Abstract: To investigate the water migration and freeze-thaw deterioration of hydraulic concrete, water absorption and rapid freeze-thaw tests were conducted on low-heat cement concrete (LHCC) and moderate-heat cement concrete (MHCC). The testing process was monitored using nuclear magnetic resonance and industrial computerized tomography (CT) to explore and analyze the water migration and distribution in hydraulic concrete during water absorption, as well as the changes in internal pore structure under freeze-thaw action. The findings indicate that both LHCC and MHCC exhibit continuous increase of total water content during water absorption, with saturation being reached after 48 hours, and LHCC shows significantly higher water absorption capacity than MHCC. The proportion of moisture in 0-0.1μm range is higher in MHCC compared to LHCC, while all other larger sizes contain lower proportions of moisture compared to LHCC. During freezing and thawing, the total porosity in LHCC and its increment are notably higher than those in MHCC. Moreover, the percentage of pores larger than 10 mm³ in MHCC is lower than that in LHCC, while the percentage of pores of other smaller sizes is greater than that in LHCC.

Key words: hydraulic concrete, moisture distribution, freeze-thaw deterioration, nuclear magnetic resonance, industrial CT