The basic thermal and hygric parameters of two different types of
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conductivity, specific heat capacity, moisture diffusivity, and water vapor
diffusion resistance factor are determined as functions of thermal load and tensile
load applied before the measurement as well as of the combination of both types of
load. The tensile load up to failure is found to be not a very significant factor
for all material properties analyzed except for the moisture diffusivity. On the
other hand, the thermal load is observed to result already at 600 C in considerable
changes in all investigated thermal and hygric properties except for the specific
heat capacity. The combinations of thermal and tensile loads lead to similar results
as the effect of the thermal load alone so that the domination of the thermal load
is apparent. This is supposed to be due to the positive effect of randomly
distributed carbon fibers that can reduce the damage of the pore structure by the
tensile stress. The resistance of the materials studied to high temperatures
expressed by the change of hygric and thermal properties after thermal load is found
to be positively affected by the application of the high alumina cement and in the
case of the Portland cement-based composite also by using the autoclaving procedure
in the production process.
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