The selection of soils for unstabilised earth building: A normative review

Earth building techniques make use of unbaked earth as a material for constructing walls. We consider that evaluation of soils is a primary question because not all soils are adequate for earth building, and not for any of the earth building techniques. Following a selection of more than 20 technical documents including standards from National Standards Bodies, we analysed the provisions they offered concerning soil suitability, for the use of unstabilised earth. The work presented here articulates the whole of the different approaches and kinds of recommendation offered, for providing a way of comparison. Particle size distribution is the property most frequently mentioned, followed in number by the organic matter and salts content. Plasticity, binding force, shrinkage, presence of cracks and compactibility are the other properties for which recommendations are given. Most of the times these are imprecise, variable and not strict enough, and a unification work would be desirable.