The difference between concrete, cement and mortar isn’t obvious to most people. It is common to think that the three are basically the same things and while we understand why the average person might get them confused, it is important to note that the three are very different – albeit related – materials. Here we will explain the basic characteristics that set these three materials apart.
What is Concrete?
Concrete is the most commonly used man-made material in construction the world over. It is partly made from a mixture of certain kinds of sand, gravel, small rocks and crushed stone. We refer to these materials as ‘aggregates’ and they make up around 60-75% of a concrete mixture. Cement is actually a part of the recipe for making concrete, so this and water make up the remaining 25-40% of a concrete mixture. The combination of aggregates and cement will be relatively dry until water is added, which activates the concrete and results in a liquid material that can be moulded into any shape. When the mixture dries, it becomes rock-hard and sets in whichever shape the builder left it in, making it an incredibly versatile material. It is easy to work with because of its liquid form which can be moulded into any shape and once it dries it will be weatherproof and strong. Other benefits include its durability, fire resistance, low maintenance, energy efficiency and environmental friendliness.
Curing concrete is important due to its impact on strength development and durability. Curing, which takes place once the concrete is placed and finished, involves maintaining the desired moisture and temperature conditions. Properly cured concrete has an adequate amount of moisture for continued hydration and development of strength, volume stability, resistance to freezing and thawing, and abrasion and scaling resistance. It is possible to purchase ready-mixed concrete so that only water needs to be added. This is useful for small jobs but for larger projects it may be wiser to purchase the dry mixture of aggregates separately from the cement and mix them together on site.
What is Cement?
Cement is an essential component of concrete but also acts as an important binding element in mortar. Cement comes in two forms: Hydraulic and non-hydraulic. Hydraulic cement, which is more commonly used, is composed of limestone, clay and gypsum and will harden when mixed with water. Non-hydraulic cement, which is made using lime, gypsum, plaster and oxychloride and doesn’t need water as it will react with react with carbon dioxide already present in the air.
The most common type of cement used is called Portland cement (or ‘OPC’) which boasts fast drying times and improved early strength. In the case of foamed concrete, it has been reported that using geo-cements and alkaline Portland cement improves the fire resistance of the material. Some uses of cement include joint making for drains and pipes, ensuring water tightness in structures, precasting, the preparation of foundations, combining to make either concrete or mortar and much more.
What is Mortar?
As previously mentioned, mortar requires cement just like concrete does but is comprised of fewer ingredients, just water, sand and cement. There is also a higher water-to-cement ratio in mortar so that it works better as a binding element but is also softer. This is what makes mortar good for holding building materials such as brick or stone together. Mortar isn’t as strong as concrete and wouldn’t last as long so it is never used as a sole construction material. Due to it’s softer composition, it will allow the bricks or stones it binds to ‘settle in’ over a long period of time without cracking in the way expected of a harder material. However, just as there are different types of concrete and cement available, there are also different types of mortar which should be carefully considered as some are harder than others and lend themselves best to different applications.