Critical values of pore size and crack width invaded by aggressive medium in cement-based materials

Based on the surface wetting theory and the durability request of cement-based materials, the critical values of pore size and crack width invaded by the aggressive medium in cement-based materials were analyzed and calculated. The water was used as the aggressive medium in the derivation. The results obtained by the mercury intrusion method and scanning electron microscope were used to verify the theoretical derivation. It is shown that the critical values of pore size and crack width are on the nanometer-scale, and closely relate to the temperature and the relative humidity in cement-based materials. The critical values of pore size and crack width slightly decrease with the increment of the temperature, but greatly increase with the increment of the relative humidity.