Part 1. Concrete as a
Material
Concrete is a very important and integral part of our modern world. Although it is less
impressive and dramatic than other more advanced technologies, it is literally the
"foundation" of our society. Concrete affects us directly or indirectly in many
ways:
- Shelter - we live, work, and play in concrete structures
- Transportation - highways, railways, shipping, and air
- Energy - food supply, water supply (human and agriculture), hydroelectric (dams), and
nuclear (reactor vessels).
Concrete is a composite
of two materials
- Coarse granular material (aggregate or filler). May be composed of many different
materials, however due to economic and structural reasons we use common rock.
- Cement or binder (basically glues the aggregate together). Cement refers to any binder
formulated from many possible chemical quantities. There are many common cements used in
civil engineering practice. The one most often used is called Portland cement.
Advantages of concrete
- Ability
to be cast - many different shapes and types of structures, offsets other
disadvantages.
- Economical
- on-site preparation, local materials, unskilled labor.
- Durable
- maintenance-free, generally no protective coatings.
- Fire
resistant - can maintain structural integrity.
Energy efficient - requires less energy to produce than steel.
- On-site
fabrication.
- Aesthetic
properties.
Disadvantages of
concrete:
- Low
tensile strength - very brittle, must be reinforced with steel to carry the
tensile stresses.
- Low
ductility.
- Volume
instability - shrinkage and creep.
- Low
strength-to-weight ratio.
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