Chemical and physical characterization of calcarenites from the protectorate period used in the Chellah site.

Abstract

The city of Rabat, capital of the Moroccan Kingdom, listed as a UNESCO World Heritage Site in 2012 and home to several historical monuments testifying to a cultural wealth and architectural diversity of which the Chellah site is part. The monument of Chellah located according to the coordinates: X = -6.8330340 / 6°49'58.9224 "W, Y = 34.0070770 / 34°0'25.4772 "N is special by its history, its architecture, its location within the city of Rabat shared heritage.This site is 7 ha in area with ramparts of 1030m in length and 4 m to 9.5 m in height, it houses 23 towers and 3 doors.The historical origin of Sala's (Chellah today) dates back to the VII-VI B.C. During the Phoenician period, this site could play the role of a seaport on the Atlantic route between Lixus and Mogador.The site of Chellah includes traces of many civilizations, such as the Phoenicians, the Mauritanians, the Almoahades and the Merinids.The historical site Chellah is at the same time a historical site, a real estate heritage, a universal heritage, an archaeological heritage, a tangible and intangible urban heritage.The historical site Chellah knows physical and chemical degradations seen its location and the particularity of the building materials as well as the techniques employed mainly for the rehabilitation.And given the importance of investigation and scientific studies before any restoration operation, we propose in this work a characterization of the stone used in previous restoration made during the protectorate period.The stone used is the calcarenites of which we propose a characterization under optical microscope and by using the technique of diffraction of the rays X DRX and the fluorescence of the rays X (FX). These analyses made it possible to affirm that this stone is a sandy limestone of a micro-sparitic cement which testifies to a bad conservation of the stone in front of the bad weather, this stone includes comparable fractions of calcium oxide and silica with a loss of fire of 25%, the analyses also made it possible to put in evidence the pathologies which touch them and the minerals of alterations.Keywords : Alteration, Calarenites, Limestone, Chellah