Civil Engineering Reference
In-Depth Information
quite large ones 0.70-0.80 (Winnefeld and Barlag, 2009; lura et al., 2010;
Winnefeld and lothenbach, 2010; Winnefeld et al., 2011). However, the
most frequently used ratios range from 0.5 to 0.6 (Bernardo et al., 2006;
Valenti et al., 2007; Gastaldi et al., 2007; Alesiani et al., 2008; Telesca et
al., 2011; Buzzi et al., 2011). Finally, there are studies varying this critical
ratio. For instance, Chen et al. (2012) studied water-to-binder ratios of 0.30,
0.45 and 0.70.
on the other hand, the variability of the water-to-cement mass ratio in
BCSAF cements is much smaller. Most studies used W/C = 0.5 with more
variability in the amount of sulfate carrier. For instance, W/C = 0.5 and 10
wt% of C
S
was initially reported (Adolfsson et al., 2007; Janotka et al.,
2007). G. S. li et al. (2007) used W/C = 0.5, and 8 and 12 wt% of C
S
H
2
,
for mortars and pastes, respectively. recently, Morin et al. (2011) studied
the hydration reactions of AeTHer
TM
using a W/C mass ratio of 0.5 and
5.3 wt% of C
S
. Aranda et al. (2011) also used a W/C ratio of 0.5 but adding
10 wt% of C
S
H
2
. Finally, Juenger and Chen (2011) used W/C = 0.45 and
variable amounts of sulfate carriers.
18.4.3 Admixtures
To the best of our knowledge, there is little work on the role of additions like
blast furnace slag or pulverized fly ash to partly replace CSA and BCSAF
cements. We can highlight two works blending yeelimite-containing cements
with mineral admixtures like fly ash, silica fume, and blast furnace slag to
study pozzolanic reactions (Zivica, 2000, 2001). Unfortunately, the water-
to-cement mass ratio used was quite small (ranging between 0.32 and 0.41),
hence, full hydration of the pastes did not take place. on the other hand,
the beneficial effects of limestone filler with CSA cement have been very
recently reported (Pelletier-Chaignat et al., 2012). The hydration reactions
have been studied for a fixed W/C mass ratio of 0.8, but two C
S
H
2
/CSA
mass ratios (0.19 and 0.40) and two temperatures (5 and 20 °C) were tested.
The compressive strengths were higher for limestone than for the same level
of substitution with an inert filler (quartz in this study).
There is also a situation where the waste to be safely disposed within
concrete may also help as an addition which influences the hydration reaction.
Municipal solid wastes were blended with CSA and the compressive strength,
pore structure, hydration phases, and leaching behavior of Zn and Pb were
characterized (Qian et al., 2008).
18.4.4 Uses of CSA cements to stabilize wastes
Intermediate-level and low-level radioactive wastes are usually encapsulated
in blended oPC cements containing high amounts of blast furnace slag or
