THERMAL, MINERALOGICAL AND CHEMICAL STUDIES OF THE MORTARS

USED IN THE CATHEDRAL OF PAMPLONA (SPAIN)

J.I. Alvarez, I. Navarro, P.J. García Casado

Department of Chemistry and Soil Science, Faculty of Science, University of Navarra, 31.080,
Pamplona (Spain)

Nº of pages: 15

Nº of tables: 8

Nº of figures: 11

Keywords: Ancient mortars, Thermal analysis, Chemical studies, X-ray diffraction, Raw
materials.

Please, send all correspondence to:

Dr. José I. Alvarez-Galindo
Dpto. de Química y Edafología
Fac. de Ciencias
Universidad de Navarra
C/ Irunlarrea s/n
31.080 Pamplona (Navarra)
Spain
Phone: 34 948 425600
Fax: 34 948 425649
E-mail: jalvarez@unav.es

1
 THERMAL, MINERALOGICAL AND CHEMICAL STUDIES OF THE MORTARS
USED IN THE CATHEDRAL OF PAMPLONA (SPAIN)

J.I. Alvarez, I. Navarro, P.J. García Casado

Department of Chemistry and Soil Science, Faculty of Science, University of Navarra,

31.080, Pamplona (Spain)

Abstract

Different ancient mortar samples of Pamplona Cathedral have been analyzed to characterize

their binder and aggregate fractions. A complete characterization has been carried out

including chemical (complete macrochemical analysis, analysis of the soluble fraction in hot

HCl (1:5) and of the insoluble residue, trace elements and soluble salts, using traditional

chemical procedures, ion chromatography and spectrophotometry techniques), mineralogical

(structural characterization, granulometric studies and X-ray diffraction) and thermal studies

(simultaneous DTA and TG analysis). A lime binder with a silica aggregate have been

established. The approximate original compositions of the classes of mortars have been

determined using the TG results. A good agreement with the other characterization techniques

has been showed by the thermoanalytical techniques. An incomplete carbonation in a sample

has been discovered by the thermal analysis.

Keywords: Ancient mortars, Thermal analysis, Chemical studies, X-ray diffraction, Raw
materials.

2
1. Introduction and objetives

In some previous papers the importance of characterising the binding materials and mortars

used by ancient builders has been highlighted [1-4]. In this study different samples were taken

from the mortars of walls and domes from the inside of the cathedral of Pamplona

(1415-1512). A further group of samples taken from the foundations of the old Romanesque

cathedral, destroyed in 1390, are also taken into consideration. The seven zones classified

with different types of mortar have already been established in a previous study [5] using a

method proposed which consisted of:

Grouping the mortars. Analysis of all the samples.

1. Examination

- macroscopic examination with the naked eye with the help of a magnifying glass.

- microscopic examination using microphotography with magnification 65.

2. X-ray diffraction: in order to establish the mineralogical phases present.

3. Rapid approximate chemical analysis with hot HCl (1:5) volume ratio (2 M) which has

proved to be the most appropriate for attack [6]. Determination of the insoluble residue,

the calcium carbonate fraction calculated by calcimetry and soluble fraction by difference

to 100.

4. Classification of the types of mortars taking into consideration the aforementioned criteria

and using as well the relationship between insoluble residue/soluble fraction

In this study the 2nd part of the proposed methodology (complete characterization of the

mortars) has been carried out. The characteristics of the previously determined types of

mortars and of their component materials are presented. The accordance among different

analytical techniques is also studied.

2. Experimental

3
The sampling procedure for mortars has been carried out taking a part of the mortars with a

chisel and throwing away the external portion of the joints, with the aim of obtaining

non-altered material. Figure 1 shows the sampling areas with a different type of mortar, just

as there has been indicated.

A representative sample of each different zone has been selected in order to apply the

complete characterization. The criteria followed have been: the state of aggregation and

structure, the available quantity and the representativity on the set.

After, the aforementioned complete characterization has been carried out. This one includes:

1. Chemical study

1.1. Chemical composition:

1.1.1. Chemical analysis of the majority components. This analysis has been carried

out by attack with a sodium carbonate - borax alkaline flux.

1.1.2. Chemical analysis of the soluble fraction and the insoluble residue resulting

from the attack of the mortar with hot HCl (1:5).

The sample ground in an agate mortar was dried in a heater until constant weight was

achieved and then 1 g of sample was taken for its subsequent analysis. A titration with EDTA

(using murexide and eriochrome black T as indicators) has been used for the analysis of

calcium and magnesium in the soluble fraction. The contents of soluble silica, Fe and Al have

been determined by atomic emission spectroscopy with inductively coupled plasma (ICP).

When the amounts of Fe2O3 and Al2O3 were higher than 1%, the determinations were carried

out by titrations using barium diphenylaminosulphonate and ditizone as indicators. Sodium

and potassium have been determined by flame emission atomic spectroscopy. The contents of

elements after an alkaline fusion of the samples were determined by traditional chemical

methods.

4
 1.2. Trace elements: the chemical nature of the trace elements and their relative

concentrations have been determined using the ICP technique, after an alkaline attack

of the sample. Detection limits were 2,7 ng/g for cadmium, 6,1 ng/g for chromium,

5,4 ng/g for copper, 1,4 ng/g for manganese, 7,9 ng/g for molybdenum, 10 ng/g for

nickel, 42,0 ng/g for lead and 1,8 ng/g for zinc.

1.3. Soluble salts: conductivity and concentrations of anions have been calculated using

an ion chromatograph, after an extraction with distilled water. The instrumental

detection limits were 0,084 g/g for chloride, 0,475 g/g for nitrate and 0,330 g/g

for sulphate.

2. Mineralogical study.

2.1. Mineralogical aggregate composition: the mineralogical phases contained in the

aggregate were determined by X-ray diffraction.

2.2. Aggregate granulometric fractions: the grading of the aggregate was obtained after

dissolution of the binding material with HCl 1:1 and sieving through a tower of

sieves.

3. Thermal studies: the differential thermal and thermogravimetric analysis were carried out

using a simultaneous DTA-TGA Stanton Redcroft STA-780 thermoanalyser, using Pt

crucibles, at 10ºC.min-1 heating rate, under 50 mL.min-1 gas flow of air.

Results and Discussion

The previous results of the X-ray diffraction analyses are showed that in the mortars of

Cathedral of Pamplona, calcite is the main component [7]. The other mineralogical phase

presents in a large quantity was -SiO2. Several samples had complex silicates in their

composition, although in small amounts. Gypsum phases have not been detected in the

mortars.

5
1. Chemical characterization

1.1. Chemical composition

- The complete characterization turns out to be the valid reference in order to compare results

achieved by others techniques of characterization. The table 1 shows the results from the

complete chemical analysis of the major components.

Calcium carbonate (calcium oxide and calcination loss) and silica were the main components

determined. Silica content was highest in the Romanesque zone (MC6) (39.13%), whilst the

two zones of the southern lateral nave (first and last sections) (MC3 and MC4) have lower

values (19.75% and 19.11%). Practically no differences with regard to composition can be

seen between these two areas. Only the amount of CaO (and consequently, of CaCO3) seems

to be greater in the MC4 than in the MC3 zone.

The sample from the central nave (MC5) was that which in this analysis had lowest values for

MgO. In contrast, the sample from the Romanesque foundations had the largest amounts of

Fe, Al and Ti oxides (R2O3 = 7,23%).

The values of sulphates were low. This indicates that there are not gypsum phases (dihydrated

calcium sulphate), which was also confirmed by the X-ray diffraction results. Magnesium

amounts were low values, therefore it seems it could discard the presence of dolomite

limestone.

- Chemical analysis of the soluble fraction and the insoluble residue

Tables 2 and 3 summarize the results of the chemical analysis of the soluble fraction and the

insoluble residue resulting from the attack of the samples using the method proposed.

It was observed that soluble SiO2 had low values. Soluble silica is one the most important

parameters in order to establish the hydraulic effect in the samples [8, 9]. The low values in

soluble silica could indicate a low hydraulic effect.

6
High values in alkaline metals (sodium and potassium) in the samples of zones MC3 and

MC4 were observed. This fact may indicate a higher amount of soluble salts.

It has already been pointed out that Mg presents low percentages. In the soluble fraction

analysis, the MgO values confirm the former results. Percentages of Fe2O3 and Al2O3 turn out

to be very low. These elements have a important relation with the hydraulic effect. As

mentioned previously, this effect coulds present low values.

The objective of the analysis of the insoluble residues is to give a full characterization of the

aggregate fraction and to obtain the quantitative chemical composition especially of those

components which, due to their low percentages or their non-crystalline nature, could not be

detected by X-ray diffraction.

The results obtained are similar in the samples analysed. It can be seen that the major

component of the insoluble residue is SiO2 (80-85%). Fe, Al and Ti oxides accounts for 7-9%

and the remainder are minor components which do not exceed 2%.

The aggregate used is fundamentally siliceous and probably associated with it are the

non-hydraulic silicates and the clays which are not soluble in acid - those elements

responsible for the Fe2O3 and Al2O3 contents.

1.2. Trace elements

The chemical nature of the trace elements and their relative concentrations indicate the

geological history of the material, in function of the parameters that have conditioned them

[10, 11]. Figure 2 shows the graphs of trace metals.

The critical study of these graphs indicates that there are not large differences in the

composition of the trace metals analysed among the mortars of the six studied classes.

Therefore, it is probable that the materials used proceed from the same quarry. This is logical

if one considers the history of the construction of the Cathedral of Pamplona.

7
However, the classes MC3 and MC4 have almost identical micro-chemical composition, their

raw material proceeds from the same quarry and zone. This also is adjusted to the other

results obtained previously in this work.

1.3. Soluble salts

In this study a measure of overall conductivity was taken in representative samples from

different zones. The aim was to evaluate overall activity in soluble salts that may affect the

state of the sample [12]. Results refer to a suspension that contains 1 mg of sample for mL,

expressed in S.cm-1 (Figure 3). The results show low conductivity in general in the mortars

analysed, which is indicative of very low levels of total salinity in the samples in comparison

with those values found in the bibliography (68-149 S.cm-1) [1].

The samples from zones MC3, MC4 and MC5, which belong to the central and southern

lateral naves have the highest values of total salinity, and coincide with the previous

observations on the degree of homogeneity and the characteristics of the samples, which are

in comparatively poor condition and very deteriorated.

The values for conductivity in the aqueous extract and the anion values are shown in the

Figure 3.

The results of the determination of anions show quite low Cl- content in comparison to some

studies (0.67-2.27%) [1], although without reaching the extreme values recorded in some

studies (<0.06%, [13]).

Nitrate content is very disparate from sample to sample, ranging from low values, of the order

of 0.05% for zones MC2 and MC5, to values under detection limit for zones MC1 and MC6.

The mortars from the MC3 and MC4 show extremely high nitrate values between 1.5-2%.

This fact means that the high values in alkaline metals in these zones could be related with

these results of nitrate values, and confirms the higher amount of soluble salts expected. This

also leads to the hypothesis that the origin of the raw material in the two samples was similar.

8
Indeed, these two samples have similar amounts of sulphate ion, which, generally, is present

in quite low levels in all the mortars analysed (from 0.007 to 0.089%).

In the figure it can be seen that conductivity varies with the amount of chloride ion in the

sample, except in those samples from the MC3 and MC4 zones, with large amounts of nitrates

which alter this relationship. The greater effect of the chloride ion on the total conductivity of

the samples is logical if the following two aspects are borne in mind:

1. Its presence in larger amounts (of the order of a higher scale in percentage terms), except

the nitrates in the zones mentioned. This fact has already been highlighted in the

bibliography [1], where the chlorides appear as the most frequent soluble salts in the

mortars analysed, and even as the only salts to be detected. However, it is not possible to

generalise from this, although in mortars from maritime environments a higher content of

these anions is to be expected [14].

2. The second aspect to be considered is the high load density of the chloride ion, due to its

small ionic radius, which leads it to have a notable effect on conductivity.

One objective of this study was to analyse the association between these variables and to this

end a correlation analysis was made of the variables. The matrix is shown in the table 4.

There is a strong association between the percentage of nitrates and sulphates (r=0.827;

p=0.022) and an association of moderate strength between conductivity and chlorides

(r=0.703; p=0.078) and nitrates (r=0.739; p=0.058) (both on the limits of statistical

significance), and somewhat less with sulphates (r=0.603; p=0.152).

Indeed, the contribution of the cations of these soluble salts to total conductivity has not been

taken into consideration; hence the moderate degree of association as these other variables

have an effect on total salinity.

9
In order to establish a mathematical relationship between conductivity and the percentages of

anions, a multiple regression analysis was performed, with conductivity as the dependent

variable. The formula that relates total conductivity to the amounts of anions is thus (Eq.1):

Total conductivity = -2.43 + 98.79 (% Cl-) + 18.72 (% NO3-) (Eq.1)

(R² = 0.987; p = 0.0002***)

The squared multiple regression coefficient R² gives the proportion of the total variance of the

dependent variable (total conductivity) which is explained by the independent variables

(percentages of anions) with a highly significant probability associated with the model

proposed. In the samples analysed, sulphates so not significantly influence conductivity,

probably as a result of their low percentages. This model corroborates the fact that chloride

ion exerts a greater effect than the other two anions on the total salinity of the mortars from

cathedral of Pamplona.

2. Mineralogical study

2.1. Mineralogical aggregate composition

In this study X-ray diffraction of the insoluble residue from the proposed chemical attack was

performed. The results obtained were compared with data from the ICDD powder diffraction

file. The results, as shown in table 5, show that the composition of the insoluble residue,

attributable to the aggregate fraction of the sample, is principally -SiO2. Non-hydraulic

silicates that exhibit diffraction peaks were studied and no differences were found in types or

quantities of mica derivatives (ICDD pattern 78-1928) and others silicates. Slight variations

were detected in clays of the smectite group and also in kaolinites (Al2(OH)4Si2O5) (ICDD

pattern 83-971). Tobermorite (hydraulic silicate Ca2,25(Si3O7,5OH1,5).(H2O) (ICDD pattern

83-1520) was not found within the insoluble residue of the attacks. In general, the complex

silicates diffraction peaks occur very closely together as a result of which individual

identification of these components is difficult.

10
No diffraction peaks for calcite are seen as it has already supposedly been solubilized after

the acid attack. The diffraction patterns for the samples are very similar and no differences

can be established between those from different zones. However, this analysis serves to

establish an initial qualitative and semi quantitative composition of the aggregate fraction,

provided that, as is the case with the samples analysed, this is siliceous in nature.

2.2. Aggregate granulometric fractions

The distribution characteristics of the grain size of the arid through a granulometric study

have also been undertaken. Figure 4 shows the granulometric distribution for MC1 zone. The

differences between the others zones are stated below.

The grading of the aggregate (after dissolution of the binding material with HCl 1:1) shows

that for the clay fraction (<0.1mm) all the samples give very high values, in excess of 20%;

with the exception of the sample from the Romanesque foundations (MC6 zone). Samples

from MC3 and MC4 zones offer very similar percentages.

The fine sand fraction (0.25-0.50 mm) is in percentage terms the most important fraction of

all the aggregates analysed, especially the material retained by the 0.25 mm and 0.50 mm

sieves (66% in zone MC1; 55% in MC2; about 50% for MC3 and MC4; 53% in MC5 zone,

and, with the highest values, 80% for MC6). The amount of material retained by the 0.05 mm

sieve in MC3 and MC4 was particularly low.

In the intermediate sand (1-1.6 mm), MC1 contains the lowest percentage of retained material

(Figure 4). MC2 offers high values in this fraction, together with MC5. Intermediate values

(4-6%) are present in MC3 and MC4 (with very similar distributions) and MC6 zone. In the

coarse sand fraction (2-4 mm) there is great variability with MC6 and MC1 (1 and 2%

respectively) offering the lowest percentages.

11
In order to catalogue the grading distribution curves of the aggregates two geological

parameters were used: the median and the “sorting index” (the quotient between the 3rd and 1st

quartile expressed in mm) [15]. The results are shown in the Table 6.

The median is used to gauge the fineness of a sand. Median values ranging from 0.5 mm to

1.6 mm correspond to intermediate sands. In this study, all the mortars analysed have mainly

fine sands in their composition. The sorting index gives an idea of the good or bad choice of a

sand for a mortar (an appropriate staging in the percentages of the different fractions): a SO <

2.5 would indicate a well chosen sand, whereas a SO > 4.5 would indicate the contrary. In this

study MC2 and MC5 zones would have a badly distributed sand, and only MC6 zone could be

considered as adequate. However, both median and SO must be interpreted with caution. It is

not possible to extrapolate from them and there must be a full awareness of the limitations of

the information they provide. Any claims cannot be definitive as they only partially evaluate

all the characteristics of the distribution of the aggregate

Furthermore, it can be confirmed that the aggregate used in zones MC3 and MC4 is, with

probability, the same.

3. Thermal studies

Interpretation of the thermo-analytical curves obtained offers the results conteined in Table 7.

Differential thermal and thermogravimetric analysis are suitable in order to establish

characteristics of the ancient mortars: it is easy the detection of main components, the nature

of the aggregate and other aspects, while the small quantity of sample. These temperature

range correspond approximately to the percentage of humidity (20º-120ºC), loss of

chemically bound water (indicative of hydraulic compounds) (300º-550ºC), decarbonation of

magnesium carbonate (550º-610ºC) and decarbonation of calcite (610º-880ºC).

In the DTA curve obtained for the zone MC1, an endothermic peak at 570ºC has been

observed (Figure 5). This peak colud be related with the transformation (Eq. 2)

12
 -SiO2  -SiO2 Tª = 573ºC [16, 17] (Eq. 2)

because there is not an associated weight loss.

The measured curve is followed by a step between 610º and 800ºC (with a minimum at

705ºC) due to the decomposition of calcium carbonate which can be estimated in the order of

22% of the total original weight (Eq. 3).

CaCO3  CaO + CO2 (Eq. 3)

A similar step for the sample MC2, related to the calcite decarbonation, with a minimum at

724ºC is also evaluated. A not clearly marked peak, due to the change of -SiO2 in -SiO2 is

observed. For the measured curves of MC3, MC4 and MC5 zones, the steps similar to MC1

zone (Figure 5) for the calcite decomposition were obtained. In most of cases carbonates

decompose bellow 600ºC, in accordance with the data of the literature [18-20].This fact also

occurs for the MC6 curve, but the minimum (at 706ºC) is obtained at a minor temperature

(Figure 6). The decrease in decomposition temperature has been related to the presence of

soluble salts, for example, that favour decomposition, and also to the dimension and defective

state crystal lattice, even to the process of carbonation [18, 21, 22]. The transformation of

-SiO2 in -SiO2 is also showed in this MC6 curve.

An important weight loss in the TG curve at 370ºC, and other at 450ºC were detected in MC6

curve. These losses could have an explanation in the fact of the loss of volatile substances

present in the mortar, for the 1st loss. The 2nd loss could be related to the combustion of the

carbon who had been formed in the previous carbonization.

Obviously, the loss of this organic matter could give an weight loss explanation to the results

that shows the highest percentage between 300º and 550ºC for all the samples (5.49%). But

the weight losses in this range may be attributed to the chemically bound water, and can be

indicative of the presence of hydraulic compounds. These hydraulic compounds, probably

calcium silico-aluminate hydrates, can have a different origin: a lime/ceramic reaction, the

13
employment of limes of marly nature, or the aggregate added after lime calcination, with an

intentional or uninentional addition.

The loss value shows an agreement with the results of a previous study that refers this weight

loss to the hydraulic water [17, 18]. Besides, these hydraulic silicates (CSH) might confirm

the previous results of chemical analysis for MC6, with the highest percentage of Fe, Al and

Ti oxides.

Significant amounts of MgCO3 have not been detected in any samples, because low weight

losses have been found between 550º and 610ºC. Furthermore, the three endothermic peaks at

250º, 384º and 441ºC, caused by the decomposition of the hydromagnesite have not been

detected, together with a loss weight between 220º and 460ºC in the TG curve. When the

shrinkage occurs, the MgCO3 hydrolysis should generate hydromagnesite

(Mg5(CO3)4(OH)2.4H2O). The three endothermic peaks are related to the hydration water loss,

the residual hydration water loss and the OH- loss [23-25].

In the case of presence of hydromagnesite an exothermic peak at 550ºC, due to the

crystallization of xMgCO3 y MgO phase should be observed. However, it has been observed

that the presence of impurities, such as Ca2+ or Cl- decreases the intensity of this peak. In the

analyzed mortars the absence of this crystallization peak is most probable due to the presence

of Ca2+.

In any case, calcite decomposition in the DTA curves seems to occur in a continuous form,

without steps. This fact can be due to the absence of different degrees of crystallinity in the

CaCO3. Calcitic aggregate should show different steps of decomposition, because the

recarbonated calcite [26], formed after calcination, losses the CO2 at a lower temperature than

natural calcites. This effect is due to the large size of the crystals in the calcareous aggregates

compared to the microcrystalline structure of the recarbonated calcite. In accordance to the

XRD results, peaks of gypsum phases have not been found in any sample.

14
It has already been pointed out that the resemblance between the samples MC3 and MC4.

This similarity was confirmed by the closeness of the zones in the building. The difference in

CO2 percentage in the TG curves between the two samples was 2.52%. This means a

difference of 5.72% in CaCO3. This difference of CaCO3 involves a value of CaO percentage

3.20% higher in the MC4 zone than in the MC3 zone. However, only a difference of 1.51% in

CaO has been determined in the previous chemical analysis. The similarity among both

samples given (macro and microchemical results) it can rule out that te 1.69% of CaO comes

from other compounds. Therefore, it must be pointed out that this Ca was present as CaO,

better hydrated, Ca(OH)2. This means that the 4.5% of the initial Ca(OH)2 in the MC3 zone

have not been carbonated.

Conclusions

All mortars studied in the Pamplona cathedral are mortars with lime binder (they can be

classified by the type of ordinary limes) and a silica aggregate.

1. Only the MC6 sample has shown a certain hydraulic effect, with a good agreement

between the results from macrochemical and microchemical analysis and DTA-TGA

studies. However, in the other mortars, the hydraulic effect can be considered to be

non-existent.

2. The calculation of the initial weight percentages of raw materials has given the values

collected in Table 8 for each class of mortar. The formulas used to calculate these

percentages are showed as follows (Eq. 4-6). They are based in a previous study with

slight modifications [27].

A A
1,351 1,351
%Ca(OH)2  100  100 (Eq. 4)
 A  100  0,260A 
100  A 
 1,351

15
 where A is %CaCO3 calculated in TG studies (temperature ranges between 610º and

880ºC, associated with CO2 loss) (Table 7).

%IR %IR
%Aggregate  100  100 (Eq. 5)
 A  100  0,260A 
100  A 
 1,351

where IR is the insoluble residue calculated in the chemical analysis [7]

%Water  100   %Ca(OH)2  %Aggregate (Eq. 6)

Assuming that the increase in weight of the original sample to the present sample is due

exclusively to the decarbonation of the slaked lime, a quite approximate theoretical

calculation can be made as to the initial percentages of the raw materials used in the

elaboration of the mixtures. Table 8 shows what can be supposed to be the initial

composition by percentage weight of the type of mortar from each zone.

4. The determined in weight binder/aggregate relationship in the classes of mortars responds

to a normal quotient (between 0.5-2.5 approximately, according to the results from the

literature [28-30]).

5. Thermal analysis have permitted to establish that the difference between MC3 and MC4

mortars is due to an incomplete carbonation in MC3. Also, the existence of dolomite,

gypsum phases and calcareous aggregate has not been proven by thermal methods.

6. The samples under study do not show high values for soluble salts. Chlorides and nitrates

are the anions which affect the total conductivity of the aqueous extract, according to the

correlation established.

7. The DTA-TGA studies have shown a good agreement with the other characterization

techniques, and they have been checked as a good method for the analysis of the ancient

mortars.

16
8. From the analysis carried out by chemical, mineralogical and petrographic methods, it can

be concluded that the choice of the raw materials was made from local sources. MC3 and

MC4 classes, with the highest values in soluble salts (alkaline nitrates) could present an

important risk of deterioration.

17
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16. N.N. Greenwood, A.Earnshaw. Chemistry of the elements. Pergamon Press, Oxford,

1984, p.394.

17. A. Moropoulou, A. Bakolas, K. Bisbikou. Thermochim Acta, 269 (1995) 779-795.

18. A. Bakolas, G. Biscontin, A. Moropoulou, E. Zendri. Thermochim Acta, 321 (1998)

151-160.

19. J. Adams, D. Dollimore, D.L. Griffiths. J. Thermal Anal. 40 (1993) 275-284.

20. L. Paama, I. Pitkänen, H Rönkkömäki, P. Perämäki. Thermochim Acta, 320 (1998)

127-133.

21. G. Martinet, F Deloye, J.C. Golvin. Bull. liaison Labo. P. et Ch. 181 (1992) 39-45.

22. G. Martinet, F. Deloye, A. Le Roux. Bull. liaison Labo. P. et Ch. 182 (1992) 21-26.

23. C. Fiori, M. Macchiarola. In: E. M. Sebastián, I. Valverde, U. Zezza, Eds. Proc. III

Congreso Int. de Rehabilitación del Patrimonio Arquitectónico y Edificación, Granada,

1996, pp. 223-237.

24. S. Veccio, A. Laginestra, A. Frezza, C. Ferragina. Thermochimica Acta, 227 (1993) 215-223.

19
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161-165.

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Proc. 267 (1992) 107-1011.

27. G. Alessandrini, R. Bugini, L. Folli, M. Realini, L. Toniolo. In: J. Delgado, F. Henriques, F.

Telmo, Eds. Proc. 7th Congress International on Deterioration and Conservation of Stone.

Lab. Nac. de Engenharia, Lisbon, 1992, pp. 667-675.

28. P. Hoffman, G. Vetter. Fresen. J. Anal. Chem. 338 (1990) 133-137.

29. G. Alessandrini, G Dassù, R. Bugini, L. Formica. Studies in Conservation. 29 (1984)

161-171.

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(1989) 37-45.

20
Table 1. Complete chemical analysis of the samples.

SiO2b CaO MgO Fe2O3 Al2O3 TiO2 SO3 Na2O K2O

a
Zone Loss
(%) (%) (%) (%) (%) (%) (%) (%) (%)
MC1 27.48 29.37 32.98 2.49 5.18 0.30 0.15 0.81 0.28 0.55
MC2 32.27 22.18 37.56 2.49 3.32 0.99 0.48 0.63 0.26 0.47
MC3 34.50 19.75 36.90 3.48 2.81 0.69 0.48 0.69 0.28 0.45
MC4 34.01 19.11 38.42 4.08 2.30 0.86 0.39 0.65 0.17 0.42
MC5 30.43 23.66 37.42 0.98 5.50 0.27 0.18 0.78 0.19 0.59
MC6 23.35 39.13 26.34 2.12 6.60 0.49 0.14 0.82 0.22 0.66
Sodium carbonate - borax alkaline flux.
Percentages related to original dry mortar.
a
Calcination loss at 975-1000ºC.
b
Total silica in the sample.

Table 2. Chemical analysis of the soluble fraction after hot hydrocloric acid attack.

a
SiO2 CaO MgO Fe2O3 Al2O3 Na2O K2O
Sample
(%) (%) (%) (%) (%) (%) (%)
MC1 0.50 32.67 2.71 4.34 0.66 0.035 0.098
MC2 0.57 37.20 2.23 3.23 0.56 0.037 0.062
MC3 0.55 36.90 2.40 2.98 0.60 0.151 0.138
MC4 0.62 38.41 2.28 2.86 0.70 0.114 0.191
MC5 0.89 36.65 0.96 3.46 0.79 0.048 0.125
MC6 0.37 31.23 1.70 6.92 0.69 0.031 0.095
Percentages related to original dry mortar
a
Acid soluble silica

Table 3. Chemical analysis of the insoluble residue obtained after hot hydrocloric acid attack.

a b
Loss SiO2 CaO MgO Fe2O3 Al2O3 TiO2 SO3 Na2O K2O
Sampl
e (%) (%) (%) (%) (%) (%) (%) (%) (%) (%)
MC1 1.91 85.78 - 1.19 7.22 1.31 0.26 0.57 1.09 1.29
MC2 3.31 84.31 - 2.02 6.32 2.15 0.64 0.61 0.60 0.27
MC3 2.80 85.19 - 1.84 5.68 1.73 0.64 0.66 0.72 0.61
MC4 2.73 85.66 - 1.58 5.28 1.96 0.89 0.64 0.70 0.56
MC5 4.21 83.27 - 1.37 6.85 1.77 0.23 0.56 0.89 0.85
MC6 2.00 88.16 - 1.26 6.17 0.70 0.14 0.72 0.47 0.73
Sodium carbonate - borax alkaline flux.
Percentages related to the sample of dry insoluble residue.
a
Calcination loss at 975-1000ºC.
b
Total silica in the sample.

21
Table 4. Matrix to correlation of the anions.

2-
Parameters Cl- NO3- % SO4 Conductivity
-1
(%) (%) (%) (S.cm )
Cl- (%) 1
% NO3- (%) 0.055 1
2
% SO - (%) -0.036 0.827 1
4
-1
Cond. (S.cm ) 0.703 0.739 0.603 1

Table 5. X-ray diffraction of the insoluble fraction.

Silica Muscovite Anorthite Albite Feldspar

Zone SiO2 (K0,93,Na0,03)(Al1.54, Ca (Al2Si2O8) Na (AlSi3O8) Na0,5K0,5 AlSi3O8
ICDD 85-798 Fe0,25, Mg0,21, Ti0,04) ICDD 76-948 ICDD 76-898 ICDD 84-710
((Si3,34,Al0,66) O10)
(OH)2
ICDD 82-1852
MC1 *** s - t t
MC2 *** t - - -
MC3 *** s - s -
MC4 *** s - s -
MC5 *** s p s -
MC6 *** s - t -
***:>75%; **:40%-75%; *:20%-40%; s= small amount (5%-20%); t=traces (<5%); - =absent

Table 6. Median and sorting-index.

Zone Median So (sorting-index)

MC1 0.220 3.05
MC2 0.237 5.34
MC3 0.205 3.69
MC4 0.206 3.38
MC5 0.225 5.07
MC6 0.230 1.51

22
Table 7. Thermogravimetric analysis: temperature ranges and associated losses.

Temperature ranges (ºC) and associated losses (%)

ZONE
20º-120º 300º-550º 550º-610º 610º-880º

MC1 0.503 1.858 0.830 22.274

MC2 0.253 2.107 0.821 28.291
MC3 0.965 2.676 0.811 28.120
MC4 0.849 2.717 0.871 30.637
MC5 0.298 1.831 0.681 28.614
MC6 1.212 5.486 0.702 18.456

Table 8. Approximate original composition of the classes of mortars (weight percentages).

Ca(OH)2 Relation
Zone Aggregate Water of
(%) (%) constitution(%) binder-aggre
gate
MC1 43.14 40.66 16.20 1.06
MC2 57.14 31.53 11.33 1.81
MC3 59.40 26.25 14.35 2.26
MC4 62.91 24.29 12.80 2.58
MC5 57.92 33.66 8.42 1.72
MC6 34.84 51.57 13.59 0.68

MC1 MC2 MC3 MC4 MC5 MC6

Figure 1. Plan of Pamplona Cathedral. Sampling areas.

23
 7

6
CONCENTRATIONS*

MC1
5
MC2
4 MC3
3 MC6 MC4
MC5 MC5
2
MC4 MC6
1 MC3 ZONES

0 MC2
Mo

Zn/2

MC1
Pb

Cd

Mn/10

Cr

Cu

TRACE ELEMENTS Ni

Figure 2. Concentrations of trace elements (*Concentrations are expressed in g/g of sample, Zn and
Mn concentrations are divided by 2 and 10, respectively, in order to balance the scales).

Sample Conductivity Concentration

(S/cm) (%)
100 2,0

80 1,6
Conductivity
60 1,2 Chloride
40 0,8 Nitrate
Sulphate
20 0,4

0 0,0
MC1 MC2 MC3 MC4 MC5 MC6
Zone

Figure 3. Results of sample conductivity and anions concentration determined by ion

chromatography (Conductivity, expressed in S.cm-1 is given for a suspension of 1 mg of the sample per mL.
The concentrations of anions are expressed as percentages of the samples).

24
 100
90
Rejected percentages

80
70
60
50
40
30
20
10
0
0,00 0,70 1,00 1,30 1,40 1,70 2,00 2,10 2,20 2,30 2,40 2,51 2,60
Log pore size (mm)

Figure 4. Granulometric curve MC1.

5 V

Figure 5. DTA and TG curves from MC1 mortar.

25
 5 V

Figure 6. DTA and TG curves from MC6 mortar

26