Page 323 - Handbook of Thermal Analysis of Construction Materials

300 Chapter 8 - Supplementary Cementing Materials

a) The material is heated up to 100°C in a N atmosphere and
2
purged by N at 100°C.
2
b) It is heated in an inert atmosphere from 100° to 750°C,
cooled from 750° to 100°C with a flow of nitrogen.

c) It is then subjected to isothermal treatment at 100°C for 5
minutes with air flow.

d) It is heated in a reactive atmosphere from 100° to 1000°C
in air.
Weight loss at 400–450°C in an inert atmosphere was ascribed to
water loss from Ca(OH) , and that at 600–750°C (inert atmosphere) was
2
caused by the decomposition of CaCO . The loss of weight in the range of
3
500–740°C in an oxidizing atmosphere signified oxidation of carbon. Table
2 gives the amounts of lime, calcium carbonate, and unburned carbon
determined in six fly ashes by TG. [16]

Table 2. TG Estimation of Calcium Carbonate, Calcium Hydroxide, and
Unburned Carbon in Fly Ashes

Fly Ash No. Ca(OH) , % CaCO , % Unburned Carbon, %
2 3

1 0.48 0.40 0.09
2 0.16 0.81 2.83
3 —— 0.37 2.39
4 —— 0.75 4.86
5 0.76 2.26 1.01
6 1.37 3.19 0.70
(Reprinted with permission from Elsevier Science.)

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