Showing posts with label Cement. Show all posts
Showing posts with label Cement. Show all posts

Mar 30, 2018

Cement, Concrete, Gunite, and Mortar

Although the terms cement and concrete often are used interchangeably, cement is actually an ingredient of concrete. Concrete is basically a mixture of aggregates and paste. The aggregates are sand and gravel or crushed stone; the paste is water and Portland cement.

Cement is a fine binding powder, which is never used alone. It is made most commonly of limestone, clay, shells, and silica sand. These materials are crushed and then combined with other ingredients (including iron ore), and then heated to about 2,700 F. This material, called Clinker, is ground into a fine powder. It is used to make both concrete and mortar.

Both mortar and concrete are widely used building materials. They cannot be substituted for each other without compromising the integrity of a build.

Concrete is much stronger and more durable than mortar. Because it needs a low water to cement ratio, it is much thinner when mixed, making it difficult to use as a bonding element. Concrete is used in structural projects and is often reinforced with steel rebar to maintain its structural integrity. It is best used for support, such as beams, walls, or other building foundations. Its unique characteristic is that it starts out as a simple, dry mixture, becomes a liquid flexible material capable of forming into any mold or shape, and ends up as a hard-as-rock material.

Gunite is a very durable mixture of cement, sand, and water that is sprayed on a surface under pneumatic pressure. It is used for tunnels, underground structures, slope stabilization, structural repairs, and swimming pools. Gunite or shotcrete material is mortar or small-aggregate concrete applied using a wet or dry process.

Mortar is used to hold building materials such as brick or stone together. It is composed of a thick mixture of water, sand, and cement. The water is used to hydrate the cement and hold the mix together. The water to cement ratio is higher in mortar than in concrete in order to form its bonding element. When mixed, it is a much thicker substance than concrete, making it ideal as a glue for building materials like brick.

Bottom line, a hydrated cement mixture forms the base of all three materials, the rock chipping in cement makes it much stronger for use in structural projects, and mortar is thicker, which makes it a better bonding element.

Incidentally, the name Portland cement comes from Joseph Aspdin, who first produced cement during the 1800s in England. He thought its color was like the color of stone from quarries on the island of Portland off the coast of England.

Jun 10, 2011

China Consumes

China consumes 53% of the world's cement. It consumes 48% of the world's iron ore and consumes 47% of the world's coal (more than the rest of the world combined). China is well ahead of the US in the consumption of television sets, refrigerators, and mobile phones. China has  become the world's second largest luxury goods consumer with 27.5% of the world's luxury goods. It also consumes 25% of the world's beer.