Water repellents in Rammed Earth Heritage Conservation: Using ancient products as a solution for contemporary challenges

Earthen heritage represents an important legacy regarding not only the history of construction but also the knowledge of a millenary practice based on empirical expertise, social conditions, and cultural development. Looking at nature and exploring all the local products that it could provide and how to use them to improve ways of living and building was a common strategy. And while earthen construction requires regular maintenance that is usually done by the local population, the preservation of earthen heritage sites is still a challenging endeavor requiring deeper research, especially from conservation science. It is possible to find natural materials with properties that can prevent degradation phenomena and protect earthen surfaces from typical deterioration agents, specifically from water in the form of rain and humidity. e present work aims to study four water repellents—one synthetic (siloxane) and three natural materials (gum arabic, linseed oil, and beeswax)—applied to rammed earth specimens and offer a case study. Laboratory and in situ tests—namely, the contact sponge method and microdrop absorption—were performed to assess the compatibility and efficacy of the applied products. e main results and conclusions are presented and discussed.