Researching in ancient engineering. Physical and chemical analysis in hydraulic roman mortars.
by Pablo Guerra
Co-authored with David Sanz Arauz. Published in: "Science and Technology for the Safeguard of Cultural Heritage of the Mediterranean Basin, pre-abstracts". 5th. International Congress, 22-25 november, 2011. Istanbul. AIC. Istambul Ünivertesi. Consiglio Nazionale delle Richerse. P. 132.
Around ten years ago investigation of technical and material construction in Ancient Roma has advanced in favour to... more
Around ten years ago investigation of technical and material construction in Ancient Roma has advanced in favour to obtain positive results. This process has been directed to obtaining some dates based in chemical composition, also action and reaction of materials against meteorological assaults or post depositional displacements. Plenty of these dates should be interpreted as a result of deterioration and damage in concrete material made in one landscape with some kind of meteorological characteristics.
Concrete mixture like calcium and gypsum mortars should be analyse in laboratory test programs, and not only with descriptions based in reference books of Strabo, Pliny the Elder or Vitrubio. Roman manufacture was determined by climatological condition, landscape, natural resources and of course, economic situation of the owner. In any case we must research the work in every facts of construction. On the one hand, thanks to chemical techniques like X-ray diffraction and Optical microscopy, we could know the granular disposition of mixture. On the other hand if we develop physical and mechanical techniques like compressive strength, capillary absorption on contact or water behaviour, we could know the reactions in binder and aggregates against climatological effects.
However we must be capable of interpret these results. Last year many analyses developed in archaeological sites in Spain has contributed to obtain different point of view, so has provide new dates to manage one method to continue the investigation of roman mortars. If we developed chemical and physical analysis in roman mortars at the same time, and we are capable to interpret the construction and the resources used, we achieve to understand the process of construction, the date and also the way of restoration in future.
The Effect of Calcination Time upon the Slaking Properties of Quicklime
by Dorn Carran
To be published in a book relating to the proceedings of the Historic Mortars Conference, Prague 2010
Lime Lump Development and Textural Alteration during the Production of Mortar
by Dorn Carran
Proceedings of the second Historic Mortars Conference, Prague, 22-24 September 2010
A Short History of the Use of Lime as a Building Material Beyond Europe and North America
by Dorn Carran
Published in "International Journal of Architectural Heritage", Volume 6, Issue 2, p117-146
Co-authors - John Hughes, Craig Kennedy, Alick Leslie
The Analysis of Sinter Samples and Hydraulic Mortars from the Nymphaeum Traiani at Ephesus, in: G. Wiplinger (Hrsg.), Cura Aquarum in Ephesus. Proceedings of the Twelfth International Congress on the History of Water Management and Hydraulic Engineering in the Mediterranean Region, Ephesus/Selçuk, Turkey, October 2-10, 2004, BABesch Suppl. 12 (Leuven 2006) 509–513.
Co-authored with Walter Prochaska, University of Leoben, Austria
Ancient Analogues of Modern Cement: Calcium Hydrosilicates in Mortars and Concretes from Gallo–Roman Thermal Baths of Western France
by Pablo Guerra
Rassineux, F., Petit, J. C. and Meunier, A. (1989). Published in Journal of the American Ceramic Society, 72: 1026–1032
The long-term durability of cementbased materials over periods of time not directly accessible to laboratory... more
The long-term durability of cementbased materials over periods of time not directly accessible to laboratory experiments has to be thoroughly assessed to guarantee the safety of a radioactive waste repository. In this work, archaeological mortars and concretes have been studied to check whether their use as analogues of actual technological cements used for waste disposal is possible. Samples of mortar and concrete have been collected from several Gallo-Roman thermae of western France; they were examined as petrographically thin sections with optical microscopy and were analyzed by X-ray diffraction of microsamples (10−3 mg) and by electron probe microanalysis. The masonry cement appears to be entirely carbonated with large voids and fissures. In contrast, the use of lime with additional crushed brick or tile for the bath structure concrete and coating mortar induced pozzuolanic reactions. Despite the fact that the matrices are essentially composed of calcium carbonate, calcium aluminosilicates with compositions close to those of hydrogrossular, hydrated calcium silicates with composition and a structure comparable with those of calcium hydrosilicate formed in modern cement, and ettringite deposits in voids of concretes could also be identified. It is suggestea that these ancient artifacts can help identify very slow processes that rule cement alteration over long periods of time. The artifacts may be considered as possible analogues of present-day materials whenever sufficient care is taken in interpreting and extrapolating data.
wiley Online Library
Characterisation of archaeological mortars from Pompeii (Campania, Italy) and identification of construction phases by compositional data analysis
published in "Journal of Archaeological Science", Volume 37, Issue 9, September 2010, Pages 2207-2223
This work describes the compositional characterisation of coccciopesto and natural pozzolanic mortars sampled in the... more This work describes the compositional characterisation of coccciopesto and natural pozzolanic mortars sampled in the Regio VI area of the archaeological site of Pompeii, with particular reference to the Casa di Pansa in Insula 6 and Casa 17 in Insula 2. Samples were studied by optical microscopy and analysed by XRF, SEM-EDS, LA-ICP-MS and XRPD. The XRF and SEM-EDS data, subjected to multivariate analysis (cluster analysis), identified the three main construction phases involved in building the Casa di Pansa. In addition, mineralogical and petrographic characteristics of the aggregate were determined and found to be compatible with pyroclastic deposits from the volcano Vesuvius. Study revealed C–S–H phases in the binder, due to pozzolanic hydration phemomena of hydrated lime with cocciopesto and natural pozzalana.
Characterisation of archaeological mortars and plasters from kyme (Turkey)
published in "Journal of Archaeological Science" 38 (2011) 794e804
The present study focuses on the compositional characterisation of Roman, proto-Byzantine and Medieval mortars,... more The present study focuses on the compositional characterisation of Roman, proto-Byzantine and Medieval mortars, sampled in the archaeological site of Kyme (Turkey), an Aeolian city, founded in the middle of the XI century BC by Greek populations. The mortars were studied through elemental (SEM-EDS, XRF), mineralogical (XRPD, De Astis calcimeter) and petrographic (polarised optical microscopy) analysis. The comparison between the samples allowed us to emphasise compositional differences within mortars of the same historical period. In particular, we detected the prevalent use of cocciopesto, which was used as a pozzolanic additive to create hydraulic mortars in the Roman and Byzantine period. The cocciopesto was used to improve the technological properties of an initially slaked lime. Furthermore, compositional similarities allowed us to attribute an unknown sample to the Roman period. Our study also pointed out the fact that the lower quality mortars belonged to the Medieval period. As a matter of fact, the most friable sample belonging to the Middle Ages turned out to be a mixture of clay, lime and volcanic sand.
Image analysis and flatbed scanners. A visual procedure in order to study the macro-porosity of the archaeological and historical mortars
published in "Journal of Cultural Heritage" 7 (2006) 186–192
This paper describes a low cost method that allows to identify, map and quantify the macro-porosity (Ø ≥ 1/16 mm) of... more This paper describes a low cost method that allows to identify, map and quantify the macro-porosity (Ø ≥ 1/16 mm) of mortar samples taken from the Roman hemicycle theatre in Sibari (South Italy). A specific tool connected to flatbed scanner has been devised for this purpose: it makes possible to acquire images of thin sections through transmitted polarised light. These images can then be elaborated by an ordinary image analysis software programs in order to extrapolate the required information. The technique can be used on mortars which have been buried underground for a considerable period of time (archaeological mortars) or on mortars exposed to sub-aerial weathering (historical mortars). In this way, carbonatic binder dissolution phenomena, and the consequent porosity increase, can be verified and studied in detail.
EFFECTS OF MILLING: A POSSIBLE FACTOR INFLUENCING THE DURABILITY OF HISTORICAL MORTARS
published in "Archaeometry" 52, 4 (2010) 668–679
In their literary texts, some classical Roman authors such as Gaius Plinius Secundus and Marcus Vitruvius Pollio... more
In their literary texts, some classical Roman authors such as Gaius Plinius Secundus and Marcus Vitruvius Pollio stress the importance of milling when preparing mortars. Following these indications, this work describes the effects of milling between lime (calcium hydroxide) and clay brick powder before and after the addition of water. Starting and resulting materials were investigated by XRPD, SEM/EDS, differential scanning calorimetry and thermogravimetry (DSC/TC), colorimetry, densimetry and porosimetry. Prolonged milling changes the mineralogy of the starting materials and increases their reactivity. The final lime pastes, starting from materials milled for varying periods of time, had different mineralogical and physical characteristics. These results may help to clarify the reasons for the marked differences in durability of some historical mortars.
I materiali del costruito tradizionale: un mondo ancora in gran parte da scoprire
in: Archeometria del costruito - l'edificato storico materiali, strutture e rischio sismico (eds. G.M. Crisci and Gattuso C.). Edipuglia, Bari. 2006
Do we know really the materials of the traditional constructions? Have we fully understood the reasons that produce... more Do we know really the materials of the traditional constructions? Have we fully understood the reasons that produce the phenomenons of decay? Reading, attentively, the scientific bibliography produced in the last years, we realize to know few the ancient materials (mortars, plasters, bricks, ceramics etc.). In some circumstances these materials show anomalous behaviors; for example, some magnesian mortars immersed in sea water for many decades shows an optimal condition of conservation, or also, we don't succeed in understanding completely the reactions of synthesis of the hydrated silicates in the historical lime mortars. The archaeometry and all scientific disciplines that belong to it can help to answer to these questions. Following, we will make a short dissertation about the things that have been done and the ways to be followed in order to understand better these processes.
Provenancing of Lightweight Volcanic Stones Used in Ancient Roman Concrete Vaulting: Evidence from Turkey and Tunisia
Co-authors: G. Sottili, F. Marra, and G. Ventura. Published in Archaeometry 52.6 (2010) 949-961; doi: 10.1111/j.1475-4754.2009.00509.x
Samples of four lightweight volcanic rocks from the vaults of Roman bath buildings in modern Tunisia (Carthage,... more Samples of four lightweight volcanic rocks from the vaults of Roman bath buildings in modern Tunisia (Carthage, Leptiminus) and Turkey (Anazarbos, Elaeussa Sebaste) were analyzed by means of thin section, XRF, and LA-ICP-MS to determine their provenances. Both samples from Turkey came from the Ceyhan-Osmaniye volcanic district in Smooth Cilicia. The use of the scoria at Elaeussa Sebaste, which is outside this volcanic district, was likely the result of cabotage along the southern coast of Asia Minor. Of the Tunisian samples, the one from Carthage is a product of Sardinia whereas the one from Leptiminus is a product of Pantelleria. Both samples from Tunisia came from nearby volcanic islands that also produced lava grain mills, many of which were destined for North Africa; therefore the lightweight scoria and pumice in Tunisia likely arrived at the building sites as secondary cargos on established regional trade routes.
Provenancing of Lightweight Volcanic Stones Used in Ancient Roman Concrete Vaulting: Evidence from Rome
Co-authors: G. Sottili, F. Marra and G. Ventura. "Provenancing of lightweight volcanic stones used in ancient Roman concrete vaulting: evidence from Rome" Archaeometry (2011); doi: 10.1111/j.1475-4754.2010.00565.x
This paper presents the geochemical analysis of lightweight scoria and pumice used in concrete vaults from ancient... more This paper presents the geochemical analysis of lightweight scoria and pumice used in concrete vaults from ancient Rome. The geochemical signatures of dark scoria indicates a provenance of the 36–18 ka lavas of Vesuvius, as opposed to the more recent events on which Pompeii was built, as previously thought. The light-coloured pumices analysed, which were originally thought to belong to the Sabatini volcanic system (north of Rome), corresponded instead to products from Campi Flegrei. These results provoke re-evaluation of the trade and acquisition of these specialized materials destined for imperial projects in the capital city.
Ash Mortar and Vaulting Tubes: Agricultural Production and the Building Industry in North Africa
"Ash Mortar and Vaulting Tubes: Agricultural Production and the Building Industry in North Africa" In : S. Camporeale, H. Dessales, and A. Pizzo (eds.), Les chantiers de construction de l’Italie et des provinces romaines: 3e rencontre. L’économie des chantiers (Paris, Ecole Normale Supérieure, 10-11 décembre 2009) (FORTHCOMING).
In this paper I examine two building materials that illustrate the way in which agricultural practices affected... more In this paper I examine two building materials that illustrate the way in which agricultural practices affected choices in the building industry in North Africa. The first is the use of ash from cereals and herbivore manure as a pozzolanic additive for creating a hydraulic mortar. Recent experimental studies have shown that ash from wheat straw and herbivore manure, which are high in silica, produce a pozzolanic reaction when mixed with lime mortar. The mortar of linings in cisterns in North Africa often contain ash, and I suggest that wheat and manure are the likely sources of this ash. The second technique is the use of terracotta vaulting tubes, the proliferation of which began in the area of modern Tunisia during the 3rd century A.D. I suggest that this phenomenon can be related to imperial agricultural policy during the 2nd century A.D., which promoted more intensive and widespread cultivation in Africa Proconsularis and with it a certain amount of deforestation. Increased exportation of agricultural products led to improved land transport networks in the interior and to the necessity for production of large numbers of terracotta amphoras for shipping liquid foodstuffs. With the concomitant growth of the ceramics industry, the vaulting tubes became an economically viable alternative to the more traditional wooden centering, which the tubes replaced. Thus the proliferation of the vaulting tubes is simply one of the many phenomena resulting from North Africa's rise as one of the major agricultural producers during the 2nd century.