Can an earth plaster be efficient when applied on different masonries?

Earth mortars are known for being ecological but also reversible, contributing to comfort and aesthetic. Nevertheless, compatibility with different masonries is scarcely assessed. A commercial unstabilised ready-mixed earth mortar was produced with an ilitic earth with addition of sand and oat straw fibres. It was used to plaster different experimental masonry walls, at protected outdoors environmental conditions. The plasters applied on the masonries were visually monitored and characterized in situ by non-destructive techniques and in laboratory by bulk density and microstructure. The same mortar used for the plasters was characterized in laboratory in fresh state and, after drying, on prismatic specimens and specimens composed by a mortar layer applied on hollow bricks. Some variation of results occurs when the same unstabilised ready-mixed earth mortar is used to plaster different masonries, what may be related to the water absorption of the masonry materials. However, after six months the earth plaster presented durability on the different masonries when protected from rain. It proves that this ecological mortar is technically efficient to plaster different types of masonry, historical or contemporary.