Åsa Ringbom

• PhD
• Professor Emeritus at Åbo Akademi University

Radiocarbon dating of mortars is a method for absolute dating of historical mortared stone structures. Successful mortar dating studies have answered chronological questions, while other studies have revealed that mortar samples can have complications and contaminants. These can cause inconclusive results even with present state‐of‐the‐art techniqu...

The 15th century cross-vaults of the medieval Modena Cathedral (UNESCO site) consist of intricate patches of different masonry portions bound by three types of lime mortars and at least two types of gypsum mortars. Such anomalous structure suggests multiple repair works over time after damaging earthquakes. The absolute dating of lime mortars (¹⁴C)...

Current methodologies for radiocarbon dating of mortars typically use mechanical and chemical separation to isolate fractions of carbon dioxide from suitable lime binder carbonates. These methods have a moderate frequency of success, but difficulties are often encountered with (a) secondary crystallisation, (b) the presence of incompletely burnt li...

Dating lime mortar samples using the radiocarbon ( ¹⁴ C) method can be difficult. This is because the contamination is similar to the primary dating material (CaCO 3 ) 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 rec...

Four lime mortar samples from the Mérida amphitheatre in Spain were dated in 2001 and re-dated in 2019 with refined dating methods and focus on carbon dioxide that was released in late CO 2 fractions when dissolved in phosphoric acid. The samples were difficult to date because they contained highly soluble, young carbonate contamination that domina...

A comparison of two different mechanical separation procedures, a settling process and sieving process, was performed in the samples preparation for radiocarbon dating of archaeological lime mortars from the Tower Keep at Irulegi Castle (Navarre, Spain). The different fractions obtained by the two different mechanical separation procedures were con...

After the last damaging earthquake in 2012, an anti-seismic reinforcement project of the cathedral of Modena was designed giving us the opportunity to investigate and date the building materials. Radiocarbon ( ¹⁴ C), optically stimulated luminescence (OSL), and thermoluminescence (TL) dating techniques were performed on the vaults with the aim to (...

When sampling mortars for radiocarbon ( ¹⁴ C) 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...

Lime lumps and bulk mortars show different ¹⁴ C contamination when analyzed in several CO 2 fractions isolated from the effervescence of an ongoing hydrolysis reaction. Age profiles of both materials are therefore highly complementary and together they can provide a reliable date. Furthermore, they can also reveal the complexity of the radiocarbon...

Absolute dating of mortars is crucial when trying to pin down construction phases of archaeological sites and historic stone buildings to a certain point in time or to confirm, but possibly also challenge, existing chronologies. To evaluate various sample preparation methods for radiocarbon ( ¹⁴ C) dating of mortars as well as to compare different...

Seven radiocarbon laboratories: Åbo/Aarhus, CIRCE, CIRCe, ETHZ, Poznań, RICH, and Milano-Bicocca performed separation of carbonaceous fractions suitable for ¹⁴ C dating of four mortar samples selected for the MOrtar Dating Inter-comparison Study (MODIS). In addition, optically stimulated luminescence (OSL) analyses were completed by Milano-Bicocca...

Absolute dating of mortars is crucial when trying to pin down construction phases of archaeological sites and historic stone buildings to a certain point in time or to confirm, but possibly also challenge existing chronologies. It should become a standard tool for archaeometric research as it contributes considerably to the historical, artistic, so...

Since 1994, our team has gained extensive experience applying accelerator mass spectrometry (AMS) radiocarbon analysis for mortar dating, totaling over 465 samples and 1800+ measured CO2 fractions. Several samples have been analyzed repeatedly. The research covers both Medieval and Classical archaeology. We therefore believe our experience can be h...

Since 1994, our team has gained extensive experience applying accelerator mass spectrometry (AMS) radiocarbon analysis for mortar dating, totaling over 465 samples and 1800+ measured CO 2 fractions. Several samples have been analyzed repeatedly. The research covers both Medieval and Classical archaeology. We therefore believe our experience can be...

This study focuses on radiocarbon dating of mortars that have withstood city fires and display visible fire damage effects. Some fire-damaged and undamaged original Medieval mortars from the same site have also been tested. The mortars were heated at different temperatures and then analyzed using the same preparation procedures as in 14 C dating of...

With the aid of interdisciplinary research it has been possible to outline the chronology of the Åland churches. 14C analysis of mortar has been the most important method in this context, and the method has been developed within the International Mortar Project, with founding members Åsa Ringbom, Alf Lindroos and Jan Heinemeier. Also dendrochronolo...

Archaeologists and experts in ancient mortars fully understand the importance of reliable mortar dating. The ultimate motivation for long and costly archaeological excavations is often to establish the chronology of different mortared constructions. In contrast to other materials or artefacts that can be analyzed and dated, mortar is often abundan...

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 A °land Islands (Finland), where no contemporary written records could shed light on the first building phases. In contrast to other material for 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, we...

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...

A method for refining lime mortar samples for 14C dating has been developed. It includes mechanical and chemical separation of mortar carbonate with optical control of the purity of the samples. The method has been applied to a large series of AMS datings on lime mortar from three medieval churches on the Åland Islands, Finland. The datings show co...

Summary. Väitösk. lisäksi 1 irtol. - Sarjalla myös ruots. nimeke. Diss. -- Åbo akademi.