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 multi-functional 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.