Characterization of waterproof-covering mortars on Ottoman monuments of “Ghar El Melh” (Tunisia)

This study is devoted to the characterization of two historic waterproof-coating mortars taken from the ottomans monuments of “Ghar El Melh” in, northeast Tunisia. The first waterproof mortar was recovered from the aqueduct channel, which was used to supply boats with water. The second type came from the terrace cupola of “Sidi Ali El Mekki” fortress. To characterize each mortar, physical, mineralogical, and chemical analyses were performed. These revealed that the two samples were mainly made of air-hardening lime mixed with pozzolanic additions. The binder/aggregate ratio was 0.6 for the aqueduct coating and 0.3 for the cupola. The relative presence of gypsum in the mortar of the aqueduct indicated its sulfatic alteration, but the two coatings were free of ettringite. Although these were in permanent contact with corrosive conditions, the two waterproof coatings showed good durability.