AC impedance profiling within cover zone concrete: influence of water and ionic ingress

Data are presented on impedance measurements on mature concrete slabs which have been subjected to a cyclic wetting and drying regime, with the test surface of samples exposed to either water or a chloride solution. Both plain ordinary Portland cement concrete and Portland cement partially replaced with pulverized fuel ash and ground granulated blast-furnace slag are studied. The variation of impedance response at discrete points through the cover region (i.e. surface 50 mm) is presented with measurements taken over the frequency range 100 Hz to 10 MHz. Features of the complex response are identified and could be used to study the influence water and ionic ingress into the cover zone concrete.