Unstabilized Rammed Earth: Characterization of Material Collected from Old Constructions in South Portugal and Comparison to Normative Requirements

Abstract

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.

Evaluation of air lime and clayish earth mortars for earthen wall renders

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Hydric Behavior of Earth Materials and the Effects of Their Stabilization with Cement or Lime: Study on Repair Mortars for Historical Rammed Earth Structures

“…35 One of the most important characteristics of porous building 36 materials is the way they transport and react to the presence of ties of the material, which, as explained, is also critical (Cid et al 57 2011; Gomes et al 2012a). Furthermore, the uses of chemical sta- ized elsewhere (Gomes et al 2012a(Gomes et al , 2014 depth and an area of 25 × 22 (cm 2 ) was formed, as seen in Fig. 3 …”

Assessing the performance of earth building materials: a review of recent developments

“…In general, the clay content should be sufficiently high to ensure acceptable levels of stiffness and strength while the expansive fraction should remain below 50% of the total clay content to avoid cracking. The analysis of existing buildings also indicates that particle size distribution cannot be used as the only parameter to discriminate between earth materials [11][12][13] and that no objective rule currently exist to assess suitability for building based solely on granular properties.…”