Relating early hydration, specific surface and flow loss of cement pastes

Flow loss in superplasticized systems has been mainly explained in qualitative and comparative ways over the past years. This is due to the intrinsic complexity of the underlying mechanism involving a change in the agglomeration degree as a result of cement hydration. The lack of robust and reliable experimental methodologies must have additionally discouraged researchers from attempting to understand the phenomena of flow loss in quantitative terms. Thanks to new analytical methods, it was possible to prove that after the so-called onset point, yield stress increases exponentially with the increase of both heat rate measured by isothermal calorimetry and specific surface. This paper also identifies the existence of a direct proportionality between the increase of heat rate and the increase of specific surface area during the acceleration period, most likely reflecting the nucleation and growth nature at this stage of the cement hydration.