Modifying Cement Hydration with NS@PCE Core-Shell Nanoparticles

Abstract

It is generally accepted that fine particles could accelerate cement hydration process, or, more specifically, this accelerating effect can be attributed to additional surface area introduced by fine particles. In addition to this view, the surface state of fine particles is also an important factor, especially for nanoparticles. In the previous study, a series of nano-SiO 2 -polycarboxylate superplasticizer core-shell nanoparticles (NS@PCE) were synthesized, which have a similar particle size distribution but different surface properties. In this study, the impact of NS@PCE on cement hydration was investigated by heat flow calorimetry, mechanical property measurement, XRD, and SEM. Results show that, among a series of NS@PCE, NS@PCE-2 with a moderate shell-core ratio appeared to be more effective in accelerating cement hydration. As dosage increases, the efficiency of NS@PCE-2 would reach a plateau which is quantified by various characteristic values. Compressive strength results indicate that strength has a linear correlation with cumulative heat release. A hypothesis was proposed to explain the modification effect of NS@PCE, which highlights a balance between initial dispersion and pozzolanic reactivity. This paper provides a new understanding for the surface modification of supplementary cementitious materials and their application and also sheds a new light on nano-SiO 2 for optimizing cement-based materials.

Effect of nano-silica particles on the hydration, the rheology and the strength development of a blended cement paste

“…In addition, the mineral additions provide additional surfaces promoting the chemical reactions: this catalytic effect, called the filler effect, partly attenuates the dilution effect, that is the replacement of the cement by less reactive materials. The filler effect could also be described as a seeding effect as nanoparticles are considered [26], involving nucleation as its physical origin. Nevertheless, the dependence to the interparticle distance also points shearing mechanisms as another plausible physical origin [27] for quartz fillers, fly ashes, slag and limestone fillers.…”

Luminescence Nanothermometry Based on Pr3+ : LaF3 Single Core and Pr3+ : LaF3/LaF3 Core/Shell Nanoparticles

“…Indeed, the lifetime curves of the samples demonstrate a complicated shape (Figures 6(a) and 6(b)). It can be suggested that there are several physical processes which can be responsible for luminescence quenching [11]. Some of these processes can be temperature dependent.…”

“…Among different methods of nanothermometry such as using nanoscale thermocouples [3] and coulomb blockade nanothermometers [4], the luminescent nanothermometers hold a special place because of its high spatial and temporal resolution, accuracy, and contactlessness [1,[4][5][6][7]. Rareearth-doped nanomaterials hold a special role in luminescent nanothermometry among other luminescent nanomaterials because of their excellent photostability [8,9], long luminescent lifetimes [10,11], sharp emission bands, high brightness [12,13], high melting point, promising magnetic properties [14,15], and good resistance to thermal and chemical attacks [16,17]. More importantly, rare earth ions doped into fluoride nanoparticles demonstrate even better optical properties in comparison with some counterparts [18].…”

“…Usually, the core serves as a scintillator, and the shell plays such screening "defensive" role although a set of functions of both core and shell can be more complicated [11,26,27]. In order to synthesize such core/shell NPs, the conventional coprecipitation [28] and hydrothermal methods [29] of synthesis have successfully been adopted during the last decade.…”

Well‐Dispersed Silica Fume by Surface Modification and the Control of Cement Hydration

“…erefore, a suitable surface agent is important for cementitious materials surface modification. Polyacrylic acid (PAA) with short branch chain of carboxyl groups is a common surface modification agent [39][40][41]. e hydrophilic groups of PAA can isolate nanoparticles by its charge repulsion and the steric hindrance after grafted on the particle surface and form a hydrophilic layer around the particle.…”