Clarifying and quantifying the driving force for the evolution of static yield stress of cement pastes

The static yield stress evolution of cement paste is mainly driven by the colloidal force and cement hydration, while their respective roles and contributions are not yet clear. In this paper, three stages are distinguished in the first 3 h evolution of static yield stress of cement pastes (with or without steel slag powder), including the initial stage (up to 30 min), the induction stage (30-60 min) and the acceleration stage (after 60 min). It was found that colloidal force mainly contributes to the large static yield stress before the acceleration stage. The role of hy-dration was found to have determined the evolution trend of the static yield stress since the induction stage, which was identified by quantifying the interaction force between the C-S-H instead of solely considering C-S-H volume fraction. Based on quantitative results, how the physico-chemical parameters control the static yield stress evolution at each stage is identified comprehensively. This study provides a deep and quantitative un-derstanding of structural build-up process of cement paste.

Automated summary

This study analyzes the static yield stress evolution of cement paste within 3 hours and finds that it is mainly driven by colloidal force and cement hydration, but their roles and contributions are not yet clear. Three stages are distinguished: the initial stage (before 30 minutes), the induction stage (30-60 minutes), and the acceleration stage (after 60 minutes). Colloidal force mainly contributes to the increase in static yield stress before the acceleration stage. Hydration has been found to determine the evolution trend of static yield stress since the induction stage, identified by quantifying the interaction force between C-S-H instead of solely considering the C-S-H volume fraction. Based on quantitative results, this study comprehensively identifies how physico-chemical parameters control the static yield stress evolution at each stage. It provides a deep and quantitative understanding of the structural build-up process of cement paste.