Abstract: Computing formulas of air-void spatial distribution density and air-void spacing factor of hardened concrete based on linear traverse method were derived according to geometric interpretations of the two parameters. By the comparison between derived formulas and regulations about air-void characteristics in foreign and domestic codes, current domestic codes were reviewed and revised. In the review, it is found that the critical ratio of cement paste content to air content is 4.33 in domestic codes of railway, highway, waterway and partial power industries. However, it is not as accurate as 4.34. Some coefficients in formula provided by domestic highway code are not in accordance with geometric interpretations. Both codes of highway and waterway industries do not realize that if the air content or paste content is presented as "%" by volume, it would be 100 times of the value of volume ratio and require formula coefficients changes. To keep formula coefficients unchanged, both the air content and paste content are suggested to be presented as values of volume ratio instead of "%" by volume. Except for railway codes, domestic codes of various industries mistakenly define the air-void number in 1 mm³ as air-void number in 1 000 mm³ in the calculation of spatial distribution density. These codes also mistakenly substitute the air-void number (unit: cm^-1) intersected by 10 mm traverse for air-void frequency (unit: mm^-1) in the calculation formula of spacing factor, the unit of which is millimeter. All the errors mentioned above need to be taken seriously and revised in future editions.

Key words: concrete, air-void spacing factor, spatial distribution density, air-void frequency, critical paste/air ratio