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.

Adding TiO2 tocoating mortars is carried out to promote self-cleaning through photocatalytic activity. However, this addition influences the workability of the mortar and, consequently, the application stage as the TiO2 used can present a large number of fine particles and a high surface area, increasing the demand for mixing water, requiring consistency adjustments before coating. In this work, three mortars (two with the addition of different types of TiO2 and one reference) were developed on a laboratory scale to maintain similar workability, using the flow table test. The amount of kneading water was changed to maintain a spread of 220 ± 10 mm and the content of air-entrained was kept constant, around 25%. The mortars were evaluated using the squeeze flow method. Then, a blind test was performed to assess the mason sensitivity during handling and application of the coating, and all mortars were considered similar. However, the yield of the compositions with TiO2 addition was lower compared to the reference composition, making it possible to explain the results based on the physical parameters of the formulations and with a more in-depth analysis of the rheological indices obtained by the squeeze flow test.