Are Concrete and Cement the same?

There is a common misconception that cement and concrete are the same thing.

19/10/2018

We asked Sephaku Cement to look at the common misconception that cement and concrete. Are they the same thing?  Comparing cement and concrete would be similar to likening a cup of tea to milk. There is a distinction between cement and concrete, where the one is an ingredient and the other is the sum total - or end result - when blending associated elements together. 

Cement and concrete are often used interchangeably, and while one can excuse the frequent muddle between the two, cement is in fact the powdery composite that is blended with other materials that results in concrete or mortar. Referred to as the generic term for cement that is used to create concrete, Portland Cement acts as the glue that binds a mixture of aggregate together to form a sticky paste. Portland Cement must be mixed with water to activate its adhesive properties and the type of aggregate (sand and gravel) that the Portland Cement is combined with will determine the number of variations of concrete or mortar finishes.

In light of the above, we can now see that (Portland) cement is the binding agent that is used to create concrete and/or mortar. Cement is typically made up of limestone, silica sand, clay or shells. Once crushed, this is then combined with a source of iron e.g. magnetite or hematite, and heated/sintered to extreme temperatures. The end result is referred to as clinker which is the brittle stony nuggets that are later ground into fine powder, with added gypsum to control the setting and/or other different additional materials e.g. Slag or fly ash etc., make up what we now know is cement.

When combined with water, cement begins to harden as a result of a chemical reaction called the Hydration Process. Binding the aggregate and cement together creates a dense, rocklike mass that we refer to as concrete.

Concrete is commonly used for foundations, walls, slabs and other masonry structures. Concrete is highly resistant to water and fairly resistant to fire. Concrete can either be fine or course which, when combined with water forms a solid end result that continues in the presence of water to gain strength and harden with time.

For added convenience, DIY enthusiasts, contractors and construction specialists can purchase ready-made concrete mixes for various building projects. Where the applicable volumes of cement, sand and gravel are pre-mixed and conveniently bagged, all that is required to prepare is to combine the concrete ready-mix with water.

The character of concrete's can be determined by the type of paste that is created using different aggregates. Making up sixty to seventy five percent of the total volume of concrete, the aggregate mixture determines the thickness and purpose of the final concrete product.

When blended with only fine sand - without any gravel or stone - the cement mix creates a compound referred to as mortar and is used to glue bricks and cladding together to form walls. Mortar is not as resilient as concrete but it does provide a pliable adhesive paste.

 

 

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