The effectiveness of TiO₂ additions to mortar to maintain initial conditions in terms of its reflectance to solar radiation

A eficácia da adição do TiO₂ em argamassas quanto à manutenção das condições iniciais em termos de sua refletância à radiação solar

Abstract

Contact of facades with degradation agents and direct incidence of ultraviolet radiation on external coatings make them more opaque over time, affecting their colour and reflectance characteristics. This study evaluated the effect of adding different TiO₂ contents to mortars applied in concrete substrates in order to verify the reflectance maintenance on surfaces after exposure over time. Mortar with different concentrations of TiO₂ (1%, 5%, 10%) were produced in relation to the total dry premix, added as a powder and compared to unpainted mortar without TiO₂ (type "A") and painted mortar without TiO₂ (type "B"), both used as a reference for colour and reflectance. Exposed over 16 months to climate conditions in São Paulo, regarding the maintenance of reflectance and solar radiation, the results showed that type "B" (0%TiO₂) painted mortar presented the best performance. Type "C" (1%TiO₂) and type "D" (5%TiO₂) unpainted mortar remained more stable. Type "A" (0%TiO₂) and type "E" (10%TiO₂) unpainted mortar showed greater differences according to the Just Noticeable Difference (JND) range caused by dirt pick up.

Keywords:
Self-cleaning mortar; Solar and luminous radiation reflectance; Heterogeneous photocatalysis; CIELAB; Dirt pick up