Multi-scale analysis of cement pastes with nanosilica addition

Abstract

The effect of the addition of nanosilica on the properties of cement pastes after 28 d of hydration was studied in a multi-scale approach through X-ray diffraction, thermal analysis, nitrogen adsorption analysis, infrared spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and compressive strength tests. The results showed an increase in strength resulting from the pozzolanic nature of the nanosilica, the reduction and refinement of the paste porosity and also the increase of the of calcium-silicate-hydrate gel polymerisation with the addition. Furthermore, NMR spectra suggested that the presence of nanosilica produces an inclusion of the Al 3 ion in the gel structure.

Synthesis and Addition of Al-Substituted Tobermorite Particles to Cement Pastes

“…There is a general agreement that nanoparticles accelerate hydration reactions of Portland cement mainly by one of the following mechanisms: the reaction with the ions dissolved from the cement grains, or the seeding effect. In the first case, the most common process is the pozzolanic reaction of silica or clay nanoparticles with dissolved Ca ions to give C-S-H gel (Björnström et al 2004;Diez-Garcia et al 2018;Gaitero et al 2008Gaitero et al , 2010Guerrero et al 2014;Land and Stephan 2015b;Perez et al 2015b;a;Yang et al 2021). Nanoparticles are more reactive than larger particles of the same composition due to the larger surface area.…”

Editorial

“…The next paper, by Guerrero et al (2014) also looks at the impact of additives on Portland cement hydration, in this instance nanosilica. The aim of the study was to try and improve the performance of cementitious composites by understanding the impact of such additions on the hydrated phase assemblages.…”