Gypsum plastering mortars with Acacia dealbata biowaste additions: Effect of different fractions and contents on the relative humidity dependent properties

•On the production of eco-efficient mortars to passively improve indoor comfort.•Study of five different waste fractions from an invasive plant: Acacia dealbata.•The biomass addition to gypsum plastering mortars enhance their hygroscopicity.•A MANOVA shows the statistical significance of each addition on mortars.•The highest moisture buffering is performed by the mortar with 10% vol. of bark.