Earth-based plasters: the influence of clay mineralogy

Earth-based mortars have been used all over the world since ancient times, in an extensive range of building types, from vernacular architecture to monuments. Plastering is one of the most common current applications of earth-based mortars, as for earthen-building conservation or contemporary architecture. Raw earth is a very diverse natural raw material, and clay minerals play a key role on plaster properties, being responsible for its setting process and the capability of balancing the indoor hygrometric conditions of buildings, which have strong benefits on energy saving for comfort and health of inhabitants and building conservation. For this study three mortars were produced with different clayish earths to assess the influence of clay mineralogy. Mortars characterizations confirmed that clay mineralogy drives important plaster properties, like vapour adsorption, drying shrinkage, and also have significant influence on mechanical resistance, dry abrasion and thermal conductivity. Within the studied mortars illitic clayish earth stands outs as more adequate for earth-base plasters, with balanced linear drying shrinkage, mechanical resistance, dry abrasion and vapour adsorption.authorsversionpublishe