Earth-based mortars for masonry plastering

Earth mortars have been applied since unknown times. Their advantages are ecological but also cover several technical aspects, in terms of compatibility with masonries, reversibility, comfort, aesthetic and health. Some requirements of a recent German standard, which focus on non-stabilized earth plastering mortars, are presented. A commercial premixed Portuguese earth mortar was made within an ECVET workshop and applied as plasters on four different experimental masonry walls, at exterior environmental conditions. The plasters were observed during six months and characterized in situ by non destructive techniques, namely by ultra-sounds and for surface hardness. The same mortar used for the plasters was characterized in laboratory in fresh state and samples of mortar (only mortar and mortar layer applied on brick) were produced and characterized after drying. The characterization of the earth plasters applied on the walls and of the mortar samples is presented and discussed, showing the viability of their use as plaster for different masonry walls.