Influence of chemical, mineralogical and geotechnical characteristics of soil on earthen plaster properties

Abstract Earth is perfectly suited for indoor plastering purposes thanks to its numerous technical, ecological and economic assets. The quantity of clay is frequently evoked to explain fresh and mechanical performances of earthen coatings but this indicator fails to give full account of the diversity of earth behaviour encountered in earth construction. This paper aims to examine plaster properties from the point of view of their geotechnical and mineralogical composition. Four types of soil were employed to design earthen plasters with variable earth to sand ratios. The behaviour of coatings was assessed through their water requirement, linear shrinkage, and flexural and compressive strengths. A noteworthy relationship was detected between the water requirement of earth plasters and the liquid limit of the raw earth employed. The mechanical resistances of plasters were found to be linked to the cation exchange capacity of the soils. The correlations between linear shrinkage, or compressive strength, and percentage passing at 2 µm were strong, justifying the widespread use of texture and clay content for soil classification, and assessment of the properties of earth-based building materials.