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

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.

Photocatalytic Performance of White Cement Mortars Exposed in Urban Atmosphere

“…The mortars exhibited similar behaviors with respect to solar radiation reflectance. Therefore, the results for each mortar evaluated can be presented concerning to the mean reflectance, as suggested by Dantas, Vittorino, and Loh [12] and Dantas; Vittorino [31]. After 12 months, type-E mortars exhibited a decrease in the reflectance under exposure to solar radiation when compared with the other mortars.…”

“…A measurement area within the range of 400-700nm, the spectral resolution of 20 nm, photometric area of 0-100% (0.01), and standard observer D65 with an aperture angle of 10° were employed. The measuring procedure was carried out as previously described by Dantas, Vittorino, and Loh [12]. c) Optical microscopy analyses IV.…”

“…An increase in the light and thermal reflectance of building facades could be an effective strategy for the reduction of urban warming, to improve indoor thermal comfort and the energy consumption of heating, ventilation, and air conditioning (HVAC) systems [7][8][9][10], which results in the mitigation of the urban heat island effect [11]. However, the constant contact between coatings and environmental degradation agents, the incidence of ultraviolet radiation [12], and the coating roughness [13] tend to decrease the reflectance and induce changes in color over time.…”