Page 529 - Handbook of Thermal Analysis of Construction Materials
P. 529

500                  Chapter 12 - Clay-Based Construction Products

































                              Figure 6. Thermograms of methylene blue complexes of illite-montmorillonite mixes. [16]



                              2.2    Other Thermal Methods


                                     Application of multiple thermal techniques to clay mineral identi-
                              fication and behavior is more advantageous than applying any single
                              technique.
                                     Rai, et al., [17]  compared the relative merits in the use of DTA and
                              DTG techniques for single, binary, and ternary systems containing clay
                              minerals kaolinite, illite, nontronite, and monmorillonite. The techniques
                              were found to be equally useful for single systems. DTA enabled semi-
                              quantitative estimation of the heat values, DTG enabled a more accurate
                              estimation of the weight losses due to desorption and dehydroxylation. For
                              the binary systems, DTG was found to be more useful because it could
                              resolve dehydration peaks more clearly than the DTA technique. In the
                              DTG, the ternary systems showed three peaks for the dehydration, and,
                              thus, the presence of all the clay minerals. It was also concluded that the
                              dynamic weight loss values were slightly lower than those obtained by the
                              static method. DTA was very advantageous in providing information on the
                              exothermal effects.
   524   525   526   527   528   529   530   531   532   533   534