cathodic protection for early 20 century steel … docs/presentations for...vinci construction uk...
TRANSCRIPT
1
Chris Wozencroft
VINCI Construction UK -Technology Centre
Cathodic Protection for Early 20th Century Steel Framed Buildings
2
Regent Street Disease
Theory of CP for historic buildings
Practical aspects of application
Guidance and regulation
Examples
Presentations Overview
• 1824 Sir Humphrey Davy reports galvanic CP of ships’ hulls.
• circa 1910 Impressed current CP of buried steel structures.
• late 1940s Impressed current system to pipeline in Africa.
• mid 1950s CP of buried reinforced concrete structures.
• late 1970s CP of reinforced concrete bridge decks in US.
• mid 1980s First building - conductive coatings used as anodes.
• early 1990s Meshless conductive overlay anodes introduced. Desalination and realkalisation in the UK.
• early 1990s CP used to protect steel framed buildings.
• mid 1990s CP using discrete anodes.
• late 1990s Galvanic CP systems.
3
4
Regent Street Disease
(Deansgate Disorder)
5
Reliance Building (1895)
Regent Street Disease
6
In-fills are generally composed of sand, cement and brick rubble fill.
In-fills
External face
The Mechanism
7
The Effect
Cracks at column and beam locations
8
• Steel and masonry contact
• No coatings/no adequate coatings
• Porosity
• Carbonation / chloride
• Poor detailing
• Maintenance
• Age
What Went Wrong?
9
Traditional Repair Options
• Netting and Fall Protection
• Strapping of Displaced Masonry
10
Traditional Repair Options • Masonry Removal and Steel Repair
11
Traditional Repair Options
Traditional repair options
• Disruptive
• Costly
• Time-consuming
• Can often be a limited-term solution
• Restoration rather than conservation
12
The CP Option
CP for Steel Framed Buildings
• First successful application - Early 1990s
• First sizable structures = 1997
13
0 1 2 3 4 5 6 7 8 9 10
VOLTAGE (V)
CURRENT (mA)
0 10 20 30 40 50 60 70
+ -
Direction of Electrical Current
OH- Generation
Monitoring System
H2O
H2O
Reference Cell Anode
CP for Steel in Masonry
Off On
14
In the Field
Stone Modillion Block
Embedded cables
and anode ribbon
15
Why use CP?
• Heritage - conservation above restoration
• Reduced construction work with shorter programmes
• Long-term solution if properly maintained
• Commercial benefits
16
“ The DETR research that Taylor Woodrow has undertaken demonstrates how modern technology can be used to develop sympathetic repair techniques and preventative maintenance consistent with English Heritage's strategy on conservation. We very much support this research” John Fiddler, Head of Architectural Conservation English Heritage
Why use CP?
17
The Challenges
• As discrete and sympathetic as possible.
• Involvement of heritage authorities
• Specialist skills (design & on-site)
• Specialist knowledge of construction type
• Availability of as-built information
• Constant survey and testing during installation
18
Examples
Blackfriars Bridge Hotel, London
St Andrew’s House, Edinburgh
Joshua Hoyle, Manchester
GMBU, Newcastle
Summit House, London
Paramount House, London
College Street, Dublin
Jam Factory, London
Lion Plaza, London
Marshall Fields, Chicago
Selfridge’s, London
Orient House, London
5 Wigmore Street, London
Boots Building, Nottingham
Indigo Jones
Kenwood House
Waterloo House, Birmingham
Imperial College Boat House
19
Examples
Selfridges, Oxford Road, London
20
Examples
The (former) Boots Building, Nottingham
21
Examples
Grosvenor House Apartments, London
22
Examples Orient House, Manchester
23
Examples St Andrews House, Edinburgh
24
Further Reading
• BSEN ISO 12696:2012
• CPA Technical Note 20
• Historic Scotland TAN20
• CPA Monograph No. 7
25