NMR T₁–T₂ correlation analysis of molecular absorption inside a hardened cement paste containing silanised silica fume

ABSTRACT

The influence of silanised silica fume addition on the pore size distribution and wettability of white cement paste was investigated using T₁–T₂ correlation nuclear magnetic resonance (NMR) relaxometry. Surface silanisation of silica fume particles was achieved by the hydrolysis reaction of APTES (3-Aminopropyltriethoxysilane) and condensation of the silanol functional groups on the surface. The methods used for characterisation of the silanised silica fume particles were scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). By adding silanised silica fume to the cement paste, the accessibility of water molecules to the porous system becomes restricted, leading to a lower permeability in comparison with the unmodified cement paste. Differential scanning calorimetry (DSC) measurements on the cement pastes saturated with Octamethylcyclotetrasiloxane confirm also that the size of inter-C–S–H and capillary pores is not influenced by the addition of silica fume in a detectable manner.

GRAPHICAL ABSTRACT

KEYWORDS:

• T₁–T₂ correlation
• NMR relaxometry
• cement paste
• silanised silica fume
• DSC thermoporometry

Acknowledgements

The author acknowledges COST Action CA15209 for the Short-Term Scientific Mission at Technische Universität Ilmenau. C.C. acknowledges Bulat Gizatullin for programming the inversion Laplace algorithm and Dr. Oleg Petrov for valuable discussions.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Calin Cadar http://orcid.org/0000-0001-9668-1266

Ioan Ardelean http://orcid.org/0000-0001-8082-6600

Additional information

Funding

This work was supported by a grant of the Romanian National Authority for Scientific Research, CNCS – UEFISCDI, project number PN-III-P2-2.1-PED-2016-0719.