Concrete Flashcards
1
Q
Concrete production
A
Uses rotary kiln
2
Q
Usage in high rises
A
- Lower stories to support the rest of the building
- Lightweight concrete used for higher stories
- Need strong soils in the area
3
Q
Concrete makeup
A
- Air
- Cement (15%)
- Water (8%)
- Fine aggregate (sand) (34%)
- Coarse aggregate (gravel) (43%)
4
Q
Where does the strenght come from?
A
Reaction between the cement and water that produces a heat - hydration
5
Q
Curing
A
- Develops strength and durability
- Reduce heat by adding water
6
Q
Fresh concrete
A
- Between mixing and setting
- Can measure workability through slump test
7
Q
Hardened concrete
A
- After setting
- Can measure tensile and compressive strength
8
Q
Strength and Durability
(One is long term, one is short)
A
Strength = short
Durability = long
9
Q
Water:Cement ratio
A
- Most important factor in strength and durability
- Can alter to obtain desired results
10
Q
Aggregates
A
- 75% of concrete makeup
- Help the strength and durability
11
Q
Classified by:
A
- Production method
- Petrological characterisitc - rock mechanics (geology)
- Particle size
- Unit weight
12
Q
Production method
A
- Natural (sand/gravel from land or sea)
- Crushed (large rocks crushed to size, sharp surfaces help them to bond and increase strength)
13
Q
Particle size
A
- Sieve analysis
- Coarse (gravel) - 4.75mm
- Fine aggregate (sand) - 0.075mm
- Silt - 0.002-0.075mm
- Clay - smaller than 0.002mm
14
Q
What affects workability?
A
- Shape
- Texture
- Porosity
- Grading (particle size distribution)
15
Q
What affects strength?
A
- Individual strength
- Deformation
- Toughness
- Hardness
- Density
