Effect of salt additives on concrete degradation (phase II): executive summary

This research builds on a previous investigation, which found that corrosion-inhibitor-added deicing salts caused degradation of concrete by both anions and cations. The latest research phase looked at methods to detect the chemical reactions between concrete and corrosion-inhibitor-added deicing salts, and to determine the chemical compositions of the precipitates formed by chemical reactions between concrete and the corrosion-inhibitor-added deicing salts. The research led to the following conclusions: * a simple method was developed for the detection of chemical reactions between deicing chemicals and concrete; * the results provided clear evidence of the chemical reactions between concrete and the corrosion-inhibitoradded deicing salts; * the different amounts of precipitates (chemical reaction products) found in the test cells were dependent on the type and concentration of corrosion-inhibitor-added deicing salts; * precipitates formed by chemical reactions between deicing chemicals and concrete were identified by using chemical analysis, scanning electron microscopy, and X-ray diffraction analysis; * and precipitates were calcium and/or magnesium phosphates as a major component, and gypsum as a minor component.Minnesota Department of Transportatio