Examples of HDG Applications 62
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Examples of HDG
Applications
62
Power distribution
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Hot dip Galvanized electricity
transmission towers
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Hot dip galvanized electricity
transmission poles
Power distribution
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Hot Dip Galvanized anchor bolts
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Power distribution Sub-station (using hot dip galvanized steel for
every component)
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Power distribution
Small fixtures (brackets, clips, straps)
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Power distribution Transformers
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Power distribution facilities
HGD cable
protection shield
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Closer view
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Electricity generation and distribution is a
critical part of a nations
infrastructure.
Reliable corrosion protection is vital.
This is why the power sector chooses
galvanizing.
Telecommunication infrastructure HDG towers
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Transportation Road & highway infrastructure
HDG safety barriers HDG lighting poles
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Transportation Road & highway infrastructure
HDG traffic signal support structure
HDG signage support structure
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Transportation Road and highway water drainage using HDG steel gratings
Transportation Road and highway water drainage using galvanized culverts (drainage tunnels)
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Transportation HDG road bridges
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Built in 1986 No corrosion after 25 years
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Transportation
HDG pedestrian bridges
Steel structurals are HDG +
paint top-coated for appearance
Pedestrian bridge
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Transportation HDG barriers to prevent rock-falls or landslip
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HDG security fencing
Fencing and railings
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HDG safety railings
Fencing and railings
HDG railings on concrete
stairs
Fencing and railings
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HDG enclosures
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Fencing and railings
Building construction
HDG for steel scaffolding is now required by law in some countries (eg. Japan & Singapore)
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Building construction (industrial) HDG steel framing
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Building construction HDG internal framework
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Building construction
HDG cable trays
Building construction
HDG walkways
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Building construction (residential)
HDG balcony structures
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Corrosion of painted stairs
Building construction
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Building construction
HDG stairs
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Building construction
HDG access and emergency scape ladders
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Building Construction HDG water storage tanks
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Marine environments
Painted
HDG
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Marine environments Comparative performance of conventional
Paint vs HDG
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Marine environments Marine facilities (eg, ports) use HDG extensively
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Marine environments
HDG
Marine environments
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Example showing industrial construction close to seawater. (Formosa Plastics Mai Liao plant, Taiwan)
Marine environments Example showing industrial construction close to seawater. (Formosa Plastics Mai Liao plant, Taiwan)
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300,000 tonnes HDG steel used in construction
HDG for architectural &
artistic applications
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Indoors use of HDG in
a modern residence
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Architectural applications
Modern roofing designs using
HDG steel + paint top-coat
Architectural applications
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HDG steel artistic structure in building lobby
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Public park walkway (1 kilometre length) showing use of HDG steel for artistic purpose
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Elevated “forest” walkway combines functionality with
appearance. All the steel structure
is HDG
Architectural design
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Protecting steel reinforcement
(rebar) in concrete structures
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Because fresh concrete is alkaline (high pH) it reacts with the rebar surface to form a a corrosion resistant “passivation” surface layer
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Rebar surface Passivation layer
Concrete
Over time, O2, H2 O, CO2 can slowly migrate into the concrete via porosity. In marine environments,
salt (chloride) can also penetrate the concrete
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O2 H2O CO2 Cl-
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CO2 migrating into concrete reduces its alkaline content. The is termed concrete “carbonation”
As the alkalinity reduces, the rebar surface loses its protective surface passivation layer The rebar is then vulnerable to corrosion as moisture and oxygen penetrate into the concrete
Effect of CO2 entering into concrete
Since the volume of rust is greater than the volume of corroded steel, tensile stresses are generated in the concrete, causing
the concrete to crack 113
Effect of steel reinforcement corrosion
Concrete spalling
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Effect of steel reinforcement corrosion
Cracks eventually reach the concrete surface. As corrosion spreads
pieces of concrete may break away (“spalling”)
Example of indoors repair being undertaken on a concrete roof exhibiting extensive rebar corrosion. The building is located in Bangkok
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Example of rebar corrosion on an office building
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Example of rebar corrosion
on a car parking structure
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At sufficient chloride levels in the concrete, the natural alkalinity of concrete is not able to form the protective passivation layer on the rebar surface The rebar is then at high risk of corrosion if moisture and oxygen penetrate into the concrete, and chloride accelerates the corrosion
Effect of salt (chloride) permeation into concrete
Examples of rebar corrosion in the severe marine environment
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Examples of rebar corrosion in the severe marine environment
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Examples of rebar corrosion in the severe marine environment
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Hot-dip galvanized steel reinforcement
in concrete
“Protecting your investment”
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Galvanized steel reinforcement products
Straight bars
Welded mesh
Stirrups and ties
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Cages
Technical benefits of galvanized rebar compared to un-coated rebar
Complete resistance to the effects of carbonation in concrete
A significantly increased resistance to the
effects of chloride-induced corrosion.
An increase in service life of the concrete of at least 4-5 times
Cost savings due to reduced concrete cover over rebar without reducing concrete durability
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Typical applications for hot dip galvanized rebar
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Structures located in marine environments (submerged tunnels, sea-walls, wharves, jetties, pontoons) Buildings with areas that are frequently wet due to water remaining for long periods of time (bathroom floors, some parts of balconies and concrete roofs) High visibility prestigious structures where even rust staining will be a problem
Underground tunnel or foundation structures in water permeable soils where there is also an elevated presence of chlorides/sulphate salts (eg, in reclaimed land areas)
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The following slides show some examples of the
use of HDG rebar
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Galv Rebar Case Study: Sydney Opera House
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Galv Rebar Case Study: Sydney Opera House
Galv steel reinforcement used in the pre- cast concrete roof sections and the concrete sea-wall
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Galv Rebar Case Study: Sydney Opera House
• 200t HDG rebar used.
• HDG cost was only 4% of contract price for the concrete walls
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Galvanized Rebar Case Study: Intercontinental Hotel, Sydney, Australia
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Deep Tunnel Sewerage System Project Location: Singapore Project: 2 x 5 km long steel reinforced concrete tunnels positioned on the sea-floor for transporting and discharging treated sewerage (from Changi water treatment plant) Singapore government required 100 years service life
Galv Rebar Case Study
Completed concrete pipes ready for laying on sea-floor. 10,000 tonnes galvanized steel reinforcement used
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Galv Rebar Case Study: DTSS (Singapore)
Galvanized reinforcement cages
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Galv Rebar Case Study: DTSS (Singapore)
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HDG coatings are damage resistant. No special precautions are required during transportation, site storage or usual handling conditions
FBE coatings are more susceptible to damage due to their softer nature (eg, abrasion damage during on-site rebar placement)
Technical comparison of Hot Dip Galvanized (HDG) rebar vs
Fusion Bonded Epoxy (FBE) coated rebar
For more information on Hot Dip Galvanizing please visit the
websites www.galvanizingasia.com www.gaa.com.au www.galvanizeit.org
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Thank you
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