, W. C. and Marvinney, R.
(2006). “Geochemical patterns of arsenic-enriched ground
water in fractured, crystalline bedrock, Northport, Maine,
USA.” Applied Geochemistry, 21, pp. 528-545.
Mason, B. and Moore, B. M. (1982). Principles of
Geochemistry, John Wiley and Sons, New York, N.Y.,
USA.
Matsuzaki, Y., Ohya, M., Ajiki, S., Takebe, M. and Aso, T.
(2006). “A study on corrosion rating process for the
weathering steel bridges with supplemental rust controlling
surface treatment.” Journal of Japan Society of Civil
Engineers, 62, pp. 581-589. (in Japanese)
Matsuzaki, Y., Ohya, M., Ajiki, S., Takebe, M. and Aso, T.
(2007). “Investigation of corrosion condition for weathering
steel brides in Shimane.” Jounral of Structural Engineering,
53A, pp. 805-816.
Miki, T. and Ichikawa, A. (2004). Modern bridge engineering,
Suri-kogaku-sha, Tokyo, Japan. (in Japanese)
Public Work Research Institute-Ministry of Construction,
The Kozai Club, and Japan Association of Steel Bridge
Construction (1993). “Report on Application of Weathering
Steel to Highway Bridges (XX)”. (in Japanese)
Stiff, H. A., (1951). “The interpretation of chemical water
analysis by means of patterns.” Journal of Petroleum
Technology, 3, pp. 15-17.
Takebe, M., Ohya, M., Adachi, R., Ajiki, S., Ota, J., Gan-ei.
R., Kitagawa, N., Furukawa, T., Matsuzaki, T., and Aso,
T., (2008) “Decrease of Accumulating Salt on a Bridge
due to Rinsing with Dew”, Zairyo-to-Kankyo, 57, pp.
188-193.
Takebe, M., Matsuzaki, Y., Ohya, M., Ajiki, S., Furukawa, T.
and Aso, T., (2007). “Study of corrosion level and
composition of accumulating salt on weathering steel
bridges.” Journal of Japan Society of Civil Engineers, 63,
pp. 172-180.
Tsujimura, M., Abe, Y. Tanaka, T., Shimada, J., Higuchi, S.,
Yamanaka, T., Davaa, G. and Oyunbaatar, D. (2007).
“Stable isotopic and geochemical characteristics of
ground water in Kherlen River basin, a semi-arid region
in eastern Mongolia.” Journal of Hydrology, 333, pp. 47-
57.
