Adequacy of mortars for adobe building renders

Rendering of adobe walls is an important task as it may greatly contribute towards their durability. However, if inadequate mortars or/ and techniques are applied, this may accentuate adobe degradation. Therefore, for this purpose the adequate choice of binder, sand, proportions and application method are crucial. This paper presents results of tests on mortars that were applied over adobe walls for five years, under natural exposure conditions and provides information on the most adequate mortars to be used on adobe surfaces. Mortars were prepared and applied as render on an existing adobe wall in the region of Aveiro (Portugal). Mortar preparation and application techniques were performed in the traditional way. After five years of exposure, mortars were sampled and tested. Acid dissolution, determination of particle size distribution, determination of mechanical strength and capillary absorption/ drying tests were performed in order to evaluate mortar properties and conservation state.