Activities and Nucleation Processes in the SiO2-CaO-H2O - Organics System

Date This project started on 01 October 2016

Status This project is Ongoing

Authors

University of Bourgogne-Dijon, FR
Empa, CH
University of Grenoble-Alpes, ISTerre, FR

Objectives

This project aims at determining the tendency of complex formation of small organic molecules with Ca and other ions as a first step towards the understanding of the effect of small organic molecules on the nucleation and pre-nucleation processes of C-S-H. The work will involve the determination of the stability and characterization of organic and ions complexes as well as the study of the kinetics and the determination of the reaction path of C-S-H nucleation with and without organics.

Organic additives are commonly used in the concrete industry to improve workability. The presence of organics generally also retards cement hydration, both the dissolution of cement clinker and the nucleation and growth of cement hydrates. The physical and chemical mechanisms responsible for the change in reactivity in presence of such organic additives are presently poorly understood.

The determination of stability and characterization of ion complexes in presence of organic molecules is expected to be a decisive step to understand the role of the latter on the nucleation process of C-S-H. They will be determined and characterized based on a combination of experiments and simulations. The C-S-H pre-nucleation and nucleation stages will be studied both in the homogeneous and heterogeneous case. This will involve measurements of the nucleation rates and induction times under controlled conditions and at various supersaturation degrees.

'