Understanding the mechanisms behind the time-dependent viscoelasticity of fresh C3A–gypsum paste. (July 2020)

• Record Type: Journal Article
• Authors: Huang, Tingjie; Yuan, Qiang; He, Fuqiang; Xie, Youjun
• Is Part Of: Cement and concrete research. Volume 133(2020)
• Publication Date: 2020-07
• Subjects: Small amplitude oscillation shear -- NMR relaxometry -- Ettringite -- Viscoelasticity -- Hydration; Cement -- Periodicals; Cement -- Research -- Periodicals; Concrete -- Periodicals; Concrete -- Research -- Periodicals; Ciment -- Périodiques; Béton -- Périodiques; Cement; Concrete; Periodicals; 620.135
• DOI: 10.1016/j.cemconres.2020.106084
• Languages: English
• ISSNs: 0008-8846

Abstract

Abstract: This paper monitored the viscoelasticity development of fresh C3 A-gypsum paste in situ by small amplitude oscillation shear (SAOS) within 5 h. The development of viscoelasticity of paste with time can be characterized by two different stages. Isothermal microcalorimetry, X-ray diffraction (XRD), scanning electronic microscopy (SEM) and low field 1 H nuclear magnetic resonance (NMR) measurements were used to investigate the underlying mechanisms behind these two stages. It was found that the first stage is governed by the increase of solid volume fraction while the second stage is controlled by the rigidification of ettringite networks. The growth of loss modulus is restricted since the formation of ettringite linkages between particles. Moreover, the considerable elasticity development of fresh C3 A-gypsum paste is stemmed directly from the increasing ettringite precipitation.