In situ SyXRD Analysis of Cement Hydration on the ms Scale

摘要

The backbone of our infrastructure and modern architecture are cementitious materials. Despite their substantial role for the society and their common involvement in the built environment, basic aspects of the hydration processes of cement are still not understood. During the first seconds of a building s life, highly dynamic reaction processes prevail. The reactions have a direct influence on the properties of the final building. Typically, these reactions are actively influenced by organic additives. These additives affect the initial formation of hydrate phases which is often interpreted based on the changes in fluid behavior and zeta potential. [1,2] Up to now, their influence has not been characterized by analyzing the crystallization processes directly. High resolution synchrotron X ray diffraction on the ms scale was utilized to characterize the initial hydration processes of this complex phase system on a structural level Figure 1 . The experiments were carried out under levitated conditions using small droplets as sample specimen. This kind of sample positioning avoids any contact with surfaces, which might influence nucleation, crystallization, and adsorption processes. The hydration of cement was influenced by polycarboxylate ethers, which belong to the most common superplasticizers. For the first time, it was possible to describe the effect of this organic additive to the early stages of the cement hydration. The combination of high resolution X ray diffraction and data processing represents a perfect analytical tool for analyzing the influence of any other organic additive to different cementitious materials