Civil Engineering Reference
In-Depth Information
Figure 2.1 shows that the total slag available to the cement market is
expected to increase, from around 180 ¥ 10
6
t/year (2008) to 290 ¥ 10
6
t/year
(2020). humphreys and mahasenan (2002) estimate that BFS intended for
cement production in 2020 will be 123 ¥ 10
6
t/year. a third source (WBCSD,
2009) provides a total BFS of 200 ¥ 10
6
t/year in 2006.
Considering all sources, the availability of blast furnace slag will not
surpass 300 ¥ 10
6
t/year. a probable scenario for 2020 is around 4 ¥ 10
9
t /
year of cement, resulting in a maximum average clinker replacement with
BFS lower than 10%. humphreys and mahasenan (2002) estimate that BFS
will replace a maximum of 7% clinker by 2020. in some places, BFS will
even decrease: according USGS (2010b), annual BFS production, in the
USa, reached a peak of 21.6 ¥ 10
6
t in 2005, but decreased to 12.5 ¥ 10
6
t in
2009. additionally, the potential use of slag in clinker-free alkali activated
cements was explored (Pacheco-Torgal et al. 2008).
a new dilemma into this equation is the allocation of Co
2
to BFS. This
will be a complex issue with several possible options, all giving very different
Co
2
intensity values for the slag (Birat 2011; Chen et al. 2010). The solution
will probably result from negotiation between the two industrial sectors.
There is no obvious interest to develop cements with higher amounts of slag
than the current standardized limits, except where a technical reason might
exist (e.g. heat of hydration or durability) or in places that have localized
surpluses due to logistic restrictions. in general, BFS should be considered
a scarce material that must be explored in a very efficient way.
700
Landfill, slag piles
Glass, fertilizer, slagwool, etc.
Cement and clinker
Internal steelworks recycling
Aggregates, road material, etc.
600
500
400
300
200
100
0
2008
2009
2010
2011
2012
2013
2020
Year
2.1
Forecast for the global use of ferrous slag, 2008-2020 (Smithers
Apex, 2009).
