Discoloration of Concrete Columns

Due to weathering effect from the past three years, TiO₂ coating may be removed from certain areas of the façade, resulting in decrease of photocatalytic activity. Defects include darkening and discolouration of concrete columns.

Stain and discolouration on the surface
(Source: Guan, 2013)

Orangey stain
(Source: Guan, 2013)