SA Affordable Housing March - April 2019 // Issue: 75 | Page 15

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About 1.6 million Chinese citizens die each year from respiratory illnesses linked to small particulate matter emissions, of which 27%
of deaths are related to cement production.
cement production can significantly lower cement factory
power demand.
Among her suggestions is the use of a single pinion kiln
drive with an air clutch and a synchronous motor and roller
presses and roller mills, in pre-grinding instead of ball mills.
Taking this to the next level the Lawrence Berkeley
National Laboratory is investigating electrifying cement
kilns to reduce cement’s immense carbon footprint. While
WWF China has pushed alternate fuels such as waste straw,
used car tyres and municipal waste instead of coal for use in
cement kilns.
There are also a number of innovations in the sector
which attempt to either replace concrete or use less of it
for the same tasks in an attempt to reduce its
environmental impact.
The use of recycled materials in making concrete is
currently finding increasing acceptance within the industry
with aggregate now being extracted from various solid
wastes including fiberglass, glass, granulated plastics, wood
products and old tyres, among others. In that line
Papercrete or fibercrete / fibrous concrete is made by using
waste paper as an aggregate material therefore reducing
the cement, which is marginally more carbon friendly.
Foamcrete is a lighter, aerated, foam-based concrete that
requires less energy to produce. Ceramicrete and glass fibre
reinforced concrete are sold as being twice as strong as
traditional concrete so builders use less of it, though the
actual studies remain inconclusive and Grasscrete is a
method of laying concrete in a chequered, cellular pattern
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that allows grass to grow between the concrete blocks
therefore uses less concrete and improves drainage and
storm run-off.
Perhaps the most promising alternative is a substance
known as Ferrock. Made from waste steel dust, it is normally
discarded from industrial processes and silica from ground
up glass, the iron within the steel dust reacts with CO 2 and
rusts to form iron carbonate. This is fused into the matrix of
Ferrock and, like concrete after it’s dried, it cannot be
melted back into a liquid form but retains its hard, rock-like
qualities.
Initial testing at the University of Arizona suggests
Ferrock may be as much as five times stronger than concrete
and can withstand more compression before breaking.
Whether it is cost effective, or able to scale to need is still in
question, but the substance’s inventor David Stone (yes,
that’s really his name) suggests that even if it is not the
exact answer or the most cost-effective solution in the
long term.
“It’s a promising starting point for developing smarter
technologies that address our insatiable hunger for
development and the devastating result it’s having on
our environment.”
All the technologies are, however, are attempting to
replace cement but no-one has come up with an affordable,
commercial-scale alternative for sand yet, something Beiser
says will be difficult to change.
“We can however be smarter about our access to it and
our usage of it,” he insists.
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