Characterization of lime mortar additivated with crystallization modifiers

Additivating mortars with crystallization modifiers is a novel approach to mitigate salt crystallization damage in historic masonry. Once verified the effectiveness of crystallization modifiers in bulk solution, the next step consists in verifying whether: (i) modifiers are still effective when mixed in mortar and going through the carbonation process and (ii) modifiers alter any mortar properties which might limit their application. This research addresses these issues for sodium ferrocyanide and borax, modifiers for sodium chloride, and sodium sulfate, respectively. Several experimental techniques have been applied to elucidate these questions. The results show that the selected modifiers are still able to alter the salt crystallization after going through the carbonation process of the mortar. Besides, no major effects of the modifiers on the fresh and hardened mortar properties were observed. It can therefore be concluded that there are no restraints for the future use of these crystallization modifiers in restoration mortars.     

Glass and glass production in the Oman peninsula in antiquity reconsidered – chemical and mineralogical investigation of sands

A batch of green‐ and amber‐coloured glass chunks and unguentaria dating from the first century CE was found in 2007 at Dibba al Hisn, a site on the Arabian Sea coast of the United Arab Emirates (UAE). Its elemental and isotopic composition revealed the glass to be of a previously unknown plant ash glass type, different from known contemporary Roman, Mesopotamian, and Indian glass. The Sr isotopic composition of the glass corresponds to locally available plants, pointing to the possible existence of a first‐century CE local glass production centre. To explore this possibility, sands from around the UAE were analysed to establish their suitability for glass making and correspondence with the Dibba finds. This paper presents the results of the elemental analysis of fourteen sands. The analysis, performed using inductively coupled plasma optical emission spectroscopy (ICP‐OES), revealed all sands to be rich in lime and alumina. X‐ray diffraction revealed the presence of calcite and other carbonate minerals, as well as antigorite and quartz. Comparison of the sand compositions to average first‐century CE non‐Roman glass found at Dibba showed them to be unsuitable as raw material for producing the glass of Dibba. The evidence thus identifies this glass batch as imported, contrary to what was suggested before. This paper also reviews the occurrence of thick‐walled unguentaria in the region.     

Palaeolithic chert exploitation in the limestone stretch of the Egyptian Nile Valley

Different raw material procurement strategies are attested in the limestone stretch of the Egyptian Nile Valley. Chert cobbles from Nile terraces or from their derived deposits were generally used. Four main procurement strategies have been recognized. During the Middle Palaeolithic intensive surface collecting was the most common strategy. However, open quarrying techniques involving features such as ditches are also attested. True subterranean mining with vertical shafts and underground galleries was known by the Early Upper Palaeolithic at 35,000 years BP. Extracted nodules were processed at the procurement sites. The study of the reduction strategies has proved valuable in gaining a better understanding of the Palaeolithic sequence of the Egyptian Nile Valley.

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Résumé Différentes stratégies d'obtention de matière première ont été reconnues dans la zone calcaire de la vallée du Nil égyptien. En majorité, ce sont des galets de chert qui ont été utilisés. Les stratégies d'obtention se classent en quatre types. Au Paléolithique Moyen la méthode la plus fréquente était la collection intensive en surface. Mais il y eut aussi une technique d'exploitation en profondeur, à l'aide de tranchées à ciel ouvert. Une véritable extraction minière avec des puits verticaux et des galleries souterraines fut pratiquée dès le début du Paléolithique Supérieur, vers 35.000 BP. Les galets extraits étaient réduits sur les sites d'exploitation mêmes. L'étude des processus de réduction nous a permis de mieux comprendre la séquence paléolithique de la vallée du Nil égyptien.