Modification of the Cement Matrix with Organic Additives for Stabilizing Pertechnetate Ions

Stabilizing properties of polyhexamethyleneguanidine hydrochloride, tetraphelylphosphonium chloride, polyethyleneimine, and thiocarbamide were evaluated in order to determine their influence on the long-term stabilization of Tc in a Portland cement compound. The modifying agents' effect on the mechanical strength under air-wet conditions was investigated. Possible impact of modifiers on the intensification of bacterial processes was taken into account during the investigation. A 2-5-fold reduction in pertechnetate leaching was observed when the investigated additives were applied. Addition of polyhexamethyleneguanidine hydrochloride was deemed preferable as it simultaneously ensured stabilization of Tc properties, provided the mechanical strength required, and protected the cement matrix from the biological degradation.