FROST DILATATION AND PORE SYSTEM OF HARDENED CEMENT PASTE UNDER DIFFERENT STORAGE CONDITIONS

摘要

Expansion as a result of ice formation and contraction due to the micro-ice-lens model and frost shrinkage were observed in hardened cement paste and concrete. By changing the storage conditions and the water cement ratio both effects have been studied with the measurement of thermal expansion of small specimens of hardened cement paste. The change of pore-size distribution by mercury porosimetry and the calorimetric data by differential scanning calorimetry are given as well. Apparently, already a change from under water storage to the storage at 100 % r.h. in air leads to sufficient empty space so that the 9 % of ice expansion is no more detected. One possible explanation for this is the formation of empty pores space by chemical shrinkage during hydration. With the experiments the predictions of the micro-ice-lens model are clearly proved.