Determination of Hydrated Phases of Nanosilica incorporated C3S and \b{eta}-C2S using Nanoindentation Technique

TL;DR

This study uses nanoindentation to analyze how nanosilica affects the formation and properties of key hydration phases in cementitious materials, revealing differences in phase density and pozzolanic activity during hydration.

Contribution

It introduces a nanoindentation-based method to quantify hydrated phases and demonstrates nanosilica's impact on phase density and pozzolanic activity in cement hydration.

Findings

Nanosilica increases high-density C-S-H formation.

Eta-C2S shows more low-density C-S-H early in hydration.

Nanosilica enhances pozzolanic activity of calcium hydroxide.

Abstract

Analysis of the mechanical properties of key phases of cementitious systems during hydration at the nanoscale is vital for a better understanding of the type and formation of key cement hydration phases. In this work, nanoindentation technique has been employed to calculate the volume fraction and elastic modulus of key hydrated phases, calcium silicate hydrate and calcium hydroxide during the hydration of nanosilica incorporated C3S and \b{eta}-C2S at certain intervals for 50 days. The comparative analysis shows \b{eta}-C2S has more dominant low-density calcium silicate hydrate, especially in the early stage of hydration. While in the case of C3S, the dominant hydrated phase is high-density calcium silicate hydrate. Furthermore, the effect of nanosilica incorporation in the matrix of these cement constituents has also been demonstrated which shows a greater decrease of LD C-S-H and formation of more HD C-S-H for both C3S and \b{eta}-C2S. By tracking the mechanical properties of the other hydrated phase, calcium hydroxide, the pozzolanic activity of nanosilica has also been demonstrated. From the comparative analysis, it can be observed that the overall mechanical property of the constitutive phases is fairly similar.