First, we should probably tell you that concrete is not the same thing as cement. Cement is a powder made from calcined lime and clay. When you mix it with appropriate water, called hydration, you get a pasty bonding material that is used to bond concrete. Cement alone would be too brittle to build all the amazing roads, bridges or skyscrapers that dot the landscape in our modern world.
Concrete is made of a proportioned mixture of cement, water and one or more of sand, gravel and crushed stone. Other aggregates that may be included in concrete are fly ash, ground slag, and silica fume. All These are manufacturer’s by-products. When properly chosen and proportioned and when they are free of foreign matter, which may reduce the quality of the concrete or hinder bonding, this mixture of cement and aggregates can be molded into any shape and then not only harden quickly, but will continue to harden for years, so that, the concrete gets tougher over time.
THERE ARE A NUMBER OF DIFFERENT KINDS OF CONCRETE. HERE IS A LIST OF SOME TYPES OF CONCRETE COMMONLY IN USE TODAY.
- Modern Concrete is the common concrete made from portland cement.
- High-Strength Concrete has a psi (pounds per square inch) capacity of 6,000.
- High-performance Concrete is characterized by ease of placement, long-term mechanical properties, toughness, longevity in different weathers.
- Ultra High-Performance Concrete has a 29,000 psi and does not need rebar or any type of reinforcement. Even if it should crack it will have a psi of 725.
- Stamped Concrete is molded to look like natural stone. This is frequently sealed for longevity.
- Self-Consolidation Concrete does not need mechanical vibration to eliminate excess air.
- Limecrete is made with lime instead of cement and is more health and environment friendly.
GETTING BACK TO CEMENT, THAT MOST VITAL INGREDIENT OF CONCRETE, THERE ARE CEMENT TYPES, TOO. HERE IS A LIST OF 13 TYPES OF CEMENT IN USE, WITH LIMITED DESCRIPTIONS.
- Ordinary Portland Cement (OPC), is the most common type because it works well for most types of construction.
- Portland Pozzolana Cement (PPC) is highly resistant to chemicals and is used where it is expected to be in contact with chemicals such as sewage or water ways.
- Hydrographic Cement repels water, is very strong. It is used in water structures such as dams, water tanks, spillways, and liquid containers.
- Rapid Hardening Cement hardens in 3 days what generally takes 7. It makes an early removal of the formwork possible. It is used in prefabricated construction, and roadwork.
- Quick Setting Cement sets earlier, but hardens at the same rate as OPC. Formwork can be removed early. This cement is used when time is an issue and in water.
- Low Heat Cement produces low heat of hydration which prevents cracking of concrete due to heat. There is increased protection against sulfates, but takes more setting time.
- Expansive Cement. One kind of two simply compensates for cement shrinkage. The other expands, and is used in places like pipes, pavement, sidewalks and tunnels.
- Sulfates Resisting Cement resists the affects of sulfates and is used where the cement is expected to be exposed to high amounts of sulfate, such as by water and soil.
- High Alumina Cement has a setting time of between 3.5 and 5 hours. This is used for cement that is exposed to high temperatures, frost and acid.
- Air Entraining Cement has a smaller water to cement ratio and is used to improve the concrete’s frost resistance.
- Blast Furnace Slag Cement is similar to OPC and is used where there are economic limitations.
- White Cement is a type of OPC, but is white and more expensive than OPC. It’s used for aesthetic and artistic projects, such as in terrazzo floors, garden paths, and pools.
- Colored Cement is made by adding 5 to 10% mineral pigments to OPC. This is also used for aesthetic and artistic projects such as floors and patios.
What are cement and concrete? From bridges and skyscrapers in the big cities to ornamental patios with fountains and fire pits in our back yards, concrete is one of the vital doors to our way of life.