Surface Resistivity Measurements Evaluated as Alternative to Rapid Chloride Permeability Test for Quality Assurance and Acceptance

Abstract

ASTM C1202 tests were conducted at various ages with the corresponding surface resistivity test, and the results were compared. Samples tested included field- and laboratory-prepared samples. The laboratory test matrix tested several mixtures common to Louisiana at a wide range of ratios of water to cementitious materials (w/cm) to evaluate the range of the surface resistivity meter. The surface resistivity measurements correlated well with rapid chloride permeability measurements across a wide range of permeability values and sample testing ages. Suitable correlations were found between both the 14-day and the 28-day surface resistivity values and the 56-day rapid chloride permeability values. The variability of the surface resistivity test results is usually less than the variability of the rapid chloride permeability test results. The surface resistivity meter was also able to identify great differences in w/cm ratios for the same mixtures. The surface resistivity meter was determined to be user friendly. The preliminary cost–benefit analysis showed that implementation of the device would save the department about $101,000 in personnel costs in the first year. It is estimated that contractors would save about $1.5 million in quality control costs. The cost–benefit ratio for this project is estimated to be about 15. A Louisiana Department of Transportation and Development test requirements procedure, TR 233, has been developed and implementation of the surface resistivity device has begun.