zA Case of Utilizing Results

Realization of a Safe and Secure Society

Trial Application of the Partial
Repainting Manual for SteelBridges (Draft)
TAMAKOSHI, Takashi, Head HOSHINO, Makoto, Senior Researcher
Bridge and Structures Division, Road Department(Keywords) Steel bridge, local corrosion, repainting, durability
1. Background and purpose
On many steel road bridges, severe paintdeterioration and corrosion occurs at ends of girders
and parts of other members exposed to harsh corrosion
environments 1), and if corrosion on a supporting part
important for load-bearing capacity advances to anextreme degree, even if only within a narrow range on
the part, there is a danger of the corrosion severely
impacting the performance of the bridge (Photo 1).
Although general items regarding repainting methods
are specified in, for example, the “Painting andCorrosion-proofing Manual for Steel Highway
Bridges (Japan Road Association, December, 2006)”,
technical methods for partial repainting, which isdifficult to perform with guaranteed high execution
quality, have not been established, and there is fearthat it is dangerous to leave local paint deterioration,
which advances rapidly, until the deterioration of theentire paint membrane has advanced to the point
where overall repainting is performed.
Thus, technology to partially repaint narrow parts
such as the ends of girders on existing road bridges(referred to below as, “partial repainting”) has beendeveloped, summarized as technical manual, and trial
application of it has been carried out on an MLITT

Photo 1. Example of Girder Edge of Main Girder Showing
Local Corrosion

IKUTA, Koichi, Research Coordinator

operated bridge.
2. Outline of the partial repainting manual (draft)
The following items are main technicalcharacteristics of the partial repainting manual (draft).
Ԙ To develop a method of ensuring sufficientsurface preparation quality on parts whereexecution conditions are spatially harsh, a test
execution was done using full-size specimens
taken from a bridge which was removed to set
execution specifications based on the combined
use of open blast and machine tools.
ԙ Because a weak point of executing partial
painting is the paint quality along the boundarywith the old paint film which has not beenrenewed, based on existing knowledge and theresults of a trial execution, a painting system
which considers recoating width and otherexecution specifications plus the adhesiveness ofthe new and old paint films was established.
Ԛ In order that rational and economical partial
painting can be done, precautions required whenplanning painting, conditions under which partial
painting should be studied, and methods ofrecording an execution for maintenance purposes
and other standards have been prepared.
And a final version of this manual (draft) has been
prepared by confirming its applicability in the field
through a trial execution at an actual bridge (Photo 2).
3. Trial application on an existing bridge
The trial application of this manual (draft) is now
beginning on MLITT operated bridges, and in thefuture, follow-up surveys of these applications of themanual and of the trial execution specimens duringcontinuous exposure testing will be carried out andreflected in the revision.
[References]1) Survey Research on Local Corrosion of SteelBridges, Technical Note of the NILIM, No. 294,
January 2006
http://www.nilim.go.jp/lab/bcg/siryou/tnn/tnn0294.htm

Photo 2. Trial Execution on an Actual Bridge