Civil Engineering Reference
In-Depth Information
18
16
BCF-8 days
BCF-30 days
BCN1-8 days
BCN1-30 days
BCN2-8 days
BCN2-30 days
BSC1-8 days
BCS1-30 days
BCS2-8 days
14
BCS2-30 days
12
10
8
Non-pozzolanic area
6
4
Pozzolanic area
2
0
35
40
45
50
55
60
65
70
75
80
85
90
95
100
Hydroxyl ion concentration (mmol/l)
6.1
Treatment results for pozzolan cement pastes at 8 and 30 days in
40 °C (acc. EN 196-5).
left for 8 days in a sealed plastic bottle in an oven at 40 °C. it should be
noted that the number of days spent in the oven can be increased depending
on the pozzolans. After the above-mentioned times, samples are vacuum
filtered through a 2.7 mm nominal pore size filter paper and allowed to cool
to ambient temperature in sealed Buchner funnels. The filtrate is analysed
for [oh
-
] by titration against dilute hCl with methyl orange indicator and
for [Ca
2+
] by ph adjustment to 12.5, followed by titration with 0.03 mol/l
EdTA solution using Patton and Reeders indicator (donatello et al., 2010;
Pourkhorshidi et al., 2010a, b).
Results are presented as a graph of [Ca
2+
], expressed as equivalent Cao, in
mmol/l versus [oh
-
] in mmol/l. Test results lying below the curve (see Fig.
6.1), indicate removal of Ca
2+
from solution which is attributed to pozzolanic
activity. Results lying on the line indicate zero pozzolanic activity and results
above the line correspond to no pozzolanic activity. it should be noted that
this procedure assumes no other source of soluble calcium is present in the
system, as leaching of calcium would invalidate this approach (donatello
et al., 2010; Pourkhorshidi et al., 2010a, b).
6.3.5 Saturated lime test
The saturated lime method is similar to the Frattini test, wherein the pozzolan
is mixed with saturated lime (slaked lime; Ca(oh)
2
) solution instead of cement
and water (donatello et al., 2010). Measurement of the residual dissolved
calcium shows the amount of lime fixed by the pozzolan. During cement
hydration, Ca(oh)
2
is precipitated; however, in the presence of pozzolan
Ca(oh)
2
reacts with the pozzolan, and this allows more solid Ca(oh)
2
to
