A review of the effect and optimization of use of nano-TiO2 in cementitious composites

Abstract

There are some problems and weaknesses related to cement-based materials, such as their very low tensile strength, low chemical resistance and the huge contribution of cement production to industrial CO2 emissions. One possible method to reduce the impacts of such problems is the partial replacement of cement in cementitious materials with nano materials. This work provides a detailed review of incorporation of one of the most widely used nano materials, namely nano-titanium dioxide, and its effect on the properties of cementitious composites. Different properties have been considered in the current study, such as fresh properties, mechanical properties (compressive strength, split tensile strength and flexural strength), durability (permeability, ultrasonic pulse velocity (UPV), electrical resistivity, carbonation resistance, freeze and thaw resistance and sulfate attack resistance) and microstructural properties. This paper also investigates the optimum content of nano-TiO2 in cement-based materials. Moreover, the cost effectiveness of use on nano-titania in cementitious composites has been discussed. Nano titania reduces the workability and setting time of cement-based materials. It can be very effective in improving the mechanical properties, durability and microstructural properties of cementitious composites.

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

“…The quantification indicator, i.e., the capillary water absorption coefficient, shows a significant decrease ranging from 37% to 81% compared to the capillary water absorption coefficient of the control sample. This observed trend is consistent with other literature references [33,36,37,41,57] and suggests a correlation with the evolution of the apparent density, indicating a densification of the material.…”

“…Regarding the apparent density of the composites in the cured state at 28 days after casting, as shown in Figure 6a, it can be observed that it increases with the addition of NT, indicating a densification of the mass, in agreement with similar reports in the scientific literature [36,37,57]. The increase in this parameter is significant, reaching 7.4% for 2% NT and 6.7% for 3% NT compared to the NT-free sample.…”

“…This is in line with the range documented in the literature, with a particular focus on confirming these effects at a crystalline phase level. It should be noted that the research methodology adopted in this case was to select the 3%NT sample for analysis because most often in the literature [36,56] this amount of NT is indicated as a variant that gives both good results in terms of the influences it has on the material characteristics and in terms of maintaining a reasonable cost.…”

“…In this context it is necessary to make the observation that the amount of NT present on the surface, being photoactivated by UV radiation, will develop some specific characteristics of the surface (superhydrophilicity [1,13,14], self-cleaning [1,13,14,[27][28][29] and antimicrobial [13,28] properties, and even the possibility of neutralizing some pollutants [1,13,27]) in the time that, NT trapped in the cement mass in the lower layers, to which UV radiation is not accessible, have initially, during the preparation of the composite and during its curing (the period of completion of the cement hydration reactions) [19,22,23,30], an impact at the rheological properties [31,32], microstructural compositional level [15,20,26] with consequences on the mechanical strength [19,[33][34][35][36] and durability characteristics [21,24,37] and also remain as a 'reservoir' of NT available for photoactivation if the upper surface layer is removed due to the stresses of the material exposed under use. At first assessment, given that UV rays do not penetrate the cementitious material and, thus, function in terms of inducing superhydrophilicity [19,38], antimicrobial [38][39][40] and self-cleaning [16,36] characteristics would only belong to the NTs on the surface of the composites; research has shown that NTs included in ...…”