Differences of cement and concrete

Helping you learn more about concrete restoration and concrete repair.

Cement was actually used by the Greeks and Romans thousands of years ago, but after the fall of the Roman Empire it ceased to be used until the 1700’s. Then a man named Joseph Aspdin realized that a clay and limestone mixture would set anywhere (including under water!) if it was superheated beforehand. His mixture is what we now call Portland cement. Many of the structures we are familiar with today, including bridges, docks, oilrigs, damns, and lighthouses utilize Portland cement.

About six billion tons of concrete are made each year. To put this in perspective, that is about one ton for every person currently inhabiting our planet. This probably makes up about fifty to sixty six percent of the worlds infrastructures.

Cement is a mixture of limestone, silicon, aluminum, iron, calcium, and a small amount of various lesser ingredients. To create cement this mixture is heated to about one thousand, four hundred and eighty two degrees Celsius (or two thousand, seven hundred degrees Fahrenheit). This heating creates a mixture of small spherical products known as “clinkers”. The clinkers are then ground into a powder, which is then mixed with gypsum, creating cement. Keep in mind that concrete is not the same thing as cement. Concrete is actually cement, which also contains sand and gravel, or crushed rock. The cement actually binds the other materials together to form what is known as concrete. Once water is added to cement or concrete a chemical reaction occurs which allows the material to harden.

Concrete will set faster or slower, depending on the amount of gypsum you add to the mixture. Make sure if your contractor wants to pour your concrete as a specific time, you’d best be ready! You can also speed up the setting time of your concrete by adding calcium chloride, or slow it by adding sugar. This works by changing the development of the internal crystals which harden your concrete as it sets.

As stated above, concrete, a masonry material, uses cement to hold together crushed stone, rock, or sand. Cement actually only makes up about ten or fifteen percent of the mass of most concrete. Although concrete is very strong, it is best to add some sort of reinforcement when it is used as a building material. One of its biggest flaws is that concrete does not stretch very well when faced with cross tensions. It actually has poor tensile strength, and therefore has difficulty withstanding forces such as wind or earthquakes, as well as any horizontal forces. One of the most commonly used reinforcement methods is to use rebar, or long steel rods. You poor the concrete over these bars, then allow it to set.

A more effective method, however, is called “prestressed” concrete. This method utilizes the same method as reinforced concrete, but the steel bars are actually stretched taut with cables before being covered with concrete, which is then allowed to harden. After the concrete has dried, the tension is released which compresses the concrete. This greatly increases the strength of the concrete itself.

Concrete is one of the more environmentally friendly building materials. Because of the large amount of rock it contains, concrete is a very durable material (it can last up to fifty thousand years!). It is often used for various outdoor structures, such as sidewalks, driveways, roads, pools, skyscrapers, subways, and many others. Another major advantage to concrete is that it most of its ingredients are among the most abundant compounds on Earth’s surface. They also do not contain any byproducts, are renewable, and can be recycled.

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Some of the differences of concrete and cement