Abstract

In traditional and historical Algerian architecture, one can find a series of mortars that were used for grouting and coating masonry. Although Algeria has a very rich heritage park, our interest mainly focuses on the mortars used in buildings from the Ottoman period, in Algiers and in particular, the mortars of the Citadel of Algiers, the Casbah and villa Mahieddine. This study allows us to determine the physical properties of a selection of mortars and identify their chemical and mineralogical composition. The chemical and mineralogical analyses showed that the studied mortars of the Ottoman period in Algiers contain raw materials in their composition, namely sand, lime, crushed brick and a few additions, such as natural adjuvant. These mortars are made according to specific proportions of binder (lime) and aggregates (sand). For jointing mortars, the proportion is one-part lime to one and a half to two parts sand (1 to 1.5 - 2), whereas for finishing mortars, it is one-part lime for two to three parts sand (1 to 2-3). The physical characteristics show significant porosity and absorption percentages for most of the mortar samples, with exception to MJ4 jointing mortar samples, taken from Villa Mahieddine and MC1 coating mortar samples, taken from the Powder House and Villa Mahieddine, where the percentages did not exceed 15% of water absorption and 27% porosity, respectively. Furthermore, the chemical analysis of the samples showed increased levels of the following oxides SiO2, Al2O3 and Fe2O3, which confirm the hydraulic nature of the mortars.

Key words: Algiers, characterisation, chemical and mineralogical composition, lime mortars, physical properties.