# Investigations on an Ancient Mortar from Ulpia Traiana Sarmizegetusa Archaeological Site, Romania
## 2 Materials and Methods
### Methods  
The material was initially characterized by microscopy; X-ray diffraction (XRD); scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDAX); Fourier-transform infrared spectroscopy (FTIR); differential scanning calorimetry with thermogravimetric analysis (DSC-TGA); and gamma-ray spectrometry. Technical information about the equipment used is provided in Appendix A.  
For gamma spectrometry analyses, detector calibration for the energy scale and efficiency was accomplished using traceable volume standard sources [24]. Spectral data were collected over a long live time of 356,000 s, in order to achieve a low detection limit.  
According to the recommendations in the literature, and the conclusions drawn from the previous analyses of the material, the selection of samples to be dated using the radiocarbon method was oriented towards the identification and extraction of mini-nodules, 2-3 mm in size, defined as 'lumps and bumps' [7; 25]. The chemical release of CO\({}_{2}\) from CaCO\({}_{3}\) was achieved primarily through chemical digestion with ortho-phosphoric acid, in the Carbon Handling System (CHS) installation, followed by the separation/purification of the gas and its reduction to carbon in the AGE 3 graphitization unit [26] (Ionplus, Dietikon, Switzerland). C-14 level determination in the carbon, intimately deposited on the iron catalyst, was carried out using the AMS method in the 1 MV HVEE particle accelerator [27] (High Voltage Engineering Europa B.V., Amersfoort, The Netherlands). The transformation  
Figure 3: Various natures and sizes of aggregates, pores, and carbonates (dusty white) in sliced, freshly made surface (N—nodules; A—aggregates; P—pores).  
of raw data to the Conventional Radiocarbon Age (CRA), in years BP, was performed using an adapted version of the BATS Program version 4.06 (04.06.2015) written by [PERSON] [28], and finally the calendaristic years calAD were obtained using OxCal curves, version 4.4.4 [29]. To verify the calibrated age, a second target (carbon deposited on iron) was obtained from the remaining extracted portion of mini-nodules (lumps and bumps), but this time using thermal CO\({}_{2}\) generation, in an Elemental Analyzer (EA, VarioMicroCube, Elementar, Hanau, Germany) [30]. The other stages proceeded similarly to the first dating attempt.  
The literature suggests a separate collection of CO\({}_{2}\) fractions from carbonates of different ages (coming from S1-S5 sources), and their individual dating if they come from lime binder [31]. This is not possible using the CHS, and the radiocarbon data from samples that undergo combustion in the EA must also be viewed with circumspection. For lime lumps, only one fraction is generally dated (if no secondary calcite is present and if they are not underburned). That is why the series of methods described above for characterizing the initial sample was used not only for material characterization but also for the radiodating strategy. Thus, there is a chance to choose the best sub-samples and also to correctly interpret the obtained radiocarbon data. If the contamination sources S1 geogenic calcite, S4 Ca(OH)\({}_{2}\) recarbonation, and S5 calcareous concretions are not highlighted, then the possible age difference between the calcite formed by S2 pyrogenic calcite and/or S3 C-S-H carbonation matters less. Given the interval in which the statue could have been built (in less than a 150-year interval), as in the case of some Roman mortars, the second fraction may be more reliable [6]. Thus, the whole fraction when using the CHS can provide a result that can be interpreted.  
A schematic workflow is given in Appendix B.