+IMPACT MAGAZINE ISSUE 22

WATER
MATERIALS
relatively low-cost way to conserve water and save money.
Pressure-reducing valves, also known as PRVs, can be set
on the main water line to reduce water pressure, while
still maintaining adequate flow. These valves have the
added benefit of expanding the lifespan of the pipes. Many
corporate green buildings have showers for employees to
use if they have cycled to work; once again, the utilisation
of low-flow shower heads can increase water efficiency.
3. Think before you flush
As many as 40% of toilets are older models with a syphonflushing
system that holds between 9 litres to 15 litres of
water and drains the entire cistern for each flush. Waterefficient
sanitaryware, such as hold-flush toilets, can result
in substantial savings, both in water and cost. Newer, more
efficient models, which are used in green buildings, can
reduce the number to about six litres per flush, through
design changes that implement gravity and air pressure
to remove waste from the toilet without having to use as
much water. A hold-flush system is another water-efficient
variant that lets the user control the flush volume – as soon
as one lets go of the toilet handle it will stop flushing. This
can save more than 50% of the flushing volume. Other
options include waterless urinals, which, while viable,
When presented with information,
people tend to have a greater incentive
to reduce consumption.
are not that popular because they require the addition of
a specific liquid. A low-flow urinal seems to be a better
compromise at this stage.
4. A drought-proof garden
Many green buildings are leading the way with
“xeriscaped” gardens – landscapes that are water-wise
due to the way in which they are designed, as well as in the
choice of plants used. The practice reduces maintenance
costs as well as water utility bills, and has a
number of other additional benefits. These
include a minimised demand for fertiliser,
as xeriscaping encourages the use of organic
soil, which can in time reduce pollution on a
wider scale. Green buildings place a big focus
on incorporating nature into their spaces,
due to the proven benefits of biophilia (the
connection that exists between humans and
nature).
Landscape architects are able to design
spaces that make use of indigenous plants,
which naturally require less water, while still
ensuring a lush feel. Green walls and other
innovative designs are helpful in “bringing
the outdoors indoors”.
5. Grey is the new black
Green buildings are renowned for their rainwater
harvesting techniques, as well as the use of grey water
and recycled water. While these water sources are not for
drinking, they can be used in a variety of ways, from flushing
toilets and doing laundry, through to basin water. With the
use of non-potable water, a building’s residents can reduce
their dependency on municipal supply, and also get them
involved in the process of learning more about water
treatment, reuse, and the benefits of using treated water
for daily non-consumption purposes. Provided that no
harsh chemicals have gone into the water, grey water can
also be effectively used to water plants and keep “living
walls” alive.
While the building industry is responsible for a large
percentage of water use, the fact that green buildings have
invested substantially into being water-wise has had the
positive impact of making these water-saving features
become more mainstream. Costs have been reduced, and,
most importantly, the average mindset is moving away
from one where water is seen as being an eternal supply
available in abundance, to the more accurate view that it
needs to be carefully conserved for future generations.
Hannes Meyer, Cementitious Executive
at AfriSam.
As part of its three-decade sustainability journey,
AfriSam has over the years championed the use
of extenders to reduce clinker content in its
composite cements. Through its Vanderbijlpark,
Gauteng-based slagment operation, the company has
pioneered the use of blast furnace slag, a by-product of
the steel industry, to promote more sustainable products
in the market.
The use of extenders in AfriSam’s composite cements
has over the years resulted in a substantial reduction in
its clinker factor without compromising the quality of
products. Blast furnace slag, a by-product of the steel
industry, remains central to the company’s efforts to
substitute clinker in its products.
MORE CLINKER SUBSTITUTION,
LESS EMISSIONS
Since 2008, the South African cement industry has
seen a year-on-year reduction in emissions per ton
of cement, largely driven by the increased focus on
clinker substitution. According to the Association
of Cementitious Material Producers (ACMP), clinker
substitution rose from 12% in 1990 to 23% in 2000 and
to a substantial 41% in 2009. The industry is pressing for
a 60% rise by 2030.
Over the years, AfriSam has accelerated its efforts to
substitute clinker through the development of composite
(extended) cements. In 2000, the company launched Project
Green Cement to increase the use of extenders to promote
more sustainable products. The use of extenders, says
Hannes Meyer, Executive Cementitious at AfriSam, has
resulted in a substantial 20% reduction in the company’s
clinker factor since 1990.
Composite cements, he explains, contain not only clinker,
but other cementitious materials such as pulverised fly ash
AfriSam’s Slagment operation was established in 1955 had has
supplied product to many flagship projects such as the Gariep Dam.
AFRISAM CHAMPIONS THE USE OF
SLAG TO REDUCE CLINKER FACTOR
(PFA) from coal-fired power stations and ground granulated
blast-furnace slag (GGBS) from steel-making plants.
GGBS has been used in the manufacture of cements
since the second half of the 19th century. Back then,
the practice was to intergrind the blast furnace slag
with clinker. However, in the 1950s, AfriSam’s slagment
operation pioneered the use of separately ground slag for
the construction industry.
LEADING THE WAY
The use of this product has grown steadily in South Africa,
with AfriSam among the frontrunners. The company’s
slagment operation plays a crucial role in the production
of its composite cements. Established in 1955, the plant
was previously owned by three companies, before AfriSam
acquired 100% shares in 2004. The raw material is sourced
from steel producer, ArcelorMittal South Africa, which is
strategically located some few metres away from the plant.
Blast furnace slag has good cementitious properties,
providing enhanced strength and durability. By evolving its
chemical and mechanical activation methods, AfriSam has
achieved a more reactive product allowing the company to
progressively replace more and more clinker while retaining
high cementitious quality and strength performance.
“Re-using waste products from other industries reduces
the amount of limestone that we have to mine and clinker
that we have to produce, thus reducing carbon emissions
from those processes, as well as minimising waste to
landfill,” says Meyer. “We are therefore constantly searching
for new extenders and additives to further reduce our
carbon footprint and our impact on the environment at
large. The end result is less clinker produced per ton of
each final product, resulting in less CO₂ generated from
our operations.”
AfriSam has reduced its carbon emissions by
33% since 1990.
The company was the world’s first construction
materials supplier to carbon footprint all its production
operations, including cement, aggregate and readymix.
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