ONEPlanet DTP - Climate Signals in Materials of the Built Environment (OP2147)

Lime is a common material of the built environment. The earliest example of its use in construction dates to 6000 BC (Carran et al., 2012). Lime is produced by burning carbonate stones at about 900°C. The lime is, then, mixed with water to form a workable paste that becomes hard upon exposure to CO2 in air through a reaction called carbonation leading to the formation of calcium carbonate:
CaO+H_2 O+〖CO〗_2→〖CaCO〗_3+H_2 O
As shown by the successful use of the radiocarbon dating method to date historic mortars (Ringbom et al. 2014), the carbonation reaction is capable of recording in a stable mineral some characteristics of the atmospheric CO2 at the time of the reaction. However, despite such evidence, and the wide use of this material, little research has been done to investigate the information that can be obtained through the study of C and O stable isotopes (expressed as δ13C and δ18O) fixed by the lime during the carbonation reaction.
This project aim at addressing this issue by analysing δ13C and δ18O in several mortar samples taken from buildings of known origin, erected in a specific area to provide information about the δ13C values of atmospheric CO2 during carbonation (Pesce et al. 2012), and δ18O values of the local water source used in the mortar mix (Pesce et al. 2017). The data obtained will be compared with natural carbonate sources (dated stalactites and lake sediments) to assess the possibility to extract climate signals from materials of the built environment.
Skills training provided: building archaeology; mortar sampling for isotope analysis; stable carbon/oxygen isotope-based climate signals.

Carran D., Hughes J., Leslie A., Kennedy C., 2012. A Short History of the Use of Lime as a Building Material Beyong Europe and North America. International Journal of Architectural Heritage. 6, 117-146
Ringbom A., Lindroos A., Heinemeier J., Sonck-Koota, P. 2014. 19 Years of Mortar Dating: Learning From Experience. Radiocarbon. 56(2), 619-635
Pesce, G., Fletcher, I., Grant, J., Molinari, M., Parker, S. and Ball, R., 2017. Carbonation of Hydrous Materials at the Molecular Level: A Time of Flight-Secondary Ion Mass Spectrometry, Raman and Density Functional Theory Study. Crystal Growth & Design, 17 (3). pp. 1036-1044
Pesce, G.L., Ball, R.J., Quarta, G. and Calcagnile, L., 2012. Identification, extraction and preparation of reliable lime sample for the C14 dating of plasters and mortars with the method of “pure lime lumps”. Radiocarbon, 54(3-4), pp. 933-942