Improving rammed earth wall thermal performance with added expanded granulated cork

Abstract

Most construction materials require large amounts of energy for production and transportation purposes and are also asso- ciated with high levels of greenhouse gas emissions. One such material, rammed earth, has the advantage of being reusable and extremely durable, while it can also be locally sourced. However, rammed earth walls have a low thermal resistance. The aim of this study is to improve the thermal performance of rammed earth walls by increasing their thermal resistance. To this end, a range of different percentages and particle sizes of expanded granulated cork were added to rammed earth samples. The thermal conductivity of the samples was then determined in the laboratory and the data obtained were used to calculate heat transfer coefficients for a model rammed earth wall. Finally, the samples were subjected to uniaxial compression tests to determine whether the added cork led to a reduction in compressive strength. It was found that adding 10% granulated cork produced a reduction of about 12% in the heat transfer coefficient of a rammed earth wall with a thickness of 0.60 m, while the 28% reduction in compressive strength recorded is within the limits set out in the relevant standards.