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Thin section analysis results showed in Table 1 highlights that structure and quarry sample are both classified as Packestone according to Dunham (1962). They have similar ranges of Bioclasts and Sparry cement, while Primary porosity is significantly higher in the quarry samples (see Figure 1). Increasing of stone porosity often is related to decreasing of mechanical properties, which is probably the reason why this specific quarry in Tierrabomba Island was abandoned for new ones in the same area at the middle of the XVII century (Álvarez-Carrascal 2018; Cabrera et al. 1995).

Figure 1: Thin Section structure and Quarry Stones, (Saba et al. 2019).

Table 1: Petrographycal analysis results.

Component	Structure stone (%)	Quarry Stone (%)
Bioclasts (B)	28.5±4.4	29.3±2.1
Terrígenous (T)	7.6±6.2	0.8±0.5
Autigens and Others (Au)	0.1±0.3	0.00±0.00
Primary Porosity (P)	34.7±5.9	45.3±2.1
Secondary Porosity (S)	0.0±0.0	0.0±0.0
Micrite Cement (M)	3.2±2.3	0.0±0.0
Sparry Cement (Sp)	27.2±6.4	21.47±1.6

From the quarry stone physical-mechanical characterization, can be highlighted that open porosity differs about 10 % from thin section analysis, which means that thin section measurements despite their low representativeness provide an acceptable approximation to porosity values compared with results coming from a large number of samples analysed whit gravimetrical measurements.

Structure and quarry stone are found as pure limestone from the X-ray analysis, with CaCO₃ higher than 98 %, and a presence of Quartz and Halite lower than 1 %, (Figure 2).

Figure 2: Structure samples X-Ray results.

Ion chromatography analysis on structure samples show a total range of salts between 0.4 % and 2.4 % of Mass on average 1.0 % in all 5 structure samples (Table 2). From the literature review it is difficult to assess if this is a high or low salt content because it should be compared with samples taken at the same depth.

Salts are usually found with higher concentration 128on the first millimetres of the material surface, while lower concentrations correspond to deeper sampling. In our case sampling depth has been 5 mm from the surface. Nevertheless, sampling depth in literature works usually it is not adequately reported (Ahmad & Haris Fadzilah 2010; C, Lopez-Arce et al. 2016). Hence, a comparison is risky and not appropriate (Figure 3).

Table 2: Stone Physical-mechanical Characteristics.

Characteristic	Quarry Stone
VR (mm3 × 105)	1.55±0.11
Ms (g × 102)	2.75±0.12
Mh (g × 102)	1.03±0.09
Md (g × 102)	1.55±0.12
P0 (%)	42.78±1.88
ρb (kg m–3)	1411±47
SUCS (MPa)	1.86±0.36

V_R is Real Volume P_o Open Porosity, ρ_b Apparent Density, m_d is the Dry mass, m_s Saturated mass, m_h water immersion mass, SUCS is Stone Uniaxial Compressive strength

Figure 3: Structure samples Ion Chromatography results elaborated with Runsalt^®.

Salt crystallization process is not directly observed in the structure surface of the area of study, nevertheless, a careful revision of the whole structure should be done to eventually detect this type of deterioration and compare salt concentrations with generic sections of the structure and define if ion chromatograph results are effectively reliable to correctly detect the deterioration process in this case of study.

Results were further analysed with Runsalt software (V. 1.9), (Bionda 2005). It is the graphical user interface to the ECOS thermodynamic model (Price 2000). It allows to define which salts are crystallizing from a mixture depending on temperature and RH conditions. The ion contents, as determined by IC, are input for the model. As an example, sample 5 ion and cation values were introduced as a input, as well as the average temperature in Cartagena, 27.7 °C according to DIMAR (2018).

Table 3: Ion Chromatography results (%), input data of Runsalt. N.= Number of Sample.

N	Cl–	SO4–	NO3–	Na+	Mg+	K+
1	0.044	0.171	0.048	0.074	0.025	0.042
2	0.196	0.15	0.005	0.25	0.036	0.003
3	0.861	0.587	0.016	0.814	0.11	0.077
4	0.481	0.162	0.035	0.431	0.037	0.064
5	0.115	0.134	0.008	0.207	0.04	0.007

Results are reported in Figure 3 and are similar for the whole structure samples. The mix of salts on the samples is identified and Relative Humidity of equilibrium (RH_eq) is reported for each salt in the solution. It is worth to mention that Cartagena stands in a tropical area, with a Relative Humidity range between 72 % to 90 % during the year, considering minimum and maximum values of daily and seasonal variations. From these preliminary studies, Thenardite and Bloedite could crystalize having a RH_eq of 75 %, although their role on the material deterioration should be further studied, for example pondering whether the number of crystallization cycles per year is relevant.

Regarding mechanical properties, SUCS varies between 1.5 MPa to 2.2 MPa which is typical of a soft pure limestone (Table 3).