Study of the influence of nano-TiO₂ on the properties of Portland cement concrete for application on road surfaces

This paper reports the results obtained in a study on the effect of the addition of TiO2 nanoparticles on the mechanical properties and microstructural characteristics of photocatalytic concretes. Concretes were produced with three types of TiO2: anatase I (10–30 nm), anatase II (50–80 nm) and rutile (10 × 40 nm), with contents of 3%, 6% and 10% in relation to the mass of Portland cement. Besides these mixtures, a reference concrete was prepared without the addition of TiO2. In the hardened state, tests to determine the compressive strength and modulus of elasticity were carried out. Also, microstructural aspects of the samples were investigated by scanning electron microscopy and mercury intrusion porosimetry. In the fresh state, the influence of the addition of TiO2 on the concrete compaction and conduction calorimetry curves was evaluated. The results obtained indicated that, with the addition of TiO2, there was an increase in the compressive strength at 28 days and a reduction in the modulus of elasticity of the concretes. The calorimetry results indicated greater formation of C–S–H (calcium silicate hydrate)-type structures in the photocatalytic concretes. The porosimetry and SEM results showed a better distribution and refinement of the pores in these concretes.