Properties of alkali activated aluminosilicate ... - thermophysics.ru

Table 6 shows that the dependence of mechanical properties on heating temperature was not
monotonic as it is usual for many other building materials. Both compressive strength and
bending strength achieved their minimum values at 800 0 C where compressive strength was
about 5 times and bending strength 2.5 times lower than for reference specimens, and then
they began to increase. After heating to 1200 0 C, the compressive strength was only by about
12% lower and the bending strength by 18% lower than those of reference specimens.
Table 7 Thermal properties of dry material in dependence on thermal load
Thermal load [ 0 C] Thermal conductivity
[W/mK]
Specific heat
capacity [J/kgK]
Thermal diffusivity
[10 -6 m 2 /s]
25 1.59 798 0.92
200 1.60 781 0.99
400 1.67 743 1.04
600 1.09 754 0.70
800 0.94 777 0.59
1000 1.10 789 0.67
1200 1.16 738 0.77
The effect of heating temperature on thermal conductivity of the studied aluminosilicate
material in dry state is presented in Table 7. Similarly as with the porosity and the
mechanical properties, the first remarkable change was observed for the heating to 600 0 C. The
thermal conductivity decreased here by about 30% in comparison with the reference material
and the decrease continued at 800 0 C where it achieved about 40%. For higher heating
temperatures, the thermal conductivity was stabilized approximately on the values measured
for 600 0 C heating.
3,5
3,0
thermal conductivity [Wm -1 K -1 ]
2,5
2,0
1,5
1,0
0,5
200 C
400 C
600 C
800 C
1000 C
1200 C
25 C
0,0
0,00 0,02 0,04 0,06 0,08 0,10
moisture content [kgkg -1 ]
Fig. 2 Thermal conductivity of the studied material in dependence on moisture content and
thermal load
6