A study on the basic mechanism of the reaction between lime, a 'n' type semi-conducting oxide (CaO), and water has led to the conclusion that the reactivity of lime with water depends on the position of the Fermi level in the lime crystal and that the reaction is a 'n' type semiconductor surface reaction. It has been observed that the lower the temperature at which thermionic emission starts in lime, the higher is its heat of hydration. Since thermionic emission may take place at a lower temperature if the thermionic work function decreases, the above observation means that the lower the thermionic work function of lime the higher is its reactivity with water. Thus the two important but diverse properties of lime, thermionic emission and hydration are connected. Explanations of the effects of impurities present as solid solution in lime on its reactivity with water, effect of retarders and accelerators, the presence of an induction period, and effect of particle size on hydration of lime have been suggested in terms of Fermi level. One corollary of this approach is that the lime of low heat of hydration should, on hydration, dehydrate at lower temperature and vice versa.

  • Corporate Authors:

    Central Road Research Institute

    Delhi-Mathura Road
    New Delhi,   India  110020
  • Publication Date: 1964-4-9

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  • Accession Number: 00265733
  • Record Type: Publication
  • Report/Paper Numbers: Annual Report 63-64
  • Files: TRIS
  • Created Date: Feb 27 1975 12:00AM