Extensive survey on radiocarbon dating of organic inclusions in historical mortars

0568915 - ÚJF 2023 RIV CH eng A - Abstract
Pachnerová Brabcová, Kateřina - Kundrát, Pavel - Krofta, Tomáš - Suchý, Václav - Petrová, Markéta - John, David - Kozlovcev, Petr - Kotková, Kristýna - Fialová, Anna - Válek, Jan - Světlík, Ivo
Extensive survey on radiocarbon dating of organic inclusions in historical mortars.
24th Radiocarbon Conference. 10th 14C & Archaeology Conference. Zurich, 11-16 September 2022. Book of abstracts. Zurich: ETH Zurich, 2022, č. článku A03_P10. ISBN N.
[Radiocarbon Conference /24./ 14C & Archaeology Conference /10./. 11.09.2022-16.09.2022, Zurich]
R&D Projects: GA MŠMT EF16_019/0000728; GA ČR GB14-36938G
Institutional support: RVO:61389005 ; RVO:68378297
Keywords : radiocarbon dating * charcoals * mass spectrometry
OECD category: Analytical chemistry; Materials engineering (UTAM-F)
https://radiocarbon24.ethz.ch/wp-content/uploads/2022/09/BookOfAbstracts.pdf

Direct radiocarbon dating of historical mortars remains challenging due to complex processes during mortar maturation that can mislead the interpretation. Organic inclusions in the mortars, such as charcoals, seeds, microbiotas, wood, or bones, represent important alternative or complementary dating material providing the date as a terminus post quem. This work adds to the determination of how reliable such organic inclusions can be for radiocarbon dating. For the analysis, we have collected 129 charcoals from five different early to late medieval castles and churches located throughout the Czech Republic. The architectural objects were chosen to meet the following criteria: i) known age documented in written sources and optimally also obtained through other dating method or complemented with radiocarbon dating of samples other than mortar‐derived ones - ii) known history of repairs and maintenance - iii) age falling before 1650 AD to avoid issues related to inconclusive radiocarbon dating in the early modern period.
Most of the samples were measured on our new AMS MILEA. The results demonstrate that a notable fraction of inclusions corresponds to charcoals from old wood, often a few hundred years old when raising the object, presumably originating from timber cut‐offs. For some sites we found several samples related to later repairs, despite trying to limit the sampling areas to original masonry only. Based on this comprehensive study, we recommend a rather high number of samples be collected per dated object, at least 5 ‐ 10 for sites with uncomplicated building history, so that radiocarbon dating provides reliable results.
Permanent Link: https://hdl.handle.net/11104/0340192