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tCements and Mortars in Historical Monuments:Contributions for the Preservation of Built Cultural Heritage

Fernanda CarvalhoCENIMAT/i3N – Centro de Investigação em Materiais, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal

Supervisor: João Pedro Veiga (Departamento de Ciência dos Materiais, FCT NOVA & CENIMAT/i3N)

The societal impact of historical constructions has generated an increased interest in the scientific community, promoting

innovative approaches to issues raised by the necessity of preserving cultural assets for the future. Materials Science has un unquestionable role

in this approach by developing strategies and methodologies, crosslinking different aspects related to cultural heritage materials, attaining a

better comprehension on their properties and historical applications, disclosing correlations and interactions between materials with different

origins and supporting a compatibility evaluation with new and improved materials in the context of qualified interventions on built heritage. The

materials under study in this work are cements and mortars from different periods of manufacture, corresponding to three important

monuments escaping traditional regional constraints: the Monastery of Alcobaça in Portugal, the Palace of Knossos in Greece and the Roman

Aqueduct of Carthage in Tunisia. Cements and mortars, used with different functions in historical buildings, may present several problems that

affect their structural application and their behavior with adjoining materials. Through and holistic approach to the study of their chemical and

physical properties, their interaction with different substrates, their compatibility with different materials and the influence of human and

environmental factors for their conservation status, will fulfill the prospect of contributing to preservation strategies of each specific monument

encompassing a global outreach of cements and mortars applied to monuments of European origin.

Case Study – Palace of Knossos

AcknowledgementsThis work was supported by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT-Portuguese Foundation for Science and Technology under the project ref. VIDB/50025/2020 and, SFRH/BD/145308/2019(F. Carvalho). The funding from the European Union Horizon 2020 research and innovation programme H2020-DRS-2015GA nr.700395 (HERACLES project) and H2020 EIT Raw Materials MineHeritage Project (PA 18111) are acknowledged.Access to FTIR and Raman equipment is acknowledged (CENIMAT and H. Águas).

The study of mortars and cements applied in built cultural heritage is fundamental to understand the characteristics of the

materials and their behavior over the years. The use of different analytical techniques allows a complete approach to the identification of the various

mineral components. The different types of mortar and cement samples showed calcium carbonate and quartz as the main components of binders

and aggregates, respectively. In the case of mortars, clay mortar samples showed the highest mineralogical variation, with the most pronounced

presence of clay minerals. The decay materials studied originate mainly from the deterioration of the cement, resulting in efflorescence and white

and black crusts. Thernadite was the main component of efflorescence samples and Gypsum was the main product found in crust samples.

Final Remarks

Abstract

Above: Plan of the Palace of Knossos in Heraklion, with the mortar sampling locations (image: HERACLES Project)

Mortarssamples

Palace of Knossos

▪ Minoan civilization

▪ Circa 22,000 m2 of occupied area

▪ Main archaeological excavations carried out

by Sir Arthur Evans in the early 20th Century

▪ Construction materials: wood, stone, mortar, clay

▪ Main reconstructions materials: cement and concrete

PlasterClay mortarBinder mortar

Fig.2: XRD from mortar samples. Quartz (Q), Calcite (C), Gypsum (G), Montmorillonite (M), Albite (A)

Fig.1: Optical microscopy of plaster, clay mortar and binder mortar. The samples are heterogeneous, with a great

variation of morphology and distribution of aggregates

Fig. 3: Optical microscopy and FTIR from each cement sample. All results present characteristic bands of calcium carbonate. In addition to these, all results

present an enlarged band in the zone between 1165 and 1016 cm-1, characteristic of the vibrations of

sulfate groups SO42- and Si-O

Fig.4: Raman results of decay materials. Left: the efflorescence samples (orange lines) was mainly Thernadite and the white crust (gray and black

lines) was mainly Gypsum. Right: all samples of black crust presents Gypsum and, in same cases, carbonaceous matter

Deterioration MaterialsWhite Crust and Efflorescence Black Crust

White Crust Efflorescence Black Crust

Cement samples

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