Cement Industry

Basics

Cement and Concrete:

The Hard Facts

 

definitions

Modern portland cement is a gray powder manufactured from limestone, clay, sand, iron ore and gypsum.

 

Modern concrete is an artificial stone made from a mixture of portland cement, water, sand or rock, and other abundant natural materials.

 

“Portland” is not a brand name nor is it related to Portland, Maine, or Portland, Oregon. It is a generic term for the type of cement used in virtually all construction today.

 

Portland cement was invented in 1824 by British bricklayer Joseph Aspdin. He named it after a prized stone quarried on the Isle of Portland off the English coast.

 

ABOUT LIMESTONE

A basic component of portland cement is limestone, which has a history of its own. A sedimentary rock, it is the product of sea shells and corals formed in shallow seas over continents 700 to 500 million years ago.

 

 

UNIQUE QUALITIES

Concrete is valued for its ability to withstand great compression occurring from the pressure of heavy loads. It is a relatively economical building material which can be molded to any shape, made porous or watertight, heavy or light in weight.

 

Durability and strength make concrete preferred for building streets and highways, schools and bridges and airport runways (56.6 percent of cement is used in public works).

 

CONTINUING INNOVATION

A generation of advanced products incorporates fibers and special aggregates to make roofing tiles, shake shingles, board siding, countertops and hundreds of other building materials.

Development of new computer programs is making the design of concrete buildings simpler and more economical.

 

Research in the last decade has produced breakthroughs that pushed high-performance concrete strength to nearly 20,000 pounds of pressure per square inch (psi). Standard concrete withstands 3,000-5,000 psi.

 

In the laboratory, strengths have reached 100,000 psi, a harbinger of taller and more economical buildings and longer, durable bridges.

 

All this would astound the Egyptians, who used burned gypsum as mortar to cement 2.3 million blocks of limestone in building the Great Pyramid more than 4,000 years ago, and the Romans in 27 BC, who made a natural cement of slaked lime and volcanic ash and used it to build aqueducts and the Roman Coliseum.

 

WHAT’S THE DIFFERENCE BEWTEEN CEMENT AND CONCRETE?

 

Cement is like the flour in a cake, it binds together all the ingredients of the concrete cake.

Standard concrete withstands up to 5,000 pounds per square inch, or the weight of two autos on  each  square inch of 12” thick roadway.

Cement Industry Basics