Differential scanning calorimetry study of ordinary Portland cement paste containing metakaolin and theoretical approach of metakaolin activity

This paper aims to investigate the hydration and pozzolanic reactions in cement pastes with different levels of metakaolin replacement, using differential scanning calorimetry (DSC) and theoretical analysis based on reaction stoichiometry. It was found that the DSC technique could follow the hydration process quantitatively by measuring the peak temperature and enthalpy corresponding to decomposition of hydration products, as functions of age. The pozzolanic process can also be followed from the measurements of the changes in the amount and the nature of amorphous material in the paste and the change of the amount of calcium hydroxide. In addition, it was confirmed that a theoretical approach using reaction stoichiometry could give a good estimation of the concentration of calcium hydroxide in a metakaolin concrete