Natalia Perez Ema

El estudio de los procesos de alteracion de la piedra que forma parte del patrimonio cultural goza ya de una larga tradicion y de amplios conocimientos consensuados por la comunidad cientifica. Sin embargo el material petreo procedente de yacimientos arqueologicos padece unas alteraciones y procesos de degradacion particulares. Estos yacimientos a diferencia de los edificios historicos, han permanecido bajo tierra, en la fase de enterramiento, durante varios siglos en la mayoria de los casos, una particularidad que condiciona irremediablemente las caracteristicas de la piedra y su estado de conservacion tras la excavacion. En este articulo se hace un analisis de las particularidades que definen el estado de conservacion del material petreo en contextos arqueologicos, para luego analizar el caso de algunos de los sitios arqueologicos mas emblematicos del conjunto emeritense, prestando especial atencion a los agentes de deterioro de tipo antropico.

espanolLas alteraciones derivadas de los trabajos de restauracion constituyen un campo de estudio para evaluar las intervenciones realizadas en el patrimonio cultural, en particular sobre yacimientos arqueologicos, puesto que se desconocen, en muchos casos, los efectos de dichas intervenciones a largo plazo. Los estudios sobre durabilidad y eficacia de los tratamientos sobre material petreo (principalmente de consolidacion) forman un campo de investigacion prolifico y en notable desarrollo en las ultimas decadas, no obstante centrado principalmente en la conservacion de edificios historicos. Las particulares caracteristicas del material arqueologico conservado in situ dificultan la extrapolacion de resultados, requiriendo estudios propios, muy escasos hasta la fecha. El caso de Merida es especialmente interesante a la hora de valorar las intervenciones que, desde los anos veinte del siglo pasado, se han ejecutado sobre los diversos bienes. En este trabajo se trata de presentar el pr...

The overall goal of the project is the study of effects of conservation treatments applied on stone material from archaeological sites, i n terms of superficial changes, effectiveness and durability. In this sense, one of the first premises is characterize the surface of the treated and untreated material in order to determine changes in physical and chemical properties.

Different treatments (consolidation and water-repellent) were applied on samples of marble and granite from the Front stage of the Roman Theatre of Merida (Spain). The main goal is to study the effects of these treatments on archaeological stone material, by analyzing the surface changes. X-Ray Fluorescence and Laser-Induced Breakdown Spectroscopy techniques, as well as Nuclear Magnetic Resonance have been used in order to study changes in the surface properties of the material, comparing treated and untreated specimens. The results confirm that silicon (Si) marker tracking allows the detection of applied treatments, increasing the peak signal in treated specimens. Furthermore, it is also possible to prove changes both within the pore system of the materialand in the distribution of surface water, resulting from the application of these products.

El estudio de los procesos de alteración de la piedra que forma parte del patrimonio cultural goza ya de una larga tradición y de amplios conocimientos consensuados por la comunidad científica. Sin embargo el material pétreo procedente de yacimientos arqueológicos padece unas alteraciones y procesos de degradación particulares. Estos yacimientos a diferencia de los edificios históricos, han permanecido bajo tierra, en la fase de enterramiento, durante varios siglos en la mayoría de los
casos, una particularidad que condiciona irremediablemente las características de la piedra y su estado de conservación tras la excavación. En este artículo se hace un análisis de las particularidades que definen el estado de conservación del material pétreo en contextos arqueológicos, para luego analizar el caso de algunos de los sitios arqueológicos más emblemáticos del conjunto emeritense, prestando especial
atención a los agentes de deterioro de tipo antrópico.

The application of conservation treatments, such as consolidation and protection ones, has
been demonstrated ineffective in many cases, and even harmful. Evaluation studies should be a
mandatory task, ideally before and after the intervention, but both tasks are complex and
unusual in the case of archaeological heritage. This study is mainly focused on analyzing
changes in petrophysical properties of stone material from archaeological sites of Merida
(Spain), evaluating, both on site and in laboratory, effects derived from different conservation
treatments applied in past interventions, throughout the integration of different non-destructive
techniques (NDT) and portable devices of analysis available at the Institute of Geosciences
(CSIC,UCM). These techniques allow, not only assessment of effectiveness and alteration
processes, but also monitoring durability of treatments, focused mainly on 1996 intervention in
the case of Roman Theater, as well as different punctual interventions from the 90’s until date
in the House of Mitreo. Studies carried out on archaeological sites of Merida permit us to
compare outcomes and also check limitations in the use of those equipments. In this paper we
discuss about the use of some techniques, their integration and limits, for the assessment of
conservation treatments, showing some examples of Merida’s case study.

Research on the assessment of the effects of conservation/restoration treatments on stone material has been significant in recent years, with focus on the early observation of decay caused by the application of these treatments. However, in the case of archaeological sites, research is still scarce and few studies on the subject have been published. Restoration, as everything else, has changed according to trends, mainly guided by the release of new products and technologies, an experimental field where scientific assessment of suitability, efficacy and durability pre-evaluations of treatments are not always conducted. Some efforts have been made to solve this problem in the architectural field, where functional needs and technical requirements force to set clear standards. Unfortunately, archaeological sites, unlike historic buildings, have specific features that preclude the extrapolation of these results. A critical review of the methodologies, products and restoration materials is necessary, coupled with deeper research on degradation mechanisms caused by these treatments in the mid- and long-term. The aim of this paper is to introduce the research on the above issues using Merida as a case study.

This study is part of a larger project whose main goal is the analysis of the effects of restorative interventions performed in selected archaeological sites in the city of Merida (Spain). Different restoration mortars are and have been used in several archaeological sites of the city of Merida (UNESCO World Heritage site): some of them are documented, such those used in the front stage of the Roman Theater from the rebuilding process, executed between the 20’s and the 60’s of the last century. Some others are currently used for punctual interventions.
The fact that the use of these mortars, both the ones used nowadays and those used in the past are linked in some cases to the emergence of efflorescences or light veils in the surface is the cause of this research. Samples of the past intervention were taken (brick, mortar, efflorescences) and raw materials of the new mortars (white cement, limes, water, synthetic mortars). X ray diffraction and ion chromatography analyses (HPLC) were carried out.
The results demonstrate that some of the raw material currently used in restorative mortars contents harmful soluble salts and that the cement used in the mortars of past interventions are the responsible for the salt crystallization process observed.

Ceramic material is certainly a key element in the cultural heritage, particularly in historical buildings. This material involves specific problems when addressing preservation, as well as conservation and restoration interventions.
This course is coordinated by International Association YOUTH IN CONSERVATION OF CULTURAL HERITAGE-YOCOCU Spain, co-organized by Geosciences Institute IGEO (CSIC, UCM), Spanish Society of Ceramics and Glass (SECV) and the Ceramic and Glass Institute (ICV-CSIC) and sponsored by ECerS, the JECS Trust and SECV.
The main goal of the course is to offer a training program of short duration focused on the ceramic material used in architectural heritage, including structural and decorative elements. Raw materials and technologies used for manufacturing, alteration and decay processes, characterization techniques for study and analysis, as well as new trends in conservation treatments will be addressed.