Influence of TiO2 Nanoparticles Addition on the Hydrophilicity of Cementitious Composites Surfaces

Andreea Hegyi,Andrei Victor Sandu,Adrian-Victor Lăzărescu,Claudiu Romila,Elvira Grebenișan,Henriette Szilagyi

doi:10.3390/app10134501

Abstract

The effect of the use of TiO2 nanoparticles in the production of cementitious composites, worldwide already known, represents an area of interest for the development of materials with self-cleaning capacity; antimicrobial, antibacterial, antifungal properties; and to contribute to the reduction of environmental pollution. This paper aims to analyze the influence that TiO2 nanoparticles have on the cementitious matrix regarding hydrophilicity, this being one of the two main parameters of the self-cleaning mechanism. Experimental tests, conducted by using the indirect method of measuring the surface water absorption, indicated that an addition of 3%-6% (relative to the amount of cement) of TiO2 nanoparticles is effective in terms of increasing the surface hydrophilicity of the cementitious composites. An excess of TiO2 nanoparticles in the composite matrix (10% TiO2 nanoparticles relative to the amount of cement) not only does not improve surface performance in terms of hydrophilicity, but also reduces them. However, in practice on a case-by-case basis, an analysis is required regarding the optimal amount of nanoparticles used as an addition in the mix-design of the cementitious materials that are intended to induce the quality of self-cleaning process, depending on the intended use, climate, degree and duration of sunlight, and so on.

Highlights

Studies conducted worldwide [1,2,3,4] have shown that one of the most important and common causes of structure degradation is the accumulation of exogenous/external, polluting, organic or inorganic materials on surfaces
The experimental results, presented as mean values from five repeated tests for each proposed mixture, provided relevant information regarding the evolution of water absorption at the surface of the tested cementitious composite materials in relation to the content of nanoparticles introduced in their composition as an indirect indicator of hydrophilicity and on the kinetics of the process
In accordance with the literature [18,20,21,22], slightly influenced by the addition of nano-TiO2, this parameter does not directly proprotionally vary with the amount of nanoparticles introduced in the cementitious matrix, with a porosity reduction compared with the control sample being between 0.7%-5.2%, except for the two extreme samples

Summary

Introduction

Studies conducted worldwide [1,2,3,4] have shown that one of the most important and common causes of structure degradation is the accumulation of exogenous/external, polluting, organic or inorganic materials on surfaces. The accumulation of exogenous/external materials initially leads to loss of aesthetic appearance, but in time causes the degradation of the building material, which implicitly determines maintenance works and repairing costs, as well as indirect costs (for example, the reduction, the hindrance or stopping the activity in the building during the repair works, etc.). One solution to improve this situation is the use of nanotechnology by creating materials with a self-cleaning capacity in the construction field. The photocatalytic oxidation-reduction reaction under the influence of ultraviolet (UV) radiation of titanium dioxide (TiO2 ) was reported as the Honda–Fujishma effect in 1972 [5].

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