Mortar Dating Using AMS 14C and Sequential Dissolution: Examples from Medieval, Non-Hydraulic Lime Mortars from the Åland Islands, SW Finland

Non-hydraulic mortars contain datable binder carbonate with a direct relation to the time when it was used in a building, but they also contain contaminants that disturb radiocarbon dating attempts. The most relevant contaminants either have a geological provenance and age or they can be related to delayed carbonate formation or devitrification and recrystallization of the mortar. We studied the mortars using cathodoluminescence (CL), mass spectrometry (MS), and accelerator mass spectrometry (AMS) in order to identify, characterize, and date different generations of carbonates. The parameters—dissolution rate, 13C/12C and 18O/16O ratios, and 14C age—were measured or calculated from experiments where the mortars were dissolved in phosphoric acid and each successive CO2 increment was collected, analyzed, and dated. Consequently, mortar dating comprises a CL characterization of the sample and a CO2 evolution pressure curve, a 14C age, and stable isotope profiles from at least 5 successive dissolution increments representing nearly total dissolution. The data is used for modeling the interfering effects of the different carbonates on the binder carbonate age. The models help us to interpret the 14C age profiles and identify CO2 increments that are as uncontaminated as possible. The dating method was implemented on medieval and younger mortars from churches in the Åland Archipelago between Finland and Sweden. The results are used to develop the method for a more general and international use.

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Delayed Hardening and Reactivation of Binder Calcite, Common Problems in Radiocarbon Dating of Lime Mortars

Radiocarbon ◽

10.1017/rdc.2020.5 ◽

2020 ◽

Vol 62 (3) ◽

pp. 565-577 ◽

Cited By ~ 1

Author(s):

Alf Lindroos ◽

Åsa Ringbom ◽

Jan Heinemeier ◽

Irka Hajdas ◽

Jesper Olsen

Keyword(s):

Carbon Dioxide ◽

Phosphoric Acid ◽

Calcium Hydroxide ◽

Radiocarbon Dating ◽

Lime Mortars ◽

Dating Method ◽

Common Problems

ABSTRACTWhen sampling mortars for radiocarbon (14C) dating it is crucial to ensure that the sample has hardened rapidly relative the resolution of the dating method. Soft and porous lime mortars usually fulfill this criterion if the samples are taken from an uncovered surface from less than a few centimeters deep. However, hard, concrete-like mortars may be impermeable for carbon dioxide and even the outermost centimeters may still contain uncarbonated calcium hydroxide. These mortars may harden very slowly and contain carbonate that formed centuries or even millennia after the original building phase, and they can still be alkaline and capture modern 14C, causing younger 14C ages than the actual construction age. Another problem is reactivation of the binder carbonate if it has been partly decarbonated during a fire later on in its history. It will be shown that these young carbonates dissolve rapidly in phosphoric acid and in many cases a reasonable 14C age can be read from 14C profiles in sequential dissolution if the measurements from initially formed carbon dioxide are disregarded. However, if a mortar was made waterproof deliberately by adding crushed or ground tile, as in Roman cocciopesto mortars, it may be very difficult to get a conclusive dating.

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Development of Radiocarbon Dating Method for Degraded Bone Samples from Korean Archaeological Sites

Radiocarbon ◽

10.1017/s0033822200034408 ◽

2011 ◽

Vol 53 (1) ◽

pp. 129-135 ◽

Cited By ~ 3

Author(s):

K J Kim ◽

W Hong ◽

J H Park ◽

H J Woo ◽

G Hodgins ◽

...

Keyword(s):

Carbon Content ◽

Depth Profile ◽

Radiocarbon Dating ◽

Archaeological Site ◽

Archaeological Sites ◽

The Past ◽

Dating Method ◽

Study Support ◽

Ultrafiltration Process

The development of radiocarbon dating for degraded bone samples collected at Korean archaeological sites has been successful through the characterization of raw bone C/N ratios and application of an ultrafiltration method. It was found that the C/N ratios of raw bone samples are inversely proportional to the carbon content and residue amount after gelatinization. We have examined a few dozen Korean archaeological bone samples for this study. Well-preserved bone samples are found to be physically dense. The range of C/N ratios of Korean raw bone samples ranged from 3.4 to 74. We found that the C/N ratios of degraded raw bone samples can be used to determine whether 14C samples are acceptable for normal pretreatment processing and eventual dating. The results of this study support that even if the C/N ratio of a degraded raw bone sample is 11, extraction of collagen for bone dating is feasible by a carefully designed ultrafiltration process. Our preliminary 14C dating results of a depth profile of Gunang-gul Cave, an archaeological site in Danyang, Korea, indicate that this site has been either geologically or anthropologically disturbed in the past, with 14C ages ranging from 28,910 ± 200 to 48,090 ± 1050 yr BP. The C/N ratios of the collagen samples of Gunang-gul were determined to be 3.2–3.6. Our study establishes a new guide for the pretreatment of degraded bone samples such as those collected in Korea for 14C dating.

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The Best possible Time resolution: How precise could a Radiocarbon dating method be?

Radiocarbon ◽

10.1017/rdc.2019.134 ◽

2019 ◽

Vol 61 (6) ◽

pp. 1729-1740 ◽

Cited By ~ 1

Author(s):

I Svetlik ◽

A J T Jull ◽

M Molnár ◽

P P Povinec ◽

T Kolář ◽

...

Keyword(s):

Mass Spectrometry ◽

Time Resolution ◽

Calibration Curve ◽

Time Scale ◽

Radiocarbon Dating ◽

Time Intervals ◽

High Slope ◽

Resolution Curve ◽

Dating Method ◽

Fine Time

ABSTRACTToday, accelerator mass spectrometry (AMS) technology enables us to carry out very precise measurements of radiocarbon (14C). Unfortunately, due to fluctuations in the 14C calibration curve, the resulting calibrated time intervals vary from decades up to centuries in calibrated age. Within a time scale of several decades, we can find several time intervals on the 14C calibration curve which correspond with periods of rapid increases in atmospheric 14CO2 activity. Some of these “high slope” parts of the calibration curve could be used for fine time resolution for radiocarbon dating of individual samples. Nevertheless, there are certain limitations owing to the properties of the samples measured. We have prepared a time-resolution curve for the 14C dating method, applying calibration curve IntCal13 and assuming an uncertainty of 14C analyses ±15 yr BP (for recent samples). Our curve of the time resolution covers the last 50 ka. We found several time intervals with time resolution below 50 yr BP for the last 3 ka. Several time intervals which can enable substantially better time resolution compared to neighboring parts of the calibration curve were also found for periods older than 3 ka.

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Characterization of Fresh and Durability Properties of Different Lime Mortars for Being Used as Masonry Coatings in the Restoration of Ancient Constructions

Sustainability ◽

10.3390/su13094909 ◽

2021 ◽

Vol 13 (9) ◽

pp. 4909

Author(s):

Fernando G. Branco ◽

Maria de Lurdes Belgas ◽

Cátia Mendes ◽

Luís Pereira ◽

José Marcos Ortega

Keyword(s):

Water Absorption ◽

Crushed Rock ◽

Rock Powder ◽

Hydraulic Lime ◽

Durability Properties ◽

Flow Table ◽

Lime Mortars ◽

Lower Porosity ◽

Durability Performance

Coatings and plasters are an integral part of masonry cladding, having a fundamental protective and aesthetic function. They are exposed to numerous aggressive actions, which produce their degradation over time. The utilization of lime, as a binder in masonry lining mortars, plays an important role in their durability and conservation. The objective of this work is to analyze the fresh and durability properties of lime-based mortars for their application in the restoration of old buildings. Four different kinds of mortars were studied with similar workability, using as binders lime putty, aerial lime, and hydraulic lime. The aggregates used consisted of sand and crushed rock powder. As fresh properties, the consistency (by using the flow table) and water retentivity were determined. With respect to durability-related properties, water absorption by capillarity and by immersion, drying kinetics, and carbonation depth were studied. Bulk density and porosity of the mortars were also obtained. Mortars with lime putty showed higher global porosity and water absorption by immersion, while aerial lime mortars presented lower porosity and higher water absorption by capillarity. Finally, the durability performance of all the studied lime mortars was overall adequate for being applied as masonry coatings in the restoration of old buildings.

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14C Mortar Dating: The Case of the Medieval Shayzar Citadel, Syria

Radiocarbon ◽

10.1017/s0033822200057647 ◽

2013 ◽

Vol 55 (2) ◽

pp. 514-525 ◽

Cited By ~ 16

Author(s):

Sara Nonni ◽

Fabio Marzaioli ◽

Michele Secco ◽

Isabella Passariello ◽

Manuela Capano ◽

...

Keyword(s):

Radiocarbon Dating ◽

Good Accuracy ◽

Time Constraints ◽

X Ray ◽

Ams Radiocarbon Dating ◽

Lime Mortars ◽

Biasing Effects ◽

Centrifugation Protocol

This paper reports the results from applying the Cryo2SoniC (Cryobreaking, Sonication, Centrifugation) protocol to some lime mortars sampled from the citadel of Shayzar (Syria). The overall aims of this project are 1) to use the properties offered by high-precision accelerator mass spectrometry (AMS) radiocarbon dating for the evaluation of absolute chronology with its typical robust time constraints (i.e. 25 14C yr), and 2) to apply the dating directly to the citadel structures in order to prevent possible biasing effects potentially affecting indirect 14C dating on organic materials found at the study site. The analyses presented in this paper have been mainly performed as a preliminary check of the Cryo2SoniC methodology in order to assess its applicability to this study site by comparing observed mortar results with archaeological expectations about the citadel development phasing and charcoals found encased in mortars. Petrographic and mineralogical thin-section analyses by optical microscopy (TSOM), X-ray powder diffraction (XRD), and scanning electron microscopy plus energy dispersive spectroscopy (SEM/EDS) investigations were carried out for characterization of the mortar samples to verify the occurrence of some features, related to their production technology, which may introduce dating offsets. The resulting 14C calibrated ages were in agreement with the archaeological expectations based on type and stratigraphic site reconstructions, in situ inscriptions, and written sources. Such results showed also a general (with 1 exception) statistical agreement among the charcoals and the analyzed mortars simultaneously, confirming the archaeological expectations for the Shayzar citadel. Results presented in this paper indicate good accuracy for the applied procedure for chronology reconstruction and highlight the capability of Cryo2SoniC to further characterize the Shayzar site.

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Successful AMS 14C Dating of Non-Hydraulic Lime Mortars from the Medieval Churches of the Åland Islands, Finland

Radiocarbon ◽

10.1017/s0033822200045124 ◽

2010 ◽

Vol 52 (1) ◽

pp. 171-204 ◽

Cited By ~ 57

Author(s):

Jan Heinemeier ◽

Åsa Ringbom ◽

Alf Lindroos ◽

Árný E Sveinbjörnsdóttir

Keyword(s):

Direct Contact ◽

Radiocarbon Dating ◽

14C Dating ◽

Hydraulic Lime ◽

Ams Radiocarbon Dating ◽

Lime Mortars ◽

Ams Dating ◽

Chemical Testing ◽

Shed Light ◽

Ams 14C Dating

Fifteen years of research on accelerator mass spectrometry (AMS) radiocarbon dating of non-hydraulic mortar has now led to the establishment of a chronology for the medieval stone churches of the Åland Islands (Finland), where no contemporary written records could shed light on the first building phases. In contrast to other material for dating, well-preserved mortar is abundantly available from every building stage.We have gathered experience from AMS dating of 150 Åland mortar samples. Approximately half of them have age control from dendrochronology or from 14C analysis of wooden fragments in direct contact with the mortar. Of the samples with age control, 95% of the results agree with the age of the wood. The age control from dendrochronology, petrologic microscopy, chemical testing of the mortars, and mathematical modeling of their behavior during dissolution in acid have helped us to define criteria of reliability to interpret the 14C results when mortar dating is the only possibility to constrain the buildings in time. With these criteria, 80% of all samples reached conclusive results, and we have thus far been able to establish the chronology of 12 out of the 14 churches and chapels, while 2 still require complementary analyses.

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Cathodoluminescence and Laser-Induced Fluorescence of Calcium Carbonate: A Review of Screening Methods for Radiocarbon Dating of Ancient Lime Mortars

Radiocarbon ◽

10.1017/rdc.2020.21 ◽

2020 ◽

Vol 62 (3) ◽

pp. 545-564 ◽

Cited By ~ 2

Author(s):

Michael B Toffolo ◽

Giulia Ricci ◽

Rémy Chapoulie ◽

Luisa Caneve ◽

Ifat Kaplan-Ashiri

Keyword(s):

Calcium Carbonate ◽

Radiocarbon Dating ◽

Size Fraction ◽

Laser Induced Fluorescence ◽

Screening Methods ◽

Particle Size Fraction ◽

Mineralogical Characterization ◽

Lime Mortars ◽

Carbon Recovery

ABSTRACTAccurate radiocarbon (14C) dating of lime mortars requires a thorough mineralogical characterization of binders in order to verify the presence of carbon-bearing contaminants. In the last 20 years, cathodoluminescence (CL) has been widely used for the identification of geologic calcium carbonate (CaCO3) aggregates and unreacted lime lumps within the particle size fraction selected for carbon recovery. These components are major sources of older and younger carbon, respectively, and should be removed to obtain accurate age determinations. More recently, laser-induced fluorescence (LIF) has provided another means of investigating the preservation state and composition of CaCO3 binders. Considered the growing interest of the mortar dating community in the latest advancements of these analytical methods, here we review the principles of CL and LIF of CaCO3, their instrument setup, and their application to the characterization of ancient lime mortars used for 14C dating. In addition, we provide examples of SEM-CL and LIF analyses using high-resolution instrumentation, we discuss current issues and propose future lines of research.

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Radiocarbon Dating History: Early Days, Questions, and Problems Met

Radiocarbon ◽

10.1017/s0033822200033695 ◽

2009 ◽

Vol 51 (1) ◽

pp. 1-43 ◽

Cited By ~ 30

Author(s):

Ingrid U Olsson

Keyword(s):

Mass Spectrometry ◽

Statistical Analysis ◽

Carbon Cycle ◽

Tree Rings ◽

Accelerator Mass Spectrometry ◽

Radiocarbon Dating ◽

Radioactive Decay ◽

Human Tissues ◽

Dating Method ◽

The Impact

W F Libby's new dating method from the 1940s, based on experience in physics and chemistry, opened possibilities to check and revise chronologies built on other principles than radioactive decay. Libby's method initially implied collaboration with archaeologists to demonstrate that it worked but also with physicists to improve the technique to measure low β– activities. Chemists, geophysicists, botanists, physiologists, statisticians, and other researchers have contributed to a prosperous interdisciplinary development. Some pitfalls were not recognized from the beginning, although issues such as contamination problems were foreseen by Libby. Pretreatment of samples was discussed very early by de Vries and collaborators, among others. This subject has not yet been abandoned. Closely related to pretreatment is the choice of fraction to be dated and chemicals to be used, especially for accelerator mass spectrometry (AMS) measurements. Calibration against tree rings and comparison with dates obtained using other methods as well as intercomparison projects are partly history but still very actual. The impact by man and climate is also studied since the early days of the method. Also, the carbon cycle has been of great interest. The tools for measurements and statistical analysis have been improved during these first 3 or 4 decades, allowing interpretations not possible earlier. δ13C determinations are mostly very important and useful, but sometimes they have been misleading in discussions of the origin of carbon, especially for human tissues—the metabolism was not yet fully understood. The history and development of the method can only be illustrated by selected examples in a survey like this.

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