Once these mixes
turned over they exhibited spread values at the end or even
exceeding the target spread value (see Table 4, SM2, 3, 4, 10).
Therefore, adjusting the w/c ratio to achieve the same spread value
was not feasible for every mix. Since spread reflects yield strength
and viscosity of the mix and air content is related to these rheological
properties, variation in spread results in variation of air content.