Analytical Characterization of Plasters and Stones

8/17/2019 Analytical Characterization of Plasters and Stones

1/9

297

YOCOCU: Contribute and role of youth in conservation of cultural heritage © ISBN: 978-88-97484-01-1

ANALY ICAL CHARAC ERIZA ION OF PLAS ERS AND S ONESCOMING FROM HE 19 H CEN URY

PALAZZO FRAGAPANE IN GRAMMICHELEF C *, E C **, E G **,

S L D **, G M *

* Faculty o Architecture, University o Catania, Italy

** Department o Chemistry, University o Catania, Italy (sladel [email protected], [email protected])

Abstract

Plaster and stone samples coming from the 19th

century Palazzo Fragapane in Grammichele(C ) were collected and characterized by using several microanalytical techniques such as X-rayDiffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray analysis(EDX), Fourier ransformed Infrared Spectroscopy (F -IR). Te Analytical investigations wereaddressed to investigate the microstructure and the composition of the different samples andto dene the type and the level of the weathering in order to design the best procedures for themaintenance and conservation of the historical building.

Keywords: Plaster, Stone materials, Physico-chemical characterization, Sicilian architecture

IN RODUC ION

A recovery interventation o a historic building belonging to the urban environment, lefor a long time in a state o neglect or without any kind o maintenance, whatever is its

architectural or artistic value, can not ignore the knowledge o the construction techniques,materials, real conditions and the types o weathering phenomena affecting the structure,Dezzi Bardeschi [1]. From this perspective, the diagnostic step, that is, all the techniques, the

procedures and the time needed or obtaining chemical and physical data in order to knowand characterize the raw materials o the building, is essential or developing appropriateanswers and solutions to the problems raised during the planning phase o a conservationor maintenance intervention, Saisi [2]. In particular, the analyses o raw materials coming

rom the external sur aces o historic buildings, that is the study o plasters, expects a deepand care ul diagnostic investigation, because nowdays, unlike in the past, the plaster is nolonger considered a “sacricial material” to be replaced cyclically in order to saveguard theunderneath masonry, but it is an important material that have to be protected and preserved,Gasparoli [3]. Always, plaster has been one o the most common materials used in constructioneld, mainly thank to the cheapness and to the ease o application. In the last years greateconomic, organizational and research efforts have been accomplished or the recovery andthe saveguard o monumental and architectural heritage existing in Italian cities and consisting


2/9

298


principally o historic buildings, churches and noble palaces. In that direction, this work wasaccomplished in order to analyse and characterize the stones and the plasters (internal and

external sur aces) o the hystorical building “Palazzo Fragapane” in Grammichele (Catania),Cantone [4], by using several microanalytical techniques or allowing an easier planning othe maintenance and preservation interventations, by respecting the building value and byminimizing the loss o historical and cultural in ormations.

EXPERIMEN AL DA A

Sampling

Te sampling was per ormed afer having prepared a detailed internally and externallymapping o the building. Te samples were placed in appropriate vessels and transportedimmediately to the laboratory. Te number and the description o the samples are reported inthe able 1, according to the Normal 3/80 and 12/83, Raccomandazioni Normal [5].

able 1: Te number of the samples and their description are reported in the table

Sample 01 Stone sample coming rom Corso Vittorio Emanuele acade (height 1.00 m)

Sample 02 Stone sample coming rom Corso Vittorio Emanuele acade (height 1.75 m)

Sample 03 Stone sample coming rom Corso Vittorio Emanuele acade (height 2.25 m)Sample 04 Crust layer sample coming rom Piazza Carlo Maria Cara a acade (height 2.10 m)

Sample 05 Crust layer sample coming rom Piazza Carlo Maria Cara a acade (height 2.00 m)

Sample 06 Degraded external plaster pieces coming rom Piazza Carlo Maria Cara a acade

Sample 07 External plaster pieces coming rom Via Garibaldi acade

Sample 08 External plaster layer coming rom Via Garibaldi acade- rst level

Sample 09 Internal plaster layer (ghiara) coming rom Via Garibaldi acade- rst level

Sample 10 Pink plaster coming rom Via Garibaldi acade- rst level (height 1.70 m)

Sample 11 Internal mortar coming rom room A;Via Garibaldi – Corso Vittorio Emanuele corner

Sample 12 Internal plaster coming rom the roo o the room A;Via Garibaldi – Corso Vittorio Emanuele corner

Sample 13 Internal plaster coming rom the roo o the room A;Via Garibaldi – Corso Vittorio Emanuele corner


3/9

299


Instrumental measurementsTe microstructure and the composition o the different samples were investigated using

analytical methods such as Optical Microscopy (OM), X-ray Diffraction (XRD), ScanningElectron Microscopy (SEM), Energy Dispersive X-ray analysis (EDX) and Fourierrans ormed In rared spectroscopy (F IR), Lewin Seymour [6] and Ciliberto[7]. Samples

were imaged using a VP LEO 1550 SEM instrument with a eld emission source and acontrolled electron energy o 15 keV. Te samples did not require any metal coating. TeSEM system was equipped with EDX microanalysis. Te microstructure was investigatedusing a Bruker-AXS D5005 XRD instrument. In rared spectra o the powdered samples wererecorded on a JASCO F IR, collecting the spectra with 80 scans at 4 cm-1 resolution andusing the KBr technique at room temperature.

RESUL S AND DISCUSSION

Samples 01, 02, 03Samples 01, 02, and 03 were collected rom different height o Corso Vittorio Emanuele

açade. All the samples showed weathering (aveolization) phenomena.Fig. 1 reports the mapping o the açade and the alveolization weathering observed in thearea where samples 01, 02 and 03 were sampled.

Te values o the electrical conductivity measurements o all the samples were similar(sample 01: 183,0 µS*cm-1, sample 02: 168,5 µS*cm-1, sample 03 155,2 µS*cm-1 ). XRDand F IR data showed the presence o calcite and a little amount o gypsum, asshown respectively in Fig. 2.SEM/EDX spectra (Fig. 3) revealed the presence o calcium, magnesium and silicon peaksconrming the origins o the samples (calcarenite stone with the presence o calcite edolomite).

Fig. 1: a) Te mapping of Corso Vittorio Emanuele façade; b) the area werethe samples 01, 02, 03 were collected.


4/9

300


Samples 04, 05, 06Samples 04, 05 and 06 were collected rom Piazza Carlo Maria Cara à acade. Tesamples 04 and 05 derived rom a thick scab visible in the acade (Fig. 4a). Te electricalconductivity values o both samples were high and similar (sample 04: 426,9 µS*cm-1, sample05: 645,1 µS*cm-1).SEM/EDX spectra (Fig. 4b) revealed the presence o calcium and sulphur peaks due to thehigh amount o gypsum phase inside the crust.XRD and F IR data (Fig. 5) showed the presence o calcite, gypsum and quartz phases.

Fig. 3: SEM/EDX spectra revealed that samples were originated from calcarenite stone.

Fig. 4: a) Tick crust present Piazza Carlo Maria Carafà façade; b) SEM/EDX spectra revealed that thescab was constituted by gypsum phase.

10 15 20 25 30 35 40 45 50 55 600

10

20

30

40

50

60

I n t e n s

i t y

2 Theta (deg)

Fig. 2: XRD and F IR of sample 02 showing the presence of calcite and a low amount of gypsum.


5/9

301


Sample 06 was collected rom a plaster layer: the electrical conductivity value was 160 uS*cm-1 and MO, XRD and F IR analyses highlighted the presence o gypsum and calcite phase asbinding and quartz (sand) as aggregate.

Samples 07, 08, 09, 10Samples 07, 08, 09, 10 were pieces o plaster coming rom Via Garibaldi acade (rstlevel). While sample 07 and 08 were external plaster pieces without any visible weatheringphenomena, sample 09 was a red coloured internal layer and sample 10 was an external pinkcoloured crust, “scialbo”. Te amount o soluble salts ound in the our samples is relativelylow. Te XRD and F IR analyses (Fig. 6) accomplished or sample 07 and 08 showed the lacko gypsum and the presence o quartz and calcite phases.

MO images o sample 09 are reported in Fig. 7.

SEM/EDX analyses (Fig. 8) revealed that sample 09 was constituted o limestone clasts havingaluminosilicate species as binding.

10 15 20 25 30 35 40 45 50 55 600

10

20

30

40

50

60

I n t e n

s i t y

2 Theta (deg)

Fig. 5: XRD and F IR of sample 05 showing he presence of calcite, gypsum and quartz phases.

10 15 20 25 30 35 40 45 50 55 600

10

20

30

40

50

60

I n t e n s

i t y

2 Theta (deg)

Fig. 6: XRD and F IR of sample 08 showing the lack of gypsum and the presence of quartz and calcite phases.

Fig. 7: Optical Microscopy image for sample 09.


6/9

302


Sample 10, coming rom a pinky crust, was a limestone scialbo (Fig. 9a) , as highlighted romMO image in Fig. 9b and rom XRD and F IR analyses showing the presence o calcite phase.

Samples 11, 12, 13Samples 11, 12 e 13 were collected in roomA (Via Garibaldi-Corso Vittorio Emanuelecorner). Te Fig. 10 shows the planimetry othe rst oor o the Palazzo Fragapane and

the position o the room A.Sample 11 was collected rom the mortarblock used or the stones o the walls o roomA and was constituted o calcite and quartz.Samples 12 and 13 were collected rom theroo o room A. Te XRD and F IR analysesrevealed high amounts o gypsum and lowamounts o calcite, as observed throughXRD and F IR analyses.

Fig. 8: SEM/EDX analyses showed that sample 09 contained limestone clasts having aluminosilicate speciesas binding.

Fig. 9 a) pinky crust called “scialbo”; b) Optical Microscopy image for sample 10.

Fig. 10: Planimetry of the rst oor of the Palazzo

Fragapane and the position of the room A


7/9

303


CONCLUSIONS

able 2 shows crystalline phases ound in the samples analyzed by XRD while able 3a showsthe values o electrical conductivity or each sample.

able 2: Crystalline phases found by XRD

Sample Calcite Dolomite Gypsum Quartz01 ++++ + ++02 +++++ +03 +++++04 +++ +++++05 +++ +++++ ++06 +++++ +++ +++07 +++++ +++08 +++++ +++09 +++ ++ ++10 +++++11 +++++ ++12 ++ +++++13 ++ +++++

I a constant relation is considered between electrical conductivity values and soluble saltcontents, that is, i we assume a constant relative composition o amounts o anions andcations, the data obtained can be expressed as a percentage amount o soluble salts containedin one gram o sample, as reported in able 3b. Te values give a good measurement o theamount o soluble salts in each sample analyzed.

able 3: a) Values of electrical conductivity of all samples; b) Teoretical % of the soluble saltsin the samples

ABLE A Electrical conductivity (µS cm-1)

Sample 01 183.0Sample 02 168.5

10 15 20 25 30 35 40 45 50 55 600

10

20

30

40

50

60

I n t e n s i t y

2 Theta (deg)

Fig. 11: XRD and F IR of sample 13 showing the high amounts of gypsum and low amounts of calcite phases.


8/9

304


Sample 03 155.2Sample 04 426.9Sample 05 645.1Sample 06 159.6Sample 07 60.0Sample 08 61.0Sample 09 63.9Sample 10 105.2Sample 11 58.9Sample 12 925.9Sample 13 930.9

ABLE BTeoretical % of the soluble

salts in the samples


Sample 03 10.55

Sample 04 29.04Sample 05 43.88Sample 06 10.86Sample 07 4.08Sample 08 4.15Sample 09 4.35Sample 10 7.16Sample 11 4.01


Te diagnostic investigations concerned both plaster samples, collected rom acades o rominternal rooms, and stone samples o Palazzo Fragapane. Samples 01, 02, 03 were collected

rom the stones o Corso Vittorio Emanuele acade. Te three samples had comparable valueso electrical conductivity. All the three samples contained calcite, although sample 1 alsocontained a little amount o gypsum. Gypsum phase was due to secondary crystallizationphenomena originated rom the inltration o solutions o calcium and sulphate ions

coming rom the surrounding sur aces covered with gypsum scialbo. Samples 04 and 05were collected rom the thick crust visible on Piazza Carlo Maria Cara à acade. Te values


9/9

305


o electrical conductivity showed the presence o high amounts o soluble salts. XRD andF IR measurements revealed that the most common phases present were gypsum, calcite and

quartz. All the data conrmed that the thick crust was originated rom a scialbo layer, visiblydistinguishable rom the underlying layers that had different morphologies and colours.Sample 06, collected rom Piazza Carlo Maria Cara à açade, too, consists essentially o calciteand gypsum as binder and quartz sand as inert. Samples 07, 08, 09, 10 are pieces o plasterssampled rom Via Garibaldi acade (rst leve). Tese plasters contained calcite as binder andquartz as aggregate. Te amounts o soluble salts were relatively low due to the absence ogypsum. Te sample 09 was an internal plaster: MO and SEM analyses allowed us to observethe limestone clasts having as aluminosilicate compounds as binder. Tis internal layer is“ghiara” material, while the visible red colour was originated rom the presence o iron, asobserved by EDX analysis. Samples 11, 12 and 13 were sampled rom room A (Via Garibaldiand Corso Vittorio Emanuele corner –rst level). Sample 11 came rom mortar block used

or the stones o the walls and it was constituted o calcite and quartz. Samples 12 and 13were collected rom the roo o room A. Te XRD and F IR analyses revealed high amountso gypsum and low amounts o calcite, as observed through XRD and F IR analyses. Tesedata explained the extremely high electrical conductivity values observed in sample 12 and13. Te analyses data showed that the presence o gypsum, which was widely used in someexternal plasters and in all internal plasters, is the most important problem or the weatheringo Palazzo Fragapane. Tere ore, subsequent maintenance and conservation interventationshave to take into account the results o diagnostic investigation in order to write the restoration

plan that saveguards the antique materials ound in the historical building and to take offcalcium and sulphate ions sources by using appropriate anti-salts products.

REFERENCES

1. M. Dezzi Bardeschi, La memoria del tempo, ovvero la permanenza e la mutazione , in Recuperaren.2, 1982.

2. A. Saisi,Il ruolo delle indagini nella diagnostica strutturale

, http://www.beniculturali.polimi.it/.3. P. Gasparoli, Le superci esterne degli edici. Degradi, criteri di progetto, tecniche di manutenzione.

Allnea Editrice, Firenze, 2002.4. F. Cantone, G. Cantone, P. Carnazzo, A. Giuffrida, Recovery of built heritage in nineteenth century

architecture. Fragapane Palace in Grammichele (C ), in Health and Creative Facilities , CIB W070Con erence in Facility Management, Heriot Watt University, Edimburgh, 2008 (pp.79-86).

5. Raccomandazioni NorMaL, Commissione UNI-NorMaL.6. Z. Lewin Seymour, X-ray diffraction and scanning microscope analysis of conventional mortars, in

Mortars, cements and grouts used in the conservation o historic buildings, Rome, 3-6 November1981, (pp. 101-131).

7. E. Ciliberto, G. Spoto, Modern Analytical Methods in Art and Archaeology . Wiley&Sons Ltd, July2000, ISBN 047129361X.

Documents

Analytical Characterization of Plasters and Stones