This document describes a method for determining the electrical resistivity of concrete in water saturated conditions. Two methods of measuring the resistivity are standardized: the volumetric method (see 3.1.3), which is the reference method, and the surface method (see 3.1.4). NOTE The volumetric method is applicable to cast specimens or cores, while the surface method is suitable for use on cast specimens, cores and on construction site, but not all these applications are covered in this document. The method can be applied to the normal range of concretes covered by current standards. It does not cover the concretes made with porous aggregates or having metallic components. The use of resistivity to assess the potential for corrosion of reinforcement in existing structures is not specified in this document. The use of resistivity to assess cores taken from an existing structure, which need pre-condition on water saturation, is not directly specified in this document.