Acknowledgments
The authors would like to thank the Abbess and the Sisterhood of the Varnakova Monastery, as well as Ch. Alexopoulou, Civil Engineer, and S. Fidani, for inviting Professor Moropoulou and the NTUA team to undertake the diagnostic study of the Church and the Cells. In addition, the authors would like to acknowledge the Central Greece Regional unit, the Governor of Central Greece, K. Bakoyannis, the Regional Councilor, P. Aravantinou, as well as the General Directorate of Antiquities and Cultural Heritage of the Ministry of Culture and Sports of the Hellenic Republic and the Ephorate of Antiquities of Phocis, A. Psalti, for their fruitful cooperation. Lastly, the authors would like to thank NTUA Associate Professor Ch. Mouzakis for the interdisciplinary cooperation, which we anticipate to continue through a Program Agreement with the Ministry of Culture and Sports and the Central Greece Region. This research was orally presented in its initial form at the 1st International Conference TMM_CH: Transdisciplinary Multispectral Modeling and Cooperation for the Preservation of Cultural Heritage, held on 10–13 October 2018 at the Eugenides Foundation Athens, Greece under the title “The effect of fire on building materials: the case-study of the Varnakova monastery cells in Central Greece” by I. Ntoutsi, E. T. Delegou, M. Thoma, M. Apostolopoulou, Ch. Papatrechas, G. Economou, and A. Moropoulou. It has since then been modified and elaborated with further results and interpretations. Lastly, we would like to thank the anonymous reviewers for their valuable suggestions and comments during the manuscript’s revision process.
Figure 1.
(
a) A general photo of the Varnakova Monastery before the 2017 fire. Arrows and dotted lines indicate the cells’ section and the catholicon. (
b) A general photo of the Varnakova Monastery after the fire – yellow dotted lines indicate the burnt cells’ area. (
c) A topographical depiction of the complex by Rural and Survey Engineer S. Zacharopoulos [
19]. (
d) The ground plan of Ch. Bouras depicting the four architectural phases of the catholicon between the 11th and 13th centuries [
18].
Figure 1.
(
a) A general photo of the Varnakova Monastery before the 2017 fire. Arrows and dotted lines indicate the cells’ section and the catholicon. (
b) A general photo of the Varnakova Monastery after the fire – yellow dotted lines indicate the burnt cells’ area. (
c) A topographical depiction of the complex by Rural and Survey Engineer S. Zacharopoulos [
19]. (
d) The ground plan of Ch. Bouras depicting the four architectural phases of the catholicon between the 11th and 13th centuries [
18].
Figure 2.
Depiction of the Monastery cells in its present state after the fire, which indicates the external, the intermediate, and the internal masonry. The church, as indicated, is to the east.
Figure 2.
Depiction of the Monastery cells in its present state after the fire, which indicates the external, the intermediate, and the internal masonry. The church, as indicated, is to the east.
Figure 3.
Different areas of the cells quarter: (a) the exterior of the external wall (historic masonry), (b) the plastered interior façade of the external wall presenting severe damages from the fire (historic masonry), (c) the lower part of the internal wall facing the courtyard (new masonry raised on a historic base), (d) the historic intermediate masonry, (e) detail from the fire-affected intermediate masonry, and (f) the new masonry of the cells’ quarter: its exterior façade seems intact after the fire, while its interior has suffered fire damage.
Figure 3.
Different areas of the cells quarter: (a) the exterior of the external wall (historic masonry), (b) the plastered interior façade of the external wall presenting severe damages from the fire (historic masonry), (c) the lower part of the internal wall facing the courtyard (new masonry raised on a historic base), (d) the historic intermediate masonry, (e) detail from the fire-affected intermediate masonry, and (f) the new masonry of the cells’ quarter: its exterior façade seems intact after the fire, while its interior has suffered fire damage.
Figure 4.
(a) Collapse of building materials from the upper part of the intermediate masonry. (b) Discolorations and scaling of the beige-grey limestone on the interior (western) façade of the new masonry.
Figure 4.
(a) Collapse of building materials from the upper part of the intermediate masonry. (b) Discolorations and scaling of the beige-grey limestone on the interior (western) façade of the new masonry.
Figure 5.
Diagram summarizing the methodological approach followed in this study.
Figure 5.
Diagram summarizing the methodological approach followed in this study.
Figure 6.
(a) Photograph of sandstone sample V1. (b) The crystalline and lithic fragments of the sandstone are observed. The cementing material is of a sparitic calcite nature (crossed Nicols). (c) Photograph of sandstone sample V2. (d) Oxidation phenomena of iron compounds into the stone mass (crossed Nicols).
Figure 6.
(a) Photograph of sandstone sample V1. (b) The crystalline and lithic fragments of the sandstone are observed. The cementing material is of a sparitic calcite nature (crossed Nicols). (c) Photograph of sandstone sample V2. (d) Oxidation phenomena of iron compounds into the stone mass (crossed Nicols).
Figure 7.
(a) Photograph of sample V5. (b,c) The stone constitutes of three to four zones (crossed Nicols). (d) The chert zone is traversed by joints filled with carbonate content, while super fine-grained iron pyrite is, also, observed (crossed Nicols). (e) The chert zone consists of amorphous siliceous material and scattered iron pyrite crystals, (metallographic microscope, incident light). (f) The fossiliferous limestone zone. The orange hue is attributed to the diffusion of iron hydroxides (parallel Nicols).
Figure 7.
(a) Photograph of sample V5. (b,c) The stone constitutes of three to four zones (crossed Nicols). (d) The chert zone is traversed by joints filled with carbonate content, while super fine-grained iron pyrite is, also, observed (crossed Nicols). (e) The chert zone consists of amorphous siliceous material and scattered iron pyrite crystals, (metallographic microscope, incident light). (f) The fossiliferous limestone zone. The orange hue is attributed to the diffusion of iron hydroxides (parallel Nicols).
Figure 8.
(a) Photograph of limestone sample V6. (b) Grey-beige micritic fossiliferous limestone: the matrix of the stone is of micritic texture, while traces of fossils and sparitic foraminiferal species are detected inside the stone mass. A great number of joints, filled with secondary calcite, traverse the stone mass (parallel Nicols).
Figure 8.
(a) Photograph of limestone sample V6. (b) Grey-beige micritic fossiliferous limestone: the matrix of the stone is of micritic texture, while traces of fossils and sparitic foraminiferal species are detected inside the stone mass. A great number of joints, filled with secondary calcite, traverse the stone mass (parallel Nicols).
Figure 9.
(a) Photograph of fire-effected limestone sample V8. (b) Grey-beige micritic fossiliferous limestone: the matrix of the stone is of micritic texture, while traces of fossils and sparitic foraminiferal species are detected inside the stone mass. A great number of joints, filled with secondary calcite, traverse the stone mass (parallel Nicols). (c) Joint rupture with a width range of 15–18 μm (crossed Nicols).
Figure 9.
(a) Photograph of fire-effected limestone sample V8. (b) Grey-beige micritic fossiliferous limestone: the matrix of the stone is of micritic texture, while traces of fossils and sparitic foraminiferal species are detected inside the stone mass. A great number of joints, filled with secondary calcite, traverse the stone mass (parallel Nicols). (c) Joint rupture with a width range of 15–18 μm (crossed Nicols).
Figure 10.
(a) Photograph of fire-effected limestone sample V7. (b) Grey-beige micritic fossiliferous limestone: the matrix of the stone is of micritic texture, while traces of fossils and sparitic foraminiferal species are detected inside the stone mass. A great number of joints, filled with secondary calcite, traverse the stone mass (crossed Nicols). (c) Joint rupture with a width range of 35 to 65 μm (crossed Nicols).
Figure 10.
(a) Photograph of fire-effected limestone sample V7. (b) Grey-beige micritic fossiliferous limestone: the matrix of the stone is of micritic texture, while traces of fossils and sparitic foraminiferal species are detected inside the stone mass. A great number of joints, filled with secondary calcite, traverse the stone mass (crossed Nicols). (c) Joint rupture with a width range of 35 to 65 μm (crossed Nicols).
Figure 11.
(a) Photograph of limestone sample V9 where two zones are distinct. (b) On the left, the grey-beige micritic fossiliferous limestone zone and, on the right, the grey-black fossiliferous limestone zone, (parallel Nicols). (c) Grains of iron oxides close to the interface of the two zones (parallel Nicols).
Figure 11.
(a) Photograph of limestone sample V9 where two zones are distinct. (b) On the left, the grey-beige micritic fossiliferous limestone zone and, on the right, the grey-black fossiliferous limestone zone, (parallel Nicols). (c) Grains of iron oxides close to the interface of the two zones (parallel Nicols).
Figure 12.
(a) Photograph of fire-affected limestone sample V10. (b) The capillary rupture of some μm width observed in the stone mass constitutes a micro-structural change. The orange hue is due to the diffusion of iron hydroxides and infers the visually observed reddening of the stone (parallel Nicols). (c) Oxidation of iron compounds due to the high temperature during the fire (parallel Nicols).
Figure 12.
(a) Photograph of fire-affected limestone sample V10. (b) The capillary rupture of some μm width observed in the stone mass constitutes a micro-structural change. The orange hue is due to the diffusion of iron hydroxides and infers the visually observed reddening of the stone (parallel Nicols). (c) Oxidation of iron compounds due to the high temperature during the fire (parallel Nicols).
Figure 13.
Correlation of CO2 and the CO2/H2OCBW ratio. The clay mortar group and cement-based mortar group are indicated.
Figure 13.
Correlation of CO2 and the CO2/H2OCBW ratio. The clay mortar group and cement-based mortar group are indicated.
Figure 14.
AREA 1: The exterior of the external masonry, on the left of the entrance to the monastic cells quarter (historic masonry, western façade). Bullets and numbering indicate where the SHR measurements were performed.
Figure 14.
AREA 1: The exterior of the external masonry, on the left of the entrance to the monastic cells quarter (historic masonry, western façade). Bullets and numbering indicate where the SHR measurements were performed.
Figure 15.
AREA 2: Intermediate masonry of the cells quarter (historic wall, eastern façade). Bullets and numbering indicate the areas where the SHR measurements were performed: (a) Three sub-areas examined below 50 cm. (b) Two sub-areas examined above 1 m. (c) The examined fire affected sandstone. Bullets and numbering indicate where the SHR measurements were performed.
Figure 15.
AREA 2: Intermediate masonry of the cells quarter (historic wall, eastern façade). Bullets and numbering indicate the areas where the SHR measurements were performed: (a) Three sub-areas examined below 50 cm. (b) Two sub-areas examined above 1 m. (c) The examined fire affected sandstone. Bullets and numbering indicate where the SHR measurements were performed.
Figure 16.
AREA 3: South-Western façade of the intermediate masonry. The area was examined after the plaster’s removal. (a) South façade of the intermediate masonry. (b) Western façade of the intermediate masonry. Numbering indicates the corner-stones examined by SHR from south to west.
Figure 16.
AREA 3: South-Western façade of the intermediate masonry. The area was examined after the plaster’s removal. (a) South façade of the intermediate masonry. (b) Western façade of the intermediate masonry. Numbering indicates the corner-stones examined by SHR from south to west.
Figure 17.
AREA 4: New masonry (Northern façade). The pillar is built from the beige-grey limestone. The examined areas by SHR are labeled.
Figure 17.
AREA 4: New masonry (Northern façade). The pillar is built from the beige-grey limestone. The examined areas by SHR are labeled.
Figure 18.
(a) Photo of the examined area 1 on the new masonry (higher masonry part). (b) Thermography of area 1. (c) Photo of the examined area 2 on the new masonry (lower masonry part-area 2 is below area 1). (d) Thermography of area 2.
Figure 18.
(a) Photo of the examined area 1 on the new masonry (higher masonry part). (b) Thermography of area 1. (c) Photo of the examined area 2 on the new masonry (lower masonry part-area 2 is below area 1). (d) Thermography of area 2.
Figure 19.
(a) Photo of the examined area 3 of the intermediate historical masonry. (b) Thermography of area 3.
Figure 19.
(a) Photo of the examined area 3 of the intermediate historical masonry. (b) Thermography of area 3.
Figure 20.
(a) Photo of the examined area 4 of the intermediate historical masonry. (b) Thermography of area 4.
Figure 20.
(a) Photo of the examined area 4 of the intermediate historical masonry. (b) Thermography of area 4.
Figure 21.
(a) Photo of the examined area 5 of the intermediate historical masonry. (b) Thermography of area 5.
Figure 21.
(a) Photo of the examined area 5 of the intermediate historical masonry. (b) Thermography of area 5.
Table 1.
Description of the selected stone samples from the cells’ quarter.
Table 1.
Description of the selected stone samples from the cells’ quarter.
Stone Sample Code | Sample Description |
---|
V1 | Sandstone of green hue. Collected from intermediate historic masonry, which is seemingly unaffected by the fire area (based on visual inspection). Second most abundant stone type used in the monument. |
V2 | Sandstone sample, collected from intermediate historic masonry, from a fire-affected area of the masonry. |
V5 | Compact black stone collected from a severely fire-affected area of the intermediate masonry. |
V6 | Grey-beige limestone from the new masonry (internal wall), which is a seemingly unaffected by the fire area. |
V7 | Grey-beige limestone from the historic intermediate masonry, affected by the fire. |
V8 | Grey-beige limestone from the new masonry (internal wall), affected by the fire. |
V9 | Limestone, with two distinct zones, one black and one grey-beige, the later similar to V7, unaffected by the fire (based on visual inspection). |
V10 | Limestone, with two distinct zones (beige-gray and black), severely affected by fire. |
Table 2.
XRD analysis of stone samples.
Table 2.
XRD analysis of stone samples.
Sample Code | Mineralogical Composition (XRD Analysis) |
---|
| Principal mineralogical components | Accessory mineralogical components |
V1 | Quartz | calcite, albite, microcline, muscovite, chlorite |
V2 | Quartz | calcite, albite, muscovite, and chlorite |
V6 | Calcite | quartz |
V7 | Calcite | quartz |
V8 | Calcite | quartz |
Table 3.
TG results of stone samples.
Table 3.
TG results of stone samples.
Stone Sample Code | Mass Loss (%) per Temperature Range (°C) |
---|
<120 °C | 120–200 °C | 200–600 °C | >600 °C |
---|
V1 | 0.20 | 0.04 | 1.19 | 5.44 |
V2 | 1.11 | 0.13 | 1.04 | 1.64 |
V6 | 0.14 | 0.03 | 0.23 | 39.30 |
V7 | 0.17 | 0.02 | 0.36 | 38.99 |
V8 | 0.12 | 0.01 | 0.16 | 38.92 |
Table 4.
Total water immersion tests results – stones.
Table 4.
Total water immersion tests results – stones.
Stone Sample Code | Porosity (%) | Bulk Density (g/cm3) | W.A.C. (%) |
---|
V1 | 3.7 | 2.4 | 1.5 |
V2 | 6.1 | 2.2 | 2.8 |
V6 | 2.6 | 2.3 | 1.1 |
V7 | 2.9 | 2.1 | 1.4 |
V8 | 2.1 | 2.3 | 0.9 |
Table 5.
Description of the selected mortar samples from the cells’ quarter.
Table 6.
XRD analysis of mortars’ samples.
Table 6.
XRD analysis of mortars’ samples.
Sample Code | Mineralogical Composition (XRD Analysis) |
---|
| Principal mineralogical components | Accessory mineralogical components |
Vm1 | Quartz | Calcite, albite, muscovite |
Vm2 | Calcite | Quartz, albite |
Vm3 | Quartz | Calcite, muscovite, albite |
Vm4 | Quartz | Calcite, muscovite, chlorite |
Vm5 | Quartz | Microcline, albite, calcite, muscovite, chlorite, |
Vm6 | Quartz, calcite | Muscovite |
Vm7 | Calcite, quartz | albite |
Vm8 | Quartz | calcite, muscovite, microcline, chlorite |
Vm9 | Calcite, quartz | - |
Table 7.
TG results of mortars’ samples.
Table 7.
TG results of mortars’ samples.
Mortar Sample Code | Mass Loss (%) per Temperature Range (°C) | CO2/H2OCBW |
---|
<120 °C | 120–200 °C | 200–600 °C | >600 °C |
---|
Vm1 | 1.17 | 0.44 | 4.02 | 7.96 | 1.98 |
Vm2 | 0.54 | 0.22 | 1.49 | 20.19 | 13.55 |
Vm3 | 1.00 | 0.25 | 2.84 | 8.32 | 2.93 |
Vm4 | 1.17 | 0.45 | 4.32 | 8.41 | 1.95 |
Vm5 | 1.23 | 0.43 | 3.81 | 7.33 | 1.92 |
Vm6 | 1.23 | 0.27 | 3.31 | 14.45 | 4.37 |
Vm7 | 1.37 | 0.51 | 2.99 | 20.93 | 7.00 |
Vm8 | 1.28 | 0.47 | 4.04 | 6.62 | 1.64 |
Vm9 | 1.50 | 0.62 | 3.11 | 18.57 | 5.97 |
Table 8.
Total water immersion tests results – mortars.
Table 8.
Total water immersion tests results – mortars.
Mortar Sample Code | Porosity (%) | Bulk Density (g/cm3) | W.A.C. (%) |
---|
Vm2 | 17.00 | 1.45 | 14.33 |
Vm4 | 31.18 | 1.63 | 25.38 |
Vm9 | 22.00 | 1.34 | 17.15 |
Table 9.
SHR values from the AREA 1 (see
Figure 14).
Table 9.
SHR values from the AREA 1 (see
Figure 14).
AREA 1 |
---|
Type of Lithotype | Rm | Rmedian | COV% |
---|
1.Beige - grey limestone | 51.04 ± 1.97 | 50.00 ± 1.25 | 7.6 |
2. Sandstone | 43.96 ± 3.14 | 44.00 ± 2.25 | 7.14 |
3.Black chert inclusion | 56.92 ± 4.72 | 58.50 ± 5.3 | 8.30 |
4.Beige - grey limestone | | | |
4a. Black calcite vein | 47.58 ± 14.20 | 42.75 ± 7.75 | 29.84 |
4b. Beige-grey limestone | 50.08 ± 5.22 | 49.50 ± 3.50 | 10.42 |
Table 10.
SHR values from the AREA 2 (see
Figure 15).
Table 10.
SHR values from the AREA 2 (see
Figure 15).
AREA 2- Under 50 cm Height |
Type of Lithotype | Rm | Rmedian | COV% |
1. Sandstone | 42.14 ± 2.67 | 42.00 ± 3.00 | 6.34 |
2. Black chert | 30.00 ± 3.96 | 30.50 ± 4.50 | 13.19 |
3. Beige-grey limestone | 15.79 ± 1.95 | 16.25 ± 2.00 | 12.38 |
AREA 2 –above 1 m height |
4. Beige-grey limestone | 17.14 ± 1.52 | 17.00 ± 1.10 | 8.87 |
5. Sandstone | 36.87 ± 2.54 | 36.90 ± 2.5 | 6.88 |
Sub-Area 6 |
6. Sandstone | 25.83 ± 5.29 | 28.00 ± 6.00 | 20.46 |
Table 11.
SHR values from AREA 3 (see
Figure 16).
Table 11.
SHR values from AREA 3 (see
Figure 16).
AREA3 |
---|
Type of Lithotype | Rm | Rmedian | COV% |
---|
1. Sandstone | 47.35 ± 1.33 | 47.00 ± 0.85 | 2.82 |
2. Sandstone | 34.57 ± 4.02 | 34.50 ± 4.50 | 11.64 |
3. Beige- grey limestone | 42.5 ± 5.62 | 43.00 ± 5.25 | 13.22 |
4. Beige-grey limestone | 46.16 ± 4.69 | 44.50 ± 5.30 | 10.17 |
Table 12.
SHR values from the AREA 4 (see
Figure 17).
Table 12.
SHR values from the AREA 4 (see
Figure 17).
AREA 4 |
---|
Type of Fire-Affected Zone | Rm | Rmedian | COV% |
---|
Fire Affected Zone (FAZ) |
FAZ burnt front | 23.86 ± 1.95 | 23.50 ± 2.50 | 8.18 |
FAZ burnt zone | 32.57 ± 1.99 | 33.50 ± 2.50 | 6.10 |
Zone between FAZ & FUZ | 48.93±3.67 | 48.50 ± 3.10 | 7.5 |
Fire Unaffected Zone (FUZ) |
FUZ middle side | 50.25 ± 4.80 | 49.50 ± 5.50 | 9.5 |
FUZ outer side | 57.14 ± 3.38 | 56.00 ± 4.00 | 5.91 |