Validated hydration model for slag-blended cement based on calorimetry measurements

Abstract

Modeling of the complex interlinked chemical reactions involved in the hydration process of slag-blended cement is rather challenging, in particular since accurate prediction of the hydration kinetics of clinker and slag hydration, respectively, is still out of reach. To overcome this challenge, we propose a hybrid modeling approach based on calorimetry measurements combined with state-of-the-art hydration models. The model features intrinsic C-(A)-S-H nanoparticles related to clinker and slag hydration, respectively, with precipitation space-dependent densities of the corresponding gel phases. Successful validation against published experimental data, obtained on 54 different mixes in 7 different laboratories, proves the model's applicability and corroborates that C-(A)-S-H gel densifies progressively during hydration, that portlandite consumption upon slag reaction is caused by the precipitation of calcium-aluminate hydrates and that the ultimate heat of slag depends significantly on its chemical composition.