Properties of an innovative multi-functional finish for the improvement of indoor air quality

Due to lifestyle changes, people spend most of their time indoors at present; thus, Indoor Air Quality (IAQ) is a matter of utmost importance. Multi-functional and innovative finishes can help to passively improve the IAQ, benefitting the health and comfort of occupants. For this study, reference and pre-mixed commercial mortars are compared to a new multi-functional hydraulic lime mortar for indoor finishes, in which conventional aggregates are substituted by a highly porous adsorbent material and biomass waste ashes. The up to 20% higher accessible porosity of the multi-functional finish led to lower density (30%), higher thermal insulation properties (30%), higher water vapor permeability (more than 40%), and improved moisture buffering capacity (three times higher), when compared to the reference mortar. Different types of photocatalytic agents (TiO2) were also added into the new multi-functional hydraulic lime mortar, in order to investigate their effect on the de-polluting properties of the finish. Even if the photocatalytic efficiency remained unexpressed under indoor conditions, due to the predominance of the adsorption process, the de-polluting properties of the new mix were more than 30% higher than that of the reference mortar. The obtained results confirm that the developed innovative multifunctional finish—besides fulfilling the ordinary requirements—is better than commercial mortars, as it can improve the IAQ passively, thus benefitting the health and comfort of occupants.