The Influence of TiO2 Nanoparticles on the Physico–Mechanical and Structural Characteristics of Cementitious Materials

Abstract

The urgent need for sustainable construction that corresponds to the three pillars of sustainable development is obvious and continuously requires innovative solutions. Cementitious composites with TiO2 nanoparticles (NT) addition show potential due to their improved durability, physico–mechanical characteristics, and self-cleaning capacity. This study aimed to evaluate the influence of NT on cementitious composites by comparing those with 2%–5% nanoparticles with a similar control sample without nanoparticles, as well as an analysis of cost growth. The experimental results showed an increase in bulk density of the material (4.7%–7.4%), reduction in large pore sizes by min. 12.5%, together with an increase in cumulative volume and cumulative specific surface area of small pore sizes, indicating densification of the material, also supported by SEM, EDS, and XRD analyses indicating acceleration of cement hydration processes with formation of specific products. The changes at microstructural level support the experimental results obtained at macrostructural level, i.e., modest but existent increases in flexural strength (0.6%–7.9%) and compressive strength (0.2%–2.6%) or more significant improvements in abrasion resistance (8.2%–58%) and reduction in water absorption coefficient (37.5%–81.3%). Following the cost–benefit analysis, it was concluded that, for the example case considered of a pedestrian pavement with a surface area of 100 m2, using 100 mm thick slabs, if these slabs were to be made with two layers, the lower layer made of cementitious composite as a reference and the upper layer with a thickness of 10 mm made of cementitious composite with 3% NT or 4% NT, the increase in cost would be acceptable, representing less than 15% compared to the cost for the exclusive use of cementitious composite without NT.

Influence of the Addition of TiO2 Nanoparticles on the Self-Cleaning Capacity of Cementitious Composites

“…As can be seen in Figure 8, the inclusion of NT in the composite matrix resulted in an increased degree of whiteness in the composite surfaces compared to the analogous sample prepared without NT for all types of aggregates. This behaviour was anticipated based on references in the literature [52,54], highlighting the use of TiO 2 as a whitening agent for a wide range of materials, from paints to products in the cosmetics and pharmaceutical industries. Although the amount of NT used as an additive was the same for all compositions (3% by weight relative to the amount of cement, the amount of cement being kept constant), it was observed that the increase in the degree of whiteness was influenced by the type of aggregates derived from waste that replaced NA, ranging from 4.89% for GBA to 14.04% for RTA.…”

“…based on the amount of cement) (R5-3NT). The proportions of natural aggregates replaced by recycled waste aggregates and the addition of 3% TiO2 nanoparticles (by weight relative to the amount of cement) were determined based on preliminary research [52][53][54]. This research evaluated the influence of these two factors on the physico-mechanical properties and durability of the cementitious composites.…”

Multifunctional Anatase–Silica Photocatalytic Material for Cements and Concretes

“…The first is the difficulty of achieving a uniform distribution of nano-and micro-sized photocatalysts in the concrete mixture [16]. The second is the reduction in the physico-mechanical characteristics of concrete products at high doses of the photocatalyst in their composition [17]. The third is the reduction in the efficiency of photocatalysts when they are mixed with concrete components owing to a decrease in the amount of absorbed light (inhibition of photon transport) and the free surface (inhibition of diffusion of reagents) for photocatalytic reactions [18].…”