Calcite formation on steamed concrete surfaces and its potential for sealing cracks

Under accidental conditions, concrete containments of nuclear power plants often remain as final barrier to the environment. To evaluate the contribution of self-healing processes of cracked concrete containments, small scale experiments were conducted for given accident scenarios to examine the mineralogical processes on cement crack surfaces in contact with hot steam-air mixes. The surface analyses with ESEM, µ-RFA and microscope showed a calcite formation, where layer thicknesses increased along the exposure times until reaching a stable level. The potential for crack healing was principally demonstrated through flow measurements, where the outflowing mass decreased during the experiments along with increasing calcite formation.