January/February 2023 - 95

increasingly important step in any
project design process. LCA can assess
the carbon impact of a product from
raw material extraction through
materials processing, manufacture,
distribution, use, repair and maintenance,
and disposal or recycling. This
" cradle to grave " approach helps to
identify the best options for any given
project to yield a long-term structure
with the lowest CO2 impact possible.
LCA tools and sophistication will
naturally grow and evolve over time,
perhaps more quickly than in past eras,
so designers will need to stay educated
on this front to ensure they are using
the most accurate available tools.
S imi l a r t o t he Su s t a i na b l e
Development Goals set forth by the
United Nations, many of the solutions
included in the PCA's roadmap are
products, technologies and approaches
that already exist today. The intent is
that by bringing together collaborators
across the entire value chain, the
cement and concrete industry will
begin to shift mindsets and increase
awareness and adoption of these
solutions to enact near-term benefits.
Other solutions are not yet available but
are possible with the right policies and
research to accelerate their development
and deployment.
The Engineer's Role in Carbon
Reduction
To achieve the ideals of sustainability
and carbon neutrality, our nation's
infrastructure must also be reliable,
resilient and durable. Consequently, to
truly achieve sustainable infrastructure,
all civil and geotechnical engineers
involved in foundations for
structures must adjust their traditional
approach to material selection, design
and construction practices to include a
focus on minimizing a project's carbon
footprint. Again, the significant
influence that these engineers have on
projects provides an important
opportunity to affect positive change,
and there are a broad range of concrete
GWP in Kg of CO2e per Cubic Yard
for 3,000 psi (20.7 MPa) Concrete Mixes
300
250
200
150
100
50
238
205
187
169
186
169
152
100%
Cement
20% Fly
Ash
30% Fly
Ash
GWP of concrete mixtures with varying SCM contents
Similar to the Sustainable Development Goals set forth
by the United Nations, many of the solutions included in
the PCA's roadmap are products, technologies and
approaches that already exist today.
solutions and approaches where
geotechnical engineers have the
opportunity to make positive decisions
to reduce the carbon footprint of
foundations.
Portland-Limestone Cement:
Specifiers should ask for blended
cements in their concrete mixes where
supplementary cementitious materials
(SCMs) are used to replace a portion of
the portland cement in a mix. These
blended cements can make concrete
more economical, increase strength
and durability, and positively influence
both fresh and hardened properties.
These blended cements also contribute
to sustainable const ruct ion by
conserving natural resources and
lowering energy consumption and
emissions. Since 2012, U.S. cement
producers have been manufacturing a
blended portland-limestone cement
(PLC) found in ASTM C595 as Type IL.
Because PLC is engineered with a
higher limestone content than ordinary
portland cement (OPC) per ASTM C150,
it can reduce the carbon footprint of
concrete by up to 10%. With numerous
research projects documenting its fresh
and hardened properties, PLC concrete
can be eas i ly impl ement ed by
specifiers through a simple change to
project specifications to allow a Type IL
cement without affecting the work of
contractors or builders.
Supplementary Cementi tious
Materials: Increasing the use of SCMs
in a concrete mix is an excellent option
because materials including fly ash,
slag and silica fume (microsilica) are
waste byproducts from other industrial
processes, and their beneficial reuse for
geotechnical applications not only
avoids disposal of these materials in a
DEEP FOUNDATIONS * JAN/FEB 2023 * 95
40% Fly
Ash
30% Slag
Cement
40% Slag
Cement
50% Slag
Cement
January/February 2023

Table of Contents for the Digital Edition of January/February 2023
