Percolation experiment across a 10-year-old interface between Opalinus Clay and Portland concrete

Abstract

An interface sample between Portland concrete and Opalinus Clay with a contact time of 10 years recovered from a field experiment was investigated by SEM-EDX and X-ray CT. The concrete side showed a large chloride ingress from the claystone alongside a decalcification and an opening of the porosity. Additional XRD, TGA and leaching experiments of the concrete at few centimetres (∼5 cm) away from the interface confirmed the chloride ingress. The interface was then subjected to a long-term percolation experiment accompanied with repeated X-ray CT-scans. Injection of synthetic claystone pore water proceeded into the claystone-part of the sample, and through the concrete part, whereby the outflow was continuously sampled. The bedding 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.