Concrete - Mechanics - Lecture Slides, Slides of Applied Mechanics

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Concrete

Concrete

• is a mixture of portland cement, water, aggregates, and in some cases, admixtures.
• The cement and water form a paste that hardens and bonds the aggregates together.
• Concrete is often looked upon as “man made rock”.

• Concrete has strength, durability, versatility, and economy.
• It can be placed or molded into virtually any shape and reproduce any surface texture.

• Concrete is the most widely used construction material in the world.
• In the United States almost twice as much concrete is used as all other construction materials combined.

Grand Coulee Dam

The Erie Canal

Properties of

Concrete

• Concrete has substantial strength in compression, but is weak in tension.
• Most structural uses, such as beams, slats, and manure tank lids, involve reinforced concrete, which depends on concrete's strength in compression and steel's strength in tension.

• Since concrete is a structural material, strength is a desirable property.
• Compressive strengths of concrete generally range from 2000 to 5000 pounds per square inch (psi), but concrete can be made to withstand over 10,000 psi for special jobs.

Portland Cement

• Portland cement was named for the Isle of Portland, a peninsula in the English Channel where it was first produced in the 1800's.
• Since that time, a number of developments and improvements have been made in the production process and cement properties.

• The production process for portland cement first involves grinding limestone or chalk and alumina and silica from shale or clay.

Three types of portland cement

are used for agricultural

applications:

• Type I cement is the general purpose and most common type. Unless an alternative is specified, Type I is usually used.

Type I