unlocking the secrets of roman concrete using 3d x -ray … · 2017. 12. 1. · roman concrete is a...
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Unlocking the Secrets of Roman Concrete using 3D X-ray Tomography Tenzin Gyephel1, Dr. Marie Jackson2, Dr. Juhyuk Moon1
1 Civil Engineering Program, Department of Mechanical Engineering, Stony Brook University 2 Civil and Environmental Engineering, University of California Berkeley
Introduction and Background Information Results
Methods and Analysis
Discussion and Conclusion
Roman concrete is a building material widely used by the Ancient Romans throughout the Roman Empire. It was mainly applied in the construction of foundations, roads, aqueducts, harbor structures, temples, and many other structures. Most of these structures, built over 2000 years ago, are still standing to this day. Similar to modern concrete, Roman concrete is composed of aggregate, water, and binding agent. The aggregates of both modern and Roman concretes consist of rocks, gravel, rubble, etc. However, modern concrete uses Portland cement as the binder, while Roman concrete used either gypsum and lime or pozzolan volcanic ash found in central Italy.
The Sovrintendenza Capitolina Beni Culturali di Roma Capitale provided drill cores of Markets of Trajan concretes.
Currently, not much is known about the mechanical properties of Roman concrete, as there are no comparable data. However, by analyzing the porosity of the concrete, we can directly “see” the porosity of the concrete. Micro-CT and Nano-CT images provide multi-scale pore structures of the composite materials of Roman concrete. Here, two sets of Micro-CT images of Roman Concrete are analyzed through AVIZO Fire to reveal the pore structures of Roman concrete.
Figure 4A and Figure 4B: Pore size distribution in the aggregates in relation with Volume and Surface Area of pores of Fig. 2 sample. The total porosity of this sample results in 0.44%
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Figure 2B: 3-D Volume Rendering of complete internal pore structure. Figure 2C and Figure 2D: 3-D Volume Rendering and color differentiation of individual pores in the aggregates.
High resolution X-ray computed tomography results on Roman concrete. Fig. 2A: ultra high resolution data (2μm/voxel) Fig. 3A: high resolution data (8.5μm /voxel)
Figure 1B
Figure 2A
Figure 3A Figure 3B
Figure 4A Figure 4B
Figure 2B Figure 2C Figure 2D Figure 3B Figure 3C Figure 3D Figure 3B: 3-D Volume Rendering of complete internal pore structure. Figure 3C and Figure 3D: 3-D Volume Rendering and color differentiation of individual pores in the aggregates.
Figure 5A and Figure 5B: Pore size distribution in the aggregates in relation with Volume and Surface Area of pores of Fig. 3 sample. The total porosity of this sample results in 0.49%.
Acknowledgment
The measured porosity is extremely low compared to that of modern Portland concrete. This explains the fact that Roman concrete is more resistant under chemical attacks. This further proves the durability of Roman concrete, as its structures have survived for more than 2000 years while modern concrete structures, less resistant to seawater, are only designed to last about 100 years. In addition to that, compared to the direct carbon dioxide emission from the production of cement, the Romans used significantly less lime and baked it at a much lower temperature compared to the current production process of modern concrete. This results in using far less fuel and releasing significantly less carbon into the atmosphere.
Figure 3A
Figure 1A Figure 1: 2000 yrs old Roman concrete under seawater
10 mm 2 mm
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10
100
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7000
1300
019
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031
000
3700
043
000
4900
055
000
6100
067
000
7300
079
000
8500
091
000
9700
010
3000
1090
0011
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1210
0012
7000
1330
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1570
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1690
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1810
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7000
1930
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9000
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2170
0022
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PORE VOLUME (MICRO-METER)
Pore Size Distribution (Volume)
1
10
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5000
9000
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017
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2100
025
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2900
033
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3700
041
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057
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6100
065
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6900
073
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7700
081
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8500
089
000
9300
097
000
1010
0010
5000
1090
0011
3000
1170
0012
1000
1250
0012
9000
1330
0013
7000
1410
0014
5000
1490
00
FREQ
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PORE SURFACE (MICRO-METER)
Pore Size Distribution (Area)
1
10
100
1000
10000
1000
050
000
9000
013
0000
1700
0021
0000
2500
0029
0000
3300
0037
0000
4100
0045
0000
4900
0053
0000
5700
0061
0000
6500
0069
0000
7300
0077
0000
8100
0085
0000
8900
0093
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9700
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012
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9000
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7000
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014
5000
014
9000
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015
7000
0
FREQ
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PORE VOLUME (MICRO-METER)
Pore Size Distribution (Volume)
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1600
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2800
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4000
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5200
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6400
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7600
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8800
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1120
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1240
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1360
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1480
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1600
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1720
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1840
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1960
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2080
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2200
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2320
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2440
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2560
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2680
00
2800
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2920
00
3040
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3160
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3280
00
Mor
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FREQ
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PORE SURFACE (MICRO-METER)
Pore Size Distribution (Area)
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