National Concrete Pavement Technology Center

Project description

Concrete made with low transport properties can be very durable even in extremely aggressive environments. This study examined the ability of resistivity testing to determine transport properties for concrete containing ternary blends of portland cement with supplemental cementitious materials. The penetrability of the concrete was tested using rapid chloride migration, rapid chloride permeability, water absorption, water permeability, volume of permeable voids, surface resistivity, bulk resistivity, and bulk diffusion. These tests were performed between 28 and 365 days of age of concrete. Extracted pore solution resistivity was measured to calculate the concrete formation factor. Chloride binding measurements were used to calculate effective diffusion coefficients. Little benefit was seen in increasing the silica fume dosage above 6% in rapid chloride migration test (RCMT) and bulk resistivity tests. Resistivity samples cured in simulated pore solution (SPS) showed better correlations to secondary absorption rate and water permeability than fog-room-cured samples. Formation factor performed marginally better for SPS-cured samples against secondary absorption rate than bulk resistivity. Chloride ingress calculations performed using formation factor were shown to conservatively simulate measured profiles. Chloride ingress simulated using formation factor from moist-room-cured samples were shown to be closer to the measured profiles than samples cured in simulated pore solution. Measurements performed on samples collected from piles with 12 years of marine exposure validated the laboratory results.