Page 11 - report P Lemoine feb 2013c

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being deemed statistically significant for p-values< 0.05.

The sample Y fired is ~ 1.6 times stiffer and ~ 3.4 times harder than Y as rec. These

results are consistent with other investigations on the effect of PowerCem additives,

showing an increase in flexural and compressive strength upon additive
5
concentration.

random positioning

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8
Hardness, GPa 6 4

2

0
Y asrec Y fired Y N2 Y acid no Y asrec

Figure 6: Bar chart of the Hardness (H) values for random positioning for Y as rec, Y
fired, Y acid, Y N2 and no Y as rec.

The table presented in figure 7 shows that this result is statistically significant (p-
value<0.05), however the coefficients of variation (COV=stdv/mean value) are huge

(68-140%). The sample noY as rec is ~ 5 times less stiff and ~9 times softer than Y
as rec. To conclude, when the indents are randomly positioned;

· Y fired has higher H value than Y asrec

· Y N2 and Y acid have similar E and H values than Y asrec
· No Y as rec has lower E and H values (less stiff and softer) than Y as rec

As hardness is a plastic property, this correlates to the increased compressive
1
strength measured in the FireSert report but also in another invesitigation, finding
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increased flexural and compressive strength upon Powercem additive concentration
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