The Influence of Nano-Fe3O4 on the Microstructure and Mechanical Properties of Cementitious Composites

Abstract

In the last decade, nanotechnology has been gathering a spectacular amount of attention in the field of building materials. The incorporation of nanosized particles in a small amount to the building materials can influence their properties significantly. And it can contribute to the creation of novel and sustainable structures. In this work, the effect of nano-Fe3O4 as an admixture (from 1 to 5 wt.% in mass of the cement) on the mechanical and microstructural properties of cementitious composites has been characterised. The study showed that Fe3O4 nanoparticles acted as a filler which improved the microstructure of a cementitious composite and reduced its total porosity, thus increasing the density of the composite. The presence of nanomagnetite did not affect the main hydration products and the rate of cement hydration. In addition, the samples containing nanomagnetite exhibited compressive strength improvement (up to 20 %). The study showed that 3 wt.% of nano-Fe3O4 in the cementitious composite was the optimal amount to improve both its mechanical and microstructural properties.

Fig. 1

TEM (a, b), SEM (c) micrograph and X-ray diffraction pattern (d) of the nano-Fe₃O₄

Fig. 2

Heat flow calorimetry of the cement with different dosages of nano-Fe₃O₄

Fig. 3

XRD spectra of the cement pastes containing nanomagnetite after 7 days of curing

Fig. 4

Consistency of the fresh mortars

Fig. 5

Flexural strength (a) and compressive strength (b) of the cement mortars after 28 days of curing

Fig. 6

Mercury intrusion porosimetry results

Fig. 7

Iron distribution on the surface of the cement mortar containing different ratios of nano-Fe₃O₄ - 1 wt%(a); 2 wt%(b); 3 wt%(c); 4 wt%(d) and 5 wt%(e)

Fig. 8

Nano-Fe₃O₄ in the cement composite (a) and reference image of the nano-Fe₃O₄ (b)