Belay Zeleke Dilnesa - Eawag-Empa Library

CHAPTER 2 MATERIALS AND METHODS
Table 1 Oxide and the phase composition of the cements used.
OPC HS OPC HS
CEM I 32.5 R CEM I42.5 N CEM I 32.5 R CEM I42.5 N
a Chemical analysis (g/100g) (g/100g) b
Phase composition (g/100g) (g/100g)
SiO2 20.34 17.55 C3S 53.5 60.0
Al2O3 5.17 4.58 C2S 18.0 5.1
Fe2O3 3.09 7.2 C3A 8.5 0.0
CaO 63.38 60.34 C2(A,F) 9.4 21.9
MgO 2.53 1.98 CaSO4 2.5 2.7
K2O 0.91 1.02
c
K2SO4 1.5 1.5
Na2O 0.2 0.33
c
Na2SO4 0.2 0.2
SO3 2.41 2.67
d
K2O 0.1 0.2
CO2 0.12 0.73
d
Na2O 0.1 0.2
TiO2 0.32 0.53 CaO(free) 1.2 -
Mn2O3 0.06 0.07 CaCO3 0.8 -
P2O5 0.25 0.34
d
MgO 2.5 2.0
Cl 0.03 0.073
d
SO3 0.2 0.3
Loss of ignition 1.01 3.24
a
XRF data corrected for ignition loss.
b
Calculated from the chemical analysis.
c
Estimated based on the alkali content and on the alkali distribution given in Taylor (1987).
d
Present as solid solution in the major clinker phases
2.1.7. Synthesis of synthetic Fe-cement
In addition, the hydration products of Al-free synthetic cements were investigated. The
clinker composition of the synthetic Fe-cement consisted of 78.5% C3S, 19.3% C2F,
0.5% Na2SO4 and 1.7 % K2SO4. The alkalis were added to mimic real Portland cement.
No Al-phases were present to allow the identification of Fe-containing hydrates.
The synthetic cements were hydrated in the presence and the absence of calcite and
gypsum with a liquid/solid ratio of 1. Different quantities of gypsum and calcite were
added while the ratio of C3S to C2F was kept constant (Table 2). The phase assemblage
was investigated after 3 days and 3 months. The results from the studies were compared
to those from studies on the synthesized phases [10-14, 19] and the studies in OPC
systems [21-23, 33-35].
17