This project developed and tested a portable field equipment, conductivity spectrum probe (CSP), for in-situ determination of chloride permeability of concrete (Fig. 1). A laboratory equipment for conductivity and dielectric measurements was assembled and calibrated with known reference materials. A number of concrete specimens, covering a range of mix design parameters and chloride concentrations, were prepared and characterized for chloride contents using standard methods. Following a preliminary testing of these specimens, the CSP was tested on a number of additional well-characterized samples obtained from the W.R. Grace laboratories in Cambridge, MA, that covered a range of concrete mix formulations, rebar configurations and chloride exposures. The tested samples were soaked in water for 6 days and retested in saturated state followed by testing in a partially dried state. The test data was correlated with chloride permeability determined independently using standard test methods. Known relationships between conductivity and chloride permeability were used to establish a functional form for relating the measured CSP data to the chloride permeability data. Additional development and refinement of the equipment is needed for its field application and implementation. The final report is available from the National Technical Information Service (NTIS # PB2003-102867).
