Chemical Engineering September 2015 - 20

Buss-SMS-Canzler
Your partner in developing new
products and processes
sustainableconcrete.org) and the
American Concrete Institute's (ACI;
Farmington Hills, Mich.; www.concrete.org)
sustainability committee.
" Concrete is not 'plain Jane' anymore
- by applying the tools of modern
science and engineering, the concrete
industry has drastically expanded concrete's
performance, aesthetic appeal
and its impact on the environment, "
she explains.
Improving durability, increasing specialization
and softening environmental
impact all require better-understood,
more highly engineered concrete products.
Effective concrete admixtures
and thoughtful concrete mix designs
are critical in obtaining desired properties,
Grace's Myers says. The industry
is responding within a number of
areas, from new cement chemistries
and more complex concrete mix designs,
to less labor-intensive methods
of concrete application that utilize selfconsolidating
concrete.
Thin Film
Dryer
Continuous contact drying of
liquids, slurries, sludges and
pastes.
Recycled materials
The concrete industry is heavily focused
on reducing its environmental
footprint by promoting sustainability
intitiatives that include minimizing energy
use, reducing emissions, conserving
water, minimizing waste and
increasing recycled content.
The increased use of alternative raw
materials, such as recycled aggregates
for concrete, and supplemenwww.sms-vt.com
We
live process engineering
and special manufacturing
Buss-SMS-Canzler GmbH
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20
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ChemiCal engineering www.Chemengonline.Com september 2015
tary cementitious materials for cement
- the material that binds concrete together
- has become a key strategy,
explains Lafarge's Buffenbarger. For
example, old concrete from demolished
buildings or pavement is being
crushed and recycled as aggregate
material for new concrete to save
natural resources. Researchers are
also investigating other recycled materials,
including ground glass from
recycled bottles, crumb rubber from
tires, plastics, fibers, recycled asphalt
pavement and mineral and inert fillers
as alternative raw materials for concrete,
Buffenbarger says.
Using concretes with higher levels of
recycled materials helps contribute toward
credits in the LEED (Leadership
in Energy and Environmental Design)
rating system, Grace's Myers notes.
While comprising only 7-15% of
concrete's volume (Figure 1), cement
Portland Cement Assoc.
Figure 1. Cement is a component of concrete that
binds together gravel and sand
is responsible for high greenhouse-gas
emissions due to an energy-intensive
process and liberation of CO2 during
production. Along with improvements
in cement manufacturing equipment
and increased use of alternative fuels,
the use of alternative raw materials in
cement production, and substituting
alternative materials into clinker (the
product of the cement-making process),
are helping to lower the CO2
and energy impact of cement.
Blended cements are those that
combine traditional portland cement
with supplementary cementitious materials,
including fly ash, slag cement
(ground blast-furnace slag) or silica
fume - all waste products from other
industries. By using higher levels of
waste materials and therefore lower
amounts of portland cement, CO2
emissions can be lowered.
Efforts are also aimed at developing
admixtures that can help enable
higher proportions of blended cement
to be used, so the level of portland
cement can again be reduced.
Although there has been considerable
work on optimizing the use
of flyash, slag and silica fume in cement,
these are considered " traditional "
supplementary cementitious
materials. More recently, researchers
and concrete industry players have
expanded their search for alternative
recycled materials to see what roles
they could play in new concrete formulations,
Buffenbarger says. These
include calcined shale, ash from municipal
solid waste, rice husk ash and
a host of others, she says.
http://www.sustainableconcrete.org http://www.con http://www.crete.org http://www.sms-vt.com http://adlinks.chemengonline.com/56201-05 http://www.Chemengonline.Com
Chemical Engineering September 2015

Table of Contents for the Digital Edition of Chemical Engineering September 2015
