Percolation Experiment Across 10-Year-Old Interface between Opalinus Clay and Portland Concrete

A compound sample recovered from a field experiment with Portland concrete in contact with Opalinus Clay for 10 years was subjected to a long-term percolation experiment. The sample has a multiply zoned narrow interface region (SEM-EDX, XRD, TGA, X-ray CT); more extensively altered on the cement side, and chloride ingress from the claystone progressed much further than the visible mineralogical alteration in the hydrate assemblage. Repeated X-ray CT-scans were performed during the experiment thanks to the X-ray transparent apparatus. Injection of synthetic claystone pore water proceeded into the claystone-part of the compound sample, across the interface region, and through the concrete part, whereby the outflow was continuously sampled with small syringes. The bedding-parallel joints that were partially desaturated rapidly saturated, while hydraulic conductivity steadily decreased to values similar to unaltered claystone. The analysis of the exfiltrating aliquots shed light on the advective/diffusive properties of water transport and multi-component solute transport.