This study examined the influence of air content on the strength activity index test specified in Annex C of JIS A 6207:2016 (Silica fume for use in concrete). The results confirmed that the effect of air content difference on the activity index was greater than that of the flow difference between the reference mortar and the test mortar. Furthermore, an investigation of quality control records over the past five years, conducted in accordance with this Annex, revealed that the air content difference between the reference mortar and the test mortar has been controlled within approximately ±1.0%.
Koizumi et al. (Fri,) studied this question.