Canadian Finishing & Coatings Manufacturing Magazine September/October 2021 - 32

PLATING AND ANODIZING: GALVANIZING
dip galvanizing was not originally intended as an architectural
finish, but this has not slowed the increasing demand for its use in
artistic and sustainable structures looking to incorporate a sleek
aesthetic.
Early to the trend, the architects of the Niagara Falls Butterfly
Conservatory specified hot-dip galvanized steel in 1997 to protect
the conservatory glass support structure and the production
houses used for caterpillar rearing (Figure 5). The coating
durability and longevity attainable by HDG were necessary
for steel components that would be regularly exposed to high
humidity and regular alkaline cleaning.
However, the natural gray appearance of zinc was unable to
provide the architect with the desired color for the conservatory
glass support structure. To achieve a smooth white color without
sacrificing corrosion protection, the galvanized steel was top
coated with a moisture-cured urethane coating system. Many
will specify a " duplex system " of paint or powder coating over
the galvanizing to achieve a specific hue and texture, but a duplex
system also provides improved longevity, 1.5 to 2.3 times the
combined lifetimes of both systems as the result of a synergistic
effect between the coatings.8,9 In its 24-year life, these benefits
have been realized as the conservatory remains home to more
than 2,000 butterflies with minimal steel maintenance. To hear
the architect's thoughts on the specification and performance of
HDG after 20 years, a video interview is available at galvanizeit.
org/butterfly.
While some do not prefer the neutral or weathered gray color
of hot-dip galvanizing, others find the contemporary or industrial
appearance combined with durable corrosion protection to be
desirable. This was the case for the University of Windsor's sevenstory
Newton Parking Structure in 2013 where over 1,400 tons of
steel were hot-dip galvanized and remain in excellent condition.
This comes as no surprise as hot-dip galvanized parking garages
have a 30-plus year history in protecting enclosure panels,
structural
elements,
steel
reinforcement
within
concrete
structures and decking, and even non-structural elements.10
Hot-dip galvanizing was primarily specified for its established
track record and likelihood of no maintenance for 75 years or
more, but the combination of hot-dip galvanized structural steel
with clear and colored glass elements added a rare aesthetic
quality the designers and university found appealing (Figure 6).
Demonstrated successful performance of HDG for parking
structures has led to other high-profile uses like the Montreal
International Airport parking structure relocation (Figure 7).
Hot-dip galvanizing will provide a modernized roof structure and
striking exterior facade to last generations while 400 tons of hotdip
galvanized reinforcing bar protects the concrete ramps and
approaches from road salts entering the parking structure.
Other building structures similarly employ HDG to achieve
a combination of artistic and sustainable structures. As a pilot
project for the Canada Green Building Council's (CaGBC) new
Zero Carbon Building Standard, the use of hot-dip galvanized
steel for the MacKimmie Tower renovation at the University of
Calgary in 2019 addressed both aesthetics and sustainability
(Figure 8). All structural steel and plates supporting the doubleskin
exterior, penthouse floor, and solar roof supports benefited
from the low environmental impact of steel and zinc. Both are
natural, abundant, and infinitely recyclable, so investment in their
use eliminates waste and ensures availability of the materials
for future generations11. Meanwhile, hot-dip galvanizing's
maintenance-free longevity ensures minimal environmental
impact over the life-cycle.
Many specifiers believe the rugged nature of HDG coatings
mean elevated aesthetics cannot be achieved for architectural
features. For projects like the MacKimmie Tower where aesthetics
are a tremendous concern, the coatings of Architecturally
Exposed Structural Steel (AESS) or facades are regularly ground,
sanded, or filed after galvanizing for featured or showcase
elements. To elevate the finish within practical limitations,
additional communication between specifiers, fabricators, and
galvanizers is necessary to achieve the anticipated finish within
budget.
The Canadian Institute of Steel Construction (CISC) Guide
for Specifying AESS and the AGA Specifier's Guide to HotBelow:
Hot-dip galvanizing was specified for the 7th Avenue Light Rail Transit
System in Calgary, Alberta, to achieve a uniform and industrial appearance together
with protection against extreme weather and high traffic.
A duplex system of HDG steel with a moisturecured
urethane coating system was specified
for the Niagara Falls Butterfly Conservatory in
1997 to protect the conservatory glass support
structure.
32
www.cfcm.ca
http://www.cfcm.ca
Canadian Finishing & Coatings Manufacturing Magazine September/October 2021

Table of Contents for the Digital Edition of Canadian Finishing & Coatings Manufacturing Magazine September/October 2021
