Development of Precision Statement for Concrete Surface Resistivity

Seventeen surface resistivity meters and 17 operators participated in the round-robin testing conducted at the Louisiana Transportation Research Center over 2 days. The tests were conducted side by side, and the individual meter's results were compared. Eight mixtures representing multiple permeability classes were tested with two replicates for each mixture. A precision statement was developed for use with Louisiana Department of Transportation and Development's TR 233, Surface Resistivity Indication of Concrete's Ability to Resist Chloride Ion Penetration. The single operator coefficient of variation (CV) of a single test result has been found to be 2.2%. Therefore, the results of two properly conducted tests by the same operator on concrete samples from the same batch and of the same diameter should not differ by more than 6.2%. The multilaboratory CV of a single test result has been found to be 3.9%. Therefore, the results of two properly conducted tests in different laboratories on the same material should not differ by more than 11%.