Ringbom, Åsa, abstract Padova Ringbom, Å., Lindroos, A., Heinemeier, J., Sonck-Koota, Pia, C and Archaeology, Ghent April 2013, RADIOCARBON Vol 56, Nr 2, 2014, p 619–635, 2014, Ringbom et al. Mortar dating and roman pozzolana, results and interpretations. A Comparison of Dating Techniques at Torre de Palma, Portugal: Mortars and Ceramics, 242-256.
Problems arise if the mortar contains natural carbonates where the proportion of the unstable isotope 14C to the stable isotopes 12C and 13C would indicate a higher age than the binder age.
These contaminants can be incompletely burnt limestone in the first stage of the process of making mortar, or limestone fragments in the aggregate.
The usual goal of archaeological excavations is to pinpoint the chronology of the site investigated.
All the traditional archaeological dating methods, such as dating artifacts, coins and ceramics, do in fact date the dwelling in and around the site, not necessarily the actual construction of the buildings. But even traditional scientific dating – dendrochronology and 14C dating of wood and charcoal – are not enough, since they can date secondary building stages and repairs after destruction and fire.
Mortars are typically made from a mixture of sand, a binder, and water.
The most common binder since the early 20th century is Portland cement but the ancient binder lime mortar is still used in some new construction.
bra_lindroos_et_al Ringbom, Åsa, Alf Lindroos, Jan Heinemeier and Kenneth Gustavsson, Dating Stone Churches in the Outer Åland Archipelago, in Archaeology and History of Churches in the Baltic Region, Symposium, June 8-12, 2010, Visby Sweden. Heinemeier, Jan, Högne Jungner, Alf Lindroos, Åsa Ringbom, Thorborg von Konow och Niels Rud, .“AMS 14C dating of lime mortar”, in Beam interactions with materials and atoms, Nuclear Instruments & Methods in Physics Research, Section B, volume 123, Nos 1-4, March (II) 1997: 487-495.
The project was initiated in 1994 as an international extension of the project of the Åland churches (1990-).
Hayen_etal_Absolute_Dating_Mortars_2016 see also Van Strydonck, Mark, 2016 – 14C Dating of Mortar a Historic Review.
Proceedings of the 4th Historic Mortars Conference HMC 2016 10th-12th October 2016, Santorini, Greece.