Technical Paper


6. In these we can see that weather we are looking at the working time or the setting time, the behavior for the reference castable is almost a linear function of the temperature (inversely proportional) while the temperature stabilizing active compound has a relatively flat profile with an apparent temperature independence.


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Figure 8: Cold MOR after curing at 20°C followed by heat treatments Hot MOR Figure 5: Working time as function of temperature


In Figure 9 the mechanical strength is measured by MOR on hot samples. The primary reason for this measurement is to validate the hot properties of the material while using the temperature stabilizing additive. No significant difference is observed between the samples.


Figure 6: Setting time as function of temperature Figure 9: Hot MOR measurements


Mechanical Strength Development Cold MOR after curing and heat treatments


Ageing behavior of castables


The working time has also been evaluated at 5°C and 20°C on castables aged in bags in a room with controlled temperature and humidity conditions (20°C, 60% relative humidity). Figure 10 and Figure 11 shows the working time after ageing up to above 6 months (or 215 days).


Figure 7: Cold MOR after curing at 5°C followed by heat treatments


The strength development is measured after different curing times and after various different heat treatments. The earlier setting results in a quicker strength development, visible already after 8h at 5°C.


20


Figure 10: Working time at 5°C on aged castables


ENGINEER THE REFRACTORIES


March 2018 Issue


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