Laboratory evaluation of various types of mortars for the conservation of Qasr al-Bint monument, Petra–Jordan

Qasr al-Bint, Petra–Jordan, has been under the constant attack of a combination of various environmental factors that resulted in severe damage and destruction to the monument. The two most important factors that have contributed to the destruction of the monument are repeated earthquakes and salt crystallization. The most obvious symptoms of damage that the monument has suffered are extensive cracks and the lost of binding mortar. Any future conservation works should include, among other things, filling these cracks and repairing the joints with suitable mortar. The properties of the mortar must be suited to the properties of the natural stone and masonry. The development of suitable repair mortars requires obtaining quantitative technical data about the mechanical, physical and chemical properties of the mortars. This paper presents the results obtained in an experimental evaluation of various types of repair mortars for potential use in the structural repair and consolidation of Qasr al-Bint. Three types of mortar were selected for the purpose of this study. The selection was based on the results of the analysis done for a large number of mortars. Two of the selected mortars were commercially available. The first has the commercial name of “Funcosil Restoration Mortar”, the second is called “Namex Mortar”, and the third mortar was prepared in the laboratory based on the analysis of the mortar used by the Nabateans in Qasr al-Bint. The mortars were compared for their compressive strength, flexural strength, bond strength with sandstones, modulus of elasticity, water absorption by total immersion and capillary action, efflorescence formation, water vapor permeability, diffusion resistance, and shrinkage deformation. The results are discussed, and recommended applications for the various repair mortars are suggested.