Civil Engineering Reference
In-Depth Information
18
Sulfoaluminate cement
M. A. G. ArAndA and A. G. d e l A T o r r e,
University of Málaga, Spain
DOI
: 10.1533/9780857098993.4.488
Abstract
: Yeelimite-containing, Ca
4
Al
3
o
12
(So
4
), cements are attracting
considerable interest for their inherently low Co
2
emissions during
fabrication, and also because they offer the possibility of tailored properties
and performances in the resulting mortars and concretes. Here, we
initially disentangle the nomenclature and compositions of these cements
and, chiefly, distinguish between yeelimite-rich calcium sulfoaluminate
cements (CSA, Al
2
o
3
content ranging between 30 and 40 wt%) and belite-
rich yeelimite-intermediate (BCSAF, Al
2
o
3
content ~15 wt%) cements,
also known as sulfobelite. Belite-active BCSAF cement may become
an alternative to Portland cement for large-scale structural applications,
although more research is still needed. Clinkering, hydration and durability
issues of pastes, mortars and concretes derived from yeelimite-containing
cements, and their blended cements, are discussed.
Key words
: calcium sulfoaluminate (CSA), BCSAF, yeelimite, Klein salt,
calcium sulfoaluminate, sulfobelite, eco-cements, Co
2
emission reductions.
18.1 Introduction
Calcium sulfoaluminate (CSA) cements are considered environmental
friendly materials since their manufacturing process releases less Co
2
into
atmosphere than that of ordinary Portland cement (oPC) (Sharp et al.,
1999; Gartner, 2004). These binders may have quite variable compositions,
but all of them contain high amounts of yeelimite, also called Klein's salt,
CSA or tetracalcium trialuminate sulfate (C
4
A
3
S
) (odler, 2000). Cement
nomenclature will be used hereafter: C = Cao, M = Mgo, S = Sio
2
, A
= Al
2
o
3
, F = Fe
2
o
3
,
S
= So
3
, T = Tio
2
and H = H
2
Tio2 The label 'eco' is
assigned to CSA cements due to the Co
2
emission savings. Co
2
emissions
from cement manufacturing industry can be classified into two main
categories: those coming from raw materials and those from the operation
processes. The former are easy to be estimated as compositions of raw
material and products are well known (Gielen and Tanaka, 2006; Alaoui
et al., 2007). Table 18.1 gives Co
2
emissions related to the production of
cement components calculated according to the stoichiometry of chemical
reactions, for example, 3CaCo
3
+ Sio
2
Æ Ca
3
Sio
5
+ 3Co
2
. Therefore, the
production of 1 t of oPC clinker composed of 60 wt% of C
3
S, 20 wt% of
488
