Page 543 - Handbook of Thermal Analysis of Construction Materials

514 Chapter 12 - Clay-Based Construction Products

3.6 Soil Stabilization

Multi-component clay-based chemistries involving reactions be-
tween clays and lime and pozzolans are of interest in the area of soil
stabilization. Thermograms [27] for kaolinite and montmorillonite treated
with lime are presented in Fig. 18. Addition of lime results in the gradual
diminution of the primary kaolinite dehydroxylation peak (500–600°C) to a
greater extent than can be accounted for by dilution alone. All samples have
a small peak at about 130°C and a broad endothermic peak at about 210°C.
The decomposition of carbonated lime is associated with endothermic
reactions at 700–800°C.

(a) (b)

Figure 18. (a) DTA curves for kaolinite reacted with various proportions of lime at 35–
40°C for 8 weeks: (A) 0% lime; (B) 25% lime; (C) 40% lime; (D) 60% lime; (E) 75% lime.
(b) Montmorillonite reacted with various proportions of lime at 35–40°C for 8 weeks: (A)
0% lime; (B) 25% lime; (C) 40% lime; (D) 60% lime; (E) 75% lime. [27]

3.7 Structural Ceramics

Structural ceramics are generally brittle composite systems with a
coarse microstructure consisting of two or more phases. Kaolinitic clays are
used in the industrial production of structural ceramics. Thermograms from
TG and DTA tests are shown in Fig. 19 for kaolin, a pottery mixture, brick