Mineralogy and technology of bricks used for the construction of the XII century ducal castle on the island of Ostrów Tumski, Wrocław (SW Poland)

Abstract

The historic bricks from the ducal castle on Ostrów Tumski (Wrocław), one of the first brickwork structures in the Lower Silesia, which dates back to the XII and XIII century, were studied and characterised by a combination of classical petrographic studies (polarising microscopy), scanning microscopy, thermal analysis and X-ray diffraction. The combined results of these methods suggest that the firing temperature ranges from 950°C, through the most common temperatures of 850–900°C, to the infrequent temperatures below 750°C. Most of the bricks were fired under oxidising conditions, occasionally over a sequence of oxidising and reducing steps, resulting in a sandwich structure. The results indicate, that low-calcareous raw materials were used, presumably Miocene-Pliocene ‘flamy clays’, exploited a few kilometres away from the castle and tempered with locally obtained sand from the Odra river. Only small differences have been recognized in: 1) clay to aplastic material ratio, 2) amount of accessory minerals, 3) grain-size distribution of aplastic materials, but no significant changes in the brick technology were observed. The observed variability corresponds well to the different constructing phases, identified previously on the basis of archaeological work. Thus, our work proves that a detailed mineralogical and petrological study may help to identify different construction phases in historic monuments.

Investigation on the Mineralogical Phase of Ancient Brick Samples of Kathmandu Valley (Nepal) Using XRD and Ftir Analysis

“…Numerous historical brick buildings have been existed until the 21 st century, which testifies to the strength of such ancient brick materials along centuries of rain storms, snow, thaw-freezing cycles, high temperatures and human-induced deterioration. A large number of studies have been reported about the ancient brick structures and materials to foster their cultural and economic importance as well [11][12][13][14][15][16][17][18][19] . The archaeological clay bricks preservation has given rise to considerable interest of scientists, architects, engineers and archaeologists recently, because the archaeological masonry needs to be restored with the substitution of bricks when they damage.…”

Study on the Physical and Mechanical Properties of Ancient Clay Brick Samples of Kathmandu Valley, Nepal

“…The main factor to manufacture these bricks is the clay raw material types used and the firing temperature during their production, because both of these affect the quality and durability of bricks (Mostaghelchi et al 2013;Rasmussen et al 2012;Dunham et al 2001;Dondi et al 1999). A large number of studies have been reported about the ancient brick structures and materials to foster their cultural and economic importance in different parts of the world (Šarić et al 2018;Amadori et al 2017;Shu et al 2017;Bartz & Chorowska 2016;Oguz et al 2014;Fernandes & Lourenço 2007;Cardiano et al 2004;Elert et al 2003;López-Arce et al 2003;Paama et al 2000).…”