Study of deterioration mechanism of concrete in multi-aggressive and freeze-thaw environment

This paper reports an experimental study on deterioration mechanism of concrete suffered quickly freeze-thaw and eroded by 3% sodium chloride and 5% sodium sulfate mixed liquid. The hydration product and microstructure of concrete specimen were tested and analyzed by XRD(X radial diffraction)and SEM (scanning electron microscope). The result indicates that with the increase of the cyclic number of freeze-thaw and the frequency of submerge in the mixed liquid, the compressive strength of concrete decrease obviously. Corrosion products such as salt emerge in the component of hardened cement paste, micro-crack and salt crystal also appeare inside the specimens. It is obvious that under the combined actions of multi-aggressive and freeze-thaw environment, there are not only physical changes but also chemical reactions occurred in concrete, which exacerbate the mechanical properties deterioration of concrete.