The nanostructure of the cement paste and its porosity

Title: The nanostructure of the cement paste and its porosity
Author(s): D. Bonen
Paper category : conference
Book title: 2nd International RILEM Symposium on Advances in Concrete through Science and Engineering
Editor(s): J. Marchand, B. Bissonnette, R. Gagné, M. Jolin and F. Paradis
Print-ISBN: 2-35158-003-6
e-ISBN: 2351580028
Publisher: RILEM Publications SARL
Publication year: 2006
Nb references: 34
Language: English

Abstract: This paper represents an attempt to characterize the cement paste structure on different length scales. On the micron to submicron scale, backscatter-mode SEM provides extremely useful information on the composition and microstructure of the phenograins and groundmass. However, the backscatter-mode SEM overestimates both the pores’ size and pores’ volume. Evidence obtained from atomic force microscopy (AFM) studies indicates that the C-S-H is mainly a particulate system made of particles in size up to about 2.5 nm. Most of the particles are roughly spherical or oval. The nanostructure revealed has no specific orientation and certainly does not have any layered or ribbon like fibers morphology as frequently is postulated in the literature. Gel pores appear in the form of an interparticle porosity and on average are about 0.9 nm in size with aspect ratio of about 1.8. The C-S-H surface area in the groundmass is highly tortuous which adds to the high surface area of the paste. AFM data conforms very well to trimethylsilylation and nuclear magnetic resonance studies.This paper represents an attempt to characterize the cement paste structure on different length scales. On the micron to submicron scale, backscatter-mode SEM provides extremely useful information on the composition and microstructure of the phenograins and groundmass. However, the backscatter-mode SEM overestimates both the pores’ size and pores’ volume. Evidence obtained from atomic force microscopy (AFM) studies indicates that the C-S-H is mainly a particulate system made of particles in size up to about 2.5 nm. Most of the particles are roughly spherical or oval. The nanostructure revealed has no specific orientation and certainly does not have any layered or ribbon like fibers morphology as frequently is postulated in the literature. Gel pores appear in the form of an interparticle porosity and on average are about 0.9 nm in size with aspect ratio of about 1.8. The C-S-H surface area in the groundmass is highly tortuous which adds to the high surface area of the paste. AFM data conforms very well to trimethylsilylation and nuclear magnetic resonance studies indicating that the C-S-H is composed of short-order dimer with smaller amounts of pentamer to octamer silica tetrahydra.


Keywords: Nanostructure, microstructure, AFM, cement paste, C-S-H (CSH)
indicating that the C-S-H is composed of short-order dimer with smaller amounts of pentamer to octamer silica tetrahydra.
Keywords: Nanostructure, microstructure, AFM, cement paste, C-S-H (CSH)

Online publication: 2006-08-02
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2351580028.115