Q:

What are the properties of cement?

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Quick Answer

Cement is a fine, gray powder that is used as a construction binding material. When mixed with water, cement reacts chemically and becomes hard and strong. Cement is categorized as either hydraulic or nonhydraulic, depending on how it mixes with water.

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What are the properties of cement?
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Full Answer

Nonhydraulic cement does not harden underwater or in damp conditions. Certain chemicals are added to make hydraulic cement, which sets underwater or in wet conditions.

Cement is made by combining silicon, aluminum, iron, calcium and other chemicals in a controlled mixture. Other materials added to the mixture include chalk, clay, slate and limestone. When combined, the ingredients form a hard substance that is ground into cement.

Cement is also known as Portland cement. It was invented by Englishman Joseph Aspdin in 1824 and was named for its similarity to limestone from the Isle of Portland. The word cement originated in the time of the Romans, whose term opus caementicium referred to masonry similar to modern concrete.

Portland cement is the main ingredient in concrete, which is made by adding rock, sand and water to form a paste that hardens. Concrete is made stronger by adding more cement and is weakened by adding more water. Concrete is used in most buildings, bridges and tunnels due to its strength. Moisture and pests do not weaken it, and it can withstand most natural disasters, including earthquakes and hurricanes.

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Related Questions

  • Q:

    How does cement harden?

    A:

    Cement hardens through a process called hydration. This process begins when water is mixed in with cement and an aggregate such as gravel or crushed limestone is added to form concrete.

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  • Q:

    How is cement made?

    A:

    Modern cement is made by combining certain chemicals that include aluminum, calcium, silicon, iron and other ingredients in a controlled process. These chemicals are derived from limestone, clay, slate, iron ore, chalk with shale, slate and blast furnace slag. When exposed to high temperatures, these materials form a rock-like substance, which when grounded into powder form and becomes what is commonly referred to as cement.

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  • Q:

    What are the mix ratios for cement and sand?

    A:

    The basic mix ratio for concrete is one part water, two parts cement and three parts sand. An alternative ratio is one part cement, two parts sand and three parts gravel with enough water added until the mixtures reaches the consistency of thick mud. Lime is also a common additive to the mix.

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  • Q:

    How do you cut cement board?

    A:

    Cut cement board by marking the cut, running a utility knife along the mark to cut the mesh overlay and snapping the board backwards to break it along the sliced line. Turn the board over, and cut the mesh on the other side at the break to complete the process.

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