G. A. Topličić-Ćurčić et al. Karakteristike rimske žbuke s arheološkog nalazišta Mediana ISSN 1330-3651 (Print), ISSN 1848-6339 (Online) UDC/UDK 904:666.971.4.017(497.11Niš)"652" CHARACTERIZATION OF ROMAN MORTAR FROM THE MEDIANA ARCHEOLOGICAL SITE Gordana A. Topličić-Ćurčić, Zoran J. Grdić, Nenad S. Ristić, Dušan Z. Grdić, Petar B. Mitković, Igor S. Bjelić, Ana J. Momčilović-Petronijević Preliminary notes This paper presents the study of the Roman mortar used for construction of floors in the buildings which possessed floor heating system – hypocaust, in the residential villa with the peristyle (Naisus, Serbia). A total of seven samples of mortar from different locations of the villa were examined and analyzed for information about its morphological, mineralogical, chemical and basic physical properties. In order to determine these properties were used: optical microscopy, the scanning electron microscopy (SEM) with EDS analysis, X-ray diffraction analysis (XRD). The mortar is dominantly made of carbonate binder and the aggregate of grain size 0,05 to 2 mm with a rare occurrence of 10 mm grains. Fragments of mortar, grains of limestone, quartz, metarmorphite and vulcanite were used for the mortar aggregate. Usage of crushed brick and reaction rim confirms its function of hydraulic binder. The weak bonds between the aggregate grains and limestone binder facilitate transport of water through the formed transit zones. Keywords: optical analysis, porosity, Roman mortar, SEM-EDS, XRD, water absorption Karakteristike rimske žbuke s arheološkog nalazišta Mediana Prethodno priopćenje Ovaj rad prikazuje istraživanje rimske žbuke rabljene za konstrukciju poda u objektima koji su imali sustav podnog grijanja – hipokaust, u rezidencijalnim vilama s peristelom (Naisus, Srbija). Ispitano je i analizirano ukupno sedam uzoraka žbuke s različitih lokacija vile s ciljem dobivanja informacija o njezinim morfološkim, mineraloškim, kemijskim i osnovnim fizikalnim karakteristikama. Za utvrđivanje ovih svojstava rabljena je: optička mikroskopija, skenirajući elektronski mikroskop (SEM), s EDS analizom, difrakcijska analiza s X-zrakama (XRD). Žbuka ima prilično ujednačene karakteristike preko cijele površine poda hipokausta. Žbuka dominantno čini karbonatno vezivo i agregat veličine zrna od 0,05 do 2 mm s rijetkom pojavom zrna dimenzija 10 mm. Kao agregat za žbuku rabljeni su dijelovi žbuke, zrna krečnjaka, kvarc, metamorfiti i vulkaniti. Uporaba drobljene opeke i prisustvo reakcijskog ruba, potvrđuje njezinu funkciju hidrauličnog vezivanja. Slaba veza između zrna agregata i krečnjačkog veziva omogućava transport vode kroz formiranu tranzitnu zonu. Ključne riječi: optička analiza, poroznost, Rimska žbuka, SEM-EDS, XRD, upijanje vode 1 Introduction The present day city of Nis occupies the location of the Roman city of Naissus, which occupied central position within Roman province Upper Moesia (Moesia Superior). The Roman Naissus was the most famous for being the birth place in 272 AD (birth dates vary but most modern historians use c. 272) of the Emperor Constantine (Flavius Valerius Aurelius Constantinus Augustus, who ruled the Roman Empire from 306 to 337 AD as 57 th Emperor of Rome). In 2013 it will be 1700 years since the Edict of Milan was enacted, which was a legal act by which in 313 emperor Constantine became the first Roman ruler to have become a Christian. In the immediate proximity of Naissus, at Mediana, in times of reign of emperor Constantine, a large residential complex with a number of luxurious villas, and auxiliary structures was erected [1]. Exploration of the archeological site Mediana was started by Felix Kanitz as early as 1864 and it is recurrently undertaken until nowadays [2]. Irrespective of the importance of the site, and the needs for restoration works, until now mortar has not been researched. The most important structure on the Mediana site is the villa with the peristyle [3]. Its length is 98,6 m, and width 63 m. It has around 6800 m 2 of floor area, of which 945 m 2 were under mosaics. Besides peristyle, in the villa compound there are several areas with specific functions. The most complex function was in the northern part of the villa with audientie hall, two stibadiums, thermae and several rooms where the owners of this luxurious villa used to reside. All these rooms in the north were adorned by frescoes, while the floor areas were differently finished, depending on the function they performed. The areas of peristyle, stibadium, audience hall, thermae and the hall had floors covered by lavish mosaics. Other rooms were covered by the floors of mortar or brick. All these areas, except the porch and corridor leading to the thermae, are characterized by the specific structure underneath them – the hypocaust, Fig. 1 [4]. Figure 1 Northern part of Roman villa Mediana with marked position of analysed samples Hypocaust is an ancient Roman concept for keeping the inside of buildings warm [5]. The floor heating system in Mediana testifies that the villa with the peristyle had to be equipped, for someone special, with all the fittings providing permenant comfort of its owners. The mortar floor slabs in the villa with the peristyle at Mediana were formed using the hypocaust system model. The floor slabs over the hypocaust were heated by the hot Tehnički vjesnik 21, 1(2014), 191-197 191