Percolation time and rigidification rate of cementitious suspensions

The stability and structural buildup of concrete can be evaluated by understanding the nature of the corresponding cementitious suspension using the small-amplitude oscillatory shear (SAOS) test through the time of percolation and rigidification rate, respectively. In the present study, four different cementitious suspensions—namely, 100% ordinary portland cement (OPC), OPC with 70% replacement of slag, OPC with 25% replacement of fly ash (FA), and OPC with 8% replacement of microsilica (MS)—were investigated. From the results, for OPC-based suspensions, the percolation time decreases for increasing dosages of high-range water reducing admixture (HRWRA) at low water-binder ratios (w/b) due to their high reactivity. In contrast, the suspensions with FA and MS exhibit a higher time for the formation of the elastic network, leading to a higher time of percolation. Further, it was identified that the suspensions with slag have the highest affinity toward the HRWRA, resulting in higher dispersion and therefore higher time required for the formation of the initial elastic network. This confirms that the dispersion and reactivity of the particles in suspensions dictate the stability and the structural buildup.