Eco-efficient plastering mortars for improved indoor comfort − The influence of A. dealbata bark addition

The passive contribution of indoor coatings to improve interior comfort is an eco-efficient challenge nowadays. Gypsum is one of the more eco-efficient binders available to produce plasters. Acacia dealbata is an invasive plant species in many countries, and the management of its wood waste for fires prevention is imperative. This study intends to evaluate the effect of using Acacia dealbata bark waste, directly after milling (raw) or with additional thermal treatment (1 h at 250 ⁰C), as an addition to an industrial gypsum-based plastering mortar to passively improve indoor comfort. To prevent the biological colonization, air lime is also added. Two clay-based plasters are used for comparison, as this type of plaster is known for being highly hygroscopic, together with a reference gypsum plaster. Results show that both the gypsum-bark mortars fulfill the standard requirements and do not show biological vulnerability. They doubled the moisture buffering of the reference gypsum plaster and got closer to the hygroscopic performance of the clay plasters. The very similar results between the two gypsum-bark mortars suggest that the thermal treatment of bark is not an eco-effective choice. So, the raw bark-added gypsum mortar is selected as a promising coating material to passively contribute for indoor comfort in an innovative, eco-efficient, way.