Amiens
Published on Nov 18, 2015
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PRESENTATION OUTLINE
A corrosion study of the ferrous medieval reinforcement of the Amiens Cathedral. Phase characterization and localisation by various microprobe techniques.
Good morning. The study I'd like to spend the next 20 minutes sharing with you was undertaken by a group of French chemists, engineers, and material scientists at the Amiens Cathedral in 2009.
Photo by photophilde
French Cathedral Building
spread of Royal power and Catholic influence
The Cathedral was built under King Phillipe August during the period of 1220-1288 CE. It was built during the Gothic period and encompasses the evolution of the style into High Gothic. Quoting from Mapping Gthic France, "Notre-Dame of Amiens is by far the tallest cathedral built at this time with a new level of rigor and an attention to form drawing upon masonic expertise from the Soissonais. This is important in marking the extension of Royal power beyond the Ile-de-France and into Picardy. Choices made in the architecture reflect the preferences of the King of France."
The Re-inforcement of 1498
The Cathedral was built on an ancient site that played host to a catholic church since the 3rd Century, over an even older site of astronomy observation and ritual for the Druids. There had been a history of fires and rebuilding in the 8th -11 centuries. It was built by 4 architects, each taking over after the death of his predecessor, there was a fire during construction of the choir, and construction was at a certain point suspended due to lack of funds. When it was completed, after several years it was discovered that the thrust of the vaulting in the triforium was causing the columns in the transcept to fail. They called in a structural expert.
A Medieval Cathedral with Lateral Thrust Issues
Material Being Examined
corrosion products and their phases
Steel chain (Fer d’Espagne) early steel - phosphorous iron alloy. (Controversy over means of production and origin) but not even steel as much as the corrosion products there-of. Corrosion is both atmospheric (wet-dry cycles) and electrochemical (anode & cathode)
Untitled Slide
Corrosion Products
- Geothyte
- Lepidocrocite
- Ferrihydrite/Ferroxyhyte
- Akaganeite
- Maghemite/Magnetite
Photo by Auntie P
a. sample sites in grey circles, sensors in black squares, b. chain, c. sample collected
What further investigation is necessary?
What does this mean for conservation?
For civil engineering?
Analysis of phases in substrate
what further investigation is necessary?
what does this mean for conservation?
what does this mean for civil engineering?
Morphology give context for more targeted analysis
Composition Analyses distribution & quantity of chemical components
Structural composition
crystallinity
Thanks!
Good morning. The study I'd like to spend the next 20 minutes sharing with you was undertaken by a group of French chemists, engineers, and material scientists at the Amiens Cathedral in 2009.
