DURABILITY OF CEMENT-BASED MATERIALS IN SIMULATED RADIOACTIVE LIQUID WASTE - EFFECT OF PHOSPHATE, SULFATE, AND CHLORIDE-IONS

The durability of a specific backfilling pozzolanic cement mortar, whi ch is employed in Spain, in concrete containers for the storage of low (LLW) and medium level wastes (MLW), has been studied by means of the Koch-Steinegger test at the temperature of 40 degrees C during a peri od of 365 days. Mortar samples were immersed in a simulated radioactiv e liquid waste very rich in sulphate (0.68 M), phosphate (0.89 M), and chloride (0.51 M) ions. The changes of the microstructure were follow ed by x-ray diffraction (XRD), mercury intrusion porosimetry (MIP), an d scanning electron microscopy (SEM). Pore solution was extracted at d ifferent periods in order to see the changes of the chemical compositi on caused by the diffusion of those ions inside the microstructure.