Non‐destructive and Destructive Structural Build‐Up of MgO–SiO ₂ Systems Enhanced by Hydration Agents

ABSTRACT This study investigated the effects of three hydration agents (HAs), Mg(CH 3 COO) 2 , MgCl 2 , and HCl, on the nondestructive and destructive structural build‐up of MgO‐SiO 2 pastes through rheological characterization. Isothermal calorimetry, X‐ray diffraction (XRD), thermogravimetry/derivative thermogravimetry (TG‐DTG), scanning electron microscopy (SEM), and zeta potential measurements were used to interpret the early‐age physicochemical processes governing structural build‐up. All three HAs accelerated structural build‐up under both testing modes, with HCl and MgCl 2 showing the strongest effects. Among the three HAs, 0.1 M MgCl 2 produced the lowest residual MgO content, the highest brucite content, and the lowest absolute zeta potential. These results indicate that MgCl 2 accelerated early hydration and was associated with stronger particle agglomeration. The results further suggest that destructive and nondestructive measurements reflect different aspects of early‐age structuration in MgO‐SiO 2 pastes, associated with reversible flocculation and hydration‐related irreversible build‐up, respectively.