Page 251 - Challenges in Corrosion Costs Causes Consequences and Control(2015)

CORROSION CONTROL OF BRIDGES 229

TABLE 4.15 Summary of Costs and Life Expectancy for New Construction Corrosion
Control
Bar Cost Increase in
Weight Per Comparison Estimated
Cost of Per Deck Deck to Baseline Percent Service
Practice Bar $1 kg kg/m 2 $1m 2 $1m 2 Increase % Life Year
Black steel 0.44 26.4 11.60 NA – 10
(baseline)
2-layer 0.66 26.4 17.40 5.80 1.2% 40
epoxy-coated
rebar
2-layer solid SS 3.85 26.4 101.64 90.04 18.6 75–120
bar
2-layer SS clad 1.54 26.4 40.66 29.00 6.0 50
bar
Calcium nitrite – – – 5.40 1.1% 30
Silica fume – – – 4.30 0.9 20

high-strength steel strands in the ducts also has been developed. A combination of
impact-echo and magnetic-based technique allows the inspection of posttensioned
systems reducing the likelihood of any sudden collapse of posttensioned bridges.
Continued development of these techniques will lead to increased reliability,
accessibility around trumpet locations, and resolution.
Table 4.15 gives the costs of new construction alternatives for bridge structures.

4.9.1.7 Rehabilitation The following is a summary of current practices in reha-
bilitation technologies (16).
Rehabilitation is achieved by overlays such as latex-modified concrete, low-slump
concrete, high-density concrete, and polymer concrete. They are commonly used for
the rehabilitation of bridge decks. This procedure extends the life of a bridge deck by
about 15 years. Impressed-current CP systems on bridge decks are now a routine reha-
bilitation technique because of the cooperative research with industry and states in the
development of durable anodes, monitoring devices, and installation techniques. Tita-
nium mesh anode, used in conjunction with a concrete overlay to distribute protective
current, serves as a durable anode for use in impressed-current CP of reinforced con-
crete bridge decks and widely accepted by state and other transportation agencies.
Several promising sacrificial anodes such as thermal-sprayed zinc, thermal-sprayed
Al–Zn–In, zinc hydrogel, and zinc mesh pile jacket have been developed for use in
CP of substructure members especially in marine environments. Industries in some
states in cooperation with FHWA carried out some developments and identification
of some anodes suitable for impressed current CP of inland concrete structures.
Significant advances have been made in the technology of CP of prestressed
concrete components through extensive fundamental research and evaluation of
CP systems that have been installed. Concerns about a loss of bond between