Opus Signinum Research Articles

An Experiment Measuring Water Consumption in Roman Hydrophobic Mortar (opus signinum)

Opus signinum is a lime mortar mix that includes crushed pottery as an aggregate. Because it is water-resistant, it was used to line hydraulic structures like pools and aqueducts. While there have been numerous recreations of Roman ‘concretes’ in the past, hydrophobic linings have received little attention, and all preliminary studies in these recreations have paid more attention to the dry components and the lime than to the hydric needs of the mortar. The experiment presented here was to gain a better understanding, with the help of traditional builders, of the process of mixing and applying hydrophobic linings and calculate the water consumption of individual samples. The data obtained contribute to assessing the water consumption needs on Roman construction sites, what associated logistics these volumes required, and what the technicalities of applying this specific type of lining were.

Mortars and Renders: The Case of the Roman Villa Horta da Torre Fronteira, Portugal

The archaeological site of villa Horta da Torre in Portugal reveals distinctive architectural features within the context of Roman villae in Hispania. Notably, the triclinium was designed with an artificial cascade originating from a double apse wall, and the walls were adorned with mosaic tessellae panels and marble skirting. During the Roman era, the surrounding area belonged to the former province of Lusitania, with Augusta Emerita serving as its capital. This study examines 11 mortar samples from various contexts and functions, such as masonry, preparatory, render, and opus signinum mortars. A set of complementary analytical techniques was employed to determine the textural and mineralogical compositions of the mortars. The aim was to gain insights into the production techniques and the selection of raw materials within the geological context of this rural construction. It was observed that the processing of raw materials and production techniques did not always adhere to the rules of Vitruvius. A comparison with other villas revealed comparatively less meticulous attention to sand selection and precise layering for mural painting. Nevertheless, it was noted that in preparatory layers for the supranucleus and nucleus tesserae, ceramic pieces were intentionally added to improve the mortar. The binder used was calcitic lime, likely obtained from locally sourced limestone. The nature of aggregates is diversified but consistent with the local geological provenance within a radius of less than 3 km, in accordance with two sand exploration sites. This research aligns with the United Nations’ 2030 Agenda for Sustainable Development, contributing specifically to SDG 11 and Target 11.4, which “aims to strengthen efforts to protect and safeguard the world’s cultural and natural heritage”.

Interpretation of Funerary Spaces in Roman Times: Insights from a Nucleus of Braga, NW Iberian Peninsula

The funerary/cult archeological nucleus of Rua do Raio (Braga, in the northwest of the Iberian Peninsula) was discovered between 2007 and 2009, under the excavation works of a necropolis of Bracara Augusta. This building exhibits a set of particularities that confirms its archeological importance. It is a construction dating from the middle of the 1st century AD, subject to two reforms, one in the second half of the 1st century AD and another in the 2nd century AD, with a trapezoidal shape and comprising ten rectangular tanks rendered with opus signinum mortars. It shows a unique architectural configuration in the city, as well as in the Portuguese territory, and the space is under musealization, together with a set of graves identified in the same archeological intervention. The present investigation contextualizes the funerary and religious architecture of the city. Its description is presented, highlighting its relevance, and an interpretative possibility is formulated.

Geomechanical modelling and stability analysis of the shallow underground water reservoir ‘Palombaro Lungo’ (Matera-Italy)

The city of Matera, as several other ancient historical cities and towns, is recovering a large part of its ancient parts developing a policy of urban regeneration. In the early 90s, during the restoration works of the main square, Piazza Vittorio Veneto, it was re-discovered a huge underground space used as water reservoir named Palombaro Lungo. It was built linking ancient pre-existing smaller caves and completed at the end of the nineteenth century making it impermeable with the cocciopesto (opus signinum) technique. The hypogeum is dug in a Plio-Pleistocene rock called Gravina Calcarenite. It is a calcareous sandstone weak rock with good mechanical properties, low permeability and easy to be dug. The internal geometry of the hypogeum and the rock thicknesses above the caves was reconstructed by the integration of topographic and GPR surveys. The paper presents a geo-mechanical model of Palombaro Lungo underground reservoir and evaluation about the stability of this structure. The stability analysis were developed using the numerical code UDEC for several transect of Palombaro Lungo assuming the calcareous sandstone blocks as deformable, trying to address the evolution of the stress–strain conditions. The case study can be considered as an example of general interest for the study of rupestrian underground reservoir of a longed form, where one planimetric dimension strictly prevails over the other. Numerical simulations showed a stress–strain state compatible with the fractures detected in situ and confirmed the absence of instability problems in the groundwater reservoir.

THE ROMAN AQUEDUCT OF KNOSSOS, A MODEL FOR NINETEENTH-CENTURY AQUEDUCT DESIGN

In this paper, we present findings from a field inspection of the Knossos aqueduct undertaken in 2019. A key contribution of our fieldwork was the architectural identification of the Roman channel underlying the nineteenth-century wall of the Ottoman-Egyptian aqueduct supplying Iraklio. While reuse of the Roman aqueduct in the nineteenth century was known from historical reports, the structural overlap has never been identified in the field or documented archaeologically, until now. We recorded the Roman channel lined with opus signinum running along the base of the nineteenth-century aqueduct's wall between Fundana and Spilia. Through this realisation in the field, we were able to establish diagnostic styles of masonry for both periods. Our architectural distinction between the overlaid aqueducts allowed us to integrate previously disarticulated components of the later system, like the reused Roman tunnel at Skalani and the nineteenth-century bridge at Spilia, into an integrated Ottoman-Egyptian water supply for Iraklio. As we approached Knossos from Spilia, we were also able to identify the point at which the Venetian aqueduct supplying Iraklio converged with the Roman system. Consequently, our 2019 fieldwork not only mapped the length of the Roman aqueduct supplying the city of Knossos but also that section of the nineteenth-century Ottoman-Egyptian aqueduct of Iraklio built directly over it and a shorter tract of the Venetian aqueduct of Iraklio that either ran alongside it or was, in turn, itself partially overlaid by the nineteenth-century system.

Archaeological and Chemical Investigation on the High Imperial Mosaic Floor Mortars of the Domus Integrated in the Museum of Archaeology D. Diogo de Sousa, Braga, Portugal

This paper intends to characterize the floor mortar layers (nucleus, rudus and statumen) of the high imperial mosaics of the domus integrated in the Museum of Archeology D. Diogo de Sousa, the oldest roman housing testimonies known in Braga, Portugal. It offers an important archaeological and historical contextualization and first chemical characterization attempt on the mortars. The study of 13 mortar samples was carried out at a chemical level through X-ray fluorescence spectroscopy (XRF). All samples presented low lime content when compared to similar studies. A high chemical similarity between nucleus mortars (opus signinum) and chemical composition differences between rudus and statumen mortars was determined, confirmed by statistical analyses. Their composition was distinctly related to the stratigraphic position of each floor mortar layer, following Vitruvius’ model, and to the external conditions and treatments (e.g., capillary rise with soluble salts and application of chemical treatments), to which they were submitted.

The “qanats” of the Los Alcores aquifer and the traditional water supply system to Seville

Due to the quality and the topographic position of its waters, the Los Alcores aquifer has been the main supply of running and drinking water for the city of Seville for many centuries. In the first century, a complex water supply system, of more than 17 km in length, was built to withdraw groundwaters in the southern part of the aquifer and whose main elements were an extensive network of “qanats”, a surface conduction and a reservoir in the city (castellum aquae). After the abandonment of this infrastructure, the surface conduction was reconstructed in the 12th century (known as Caños de Carmona), which was made up of a canal and, in the part closest to the city, by a brick aqueduct over arches. Since the end of the 19th century, the urban, industrial and the transport network development and the conduction of water from the reservoirs of the Sierra Morena produced, once again, the progressive abandonment and destruction of these infrastructures. However, a large part of the “qanat” network excavated in the Los Alcores aquifer has been preserved and recently the GEOS and AAES speleological groups have explored about 20 km of water mines. The characteristics of tunnels and vertical shafts, the construction techniques, the discovery of Roman mortar (opus signinum) and bricks (opus testaceum) and the Arab chronicles suggest that this network of “qanats” was made mainly during the Roman domination period.

From the Roman Mosaic to the Portuguese Pavement: Continuity of an Artistic Expression in Time and Space

The embellishment of pavements has always assumed a crucial role in what can be considered the furnishing of private and public spaces. The best known in antiquity has been, without doubt, the mosaic in all its forms: pebble mosaics, opus signinum, opus tessellatum, opus sectile.The mosaic, of Greco-Roman and Byzantine tradition, is one of the architectural and artistic elements that, for centuries, had been used to decorate the room in which they were placed. The beauty, coupled with the durabi-lity and strength of the material, was a determining aspect of the use of the mosaic as a pavement: two closely related aspects when looking at the Roman mosaic, which can still be found today on the Portuguese pavement or Portuguese mosaic, as it is called on the other side of the Atlantic.In this article, we intend to illustrate the continuity of an art, which has kept many classic motifs alive through the centuries taking it far beyond the territories of the Roman Empire.

Un edículo republicano dedicado a Atargatis en Carthago Nova

Se analiza un conjunto de estructuras halladas en el sector nororicntal del cerro del Molinete (Cartagena). Consisten en un edículo pavimentado con opus signinum en el que se halla inscrita una dedicación a Atargatis asociado a una serie de cubetas e instalaciones de carácter hídrico. Al lado, restos de un gran basamento que podrían constituir el podium de un templo. La cronología de finales del siglo II a.C. indica la penetración directa de estos cultos desde oriente y su trasmisión a través de los esclavos y libertos sirios, bien documentados en la epigrafía de la ciudad.

Mosaics of the Hispanic Meseta Norte: Phases, Officinae, Artistic Taste

About 400 mosaics are known in the Meseta Norte (today, Comunidad Autónoma of Castilla y León), with chronological variants, most of them of the 4th and 5th centuries; with stylistic variants, geometrical topics in preference to figurative themes; with topographical variants, predominantly rural findings against urban findings; and with technical variants, exceptionally sectilia, only one case of signinum and the rest, tessellati. We know nothing about the mosaic workers, just the signature of one who worked in the Baths of La Olmeda (Palencia): Sil [o]. However, stylistic, morphological, or material concordances allow us to suspect the existence of workshops, which usually operated in regional areas. Surely the former ones were Italic workshops serving people of that origin (opus sectile and opus signinum, Asturica Augusta). Almost two centuries after another officina is documented, known as Clunia-Uxama-Asturica, because it worked in these three cities, and their consequences are still tracked in the late third century in certain domus of the above-mentioned cities. The great mutation of Roman mosaic in the Mesetas occurred in the fourth century with the spectacular display of villas, unparalleled in Hispania. Serving these new customers a large number of workshops was developed, for instance, the designated one as the NO peninsular workshop, which worked in the provinces of León and Zamora; the so-called one as Prado-Almenara workshop, because of its presence in these villas from Valladolid, and also in La Valmuza (Salamanca) where another workshop took part closely linked to some villas from La Mancha. Finally, the Cuevas-Valdanzo workshop, whose taste for the aniconism links these villas of Soria with other more western ones.

UBC Excavations of the Roman Villa at Gerace, Sicily: Results of the 2015 Season

A second season of excavation was conducted in 2015 at Gerace (Enna province, Sicily). In the small late Roman villa of ca. 370/375 ad identified by earlier work, the largest room, in the west wing, was found to have a floor of opus signinum, but the west corridor, in contrast to the mosaic-paved south corridor, had a floor of beaten earth throughout its life. The villa may never have been completely finished, even though occupation debris suggests it was frequented for much of the fifth century. Of the small freestanding bath-house at a higher level alongside it, only a single heated pool had survived later demolition. In its place two storerooms were inserted deep into the earth for efficient insulation. In the fire that destroyed the villa ca. 450/530 ad, a date supported by C14 analysis, the contents of these stores were carbonized: a huge cache of thousands of seeds, principally barley but also including wheat, grapes, and legumes, was uncovered there. The much larger, earlier store-building to the east, provisionally dated to ca. 325/350 and destroyed ca. 360, is now shown to have been a basilican structure. Three earlier phases of building have been detected below it; there is also a sherd of Attic Black Figure pottery, attesting activity at Gerace ca. 500 bc. A further 37 examples of stamps on roof tiles were discovered, including a single example from a hitherto unrecorded die; they were all part of the production, probably on site, of Philippianus, the likely owner of the Gerace estate in the late fourth century. After the fire of 450/530 ad, early Byzantine structures (seventh century?), much disturbed by the plough, occupied part of the site of the late Roman villa.

Identifying wine and oil production: analysis of residues from Roman and Late Antique plastered vats

The production of oil and wine was an important aspect of the ancient Mediterranean economy. Among the material remains related to the production of these substances, installations used for their production provide evidence that is still unexploited. Although archaeological studies have been carried out on these installations, problems can arise in the identification of their function, as wine and oil production structures can be similar and the archaeological traces insufficient to establish which substance was produced.Archaeometry, in particular the chemical analysis of the organic residues left by substances, is valuable for identifying the substances that were actually produced and in interpreting the function of these structures. In particular, analyses can be carried out on the plastered coatings of the vats found in these installations. In this paper, we present the results of the analyses of samples of opus signinum (broken ceramics mixed with lime) used to coat vats from installations that were thought to have produced wine or oil. The vats were found in different Roman and Late Roman sites in Italy and in the Balearic Islands and were investigated in order to verify the preservation of the organic residues and their origin. The samples were analysed by gas chromatography/mass spectrometry to identify the presence of oil or wine markers.

Una inscripción republicana de la sede de una posible corporación en La Cabañeta (El Burgo de Ebro, Zaragoza): nuevos datos sobre la ocupación romana del valle del Ebro

This paper faces the study of a Latin Roman republican inscription made on an opus signinum floor. This script speaks about two magistri being in charge of a work. Also, the features of text, and the structure of building in witch it has been found, induce us to think that we are dealing with the office of an Italic immigrant corporation, probably dedicated to trade.

The Decorated Pavements of Morgantina II: The Opus Signinum

Opus signinum, a paving material formed of crushed terracotta set in a matrix of cement, is a form of pavement found frequently in the western Mediterranean. The technique is thought to have begun in North Africa, and is commonly found in Hellenistic Sicily and Southern Italy.The Hellenistic town of Morgantina in central Sicily has a great number of signinum floors, which are found primarily in the houses. Thus a study of the floors is a study of private interior decoration. The houses and their attendant floors date from the third century B.C. to the mid-first century A.C. Designs of inset tesserae often enliven opus signinum, and several linear patterns of inset tesserae are common in Morgantina and in other floors in the western Mediterranean. The Morgantinian signinum floors appear in houses that also have mosaic floors, thus affording a comparison of contemporaneous and possibly related paving techniques. Thus far no comprehensive study has been made of all of the opus signium from any site, and the present work is an attempt to establish a model for such a study.

New Light on the Origins of Floor Mosaics

SummaryRecent discoveries of pebble mosaics in various settlements in southern Spain from the seventh to the fourth centuriesB.C.reveal an early tradition in floor-making. These discoveries have thrown new light on the origins of the most commonly used floors in Roman times,opus signinumandopus tessellatum. The first technique, thought to be Italian in origin, was probably developed in Italy from previous experiments in other Mediterranean sites which were of Punic origin. The origin of tessellated floors has been widely discussed and, although they were being produced on a large scale in Italy towards the first centuryA.D., we can assume that there existed a long experimental stage prior to the Roman period in which two general types of mosaic floors were developed—those with a uniform surface and those formed with small elements.

Form, Function and Technique in the Pavements of Delos and Pompeii

The present study looks closely at the mosaic pavements of Delos and Pompeii, dated in the late 2nd and early 1st centuries B.C., in an attempt to account for the great differences in form, function, and technique observable in the genre. The earliest mosaics of Pompeii are of opus signinum, a cement embellished with designs picked out in white marble tesserae. Also common are pavements of irregularly cut stones and opus sectile. Contemporary pavements in Delos are polychrome, tessellated and concentrically arranged with decorative frames surrounding central, often figural, panels. Threshold mosaics at Delos are figural and have only a casual relation to the main pavement of the room. At Pompeii they are geometric and serve to distinguish functional areas of the house or room. At Delos finer materials are used for the central portion of the pavement; at Pompeii the material of the pavement is uniform over the entire surface. Finally, at Delos lead strips are used to outline some geometric motifs, a technique unknown at Pompeii. These differences are attributable to the respective origins of the Pompeian and Delian pavements. The signinum floors of Pompeii can be traced to 3rd century B.C. Punic establishments in North Africa and Sicily. The appearance and technique of the Delian floors-including the use of lead strips-go back to pebble mosaics like those found in Olynthus, dating from the late 5th and early 4th centuries B.C., and Pella, dated in the late 4th century B.C. The continued adherence of Eastern and Western mosaicists to their distinctive traditions is reflected in Pompeii and elsewhere in Italy in the tessellated pavements of the 1st and 2nd centuries A.C., which translated into black and white the designs characteristic of the early signinum pavements. The Eastern type of centralized, polychrome pavement can still be seen in the 1st century A.C. at Olympia, Corinth and Antioch, long after the East had submitted to Roman domination.

The Ruined Church of Stone-by-Faversham

SummaryThis article contains a report of excavations conducted in 196J and ig68 at the ruined church (or chapel) of Stone-by-Faversham, Kent. They were designed to establish whether or not the central part of the building (subsequently the western part of a medieval chancel) was an original Roman structure. The evidence, derived from the type of construction, an opus signinum floor, from the coins, burials, and pottery found in association with the building, all indicate that in origin it was either a mausoleum, or possibly a martyrium, probably datingfrom thefourth century A.D.A Roman structure subsequently incorporated into a Christian church is unique in this country. The question as to when and how this transformation occurred is discussed in the context ofthepossible survival of Christianity in Sub-Roman Kent, and of St. Augustine's mission. Further excavation revealed foundations of a pre-Conquest wooden nave, and throws fresh light on the methods used by the Anglo-Saxons in building wooden churches.

Roman Britain in 1938

Mr. V. E. Nash-Williams reports discoveries on three sites. (1) At Llantwit Major, Glamorganshire, where a house was partially excavated in 1888, trial cuttings showed that the structural remains covered an area of about 2 acres, enclosing roughly a square of about 300 ft., on the N, S, and W sides of which were the main buildings with detached outbuildings on the E side. In its final stage the plan was of winged-corridor type with main range on the W and others to the N and S, the latter possibly additional; it was fronted by an internal colonnade of imported freestone and faced on to a cobbled courtyard. A subsidiary range had been tacked on at right angles to the N wing. The walls of local limestone and sandstone remained up to 6 ft. and were decorated with coloured plaster; the floors were mostly of opus signinum. A hypocaust or furnace-chamber in the western or main range, after long use, had been filled in with refuse and a small iron-smelting furnace had been built over it. Two rooms in the N wing, opened in 1888, were cleared ; much of the geometric pavement survived. Three or four more skeletons were found ; they had been buried in rough cists sunk into the pavement or cut through the walls, and therefore at a period when the house was no longer in use. A massively constructed outbuilding, measuring 80 by 26 ft., stood just within the remains of a ditch system. (2) At Caerleon a trench was cut on the SW side of White Hart Lane in the praetentura of Isca abutting on the SE defences. It revealed the primary clay rampart, 15 ft. wide and 6 ft. high, with the inner face of the latest stone rampart outside it ; inside the rampart, and between it and the rampart roadway, a stone building had been inserted (cf. JRS xix, 182). The roadway was 20 ft. wide and heavily metalled and was bordered by the stone culvert of the main drainage-system. On the inner side of the roadway the walls and floor of a stone building, probably a barrack-block, were found.