Page 538 - Handbook of Thermal Analysis of Construction Materials
P. 538
Section 3.0 - Applications 509
et al., [25] found that a sensible reduction in organic matter by any method
invariably was followed by a consequent reduction of the dark color. The
DTA technique was applied to investigate the effect of various treatments
on the exothermal effect occurring due to the organic matter. Treatment
with 10% sodium hexametaphosphate at the boiling point, or with H O at
2
2
80°C, or the dichromate was effective in removing the color and so was
heating the clay at 400°C. It was concluded that the oxidation of the organic
matter was responsible for the dark color, and it occurred in stages at 325°
and 410°C.
Figure 13. TG-DTA curves for brick-clay powders: (a) 1; (b) 2; (c) 3; (d) 4; (e) 5; and
(f) 6. [23]
