The terms ‘cement’ and ‘concrete’ are often used interchangeably but they aren’t actually the same thing. The major difference is that cement is the grey powder that is mixed with sand, stone and water to create concrete – cement is an ingredient of concrete.
Cement has been used as a binder of materials for centuries, stemming from other binding elements such as clay and volcanic ash. The use of cement can be traced back to Ancient Macedonia (~800 BC) but it became highly popular and started to revolutionise building during the Roman Empire (from 27 BC onwards).
Cement made from lime and volcanic ash allowed the Romans to build huge structures such as the Pantheon and their aqueducts. Today, cement is made of a mixture of calcium, silicon, iron, aluminum and other chemical compounds. These dry chemicals come from sea shells, chalk, limestone, clay, silica sand, and iron ore.
Two types of cement
Cement comes in two forms; hydraulic and non-hydraulic. Hydraulic cement is that which needs water to start the chemical reaction that hardens the mixture. Hydraulic cement is water resistant once it has fully cured, and it can even harden under water.
Non-hydraulic cement is that which does not need water to set. It has a much longer drying time than hydraulic cement and is not water resistant. For these reasons, hydraulic cement is the binding agent of choice for the majority of builders and developers.
Cement is an ingredient of concrete
Concrete is simply a mix of cement, water and aggregates (or inert solid materials such as gravel, sand and recycled concrete). Aggregates make up about 70% of the concrete mixture and the type of aggregate used depends on the purpose of the concrete.
Cement makes up about 10% to 15% of the concrete mix and is what binds the ingredients of concrete together. When making concrete, the cement and water harden to bind the aggregates together. This hardening process continues for years, meaning that concrete gets harder as it gets older.
Concrete is extremely durable, fire resistant and does not require much maintenance, which is why it is one of the most-widely used man-made materials on the planet. It is used to build most roads, pavements, dams, bridges and large buildings.
How to tell if the concrete is properly mixed
Using the right ratios of cement, water and aggregate is key to mixing the perfect batch of concrete. The character of the concrete is determined by the cement/water paste. Not using enough cement/water paste means that the concrete will be rough and porous. Using too much cement/water paste will create a smooth concrete but it will be more brittle and susceptible to cracks.
A properly-portioned concrete mixture will have the right workability when pouring and the correct durability and strength for long-lasting applications. A good batch of concrete typically comprises 10% to 15% cement, 15% to 20% water and 60% to 75% aggregates.
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LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges.
LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo brand for over 30 years. Our head office and fully-integrated plant are located in the Mbeya Region in Southwest Tanzania.
At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.
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