Identifying and Quantifying Material Properties That Impact Aggregate Resistivity of Electrical Substation Surface Material

The IEEE Standard 80-2000, Section 12.5 suggests that the resistivity of the surface aggregates used in grounding systems should be tested. Annex D of the IEEE Standard 81-2012 details some test methods that have been used but, to date, a procedure has not been standardized. Because of this lack of a standardized testing procedure, many of the methods used to date quantify few, if any, of the materials properties make the reproducibility of results difficult at best. The discussion herein recognizes that the resistivity of aggregates and aggregate mixtures is impacted to varying degrees by the particle-size distribution, degree of compaction, resistivity of the water used, and moisture content. The intent of this dissertation is to identify and employ existing testing methods, ordinarily recognized in the civil engineering profession, to quantify these aggregate material properties and demonstrate the impact each has on the resistivity of the material being tested.