Concrete future - Concrete Mix Design, Quality Control and Specification - page 285

quality and innovation, and improving construction practices. Some have
become very cynical about sustainability because it can be more “spin”
than substance and “spin” will not provide for the needs of humanity.
However, if we all work to remove the various impediments to the sustain-
able use of concrete, this wonderful material can be used to its full potential
in the service of mankind.
13.2 SUSTAINABILITY
Boudewijn M. Piscaer
The Pantheon in Rome demonstrates that concrete can be a highly
sustainable material for a multifunctional building of almost 2000 years
old. There is no such building in wood or metal. For fire resistance and now
also for heat storage/exchange, concrete has an important role to play for
sustainable living.
A “green” concrete that is not durable is not sustainable. Around 50%
of durability failures in concrete are due to poor installation, 30% engi-
neering design error and 20% poor mix. Most congresses and organisa-
tions focus on the 30 and 20% at an academic level. But do we include the
installers and those who use the concrete?
Depending on the process roughly 1 ton ordinary Portland concrete
(OPC) equals 1 ton of CO 2 , which equals 1.6 tons of raw materials (600 kg
lost as CO 2 into the atmosphere through calcination). In 2012 this amounts
to 3.3 billion tons of CO 2 per year and 2 billion tons of raw materials lost
by calcination. If we continue to produce concrete the same way as we do
now, CO 2 from Portland cement could increase 260% by 2050 due to the
increasing demand for concrete in the developing world. If most energy
production will have been converted from fossil fuels to renewable sources,
Portland cement could account for up to one-third of the global CO 2 output
if we do not take action.
On average, 10 tons of aggregates are used per capita per year. Energy for
production can vary from 3 kWh to 8 kWh per ton. Transport of aggregates
has a considerable impact on society as well. In some mega cities, it has to
come 200 km by truck. Availability is in some countries under pressure and
this will result in using more nonconventional recycled materials.
From experience we know that more sustainable concrete does not have
to cost more. Reducing the environmental impact of concrete goes hand in
hand with improving social conditions, such as training plus increasing the
prosperity of all involved in the industry and beyond. The primary task is
to learn how to do more with less. Since Portland cement has the greatest
environmental impact in concrete, the key objective of independent pro-
ducers is to reduce its use. As we learned from high-temperature-resisting
refractory concrete, when you use less of a critical ingredient, it has to be of