Quality assurance of concrete using electrical resistivity measurements
University of New Brunswick
This study was focused on evaluating the use of electrical test methods to evaluate the permeability of concrete in New Brunswick Department of Transportation and Infrastructure (NBDTI) structures and various laboratory-produced samples. Many transportation departments currently use the Rapid Chloride Ion Penetrability (RCP) test (ASTM C1202) to evaluate concrete placed in highway structures as a means of quality assurance. In this study, concrete samples were taken from thirteen (13) separate NBDTI bridge projects and six (6) laboratory (lab) mixes. All samples were cast on-site or in the lab, cured in similar conditions and tested for surface resistivity (SR), bulk resistivity (BR), bulk conductivity (BC) (ASTM C1760) and RCP at an age of 56 days. In-situ SR testing was also performed on three separate structures and compared to values obtained on samples cured in lab conditions. This study concludes that a good correlation exists between results obtained by SR, BR, BC and RCP testing. These test results indicate that electrical resistivity testing (SR, BR or BC) could be adopted as a substitution for the RCP (ASTM C1202) test for quality assurance testing using lab-cured cylinders. The small sample set of in-situ SR test results proved too variable to determine the viability of consistent quality assurance specifications without further testing and development of concise correction factors.