project - Trademax Publications

concrete
Concrete’s vital
sustainable role now
recognised
Appreciating the sustainability of concrete as a building material is proving to be
increasingly important as the global concern about environmental preservation
continues, according to Daniel van der Merwe, architect at the
Cement & Concrete Institute (C&CI).
Van der Merwe says although concrete is the most
commonly used building material in the world, much
of what it can offer as a sustainable material is
overlooked.
“Materials specification must play a critical role to reduce
the embodied energy in a building. Materials manufacture
also needs to be factored in terms of measurable emissions,
energy and finite material consumption. Buildings must now be
constructed with a longer lifespan in mind, with the emphasis
on durability and retrofitting rather than demolition,” he states.
Van der Merwe says the cement and concrete industry has
committed itself to responsible manufacturing. It has managed
to boost production while decreasing the use of raw finite
materials, while the use of cement extenders has significantly
reduced the clinker portion
in certain cement products.
“Cement producers have already
reached 50% of the set target of
the Department of Minerals and
Energy which calls for a 15%
reduction of energy consumption
by 2015. Through the use of
alternative fuels and resources –
including hazardous waste and
scrapped tyres – as a fuel source,
further reductions are possible.”
“New permeable concrete pavers, soil erosion blocks and
embankment stabilising blocks save water and prevent storm
water run-offs and flooding; and self-compacting concrete in
sustainable developments allows for architectural achievements
previously regarded as impossible.
“Moreover, new research is producing exciting data on the reabsorption
of carbon dioxide by hardened concrete.
A Danish study has found that 50% of the volume of concrete
will be ‘carbonated’ over 70 years of any building’s service
life.
This sponge effect makes concrete a more green choice than
previously thought. And it emphasises how global sustainability
can be achieved with concrete,” van der Merwe added.
The fitting of bag house filters, or
electrostatic precipitators, is further
reducing particulate emissions;
and chemical admixtures are
helping to reduce the cement and
water content in concrete mixes.
Through lightweight void form
precast hollow-core slabs, the
volume of in-situ concrete is also
being substantially reduced.
Concrete buildings offer unparalleled durability, says the C&CI
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SA Affordable Housing November/December 2009