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

Abstract

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 hydration 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 understanding of structural build-up process of cement paste.