Influence of different pretreatments on mortar dating results

Michalska, Danuta

doi:10.1016/j.nimb.2019.03.038

Cited by 12 publications

(13 citation statements)

References 30 publications

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“…14 C dating of archaeological lime-binders deviate from the true age due to contaminates, especially in the case of pozzolanic/hydraulic mortars (Ringbom et al 2014;Michalska 2019). This is also true for pure lime-binders, presumably due to residual geogenic or secondary carbonates (Folk and Valastro 1976).…”

Section: Discussionmentioning

confidence: 99%

Prescreening Hydraulic Lime-Binders for Disordered Calcite in Caesarea Maritima: Characterizing the Chemical Environment Using FTIR

et al. 2020

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Hydraulic lime binders are considered a technological marvel which revolutionized construction techniques in antiquity. The core material is made of a binder that is a mixture of calcite and hydraulic phases, which are amorphous silicate compounds that nanostructurally polymerize into insoluble phases that harden even underwater, formed during the reaction between lime and reactive silicates such as volcanic ash. This is also what makes hydraulic lime so hard to radiocarbon (14C) date. These insoluble phases contain carbonates that may set centuries following their application, resulting in younger ages, which may contaminate the calcite fraction that is favorable for 14C dating. This calcite fraction forms upon the incorporation of atmospheric carbon dioxide during the setting of the hydrated lime. Therefore, different characterization methods are being constantly developed for identifying and characterizing the components of hydraulic lime-binders. In this work, we present a rapid characterization technique based on Fourier transform infrared spectroscopy (FTIR) that characterizes the atomic disorder and chemical environment of the carbonates and silicates fractions in the binder. The atomic disorder of the calcite crystallites was determined by the ν2 and ν4 vibrational modes, and the silicates were characterized by the main peak asymmetry and full width at half maximum (FWHM). Different hydraulic binders from Caesarea Maritima were examined, including Herodian mortars from the underwater breakwater and on-land plasters and mortars from the portʼs warehouse and vaults. Hydraulic binders, in which the calcite fraction in the binder shows atomic disorder that is comparable to modern plaster binders, was associated with silicates that have asymmetry and FWHM of clays and quartz. These materials are considered to be in good preservation state for 14C dating since their carbonates crystallites are disordered and did not interact with the environment chemically to form stable and ordered crystals. Interestingly, the atomic disorder of binders that underwent chemical alterations and recrystallization processes, are associated with reactive silicates aggregates such as volcanic ash (pozzolana). These results suggest a new way to prescreen materials for radiocarbon dating based on the composition of lime-binders and preservation state of the carbonate fraction and hydraulic products.

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Section: Discussionmentioning

confidence: 99%

Prescreening Hydraulic Lime-Binders for Disordered Calcite in Caesarea Maritima: Characterizing the Chemical Environment Using FTIR

et al. 2020

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“…4). Examples are X-ray diffraction (XRD) (Ponce-Anton et al 2018), optical microscopy (Pesce et al 2009), stable isotopes (Pachiaudi et al 1986;Van Strydonck et al 1986;Ambers 1987), thermogravimetric analysis or differential scanning calorimetry (TGA/DSC) (Ponce-Anton et al 2018;Michalska 2019), Fourier-transform infrared spectrometer (FTIR) (Chu et al 2008;Poduska et al 2012), leach rates (Lindroos et al 2007;Michalska and Czernik 2015), inductively coupled plasma mass spectrometry or inductively coupled plasma optical emission spectrometry (ICP-MS/OES) (Al-Bashaireh 2016; Barrett et al (2020a). Sample from Lumen Christi, Northern Ireland, UK.…”

Section: Characterization Methodsmentioning

confidence: 99%

“…For example, the pozzolana sample Rome 025 from Trajan's Market showed increasingly delayed hardening with a sampling depth > 3 cm (Lindroos et al 2020). Further, a pozzolana mortar stays chemically active after the time of construction and recrystallizes new carbonates (Michalska 2019). If the pozzolana ash's parent volcanic system interacts with deposits of carbonate minerals, the pozzolana itself may contain dead carbon (Jackson et al 2010).…”

Section: Sampling Hydraulic Mortarsmentioning

confidence: 99%

A field guide to mortar sampling for radiocarbon dating*

et al. 2021

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“…Hip 61 it is a carbonate mortar with a carbonaceous-basaltic aggregate, taken from the northern wall of the facade of the pastophorium, NWC. Few samples (bulk material, grain fraction, suspension) of this mortar were 14 C dated using different pretreatment methods, giving the results: 1080 ± 100 (Gd-18388), 1490 ± 30 (Poz-16078) (Michalska Nawrocka et al 2007;Michalska 2019) Detailed information about the site, the precise location of sample collection points and the applied 14 C dating preparation technique can be found in Nawrocka et al (2005Nawrocka et al ( , 2009; Michalska Nawrocka et al (2007); Kabacińska et al (2014b); Michalska (2019); Michalska and Pawlyta (2019).…”

Section: Experimental Sample Collectionmentioning

confidence: 99%

“…In these studies, we found several signals generated in lime mortars by γ radiation and examined the dose response curves. Since those samples were not suitable for EPR dating, because of their relatively young (for this technique) age, and the collection method (suitable for 14 C, but not for trapped-change dating), we focused only on their physicochemical properties, and not age determination ( 14 C dates can be found in Michalska 2019 andMichalska andPawlyta 2019). Research conducted during the last few years by the main author and coworkers (Kabacińska et al 2014a(Kabacińska et al , 2017(Kabacińska et al , 2019 as well as a few different groups (Bartoll et al 2000;Sato et al 2004;Kundu et al 2005) clearly show that radiation defects can also be generated in calcite, instead of bleached, by UV radiation.…”

Section: Introductionmentioning

confidence: 99%

Radiation Defects in Lime Mortars and Plasters Studied by EPR Spectroscopy

2020

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Electron paramagnetic resonance (EPR) spectroscopy is a well-established method of dating based on trapped charges, applied to various crystalline materials, including carbonates, bones, and teeth. It provides a detailed insight into the structure of radiation defects—paramagnetic centers generated by irradiation, without the need of a painstaking sample preparation, often challenging in other methods. Using EPR we studied the effect of γ radiation on lime mortars and plasters from ancient settlement Hippos in Israel, in order to analyze the process of defect generation. Analysis of the complex spectra revealed the presence of radiation-induced species, including CO2–, NO32– and organic radical. Using an artificial UV source, we generated relatively strong signals of paramagnetic centers, analogous to those created by γ irradiation, reaching their maximum intensity after 5–6 hr of UV exposure. Our results confirm the previous reports that radiation defects can also be generated, instead of bleached, in calcite by UV radiation, which is crucial for identifying the issues related to light exposition, affecting the accuracy of age determinations in trapped-charge dating methods.

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Influence of different pretreatments on mortar dating results

Cited by 12 publications

References 30 publications

Prescreening Hydraulic Lime-Binders for Disordered Calcite in Caesarea Maritima: Characterizing the Chemical Environment Using FTIR

Prescreening Hydraulic Lime-Binders for Disordered Calcite in Caesarea Maritima: Characterizing the Chemical Environment Using FTIR

A field guide to mortar sampling for radiocarbon dating*

Radiation Defects in Lime Mortars and Plasters Studied by EPR Spectroscopy

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