The Cannero Castle (Italy): Development of Radiocarbon Dating Methodologies in the Framework of the Layered Double Hydroxide Mortars

Ricci, Giulia; Secco, Michele; Marzaioli, Fabio; Passariello, Isabella; Addis, Anna; Lampugnani, Paolo; Artioli, Gilberto

doi:10.1017/rdc.2020.31

Cited by 17 publications

(24 citation statements)

References 45 publications

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“…Wet separation is reported to contain more amorphous phases, such as LDH and C-S-H, compared with bulk analysis, which is favorable for radiocarbon dating (Addis et al 2019). Looking into the atomically disordered calcitic fraction of wet separated fractions, compared with bulk 500 μm sieved powders, FTIR examinations of hydraulic materials from Cannero, Italy (Ricci et al 2020 in this issue), show a clear trend towards pristine and disordered crystallites in the wet fraction, based on the grinding curve plot of calcites ( Figure S3A). The materials were hydraulic showing large FWHM and asymmetry peak shape analysis ( Figure S3B), supported by XRD examinations (Figure S3C), which help in the radiocarbon dating process.…”

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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“…It is expected that there will not be a single solution to this problem, but an array of different methods adapted to specific mineral mixtures might work. As an example, thermal treatments seem to be very efficient for the removal of LDH phases from the carbonate mixture (Ricci et al 2020 in this issue).…”

Section: Figurementioning

confidence: 99%

The State-of-the-Art of Dating Techniques Applied to Ancient Mortars and Binders: A Review

2020

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The most recent workshop on mortar dating (25–27 Oct. 2018, Bordeaux, Montaigne University, France), which closely followed the publication of an extensive round robin-exercise involving several laboratories, was an opportunity to review the history and challenges of mortar dating methods and procedures currently in use. This review stems from the keynote lectures presented at the meeting, and wishes to summarize recent results, present trends, and future challenges. Three major areas are brought into focus (1) radiocarbon (14C) dating of complex mortars: can we assess the chances of successful dating?, (2) 14C dating of archaeological carbonate materials: difficulties, new directions and applications, and (3) single grain optically stimulated luminescence (OSL) dating of mortars in architectural archaeology: the current state of the art. This paper reflects the material presented by the authors and discussed at the workshop.

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“…14 C dating of lime mortar has challenges such as geological carbonate, recrystallization, fire damage, delayed hardening and layered double hydroxide compounds (Labeyrie and Delibrias 1964;Stuiver and Smith 1965;Baxter and Walton 1970;Sonninen and Jungner 1989;Heinemeier et al 1997;Artioli et al 2017;Ricci et al 2020). Geological carbonate is several orders of magnitude older than the 14 C half-life, and thus contains essentially no 14 C atoms.…”

Section: Ca Ohmentioning

confidence: 99%

“…It introduces a delay between the time of construction and the time of hardening, and it can leave unreacted calcium hydroxides (portlandite) so the sample is alkaline and absorbs modern CO 2 when sampled (Sonninen and Jungner 1989;Heinemeier et al 1997;Michalska et al 2017). Layered double hydroxide (LDH) compounds can form from magnesium phases in dolomitic lime mortar and ancient hydraulic mortars such as pozzolana and cocciopesto (Massazza 2003;Ponce-Anton et al 2018;Ricci et al 2020). LDHs can exchange carbonate anions with the atmosphere throughout the mortar's life and introduce young carbon dioxide (Artioli et al 2017;Ponce-Anton et al 2018;Ricci et al 2020).…”

Section: Ca Ohmentioning

confidence: 99%

Comparison of Thermal Decomposition and Sequential Dissolution—two Sample Preparation Methods for Radiocarbon Dating of Lime Mortars

et al. 2021

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Dating lime mortar samples using the radiocarbon (14C) method can be difficult. This is because the contamination is similar to the primary dating material (CaCO3) and consequently difficult to remove. Mortar can also have late-in-formation pyrogenic carbonate from interactions with the environment after the initial hardening phase, such as recrystallization, fire damage or delayed hardening. When 14C dating a system of primary dating material, contamination and late-in-formation pyrogenic carbonate, one approach is multi-fraction dating with conclusiveness criteria. If a sample has sufficient contamination or late-in-formation pyrogenic carbonate, the criteria evaluate the result inconclusive. To improve inconclusive results from such samples, this study investigates sample preparation by thermal decomposition. Here samples that were inconclusively dated by the authors’ traditional method, sequential dissolution with 85% phosphoric acid, are investigated further. This study finds that CO2 thermally decomposed at low temperatures contains some late-in-formation pyrogenic carbonate. By rejecting CO2 decomposed at low temperatures, Kastelholm castle and Kimito church in Finland are conclusively and accurately dated. Furthermore, a preheating method removes some late-in-formation carbonate, but not enough for a conclusive result. Finally, thermal decomposition finds difficulty in discerning binder carbonate from limestone and marble contamination.

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The Cannero Castle (Italy): Development of Radiocarbon Dating Methodologies in the Framework of the Layered Double Hydroxide Mortars

Cited by 17 publications

References 45 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

The State-of-the-Art of Dating Techniques Applied to Ancient Mortars and Binders: A Review

Comparison of Thermal Decomposition and Sequential Dissolution—two Sample Preparation Methods for Radiocarbon Dating of Lime Mortars

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