We determined the structural evolution of C 3 A pastes (comprising 10 wt.% C 3 A, 90 wt.% quartz, and a water-to-solid ratio of 0.8) during hydration using oscillatory SAOS tests. These tests were performed at a strain of 10 -4 and an angular frequency of 1 rad s -1 , in both the absence and presence of sodium salts.