Performance of ready-mixed clay plasters produced with different clay/sand ratios

Abstract Recent studies have shown that the usage of earthen building materials such as adobe, rammed earth and clay plaster has increased due to their moisture balancing and breathing characteristics, availability of their raw materials, suitable costs, sustainability and environmentally friendly properties. Although making adobe and clay plaster is quite an old building application, nowadays, more durable clay plasters can be produced on the basis of quality control in the industrial sense. In the literature, there are many studies dealing with adobe and rammed earth materials. However, investigations covering the characteristics of clay plasters are limited. In this study, the performance of ready-mixed clay plasters was examined with regard to the moisture content of the samples during the test, the mixture content of the water and the clay/sand ratios. Compressive strength and shrinkage (volumetric and observational) of the clay plasters were considered as key parameters for the performance analysis. In addition, simple field tests, used for analysis of the composition of earth building materials, were carried out in order to evaluate the effect of the clay/sand ratio on the performance of the clay plasters. As a result, an increase in the initial water content of the mixture and/or the moisture content of the samples during the test had a negative effect on the compressive strength. Furthermore, the optimum clay/sand ratio was between 0.43 and 0.66 by weight when the shrinkage and compressive strength results were considered all together.