Page 131 - ICJ Jan 2023

TECHNICAL PAPER COLLECTOR’S EDITION

Table 1. Embodied energy and associated DEMAND FOR CEMENT IS INCREASING
CO emissions Figure 1 shows the projected increase in demand
2
for common construction material [1]
for cement. Most of the increase in the coming
Material Embodied CO 2 decades will be in emerging and developing
Energy (MJ/ (Kg CO /kg)
2
kg) countries, which already make up over 80% of
global production. Today, China’s production
Normal concrete 0.95 0.130
alone exceeds that of the whole world 10 years
Fired clay bricks 3.00 0.22 ago. India is the country in which the increase is

Road & pavement 2.41 0.14 likely to be the largest – today the consumption per
th
capita in India is only 1/6 that in China.
Glass 15.00 0.85
Wood (plain timber) 8.5 0.46 OPTIONS TO REDUCE
ENVIRONMENTAL IMPACT
Wood (multilayer 15 0.81
board)
Cement production accounts for the overwhelming
Steel (from ore) 35 2.8 majority of the CO emissions associated with
2
concrete. Unlike other materials, less than half
(~40%) the CO emitted during cement production
2
Table 1 shows relative figures for the energy is related to fuel and electricity. The remaining
and CO emissions of some common building 60% comes from the decomposition of the
2
materials [1]. Here, typical values for concrete main raw material – limestone, or CaCO . Great
3
are shown, as this is the final product used in the improvements have been made in the last few
field. As discussed elsewhere [2], there is a huge decades in lowering energy-related CO . Today,
2
scope also for reducing the amount of cement in the production of Portland cement clinker is one
concrete and it should always be borne in mind of the most efficient industrial thermal processes
that sustainability can and should be considered in existence (approaching 70% of theoretical
at all stages of the process. The figures in Table 1 efficiency) and it is unlikely that significant further
are per kg and the strength of concrete is not the gains can be made here as discussed in more
same as the specific strength of steel or wood. detail by Gartner [4]. Furthermore cement plants
These issues have been considered by several can now use a wide range of substitute fuels,
authors [e.g. 3]. Nevertheless, the advantages of
concrete remain clear in most construction related
application; even more so when the availability of
materials to substitute concrete is considered. As
an example, although the amount of wood used
worldwide is around one tenth that of concrete,
our consumption of wood is already considered to
be unsustainable; we are cutting down more trees
than we are planting. It follows that, independent
of any other considerations; wood cannot make
a significant further contribution to meeting
the increasing demand for building materials
worldwide.

132 The Indian Concrete Journal | November 2018