Concrete admixtures are manufactured chemicals that are added to the concrete before or during the mixing process. The commonly used admixtures are air-entraining agents, water reducers, water-reducing retarders, and accelerators. The complete admixture range can be classified by function as follows:
- Air-entraining admixtures
- Water-reducing admixtures
- Plasticizers
- Accelerating admixtures
- Retarding admixtures
- Hydration-control admixtures
- Corrosion inhibitors
- Shrinkage reducers
- Alkali-silica reactivity inhibitors
- Coloring admixtures
- Concrete superplasticizers
These chemical admixtures are used to give special properties to fresh or hardened concrete. They may enhance the durability, workability or strength characteristics of a concrete mixture. Furthermore, admixtures are used to get over difficult construction situations, including hot or cold weather environment, pumping requirements, early strength requirements, or very low water-cement-ratio specifications.
Concrete Admixture Range by Corrotech
- Accelerator – Accelerating admixtures are used to intensify the rate of hydration and strength development of concrete at an early age. The most common accelerator component is calcium chloride. However, it could promote corrosion activity of steel reinforcement. Accelerating admixtures are particularly useful for modifying the properties of concrete in cold weather.
- Corrosion inhibitors – This type of admixture falls into the specialty admixture category and are commonly used to slow corrosion of reinforcing steel in concrete. Corrosion inhibitors can significantly reduce maintenance costs of reinforced concrete structures throughout a typical service life of 30 to 40 years.
- Waterproofing solutions admixture – Waterproofing admixtures contain organic polymers which react with free lime produced during normal hydration to produce a hydrophobic material. Use of such admixtures will significantly reduce water absorption and chloride ion progression and will provide integral waterproofing even if the surface of the cured concrete is damaged.
- Retarders – Retarding admixtures are often used to delay the rate of setting of concrete. High temperatures of fresh concrete are usually the cause of an increased rate of hardening that makes placing and finishing troublesome. One of the most practical methods of counteracting this effect is to reduce the temperature of the concrete by cooling the mixing water and/or the aggregates.
- Superplasticizers – these admixtures are the improved version of plasticizers with extremely effective plasticizing effect on wet concrete. Superplasticizers result in a significant enhancement in workability at a given water-cement ratio. For continual workability, reduction of water content up to 30% may be achieved by the use of these chemical admixtures.
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