1
00:00:00,160 --> 00:00:03,800
In the framework of the restoration of the amphitheater,
what new approach are you considering?
1b
00:00:04,160 --> 00:00:08,579
Our work comes after some experimentations
2
00:00:08,579 --> 00:00:16,000
that enabled a scientific committee to raise some questions.
3
00:00:16,219 --> 00:00:19,150
As these questions were raised,
4
00:00:19,150 --> 00:00:21,400
studies were undertaken that opened some avenues of inquiry.
5
00:00:21,600 --> 00:00:23,800
However, none of them came up with a definitive response
6
00:00:23,800 --> 00:00:26,600
because the questions are fundamentally rather complex.
7
00:00:27,100 --> 00:00:32,400
I think everyone experienced the need to make a comprehensive study.
8
00:00:32,670 --> 00:00:35,500
Which is what we are doing today.
9
00:00:35,700 --> 00:00:38,500
And we're starting to see some elements emerge
10
00:00:38,500 --> 00:00:41,700
through which the studies that were conducted have been applied a particular situation.
11
00:00:41,900 --> 00:00:44,500
The diagnosis we made
12
00:00:44,500 --> 00:00:47,100
is one that concerns the entire amphitheater
13
00:00:47,100 --> 00:00:50,300
its outside facades, the interior of the cavea,
14
00:00:50,300 --> 00:00:55,800
the wide corridors for circulating, the staircases…All of that forms an ensemble.
15
00:00:56,300 --> 00:01:03,800
The conclusion of this diagnosis is that we cannot
16
00:01:03,800 --> 00:01:09,800
separate too distinctly the facade from the interior of the cavea.
17
00:01:09,800 --> 00:01:14,630
There's an outside block--a crown with the facade and
18
00:01:14,630 --> 00:01:18,800
the tiers that are below this crown, and an inside block.
19
00:01:18,800 --> 00:01:21,450
All of that houses the wide hallways for circulating within.
20
00:01:21,450 --> 00:01:25,580
This ensemble should be treated as a whole,
21
00:01:25,580 --> 00:01:27,800
part by part, given the scale of the monument,
22
00:01:27,800 --> 00:01:31,100
then, in a second phase, the remainder of the cavea.
22b
00:01:31,200 --> 00:01:35,160
What are the decisive factors in terms of the damage?
23
00:01:35,300 --> 00:01:40,800
The first observation we made immediately
24
00:01:40,800 --> 00:01:43,800
was of a very specific pathology:
25
00:01:43,800 --> 00:01:46,500
sorts of large flakes had formed
26
00:01:46,500 --> 00:01:48,500
and were continuing to form,
27
00:01:48,500 --> 00:01:51,250
including on the stone used for previous restoration.
28
00:01:51,250 --> 00:01:54,400
That's important because it's a process
29
00:01:54,400 --> 00:01:58,959
specific to this stone and in this configuration.
30
00:01:58,959 --> 00:02:01,500
We looked at what was happening on the amphitheater
31
00:02:01,500 --> 00:02:06,400
but also on other monuments built of Barutel stone.
32
00:02:06,420 --> 00:02:10,400
There's an ancient entrance in Nîmes that is built of Barutel stone
33
00:02:10,400 --> 00:02:15,800
and of which all that really remains is an arch, with not much of a load to support.
34
00:02:15,800 --> 00:02:19,000
So it's an arch with a light load. There's one facade that's nearly intact,
35
00:02:19,000 --> 00:02:24,000
and the other that has exactly the same kinds of degradation, the pathology
36
00:02:24,000 --> 00:02:27,100
we observe on much of the amphitheater.
37
00:02:27,100 --> 00:02:29,599
Which is linked to its exposition to rain.
38
00:02:29,599 --> 00:02:33,000
We made an overall list of all of the parts damaged
39
00:02:33,000 --> 00:02:37,000
and a map that sums up all of our observations.
40
00:02:39,800 --> 00:02:47,500
When we really observe on this map the location and the degree of this deterioration
41
00:02:47,500 --> 00:02:55,400
we realize that the most severely damaged parts are those that are the most exposed to wind and rain
42
00:02:55,489 --> 00:03:00,000
so there's an absolutely obvious correlation.
43
00:03:00,000 --> 00:03:02,029
So that's for the water that comes from the exterior.
44
00:03:02,029 --> 00:03:05,939
The second element, which is really new,
45
00:03:05,939 --> 00:03:10,000
is that by drilling core samples at the joint lines,
46
00:03:10,059 --> 00:03:11,889
which we opened up like a book
47
00:03:11,889 --> 00:03:16,200
we realized that the interior of these joints
48
00:03:16,200 --> 00:03:19,800
was covered with calcite brought by the movement of water
49
00:03:19,800 --> 00:03:25,500
within the masonry that was pieced together with no mortar.
50
00:03:25,500 --> 00:03:28,500
If the masonry had been put together with mortar, the mortar would have been a sponge
51
00:03:28,500 --> 00:03:30,789
and the water wouldn't have circulated.
52
00:03:30,789 --> 00:03:35,800
Here, it circulates as if it were in a karstic network.
53
00:03:35,800 --> 00:03:38,500
Then from time to time there are resurgences.
54
00:03:38,500 --> 00:03:41,900
It functions like a limestone plateau.
54b
00:03:42,000 --> 00:03:45,800
What are the aggravating factors?
55
00:03:46,000 --> 00:03:48,400
There's a very clear relationship with water.
56
00:03:48,400 --> 00:03:52,600
Stone does not deteriorate if it is sheltered from water.
57
00:03:52,600 --> 00:03:56,800
There's also a relationship with the load: the more substantial the load is, the more the stone deteriorates.
58
00:03:56,859 --> 00:04:03,000
But ultimately, it's a factor that's not that important.
59
00:04:03,000 --> 00:04:09,500
There's another element that comes into play, but it's role is not absolutely clear:
60
00:04:09,500 --> 00:04:11,669
the susceptibility to frost.
61
00:04:11,669 --> 00:04:14,739
Nîmes may well be in the South of France,
62
00:04:14,739 --> 00:04:18,500
but there are quite a few days per year below freezing.
63
00:04:18,500 --> 00:04:22,100
We did some freeze cycle studies
64
00:04:22,150 --> 00:04:27,000
and we observed that there is deterioration, but which remains relatively reasonable.
65
00:04:27,069 --> 00:04:32,500
So frost is only an aggravating factor, and not a decisive factor
66
00:04:32,500 --> 00:04:35,600
because the damage is quite general,
67
00:04:35,650 --> 00:04:38,199
and more or less serious according to the exposure.
68
00:04:38,199 --> 00:04:41,800
If there were certain stones that were sensitive to frost and others not,
69
00:04:41,800 --> 00:04:44,200
a certain type of stone would be damaged
70
00:04:44,200 --> 00:04:51,100
while a whole other series of stones would not be affected by that pathology.
71
00:04:51,189 --> 00:04:57,900
We focused our set of hypotheses
72
00:04:57,900 --> 00:05:03,129
around a combination of causes that would lead to that pathology.
73
00:05:03,129 --> 00:05:08,000
We haven't yet established in what order
74
00:05:08,000 --> 00:05:12,300
the succession of factors produces the result.
75
00:05:12,300 --> 00:05:15,349
We're advancing
76
00:05:15,349 --> 00:05:19,800
but we haven't yet exactly reached our destination.
77
00:05:19,800 --> 00:05:23,100
We know that if we block off the entrance of water from the outside
78
00:05:23,100 --> 00:05:25,100
and the water running inside
79
00:05:25,100 --> 00:05:27,200
we will have resolved, I believe, 90% of the problem.
79b
00:05:27,500 --> 00:05:31,200
Are there any other factors for damage?
80
00:05:31,400 --> 00:05:38,800
The laboratory that worked with us looked at these stones very attentively.
81
00:05:38,849 --> 00:05:44,000
It noticed that there were stone facies
82
00:05:44,000 --> 00:05:47,000
that is the appearance of the stone,
83
00:05:47,099 --> 00:05:51,179
which were geologically different:
84
00:05:51,179 --> 00:05:54,330
some stones contained seashells of a certain kind.
85
00:05:54,330 --> 00:05:56,900
That implies different quarries
86
00:05:56,900 --> 00:05:59,869
or areas in the same quarry that were different.
87
00:05:59,869 --> 00:06:04,219
We're going to continue this advanced research
88
00:06:04,219 --> 00:06:09,100
to see if there's a correlation between the facies of the stone
89
00:06:09,100 --> 00:06:12,700
and the extent of the damage.
90
00:06:12,700 --> 00:06:16,300
But those are all secondary factors.
91
00:06:16,300 --> 00:06:19,539
If there were a certain type of facies that gets damaged and not the others,
92
00:06:19,539 --> 00:06:21,500
we would have noticed that long ago.
93
00:06:21,500 --> 00:06:25,200
It's clearly not the case.
94
00:06:25,279 --> 00:06:29,900
I think that it's really a combination of factors,
95
00:06:29,900 --> 00:06:33,800
which in certain conditions cause this damage.
95b
00:06:34,000 --> 00:06:37,800
What factors have you dismissed?
96
00:06:37,900 --> 00:06:41,040
Yes, there is one element, which is the constraint,
97
00:06:41,040 --> 00:06:44,039
the load on the stone.
98
00:06:44,039 --> 00:06:47,889
At one time, it was thought that the Barutel stone,
99
00:06:47,889 --> 00:06:51,029
which is very strong and can bear a heavy load
100
00:06:51,029 --> 00:06:54,300
when it is wet, the lower part for instance,
101
00:06:54,300 --> 00:06:59,900
would lose 30% to 50% of its load-bearing capacity.
102
00:06:59,900 --> 00:07:05,200
In the work on the first section, some stones were changed,
103
00:07:05,200 --> 00:07:08,900
which exposed the beds of the stone.
104
00:07:08,900 --> 00:07:11,900
On these beds of the stones, there was a kind of edge for adjustments,
105
00:07:11,900 --> 00:07:15,900
and the inside part was hollowed out. So the load was concentrated on these edges.
106
00:07:15,940 --> 00:07:22,500
The accumulation of all of that, along with the stone that expanded due to the effects of humidity
107
00:07:22,580 --> 00:07:24,900
could explain according to some studies which concluded
108
00:07:24,900 --> 00:07:31,000
that this stone
109
00:07:31,000 --> 00:07:34,000
which was weakened by all of these factors
110
00:07:34,000 --> 00:07:37,300
and bearing a significant load
111
00:07:37,300 --> 00:07:40,500
but far from its load-bearing capacity,
112
00:07:40,500 --> 00:07:43,339
that this stone would break.
113
00:07:43,339 --> 00:07:46,300
But the reality we discovered
114
00:07:46,300 --> 00:07:51,349
is that the margin of the bearing capacity is huge, so that can't be the explanation.
115
00:07:51,349 --> 00:07:54,410
We see examples of stones bearing little weight
116
00:07:54,410 --> 00:07:56,499
that are nevertheless very damaged.
117
00:07:56,499 --> 00:08:00,400
There may be perhaps a correlation:
118
00:08:00,400 --> 00:08:03,440
if the stone is bearing a heavy weight, it can be a bit more damaged.
119
00:08:03,440 --> 00:08:06,500
However, it does not get damaged because it's bearing weight.
119b
00:08:06,800 --> 00:08:10,500
How do you define a restoration?
120
00:08:10,600 --> 00:08:16,189
We worked with an Italian restorer, Carlo Usai,
121
00:08:16,189 --> 00:08:19,700
with whom we had worked at the Louvre
122
00:08:19,700 --> 00:08:21,819
and on the tomb of the kings in Jerusalem.
123
00:08:21,819 --> 00:08:25,400
He came to do a cleaning test,
124
00:08:25,400 --> 00:08:28,400
which we could observe because it was done at the ground level.
125
00:08:28,499 --> 00:08:32,700
He also performed joint sealing tests and others with mortar.
126
00:08:32,700 --> 00:08:38,000
That gives a rather good idea of the spirit in which we wanted to carry out the work.
127
00:08:38,000 --> 00:08:40,000
It's a technique.
128
00:08:40,000 --> 00:08:43,800
But it goes beyond the technique: we're trying to manage the image.
129
00:08:43,890 --> 00:08:48,000
The cleaning consists in removing the black,
130
00:08:48,000 --> 00:08:50,500
but we don't remove what are called the oxalates
131
00:08:50,500 --> 00:08:55,000
that is these somewhat orange traces
132
00:08:55,000 --> 00:08:58,200
which are at the same place as the black traces.
133
00:08:58,200 --> 00:09:01,490
We try to not to remove everything.
134
00:09:01,490 --> 00:09:07,200
If you "rewhiten" all of the facades
135
00:09:07,200 --> 00:09:10,500
and in Nîmes, there's lots of sun
136
00:09:10,500 --> 00:09:14,200
all of the hollow parts appear to be very dark
137
00:09:14,200 --> 00:09:18,800
they are accentuated by the shadows created against a white background.
138
00:09:18,820 --> 00:09:25,000
We're tempted to fill in the holes that cause these shadows
139
00:09:25,000 --> 00:09:27,300
and break the architectural lines.
140
00:09:27,300 --> 00:09:35,000
As a result, we slide quite naturally toward increasingly significant reconstitutions.
141
00:09:35,000 --> 00:09:39,700
Whereas, if we don't completely clean the facade,
142
00:09:39,700 --> 00:09:43,000
it appears rather naturally
143
00:09:43,000 --> 00:09:48,000
with lines that compete a bit with the architecture,
144
00:09:48,000 --> 00:09:51,700
but not too much. Which means that we can leave some shadows.
145
00:09:51,700 --> 00:09:54,500
We will work then on the hollow parts of the shadows,
146
00:09:54,500 --> 00:09:59,900
not by filling them in, but by working with the mortars,
147
00:09:59,900 --> 00:10:07,300
in a way that creates an image that it a bit "tighter" than
148
00:10:07,300 --> 00:10:15,500
its current appearance that is distorted by the black and the white traces.
149
00:10:15,500 --> 00:10:23,000
Our goal is to achieve something more homogeneous, while changing the minimum number of stones.
150
00:10:23,000 --> 00:10:27,000
When I say minimum, it's really as few as possible.
150b
00:10:27,200 --> 00:10:31,000
How are your actions inscribed in time?
151
00:10:31,160 --> 00:10:35,000
Of course, in an ancient monument, one must feel the thickness of time.
152
00:10:35,000 --> 00:10:39,500
If the restoration cancels that effect,
153
00:10:39,500 --> 00:10:44,700
you remove a great amount of the value from the monument.
154
00:10:44,700 --> 00:10:48,209
That is even truer when the building is 2,000 years old.
155
00:10:48,209 --> 00:10:54,200
Our analysis has always taken account of time.
156
00:10:54,200 --> 00:10:58,510
For instance, we tried to understand if the areas that were long protected
157
00:10:58,510 --> 00:11:01,200
by the presence of houses,
158
00:11:01,200 --> 00:11:02,800
which had protected the facing materials,
159
00:11:02,800 --> 00:11:11,400
were more exposed to the forces of decay.
160
00:11:11,400 --> 00:11:13,500
It's not completely obvious.
161
00:11:13,500 --> 00:11:22,000
Or rather, was it when the outer arches were re-opened
162
00:11:22,000 --> 00:11:27,500
and these areas were exposed to the rain?
163
00:11:27,500 --> 00:11:29,500
We also tried to understand that.
164
00:11:29,500 --> 00:11:35,500
It's similar for the lower part of the buttresses, which were buried under 1.5 m of debris.
165
00:11:35,500 --> 00:11:38,700
In the photographs taken shortly after the excavation of the Arena
166
00:11:38,700 --> 00:11:44,200
to its original level, we can clearly see
167
00:11:44,200 --> 00:11:47,900
whether or not these stones had been severely damaged.
168
00:11:47,900 --> 00:11:52,300
Apparently, they were not. Yet today, they have been replaced.
169
00:11:52,320 --> 00:12:00,500
Which means that in 100 to 150 years, stones that were relatively well preserved,
170
00:12:00,500 --> 00:12:08,200
because they were buried--thus protected from the cold and the wind--,
171
00:12:08,200 --> 00:12:12,900
as soon as they were unearthed, they deteriorated very quickly.
172
00:12:12,900 --> 00:12:18,500
So we see there is an interpretation of the pathologies over time.
173
00:12:18,550 --> 00:12:22,000
And time is not counted in decades, but in centuries.