Long-term properties of self-cleaning alkali-activated slag-based mortars with titanium dioxide nanoparticles

Titanium dioxide (TiO2) is considered one of the most efficient photocatalysis to produce self-cleaning cementitious materials. At the same time, alkali activated binders have become one of the most interesting low-carbon alternatives to Portland cement. For this, the addition of titanium dioxide nanoparticles in one-part alkali-activated slag-based (AAS) mortars was analyzed to evaluate the effect on the rheological and mechanical properties, dirt pick-up resistance as well as self-cleaning capability. This paper reports a two-year campaign of outdoor exposure in an industrial environment in Northern Italy to investigate the natural photoactivity of the mortars doped with different TiO2 dosages. The experimental results indicated limited effect of nanoparticles on the rheology and mechanical properties of AAS mortars. It was also highlighted the beneficial effect of TiO2 addition in self-cleaning capability under natural and accelerated conditions and the fundamental role in photocatalytic efficiency of the alkali content.