Local structure and Ca/Si ratio in C-S-H gels from hydration of blends of tricalcium silicate and silica fume
Articolo
Data di Pubblicazione:
2021
Citazione:
Local structure and Ca/Si ratio in C-S-H gels from hydration of blends of tricalcium silicate and silica fume / A. Cuesta, I. Santacruz, A.G. De la Torre, M. Dapiaggi, J.D. Zea-Garcia, M.A.G. Aranda. - In: CEMENT AND CONCRETE RESEARCH. - ISSN 0008-8846. - 143(2021 May), pp. 106405.1-106405.10. [10.1016/j.cemconres.2021.106405]
Abstract:
At the microscale, C-S-H gels from alite, or neat Portland cements, has a Ca/Si ratio close to 1.80. At the nanoscale, C-S-H is described by a defective tobermorite structure which allows a maximum Ca/Si ratio close to 1.40. There is no agreement in the location of the extra 0.40 mol of Ca(OH)2 at the nanoscale. Atomistic modelling studies reported Ca(OH)2 species within the tobermorite interlayer space. Other works point toward a fine intermixing of defective tobermorite and nanoportlandite. Here, we have prepared a series of alite blended with silica fume and studied the pastes by several techniques including synchrotron pair distribution function (PDF). In the employed conditions, the C-S-H gel formed by the pozzolanic reaction has nearly the same local structure than the primary C-S-H gel. Furthermore, differential PDF points toward Ca(OH)2 excess having a local structure compatible with few-layer thick nanoparticles stretched along the c-axis.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
amorphous material; nanostructure; pair distribution function; pozzolanic reaction; SCMs; synchrotron radiation
Elenco autori:
A. Cuesta, I. Santacruz, A.G. De la Torre, M. Dapiaggi, J.D. Zea-Garcia, M.A.G. Aranda
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