Multifunctional wall coating combining photocatalysis, self-cleaning and latent heat storage

Mortars, one of the most common construction materials, have not received any substantial modification for many decades. This has changed in recent years; new compositions are now being developed, with new properties, using nano-additives, fibres and capsules. In this work, surfaces with new and innovative functionalities that promote energy savings and improve air quality have been developed and studied. Incorporation of phase change materials (PCM) and titanium dioxide (TiO₂) nanoparticles in construction products is currently under study by different research groups. However, these studies only address their incorporation separately. Adding new additives into the mortar's matrix can be complex - due to microstructural modifications that will influence both fresh and hardened state properties. Moving from a single additive to multiple additions, as in this study, increases the system's complexity. Only with a good understanding of the microstructural properties, it is possible to add multiple additives (including nano and microparticles) to mortars, without damaging its final quality. This work demonstrates that a higher additive content is not always a guarantee of better results; lower additions can often provide a better compromise between performance and final mechanical properties. The results presented in this paper confirmed this and show that combining PCM microcapsules and TiO₂ nanoparticles open a new path in the development of mortars with multiple functionalities. In this study, a new material with depolluting, self-cleaning and heat storage was created. For the development of new and innovative mortars, a proper balance of multiple additives, supported by the study of microstructural changes, can lead to an optimization of the compositions, ensuring that the mortar's final properties are not affected.