You can estimate the values when both exposure conditions and strength must be considered; use the lower of the
two indicated w/c ratios. If flexural strength rather than compressive strength is the basis for design, such as a
pavement, perform tests to determine the relationship between the w/c ratio and flexural strength. An
approximate relationship between flexural and compressive strength is as follows:
f 'c = compressive strength, in psi
R = flexural strength (modulus of rupture), in psi, third-point loading
K = a constant, usually between 8 and 10
Table 2- 1. Maximum w/c ratio for various exposure conditions.