Advanced decay of the Fontvieille porous limestone used in the construction of Pouillon’s housing estates in Algiers (Algeria)

Abstract

Numerous residential complexes were designed and built on the coastline of Algeria during the 1950 s by the renowned architect Fernand Pouillon using the Fontvieille soft porous limestone (Provençal Molasse) belonging to the Miocene deposits (French quarries). An important part of this architectural heritage is prematurely affected by visible decay phenomena of the building stone such as disintegration, differential erosion, encrustation, and biological colonization, and orange patina. The Climat de France estate located in an urban maritime area that has a typical Mediterranean climate, and considered to be one of the most important and populous in Algiers, is a distinctive example. The primary research objective was to describe the major decay patterns observed and the related processes and mechanisms affecting the Fontvieille porous limestone. The mineralogical, chemical, and petrographical analysis, combined with petrophysical and mechanical tests, were performed using analytical techniques (X-ray diffraction (XRD), X-ray fluorescence (XRF) spectrometer, scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDX)), and other standard methods on samples of this limestone coming from the buildings’ façades. The alteration degree quantification was performed using an artificial aging test and revealed severe damage. The results proved that the stone is highly affected by physical–chemical deterioration mechanisms, which induced the reduction of its mechanical properties. This stone is vulnerable to salt crystallization effects through wet-dry cycles resulting from macro- and micro-climatic changes, in addition to permanent sea spray exposure. The storage and transfer properties of the limestone are closely linked to emergence of the decay patterns in a relatively short time due to these particular coastal North African climatic conditions.