## Concrete An Example of Concrete Construction

The word concrete comes from the Latin word "concretus", which means "hardened" or "hard".

Concrete is an aggregate material composed primarily of: cement, water, and aggregates (aggregates can be a number of materials including gravel, limestone, sand, etc). Because concrete is not a homogeneous material it's strength and structural properties will vary greatly dependent on how it is made.

The American Concrete Institution (ACI) provides the design criteria for most concrete elements. The Design Codes currently being used by the IBC is the ACI 318.

### The different types of concrete:

Different types of concrete can be used in a variety of special circumstances and are labeled the following:

### Testing Procedure:

Concrete will normally be tested at 28 days to determine the strength of the concrete.

### Common Concrete Properties :

Common Concrete Properties include (english units):

• E =2,500-4,500 ksi
• Poisson's ratio (v) = 0.1-0.2
• Thermal deformation = 6.7x10-6 1/şF
• Plain Concrete
• γ = weight density = 145 pcf
• ρ = mass density = 4.5 slugs/ft3
• Reinforced Concrete
• γ = weight density = 150 pcf
• ρ = mass density = 4.7 slugs/ft3
• Lightweight Concrete
• γ = weight density = 70-115 pcf
• ρ = mass density = 2.2-3.6 slugs/ft3

Common Concrete Properties include (metric units):

• E =17-31 GPa
• Poisson's ratio (v) = 0.1-0.2
• Thermal deformation = 12x10-6 1/şC
• Plain Concrete
• γ = weight density = 23 kN/m3
• ρ = mass density = 2,300 kg/m3
• Reinforced Concrete
• γ = weight density = 24 kN/m3
• ρ = mass density = 2,400 kg/m'^3
• Lightweight Concrete
• γ = weight density = 11-18 kN/m3
• ρ = mass density = 1,100-1,800 kg/m'^3

### References:

1. Gere, James M. "Mechanics of Materials, Sixth Edition",2004

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