CPI - February 2011 - Working with Ductal® UHPC

Concrete Plant International
North America Edition
FEBRUARY
20111
SPECIAL PRINT | CONCRETE TECHNOLOGY
Working with Ductal Ultra-High Performance Concrete
SPECIAL PRINT
CPI 01/11

CONCRETE TECHNOLOGY
Lafarge North America, T2W 4Y1,Calgary, Alberta, Canada
Working with Ductal Ultra-High Performance Concrete
Introduced to the world in the mid-90’s, Ductal ® Ultra-High-Performance Concrete (“UHPC”) has come a long way. With its unique combination
of ductility, strength, durability and aesthetics, precast elements can have thinner sections and longer spans that are lighter, more grace ful
and innovative (compared to conventional concrete). Highly moldable, it replicates form materials with amazing precision. Compressive
strengths reach up to 200 MPa and flexural strengths up to 40 MPa, providing improved durability and impermeability against corrosion,
abrasion and impact. Furthermore, it is sustainable. UHPC structures are expected to have an extended service life, resulting in less environmental
impact over time.
The purpose of this article is to help precasters learn about Ductal UHPC and the potential opportunities that exist through production of innovative
products and solutions that compliment their existing precast products and businesses. The following article is an introduction to UHPC
and the first in a series of related articles that CPI will publish in future issues.
Vic H. Perry, Peter J. Seibert, Lafarge,
North America
As one of the pioneers in Ultra-High
Performance Concrete (UHPC), Lafarge
worked closely with Bouygues in the early
90’s to explore new possibilities in ad vanced
concrete technologies. After ten years of
research, they produced an innovative
material with unique technological performances.
The main principle of this technology
is based on systematic elimination of inherent
weaknesses associated with conventional
concrete. The ductile behaviour of this
material is a first for concrete, with the
capacity to deform and support flexural
and tensile loads, even after initial cra -
ck ing. These performances are the result of
improved micro-structural properties of the
mineral matrix, especially toughness and
control of the bond between the matrix and
the fiber.
Today, Ductal is a family of UHPC products.
Two types of fibers are used to make Ductal
Sanderling Drive Pedestrian Overpass, Canada
products: high carbon metallic or poly-vinyl
alcohol (PVA) fibers. The fiber and chemical
formulation is customized to best fit the
application requirements. When selecting a
Ductal product, determining factors include
strength, ductility and rheology requirements,
exposure to corrosive agents, desired
aesthetics and exposure to human contact.
The optimization of granulars, the fibers
and admixtures provides a very low porosity
in a cement-based mineral granulometric
matrix. The premix components consist of
granular material with a diameter less than
1 mm, and a highly reduced water-cement
ratio (less than 0.25, depending on the type
of Ductal formulation). Elimination of
coarse aggregates, along with the granular
gradation and fiber aspect ratio, facilitates
a high fiber content and isotropic dispersion.
There is almost no carbonation or penetration
of chlorides and sulfates and a high
resistance to acid attack. Its superior durability
characteristics are due to a combina -
tion of fine powders, selected for their relative
grain size and chemical reactivity. The
net effect is a maximum compactness and a
small, disconnected pore structure. Ductal
has almost no shrinkage or creep, making it
very suitable for prestressed applications.
The use of this material for construction is
simplified through the elimination of reinforcing
steel and its ability to be virtually
self-placing or dry-cast.
Overall, Ductal solutions can offer advantages
such as speed of construction, im -
proved aesthetics, superior durability and
impermeability against corrosion, abrasion
and impact – which translates to reduced
main tenance and a longer structural life
span.
Over the years, Ductal has been subjected
to a significant amount of rigorous testing
and field trials. In the USA, Canada,
France, Japan and Australia, several offi -
cial documents now prescribe Ductal for
building, infrastructure, manufacturing,
artis tic and industrial designs. Today, this
material is used for a variety of applications
such as bridge beams and decks, joint fill,
solid and perforated wall panels/facades,
urban furniture, louvres, stairs and floors,
pipes, piles, marine structures and others.
Target markets
Ductal has been used successfully by many
precasters in ways that compliment their
existing businesses. Due to its advanced
characteristics (compared to conventional
concrete) including durability, strength,
reduced weight and aesthetics, Ductal has
opened the door to new opportunities for
precasters in the structural and architectural
markets.
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CONCRETE TECHNOLOGY
Vic H. Perry received his Bachelor of Civil Engineering with Distinction in 1978 and Master of Applied Science
in Structural Engineering in 1984 from Dalhousie University in Nova Scotia, Canada. In 1999, he was bestowed a
Fellow of the Canadian Society for Civil Engineering (CSCE) and elected President of the CSCE in 2010. Since 1997,
Vic has been involved in the development of Ductal (UHPC), initially as Director of Marketing (Ductal) for the
Lafarge Group in Paris, France and since 2001, as Vice-President & General Manager Ductal, Lafarge North
America, in Calgary, Canada.
Vic.Perry@Lafarge-na.com
Peter J. Seibert obtained his Bachelor of Civil Engineering from the University of Toronto in 1996, a Masters in
Civil Engineering from Queen’s University, Kingston, Ontario in 1998 and an MBA from Wilfrid Laurier University,
Waterloo, Ontario in 2003. Based in Calgary, Canada, Peter is the Technical Director for Ductal (UHPC), responsible
for the manufacturing, supply chain, quality control and technical aspects of Ductal throughout North America
since 2006.
Peter.Seibert@Lafarge-na.com
to their design efficiency, fast installation
and low initial costs. However, the standard
grouting material in the joints is often the
first part of the bridge to fail due to contin -
uous highway impacts causing the joints to
leak. Recent applications of in-field casting
of Ductal in the joints have resulted in the
joints being the strongest link in the precast
bridge system. This concept creates new
opportunities for precasters who can now
offer a new solution for bridge owners by
utilizing their existing precast product offer -
ing in combination with Ductal. Manufac -
turing of deck panels or box girders in a
precast plant results in high quality concrete
elements and, when combined with Ductal
joint fill, the precaster will be able to offer
an innovative, extremely durable, high quality
bridge deck for the bridge owner and
the general public.
The Atrium, Canada
Structural market
According to the Federal Highway
Administration (FHWA) National Bridge In -
ven tory (NBI) Study, approximately
156,000 bridges in the USA are structurally
deficient or functionally obsolete. State,
provincial and municipal engineers are seeking
new ways to build better bridges, there -
by reducing maintenance costs that are
diverted from capital budgets required for
building much needed highways and
bridges. Therefore, the FHWA launched a
program, “The Bridge of the Future”, to
help drive new solutions for building
bridges.
Implementation of new technologies in the
bridge sector has been a long journey due
to the conservative nature of this segment.
Highway bridge engineers, bestowed with
guardianship of the public money and safety,
have always demonstrated the technology
before using it. In many applica tions,
prototypes were manufactured to test and
validate the bridge design concept. In addition,
new bridge sections and solutions
have been developed in North America.
One of the best Ductal UHPC applications
which utilizes existing precast products for
the bridge market involves a unique joint fill
solution for precast deck panels or precast
box-girders. Historically, these elements were
preferred by owners for bridge systems due
Precast Ductal waffle panels also take
advantage of the material’s high durability
aspects. For this design concept, full-depth
precast deck panels must be 8“ (200 mm)
to ensure deck stiffness, leaving a 2.5“ (62
mm) uniform deck with 5.5“ two-way ribs.
The precast panels are then jointed togeth -
er in the field using Ductal joint fill. In 2010,
the Iowa Department of Transpor tation
requested UHPC waffle deck panels for a
bridge project with UHPC joints.
Innovative, new bridge girder sections
made with UHPC have been developed in
recent years. In particular; the pi-girder
(with a cross-section that resembles the
Greek symbol, “π”), resulting in a com -
bined section of girder and built-in precast
deck. The first bridge to use these UHPC pigirders
was installed in North America in
2009. This highly optimized girder section
may also open new opportunities for precasters.
To date, Ductal has been used for three
pedestrian bridges in Canada where the
architecture of the structure was the main
driver (besides strength and durability).
Examples of other structural elements that
have been produced in Ductal UHPC are
piles, pipes and protective cladding systems
for infrastructures in marine environ -
ments. For each of these applications, precasters
were able to use and slightly modify
their existing plant equipment and formworks
in order to offer a more optimized
precast section which utilizes the material’s
strength and durability characteristics.
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CONCRETE TECHNOLOGY
Ductal waffle deck panel, USA
Jakway Park Bridge pi-girders, USA
Architectural market
Due to Ductal’s plastic and hardened prop -
erties, plus the elimination of rebar, pre -
casters can achieve complex, architectural
shapes that are extremely durable, cost
effective and require little maintenance. The
material replicates textures, form and shape
with high precision and can be produced in
a range of long-lasting colours. This material
works well for new, innovative concrete
applications and supports new trends in
architecture: purity of line, delicacy, enhance -
ment of texture and mineral bias.
With Ductal, precasters can offer new, innovative
building envelope solutions for creative
architects. For instance: structural, decorative
perforated facades in mesh or lattice-style
designs; ultra-thin, lightweight panels
with large surface areas and perforation
rates that exceed 50% and full facades
with complex shapes, curvatures and tex -
tures.
Ductal has also been used in a variety of
urban furnishings. Because of its strength
and minimalistic use, impact resistance,
dura bility and low maintenance requirements,
it is an excellent alternative to traditional
materials. New sculptures, benches,
bollards and street furnishings have been
added to product offerings of traditional
precast manufacturers. As well, interior
designers and precasters may also create
new, contemporary, lightweight, coloured
and textured products such as chairs, stairs,
and tiles for floors and walls.
Business Plan for UHPC Applications
For manufacturers to successfully commercialize
precast elements using Ductal, a
business plan for the proposed solution
must be developed and validated. Once
precasters understand the material’s technical
properties, they may seek “problems that
require a solution” which, in turn, must be
validated by an economic analysis (compared
to current alternatives).
When looking at the pricing structure for
UHPC, precasters should keep in mind that
a new, innovative solution with superior
technical characteristics will result in a very
different look and size compared to elements
produced with alternative/traditional
Thiais Bus Shelter, France
Shawnessy LRT Station, Canada
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CONCRETE TECHNOLOGY
materials such as wood, metals or conventional
concrete. The economics of the entire
innovative solution must be validated; it is
not simply a unit price comparison.
Ductal, like metals or conventional concrete,
has a wide range of products with a
range of unit selling prices but is used in different
ways. The range in unit price is be -
tween concrete and metals and, when used
in an optimized manner, it provides solu -
tions that are extremely durable and cost
competitive. Comparing UHPC with ready
mix concrete which is sold in North Ame r -
ica between $100/m 3 to $180/m 3 , cost
can vary from $2,500/m 3 to $4,500 /m 3 ,
depending on the formulation within the
UHPC family of products for various applications.
This pricing structure also varies in
different markets and regions around the
world.
This pricing comparison may seem interesting
however, when buying various types of
steel, an order of magnitude of $8,000/ m 3
for black steel and $30,000/m 3 for stainless
steel is evident. This clearly shows that
the entire economics of the finished UHPC
solution (including material costs, manufacturing
costs, distribution costs and market
economics) must be considered when
reviewing the pricing structure which should
not be based on unit pricing of materials. It
is higher priced when compared with conventional
concrete but the volume of material
required is greatly reduced and it provides
many superior results/benefits and
cost effective solutions that conventional
concrete cannot.
Development of the business plan also
requires that precasters review their distribution
and promotion strategies since they are
the experts when it comes to understan ding
the local markets, accessibility and market
tolerance. In addition, they will de velop
their own value proposition for any new,
innovative solutions. After the business plan
has been completed, prototypes of the proposed
solution must be tested, opti -mized
and certified. Successful UHPC commercialization
relies on the above business strategies,
in order to create continuous production
and sales.
Commercial and technical partnership
with precasters
Ductal UHPC is a full-fledged technological
solution that creates new opportunities for
precasters to develop and expand their
area of expertise and business. In order to
use the material for a specific application,
the precaster must first obtain a Ductal sublicense.
Then, Lafarge will provide support
and necessary training which will allow
them to gradually master the technology
and commence production of a profitable
solution. For many Ductal projects or product
applications, the experts at Lafarge can
also facilitate important liaisons be -tween
the precaster, owners, engineers, archi tects
and academics worldwide.
For many new, innovative applications, prototype
testing is required, therefore Lafarge
provides guidance based on previous
experience and product applications. By
taking advantage of the material’s technical
characteristics, precasters can optimize
a new, innovative UHPC solution with a
design, size or texture that will be very different
compared to alternative products
made with traditional materials.
For a successful partnership, Lafarge contributes
its materials expertise and commer -
cial know-how, while the precasters provide
their technical skills in the industrial process
and knowledge of their desired markets.
The success of innovative projects requires
regular study and development of original
processes. Hindsight and Lafarge's experiences
with the many different Ductal applications
and products allows them to pro -
vide the best guidance and suggest innova -
tive methods for using the material.
Future Articles in CPI
Lafarge will publish several articles on
UHPC in future issues of CPI, on the follow -
ing topics:
· Equipment and production techniques
using Ductal
· Manufacturing of UHPC structural
products
· Manufacturing of UHPC architectural
products
· Manufacturing of UHPC artisan products
FURTHER INFORMATION
Museum of Modern Art, France
Lafarge North America
10655 Southport Road SW., Suite 1200
T2W 4Y1,Calgary, Alberta, Canada
T +1 403 271 9110
F +1 403 278 7420
ductal@lafarge-na.com
www.ductal-lafarge.com
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