Environmental Engineering Reference
In-Depth Information
Figure 1.5.1
Typical composition of hydraulic cement concrete
limestone. To get a measure of the feasibility of producing concrete from
CO
2
, we will estimate the amount of CO
2
we could sequester if all the
aggregate were made from limestone (CaCO
3
) formed from CO
2
.
Carbon dioxide can be sequestered in concrete via the formation of
CaCO
3
. This is accomplished in the presence of water, and various cal-
cium phases such as Ca(OH)
2
and CSH (Calcium Silicate Hydrate), which
are present in concrete. First, CO
2
reacts with water to form carbonic acid:
CO
2
+
H
2
O
→
H
2
CO
3
The carbonic acid will then react with the calcium phases to form
calcium carbonate and water:
H
2
CO
3
+
Ca(OH)
2
→
CaCO
3
+
2H
2
O
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