United States Department of Transportation
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Evaluation of Surface Resistivity Measurements as an Alternative to the Rapid Chloride Permeability Test for Quality Assurance and Acceptance – Implementation Report
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2012-10-01
[PDF-780.00 KB]
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Edition:Implementation report; May 2011-June 2012.
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Abstract:Many contracting agencies currently use permeability specifications in portland cement concrete (PCC) pavements and structures. This project followed the implementation of the surface resistivity test (TR 233) on a field project in Louisiana. Additionally, a precision statement was developed for TR 233, and a ruggedness study was conducted to determine influencing factors on the results of TR 233 testing.
The single operator coefficient of variation of a single test result has been found to be 2.2 percent. 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 percent. The multilaboratory coefficient of variation of a single test result has been found to be 3.9 percent. Therefore the results of two properly conducted tests in different laboratories on the same material should not differ by more than 11 percent.
The collected data only covered the moderate, low, and very low permeability classes; because of this, the precision statement should only be used for values within these ranges. Further testing is recommended to investigate values in the high and negligible permeability classes. The surface resistivity test shows lower variability than rapid chloride permeability test.
The ruggedness study showed age and aggregate type as significant factors for surface resistivity. An additional factorial was used to compare individual factors against a control sample. The additional factorial suggested age, calcium nitrite, aggregate size, and aggregate type as significant factors for surface resistivity. However, comparative rapid chloride permeability testing on the same sample sets concluded that all significant factors determined will either affect the permeability of the sample in general or influence rapid chloride permeability as well.
The project specific cost benefit analysis showed that the Department saved a total of about $10,000 over three months, $40,000 for a full year, or $160,000 for the life of the construction project, for the Caminada Bay Bridge project after implementing the surface resistivity meter. Using a conservative savings of about $20,000 per year per project and an average of 50 projects per year, the Department is projected to save about $1,000,000 in operational costs when the surface resistivity test is implemented statewide. The savings for contractor QC are expected to equal or exceed DOTD operational cost savings when the surface resistivity test is fully implemented due to the specifications requiring that the contractor conduct QC testing at a frequency equal to or greater than the frequency of QA testing by the Department.
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