Experimental Investigation of the Variation of Concrete Pores under the Action of Freeze-thaw Cycles

The variation of concrete pores under the action of freeze-thaw cycles was investigated experimentally by using the X-ray tomography (X-ray CT). Firstly, the statistical characteristics of concrete pores of testing specimens were obtained by the X-ray image analysis. Secondly, the variations of porosity and pore volume of concrete were analyzed and discussed through the comparison with the above characteristics. Thirdly, the failure process of the concrete specimens under the freeze-thaw cycles was investigated by scanning the interior structure of concrete specimens. The results showed that there was no big variation of both the amounts and volume of concrete pores that were located at the interval [0.5 mm3, 20 mm3], while a huge change was observed during the process of the experiment for the pores in other intervals. The severity of damages caused by the repeated freezing and thawing actions gradually ranged from surface spalling to a completed disintegration of the interior concrete specimens after 30 freeze-thaw cycles.