The author was invited to present orally the research performed in this thesis at a meeting of the RILEM TC 274 that was held in Université de Pau et Pays de l’Adour at Anglet, France, in October 2019.
Gomes, R. (2019). Assessment of hygrothermal characteristics of earthen materials. RILEM TC 274 meeting.One of the biggest challenges currently faced by society is the fight against climatic change. The building sector is an important part of the total emissions of carbon dioxide. Hence, there has been a rising interest on the building sector to reduce its impact on the environment.
Earth is used as a construction material since ancient times and its known for its sustainability, hygroscopic and thermal behaviour, making it a natural moisture buffer, helping in the regulation and control of the indoor air quality, maintaining the levels of relative humidity inside the buildings, providing a healthier environment for their occupants.
Despite being an ancient building material, its use is not disseminated across the world, mainly due to the lack of appropriate and specified standards for assessing its characteristics. Therefore, studies must be performed with the aim to establishing technical guides and standards for earthen building materials.
The aim of this dissertation is to elaborate accurate, repeatable and reproducible test protocols in order to measure the dry mass and the water vapour permeability for earthen materials. Furthermore, there is the need to confirm the reliability of the different methods assessed, mainly through round robin tests performed in different laboratories.
Samples manufactured with a chosen reference earth at two laboratories are tested at both laboratories. Firstly, it is evaluated the similarity of samples fabricated at different laboratories with the same protocol, and finally, the assessment of the hygrothermal characteristics is studied.
Results show that samples manufactured with the same earth at different laboratories with the same protocol can be considered similar regarding their apparent and dry densities and thermal conductivity, however with slightly differences. Samples manufactured at ENTPE present lower apparent and dry densities as well as lower thermal conductivity values than the ones manufactured at NOVA. Therefore, the assessment of the water vapour permeability is studied based on three different methods, showing similar results by the experimental data collected. The wet cup test performed through the gloves box obtained the lowest variations of the water vapour resistance factor. Several drying-methods were studied mainly through sorption isotherms and cycles of drying-wetting, with one outcoming drying-method. Oven-drying at 105ºC prove to be an accurate and repeatable dry-method and able to allow the material to return to its initial state from a hygroscopic point of view
