The Monumental UNESCO Site of Panamá Viejo: Investigation of the Masonry Mortars

Abstract

The presented study illustrates the characterisation of several artificial materials (bedding, joint mortars, and plasters) belonging to the masonries of the UNESCO site of Panamá Viejo, located in Panama City (Panama). This monumental site represents the first Spanish settlement on the Pacific Coast, founded 500 years ago, in 1519. Through mineralogical and petrographic analyses of the collected samples, as stereomicroscope and polarized light microscopy (PLM) observations of bulk and thin sections, respectively, environmental scanning electron microscopy and micro-chemical investigations (ESEM-EDX) and X-Ray Powder diffraction (XRPD) analysis, it was possible to identify the composition of the materials utilized for the production of mortars and plasters, in addition to the determination of their state of conservation. Therefore, this work represents a substantial step for the preservation of the Panamá Viejo site, in order to support the selection of the most suitable restoration products, such as consolidants, protectives, etc., but also for choosing the most compatible materials for possible replacements/integrations in the masonries.

Characterization of the Stone Masonries and Evaluation of the Environmental Impact in Panamá Viejo: A Contribution for the Conservation of the Monumental Complex

“…In addition, the microchemical investigation, performed by energy dispersive X-ray spectrometry (EDS), identified Ca as the principal element present in the patina, also with the presence of O, suggesting a composition mainly formed by calcium carbonate (Figure 10c). The development of calcite, as a precipitated secondary mineral, was also supported by its identification in the masonry mortars previously studied [13]. Analyzing the samples using mercury intrusion porosimetry (MIP), it was noticed that all the samples showed an average pore diameter of less than 0.2 µm, which is the threshold for micropores.…”

“…Among the monuments of the complex, eight structures were carefully chosen for investigation. The selection was based on their significance and with the aim of providing a comprehensive representation of the entire site, in accordance with the patronage [4,13]. For evaluating different environmental conditions, structures situated in different positions were considered, such as those near the sea, those farther away, those adjacent to roads, and those that are not.…”

“…Only the stonework type has survived to the present day, which was constructed with rocks and mortars. Consequently, the focus of this study is on the stone of this typology of masonry, while the mortar elements were investigated in a previous work [13].…”

“…Temperature ( Lastly, in the presence of water, the ions can create an aggressive environment, forming acids, such as hydrochloric, sulfuric, or nitric acid. The chemical action of these compounds can cause the dissolution of carbonate-based stones and mortars [13]. The calcite of secondary precipitation can crystallize within pores (causing internal tensions) and/or on the surface.…”