Over the last 14 years, the North Carolina Department of Transportation (NCDOT) has been specifying the addition of calcium nitrite corrosion inhibitor to concrete in chloride-corrosive environments. To ensure that nitrite inhibitor has been added at the specified dose, NCDOT has been testing both hardened and plastic concrete. Several instances have been observed in which the nitrite level did not meet the specified minimum. Data relative to sampling techniques, chemical testing, and the variability of hardened concrete are summarized. Data are also presented about the ability of nitrite to leach from a concrete pile in immersion service in a marine location. The results of a new method for testing plastic concrete are compared to the old method for hardened specimens.
Abstract