Which characteristic is most important for frost-resistant bricks?

The most important characteristic for frost-resistant bricks is porosity. Bricks with the appropriate level of porosity can allow moisture to escape, reducing the risk of water entering the brick. When water freezes, it expands, which can cause bricks with high moisture content to crack or spall. Therefore, frost-resistant bricks are designed to have a controlled porosity that minimizes water absorption while still allowing any moisture that may get in to evaporate.

This characteristic ensures that the bricks can withstand freezing and thawing cycles without sustaining damage, which is crucial for maintaining the structural integrity and longevity of brickwork in cold climates. Other features like color, texture, and thermal conductivity can be important in different contexts but do not directly influence the frost resistance of bricks as critical as their porosity does.