Highlights  Rammed earth wall may suffer degradation with natural ageing and can be repaired with earth-based mortars  Environmental performances of earthen mortars are substantially better than cementitious mortars but their physical properties are not well known  The influence of additions of binders and hemp fibers in earth mortars is assessed  The additions of the hemp fibers decreases thermal conductivity and drying capacity  The addition of the binders increases capillarity, decreases the drying and is not significant for mechanic properties.

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Earthen building materials bear interesting environmental advantages and are the most appropriate to conserve historical earth 7 constructions. To improve mechanical properties, these materials are often stabilized with cement or lime, but the impact of the stabilizers on 8 the water transport properties, which are also critical, has been very rarely evaluated.

Unstabilised rammed earth is a recyclable, economical and eco-friendly building material, used in the past and still applied today. Traditionally, its use was based on a long empirical knowledge of the local materials. Because this knowledge was mostly lost or is no longer sufficient, in many countries normative documents have been produced to allow the assessment of rammed earth soils. With the aim of contributing for a refining of these normative requirements, this article presents a research work that included: (i) collection of unstabilised rammed earth samples from six constructions in Alentejo -Portugal; (ii) a literature survey of normative and complementary documents to identify the most mentioned key-properties of the soil for rammed earth construction, the test procedures to evaluate those properties and the corresponding threshold limits; (iii) a discussion of the test procedures and of the thresholds limits in the light of the experimental results obtained for the soil samples. The analyzed properties are the particle size distribution, maximum particle size, plasticity, compaction, linear shrinkage, organic content and salt content. The work highlights the advantages of taking into account the characteristics of existing constructions as a basis for the establishment and further refining of consistent threshold values. In particular, it shows that it is essential to adjust the requirements to the specificities of local materials.