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CE332 Test 2 - 02
Concrete and Cement
Term | Definition |
---|---|
Cement | Powder |
Cement Paste | Cement + Water |
Mortar | Cement + Water + Fine Agg |
Concrete | Cement + Water + Fine Agg + Course Agg |
Binder | Everything that is not agg or fiber |
Non-Hydraulic Cement | Soluble in Water -Gypsum -Lime -Quick lime |
Hydraulic Cement | Does not dissolve in Water -Portland Cement |
Concrete Pros (4) | -Durable -Economical -Formed on site -Water resistant |
Concrete Cons (4) | -Brittle -Low strength to weight ratio -Formed on site (Quality control) -Creep |
Concrete by Volume (2) | ~25% Cement Paste ~75% Agg |
Concrete by cost (1) | ~60% Cost of cement |
Ingredients of Cement (LISA) | From limestone (Determines location of the plant!) -Lime (63%) From clay -Iron (2.5%) -Silica (22%) -Alumina (6%) |
Kiln - what's is it and products | Rotating cylinder, very hot! Produces: Clinker: -Lower T ->C2S -higher T-> C3S |
Gypsum | Added to cement to prevent early reaction High in Sulfate |
4 Chemical name components of cement | Alite C3S Belite C2S Aluminite C3A Ferrite C4AF |
Alite (3) | C3S Second fastest High strength throughout all of its lifetime |
Belite (3) | C2S Slowest at first Gains the most straight throughout all of its lifetime |
Aluminite (5) | C3A Fastest High heat release Must add Gypsum to control the reaction (higher sulfate) Low strength |
Types of cement and their characteristics (5) | I - General Purpose II - General Use with moderate sulfate resistance III - High early strength (+C3S, finest) IV - Low heat of hydration (+C2S, -C3S) V - High Sulfate resistance (-C3A) |
Heat of Hydration 5 Stages | I - Initial Mixing, Rapid heat evolution II - Dormant, transportation and placement III - Acceleration, initial to final set --Finishing and Curing IV - Deceleration, No longer workable V - Steady State |
Water-Cement Ratio | High w/c --> More workable, less strength Low w/c --> Less workable, more strength |
Products of cement hydration | Alite + Belite: -Good glue CSH -Bad Glue CH Aluminate + Gypsum: -Ettringite CASH |
Aluminate -> Gypsum Reaction | Little Gypsum: --> Flash set (bad, early reaction) More Gypsum: --> False Set (ok, just mix) |
Ettringite | Formation of needle shaped that could cause stress Formation after setting: Good, can rearrange Formation before setting: Bad, can lead to expansion and fracture (Sulfate attack) |