In situ observation of cement particle growth during setting

Abstract

The evolution of the cement paste microstructure is a complex phenomenon, which governs the setting of concrete. During setting, cement particles tend to flocculate and agglomerate due to their surface charges, attraction forces and variety of other reasons. However, it is still unclear how these developments in cement paste microstructure influence the setting of concrete. In order to better understanding the correlation between cement paste microstructure development and corresponding concrete behavior during setting, in situ observations on cement particles behaviors are essential. In this study, in situ observations on microstructure development of fresh pastes were made on three different cement pastes by using a newly developed Quantomix WETSEM™ capsuling system in a conventional scanning electron microscope. Further, by employing image analysis techniques on the captured images, microstructure changes of these cement pastes were investigated quantitatively. During the study single and multiple particle growth, hydration rate of different cement particles, and total solids growth in association with various solid concentrations and corresponding heat of hydration were studied quantitatively and as well as qualitatively. The purpose of this quantitative study is to investigate the feasibility of using such a new technology to evaluate the factors influencing the cement paste microstructure evolutions during setting.