Studies of capillary porosity of clinker phases during hydration

The capillary porosity of clinker phases, i.e. 3CaOSiO(2), beta 2CaOSiO(2), 3CaOAl(2)O(3) and 4CaOAl(2)O(3)Fe(2)O(3), at the early stages of hydration has been studied by the methods of Differential Scanning Calorimetry and n itrogen adsorption (BET). It was established that pores of 3-70 nm were formed during the hydration o f 3CaOSiO(2) and the maximum of their distribution was found at about 10 nm . The hydration of 2CaOSiO(2) is much slower and the porosity is one order of magnitude lower. During the hydration of 3CaOAl(2)O(3) the content of cr ystalline hexagonal hydrates prevailed and the porosity was in the range 5- 90 nm with the average pore diameter of about 16 nm. This average pore diam eter was much smaller for thermoporosimetry and lay at about 7 nm. The hydr ated 4CaOAl(2)O(3)Fe(2)O(3) sample had the porosity in the range 3-90 nm wi th the maximum of the pores distribution at about 4 nm. There are some diff erences between the porosities measured by BET and thermoporosimetry. Princ ipally thermoporosimetry gives no information about larger capillary pores in the range 30-50 nm.