Sensitivity of electrode contact solutions and contact pressure in assessing electrical resistivity of concrete

This paper covers some aspects of the development of a simple and robust electrical resistivity test method which has the potential for assessing the durability of concrete. A simple low frequency AC end-to-end resistivity test was adopted as a laboratory test method and has the potential of being preferred as a quality control test in readymixed concrete plants. The test method forgoes the need for cast-in place electrodes or silver paint for electrode-concrete interface. The work presented here examines the sensitivity of electrode contact solutions and contact pressures at the electrode-concrete interface with the use of synthetic sponges. Five concretes conforming to C32/40 compressive strength class in BS EN206-1/BS 8500-1 made from five different cement types were investigated and the work highlighted the need for using a reference conductive contact solution and a contact pressure.