Concrete Additives
Concrete additives are substances that are added to concrete to improve its properties, such as workability, strength, durability, and resistance to specific environmental conditions. Concrete additives can be classified into two main types: chemical and mineral additives.
Chemical admixtures
Chemical admixtures are chemical compounds that are added to concrete to modify its properties. Common chemical admixtures include:
- Water reducers: Water reducers reduce the amount of water required to produce a workable concrete mix. This can improve the strength and durability of concrete.
- Set retarders: Set retarders slow down the setting time of concrete. This can be useful in hot weather or when concrete needs to be transported over a long distance.
- Set accelerators: Set accelerators speed up the setting time of concrete. This can be useful in cold weather or when concrete needs to be placed quickly.
- Air-entraining agents: Air-entraining agents introduce microscopic air bubbles into concrete. This makes concrete more resistant to frost damage and deicing salts.
- Superplasticizers: Superplasticizers are a type of water reducer that can significantly reduce the amount of water required to produce a workable concrete mix. This can lead to significant improvements in concrete strength and durability.
Mineral admixtures
Mineral admixtures are finely ground materials that are added to concrete to improve its properties. Common mineral admixtures include:
- Fly ash: Fly ash is a byproduct of coal combustion. It can be used to replace a portion of the cement in concrete mixes. This can improve the workability and durability of concrete, and it can also reduce the cost of concrete.
- Silica fume: Silica fume is a byproduct of the production of silicon metal and ferrosilicon alloys. It is a very fine powder that can be used to improve the strength and durability of concrete.
- Ground granulated blast-furnace slag: Ground granulated blast-furnace slag is a byproduct of iron production. It can be used to replace a portion of the cement in concrete mixes. This can improve the workability and durability of concrete, and it can also reduce the cost of concrete.
Conclusion
Concrete additives are an important part of the concrete industry. They can be used to improve the properties of concrete in a variety of ways. By carefully selecting the right concrete additives, engineers can produce concrete that meets the specific requirements of each project.
