Concrete Planet

Claims concrete very early discovery, used for temples
- Not convincing
Joseph Davidovits
- Pyramids concrete, book says nonsense
- Geopolymer concrete
Reinforced concrete
- Starts out alkaline, then moisture seeps in
- Rebar oxidizes, volume increases, breaks concrete
- NOT fireproof, surface bakes out and powders
  - Collapsed buildings 1906 SF quake
- High strength concrete - fast cure, 70% stronger, but cracks easier and corrodes faster
  - Normal 21MPa, High Strength 31-37MPa, in 7 days
  - Service Life 50 years, average age 42 years
  - Partial repair, $2.2T
- Sewage as corrosive as seawater
- Sacrificial anodes, aluminum or magnesium
- Active cathodic protection adds 15% to bridge cost
  - too much and makes hydrogen
- Glass fiber polymer rebar
  - Hard to shape
  - RF transparent
- Carbon fiber rebar
- Aluminum bronze cheaper than "stainless" steel
- Roman structures, Hockney viaduct has no rebar, still stands
Concrete shrinks while setting, and changes volume with moisture
Megatons of CO_2_ from kilning lime (Calcium Carbonate into Calcium Oxide )
- Second largest source after power plants
Edison concrete houses and appliances
Three Gorges - 27 M cu meters
Sydney Opera House - Jørn Utzon Denmark

http://en.wikipedia.org/wiki/Properties_of_concrete
2,400 kg/m³
Portland cement 8to12 microstrains/°C)(8-12 1/MK)
Reactive Powder Concrete, up to 800MPa lab, 200MPa deployed
- Steel wool fibers - yikes!