June 2021 No.92
Japanese Infrastructure Newsletter

IDI

QUARTERLY
Infrastructure

Development Institute—JAPANCONTENTSTAPS - Al-Mg Plasma Arc Thermal Spray Coating for Corrosion Protection

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OCTAS Modeler

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Infrastructure Development Institute – Japan (IDI)
Plaza Edogawa-bashi 3F. 1-23-6, Sekiguchi, Bunkyo-ku, Tokyo, 112-0014, JAPAN
Tel: +81-3-5227-4107 Fax: +81-3-5227-4109 E-Mail: idi17@idi.or.jp Website: http://www.idi.or.jp/en/Infrastructure Development Institute - Japan

TAPS - Al-Mg Plasma Arc Thermal Spray Coating for Corrosion Protection
High durability and low maintenance costs for bridge components in harsh environments
1. Introduction
Kawakin Core-Tech is a top Japanesemanufacturer with more than 70 years ofhistory engaged in the development, design,
manufacture, and sales of seismic devices(seismic isolation and dampers), and structural
bearings, and expansion joints for bridges andbuildings. We are ready to respond to global
needs for safety and reliability, and we lookforward to supporting you in your project.
2. Outline
Components made of steel in bridges
are expected to suffer remarkable corrosion
damage from water leakage if not adequately
protected. This is particularly troublesome forbridge components such as bridge bearings(Figure. 1) since their location complicates
regularinspections
andmaintenance
operations.Moreover, their complex shapes arechallenging to be evenly coated, and any scratchthat occurred during transportation or
installation can easily trigger the appearance ofrust in these damaged areas. This will lead tocontinuous,
labor-intensive,andcostlymaintenance operations that will expand thestructure's life cycle cost.

Corrosion is a process of degradation inwhich the metal is being oxidized by its
surroundings, usually H2 O and O2. As a result,a continuous metal loss and a compound that weknow as rust are formed and deposited on thesurface (Figure. 2).
The most common approach to avoid
the appearance and development of corrosion isto provide a coating layer to physically prevent
water and oxygen from coming into contact withthe steel, and preventing the formation of rust(Figure. 3). Paint coatings follow this approach,but regular repainting is necessary because of
the degradation of the paint caused by its
exposure to wet and dry cycles of direct sunlightand rainwater. When the paint coating is
cracked, rust starts to form, and the expansive
nature of this rust will increase the size of thecrack, accelerating the deterioration process(Figure. 4).
Paint only forms a protective layer, butother technologies have been developed toprovide sacrificial protection that canovercome these disadvantages of paint coatings.
When steel is coated with metals with a higher
ionization tendency than Fe, such as Cr, Zn, Al,or Mg, rust develops faster in the coating andprotects the base material (Figures. 5 and . 7).

Figure-1 Corrosion of bridge bearings
Fe2+ OH-

O2

O2

H2 0

e-

e-

Figure-2 Corrosion mechanism

O2

H20

O2

O2

H2 0

O2

Paint

Paint

Iron / Steel
Figure-3 Paint protection layer

Fe(OH)2

Iron / Steel

Figure-4 Damaged paint coating2

Infrastructure Development Institute - Japan

Corroded coating

O2

H20

O2

H2 0

O2

More reactive metal coating

O2

Metal coating

Iron / Steel
Figure-5 Metal coating

Iron / Steel
Figure-6 Hot-dip galvanizing

A standard anti-corrosion method thatapplies this principle is hot-dip galvanizing. In
this case, the base metal to be protected isimmersed in a kettle containing molten Zn(Figure. 6). Since Zn's melting point is 420 °C,
high strength materials cannot be hot-dip
galvanized because their material strength will
be reduced. In a corrosive environment, Zn willoxidize and form a stable Zn oxide layer thatwill prevent the corrosion of the Fe and coverscratches (Figure. 7), conferring long-term
corrosion protection. However, in marine
environments, this protective coating becomes
extremely porous, unstable, and it is easily
washed away. Consequently, corrosion isdeveloped, degrading the base material after ashort period of exposure.
Due to the need to develop a durable,easy-to-use and cost-effective method to protect
bridge steel components in harsh environments,
a study group formed by professionals in thefield was established in 2013. They have held
activities to develop a patented method toprotect steel girders, bolts, bearings, and otherbridge components against corrosion. This new
Japanese technology (Transfer Arc Plasma
Spraying or TAPS🄬) is based on melting andspraying a wire of Al-Mg alloy onto a metal
surface using a plasma arc spraying method.

Figure-7 Sacrificial protection

3. Detailed Description
Al
and
Mg
have
excellentcharacteristics to be used for protective coatings.
However, due to their high melting point(higher than 600 °C), it is costly to melt themand apply them as Zn is used in hot-dip
galvanizing. Furthermore, high temperatures
can affect some materials creating distortions
and strength degradation. TAPS proposes theapplication of Al and Mg through plasma arc
thermal sprayingto make the most out of these
two metals' excellent corrosion protection
characteristics. This is a process in which a
modified gas or electric arc welding equipment
equipped with compressed air is used to melt
and project a metal wire onto a steel surface(Figure. 8)(1) Main features of TAPS(a) Long-lasting anti-corrosion protection.
The accelerated corrosion tests withsalt spray carried out on steel plates, nuts andbolts highlight the excellent anti-corrosion
performance of TAPS which can be six times
more durable than the performance of hot-dip
galvanizing
methodundermarineenvironmental conditions. (Figure. 9). In thetest, specimens were treated with different anticorrosion coatings, i.e., heavy-duty anti-

Figure-8 Al-Mg plasma arc thermal spray application

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Infrastructure Development Institute - Japan

Figure-9 Results of accelerated corrosion tests performed in steel plates and bolts

Figure-10 Application of TAPS on bolts
corrosion paint coating, Zinc hot-dip galvanizedcoating and Al-Mg thermal sprayed coating.
The test pieces were then inserted in achamber where they underwent wet cycles, i.e.,
the test pieces were sprayed with water and salt
and endured humid cycles and dry cycles thatwere switched automatically to simulatemarine environmental conditions.
After approximately 9 months (6,000
hours) of exposure in the accelerated test, rust
was observed in the cross-cut areas of the steel
plate test pieces coated with heavy-duty paintcoating and in the hot-dip galvanized bolts andplates.
On the other hand, test specimens
coated with Al-Mg plasma arc thermal spray
showed a highly stable protection layer during
the whole duration of the accelerated test.
Apart from this, the results of a series of outdoor
exposure tests, which were conducted in Japan,
Vietnam, or Myanmar, also highlight theexcellent anti-corrosion properties of the test

Figure-11 TAPS application equipment
specimens treated with Al-Mg Plasma Arc
Thermal Spray after years of exposure.
(b) Applicable in high-strength bolts,
including the thread.
The temperature of the molten metal
applied to the base material is not high. Thus,
TAPS is an anti-corrosion method that can beapplied to high-strength materials, such as
high-strength bolts (Figure. 10), without
creating strength degradation or distortions.
Kawakin can also apply this coating evenly tothe threaded part.
(c) Applicable on-site
The necessary equipment to apply
TAPS on steel components is compact andportable (Figure. 11) and can be used at aconstruction site. This makes TAPS an
appealingtechnology
forrepairandmaintenance projects.

4Infrastructure Development Institute - Japan

Figure-12 Application of TAPS on bridge bearings

Figure-13 TAPS application on expansion joints
4. Scope of application
performance is directly linked to the stability
Al-Mg Plasma Arc Thermal Spray is aand serviceability of the structure. TAPS
Japanese technology used to protect different
prevents deterioration of these components
steel bridge members, including steel girders,even in harsh environments, leading to safer,bridge bearings, expansion joints, and highmore reliable, and more resilient structures forstrength bolts.
an extended amount of time.
5. Anticipated Results(1) Long durability of steel components even inharsh environments.
Compared to conventional coatings,
the superior anti-corrosion protection capacityof TAPS provides more durability to steel bridgecomponents located in marine areas. Based ontheaccelerated test results explained before, ,the expected durability of TAPS in marine
environments could be around 100 years.
(2) Lower life cycle costs
Steel components treated with TAPS
have a longer life cycle, and thus, direct andindirect costs related to repainting andmaintenance operations are greatly reduced.
This leads to significantly lower life cycle costsof the bridge structures.
(3) Safer infrastructures
Bridge bearings and expansion joints
are critical bridge components since their

6. Record of implementation
The Al-Mg Plasma Arc Thermal Spraytechnology is an anti-corrosion coating with anextensive track record of applications in Japan.
NEXCO, i.e., a company that manages theJapanese highway network, has officiallyadopted this technology in its design andconstruction standards for the anti-corrosion
protection of bridge bearings.
Apart from Japan, TAPS has also been
applied in essential bridge projects in Asia andAfrica due to its capacity to prevent theappearance of rust in steel bridge members
located in harsh environments. Some of theseproject references are summarized in Figure 14.
In most of the selected examples of theseapplications, the bridges were typicallylocated in a marine environments where highconcentrations of airborne salinity wereobserved. In these projects, the application of5

Infrastructure Development Institute - Japan

Figure-14 TAPS project references
TAPS in the steel components of both rubberand steel bridge bearings, and expansion joints,brought incredible benefits such as theextension of life cycle for bridges and the
reduction of the life cycle costs.
7.Conclusion
Corrosion is one of the mostdetermining factors affecting the deteriorationof bridges, especially in those viaducts locatedin marine environments. Therefore, providing
durable anti-corrosion protection coatings forcritical steel components of bridges is of great
importance to ensure the durability andserviceability of these structures.
TAPS is a Japanese technology developed toprovide exceptional corrosion protection bymelting and spraying Aluminum-Magnesium
alloy wire onto a metal surface using a plasmaarc spraying method.
The extensive experimental testing andapplication track records on bridge bearingsand expansion joints highlight the benefits ofthis anti-corrosion coating, specifically its:•

High-durability: Six times more durable
than
conventionalanti-corrosion
coatings in marine environments.
• Wide range of applications: Applicableto high-strength bolts, including thethreaded part.
• Cost-effectiveness:The
superior
durability will lead to remarkably lower
life cycle costs of the bridge.
8.Contact Information
Please contact us for further
information on TAPS or other of our bridge
devices and technologies using the contact
information below. Our engineers and businessprofessionals will be happy to assist and provide
guidance in all stages of your project.
•
•
•
•
•
•
•

Company: Kawakin Core-Tech Co., Ltd.
Department: Int. Business Department
Job title: Int. Business Development
Manager
Person in charge: Javier Lopez
E-mail: info@kawakinkk.co.jp
Tel: +81 48 259 1117
Web: www.kawakinct.co.jp/english
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Infrastructure Development Institute - JapanOCTAS Modeler
1. What is OCTAS Modeler?
The OCTAS Modeler is a compact BIM
platform with three-dimensional visualizationand modeling functions for geological andgeotechnical models. It stores and manages
geological survey data, geological interpretation
data, geological and geotechnicalrisk information, and attributes informationsuch as readable data, which can be utilized insubsequent construction processes (Figure.1).
This platform aims to visualize
geological and geotechnical risks that have aserious impact on infrastructure construction
projects, sharing risk management information,and passing on the geological and geotechnical
BIM (Building Information Modeling) data to
the next project phase.

Figure1:Various functions of OCTAS Modeler

2. Background of the development
Geotechnical engineers need to provide
reliable geological and geotechnical models at
the key stages of the infrastructure life cycle,
specificallyatthestagesofSurvey/Design/Construction/Maintenance for
an infrastructure. These models include
highly specialized information that is
professionally handled in two-dimensional
drawings and documents.
In response to the expansion of theinternational BIM market and efforts toimprove the productivity of society as a wholethrough digitization technology, projects using“BIM for Infrastructure” are increasing inJapanese construction market.
Using BIM data in construction
projects provide advantages when sharing
information among various stakeholders andobtaining a prompt consensus. In addition, theexchange of three-dimensional CAD data isuseful for improving practical productivity.
Handling geological and geotechnicalinformation in BIM is causing inevitablechanges in the way both information is sharedand inherited, which has been dependant on
previous two-dimensional drawings anddocuments.
In order to respond to these changes in
the construction environment and fulfill needs,"OCTAS Modeler" has been developed as athree-dimensional geological and geotechnicalmodeling and management system.
Since many of the important structures,such as urban infrastructure and large plants,
are built in plains (open fields), "OCTASModeler"targets
high-demand
threedimensional geological and geotechnical models
constructed on plains.
3. Development concepts
The development concept of OCTASModeler is shown in Figure. 2. In thedevelopmental process, we aimed to carry out
these followingobjectives.
①. Visualize ground information using asimple procedure
7②. Centralize the management of groundinformation③. Make important data sustainable④. Share the same information among
stakeholders⑤. Reducing the costs for updating modelwith additional ground information
In order to evaluate the quality of threedimensional geological and geotechnical models,
it is necessary to refer to geological survey
information, i.e. the fact data, used to construct
the model
together with the geologicalinterpretation information that shows theconcept of modeling.
In addition, the visualization of geological andgeotechnical risks and related attributes,
together with the models themselves,areimportant for prompt technical decisions.

Infrastructure Development Institute - Japan
In order to save man-power in the processof constructing
and updating the threedimensional geological and geotechnical models,
it is necessary to cut down the procedures formodeling, and to update work by adding andreviewing the new data in a short period of time.
For complex geological and geotechnicalmodels such as faults, folds, and cracks inmountainous areas, as well as groundclassification and landslide models, werecommend the use of "GEO-CRE", anotherproduct of ours, due to its advanced modeling
functions (Figure 3).
Thethree-dimensional
geologicalandgeotechnical models created by GEO-CRE isexported as CAD data, then imported into the
OCTAS Modeler for the following use.

①Visualize ground information using a simple procedure・Three-dimensional geological and geotechnical models can beconstructed using simple procedures・Flexible vision in three dimensions from various perspectives
・Superimpose a three-dimensional CAD data structure model・Three-dimensional geological and geotechnical models can be used as
CAD data.
・It is possible to create a cross section or extract data at any location.
・Possible to output cross section using two-dimensional CAD
data.
・Point cloud data obtained by drawing can be overlaid and displayed.

②Centralize the management of ground information
・Available as a compact geological and geotechnical information database
・The quality of the ground information can be recorded, so the reliability of the threedimensional ground model can be understood.
・The BIM for Infrastructure attribute information can be recorded (can be extended if
needed).

③Make important data sustainable
・Open formats are adopted for ground information and three-dimensional groundmodel data.
・Information regarding three-dimensional geological and geotechnical models
can be passed on to the post-process.

④Share the same information among stakeholders
・Providing authority to various viewers for free who are able to access thegeological and geotechnical information and three-dimensional geologicaland geotechnical models
・The same project file as the OCTAS Modeler can be reproduced⑤Reducing the costs for updating model with adding ground information
UPDATEDISCOUNT

・Existing geological information can be quickly reused
・Reduces the time and cost of updating the three-dimensional
geological and geotechnical models

8Infrastructure Development Institute - Japan
Figure 2:Development Concept of OCTAS Modeler

Figure 3: Roles of OCTAS Modeler

Table 1: Software Function Comparison
Main Functions

GEO-CREOCTAS Modeler

OCTAS Manager

3D visualization

✔

✔

✔

3D geological and geotechnicalmodeling✔

✔

Only browsing

Boring columnar view
Input

✔

✔

Only browsing

GIS

-

✔

Only browsing

Cross section creation and 2DCAD output

✔

✔

✔

Project Management

✔

✔

✔

Attribute information
management-✔

Only browsing

4. Main features(1) Data management function
All data are classified into each data
category and stored in a predeterminedhierarchical folder by the project management
function. The geological information handled,thethree-dimensional
geologicalandgeotechnical models, and their attributeinformation files are written in an open
format so that various construction
information system platforms can use them.
For the time being, the attributeinformation related to the three-dimensional

geological and geotechnical models is recorded
in an external reference file due to the BIM
data exchange standard for the ground not
being established yet.
"3-D Geological and GeotechnicalModelsInheritance
Sheet
(URL:
https://www.3dgeoteccon.com)" is employed as
the external reference file.
For geological and geotechnical risk
information, it is stored as a document file,such as a pdf file in the project folder and isdisplayed by using the link on the screen.
(2) Modelling function
9

The modelling function allows todevelop various three-dimensional models byusing simple procedures such as the geologicaland geotechnical model, bearing stratum
model, soil compartment model, soil strength
model and the groundwater table model.
BS-Horizon is employed to interpolate
a surface, and IDW (Inverse Distance
Weighting) is used as a three-dimensional
interpolation algorithm for the voxel model.
The interpolation algorithm suite can beextended in the future.
(3) Basic Function
The interface consists of threedimensional viewers and minimal set offunction buttons and operation panels. The
operation panel has a simple GIS function, aInfrastructure Development Institute - Japan
monitoring function, a preview screen, and adata view function that enables retrieval andextraction of time series data (Figure.4) andmonitoring data (Figure.5).
The walkthrough function is a
simplified VR that is capable of visualizing athree-dimensional data model through user's
eyes (Figure.6). Moving the viewpoint along awalk-through path is also possible.
You can edit, display, and print
geological logs as a function of “editing groundinformation”. You can also create crosssectional views of various models and output
them into two-dimensional CAD crosssections.

Figure 4: An example of a visualization of time series data10

Infrastructure Development Institute - Japan

Figure 5: Visualization of monitoring data and an example of retrieval and extraction

Figure 6: An example of a walkthrough display of ground laser point group data11

Infrastructure Development Institute - Japan

Figure 7:An example of a visualization of 3D geophysical survey data
(4) Visualization function
Three-dimensional visualizable data
formats (format extension) are as follows.
•
Log data (*.xml http://www.calsed.go.jp/mg/wpcontent/uploads/guide_bor4.pdf)•
Geophysical exploration data (*.inp(Figure.7)
https://www.cybernet.co.jp/avs/documents/pdf/support/avsexpress/ucd_ascii.pdf)•
Topographic data (*.csv)•
Surface model and voxel model (*.csv)•
Colored point cloud data (*.txt, *.las(Figure.6))•
Three-dimensional model with texture(*.wrl)•Geological model created by othersoftware (*.dxf)•
Measurement/monitoring data (*.csv)(5) Delivery, inheritance and sharing of data
The dataset of OCTAS Modeler isdelivered to clients and stakeholders withOCTAS Manager, which is the free viewer
version of the OCTAS Modeler. The OCTASManager can be issued from the operation
panel of the OCTAS Modeler.
When only limited three-dimensionalmodel data are delivered, a compressed filecan be used. This file can also be encrypted forenhanced security.
5. Future prospects
In order to make OCTAS Modeler aconvenient communication tool in BIM for
infrastructure that is suitable for integrated
management of geological information, threedimensional modeling, and information sharing,
we are continuously improving and expanding
the various functions of the OCTAS Modeler.
The development of the English language
interface of the OCTAS Modeler is also
underway.

[Contact Information]
OYO Corporation
Engineering Headquarters Research and Development Center
Group Manager
Syoichi Nishiyama
EMAIL: nishiyama-shoichi@oyonet.oyo.co.jp
HP: https://www.oyo.co.jp/

12About IDI and IDI-quarterly
Infrastructure Development Institute-Japan (IDI) is a general incorporated
association operating under the guidance of Ministry of Land, Infrastructure,
Transport and Tourism of Japanese Government.
IDI provides consulting services to facilitate international assistance to developing
countries, to promote international exchange of information and human resources,
and to support globalization of project implementation systems targeting bothdeveloped and developing countries in the field of infrastructure.
IDI has been publishing a free quarterly journal called “IDI Quarterly” since1996 to
introduce information related to public works and construction technologies
developed in Japan, to foreign countries. We have distributed the journal toadministration officials in more than 90 countries around the world via e-mail.
It will be highly appreciated if you could send us your opinions, impressions, etc.
regarding the articles.
We also welcome your specific requests regrading technologies you would like to
see on following Quarterly issues.