Admixtures play an important role in improving the properties of the concrete mix, thereby resulting in superior quality output. However, with so many admixtures available on the market, it is often difficult to select the right one for your project. This article provides a detailed guide on the best admixtures for concrete that are popularly used for construction projects in India.
Admixture and Its Types
Admixtures are chemical compounds that are added to concrete during the mixing process to modify its properties and improve its performance. These materials can be added in small quantities and can have a significant impact on the properties of the finished concrete.
There are many different types of admixtures that can be used in concrete, each with its own set of properties and benefits. Some common types of admixtures include:
- Water-reducing admixtures
- Superplasticizers
- Air-entraining admixtures
- Accelerating admixtures
- Retarding admixtures
- Corrosion Preventing Admixtures
- Bonding Admixtures
Five Best Admixtures for Concrete
Admixtures are used based on the requirement of the project. As a result, there is no single admixture that can prove to be the best for concrete in every project. However, some admixtures are commonly used, depending on the requirement of the project.
1. Best Admixture To Alter the Setting Time
Admixture can be used to alter the setting time of the concrete, i.e., either increase the setting time or decrease it. These admixtures are known as accelerators and retarders. Accelerators are used to speed up the setting time of concrete when working in colder regions. In contrast, retarders are preferable for hotter regions to avoid the quick setting of the concrete, allowing for a longer time to shape and finish the project.
Calcium chloride is one of the most commonly used accelerators, due to its easy availability and low cost. Apart from that, triethanolamine, silica fume, silica gel etc., are some other available accelerators. On the other hand, gypsum, common sugar, and salt are some of the commonly used retarders.
2. Best Admixture to Reduce Water Requirement
The workability of the concrete depends upon its softness, which generally increases with the increase in water content. However, increasing the water content beyond a certain limit can affect the strength and durability of the final project. To resolve this issue, you can add water-reducing admixtures, known as plasticizers. These admixtures are available in three types: standard plasticizers, mid-range plasticizers, and superplasticizers.
While standard plasticizers reduce the water requirement of concrete by 10%, mid-range plasticizers reduce it by 15%. On the other hand, superplasticizers reduce the water requirement by 30%. Therefore, adding plasticizers improves the workability of the concrete while improving its overall strength. Calcium and sodium are two of the commonly used plasticizers.
3. Best Admixture To Impart Waterproofing
Waterproofing admixtures generally consist of elements such as aluminium sulfate, zinc sulfate aluminium chloride, silicates, etc. These elements seal the pores of the concrete preventing the water from penetrating through it, which can cause cracks, corrosion, and weakening of the structure over time.
These admixtures are ideal for various projects such as making a concrete water tank or bathroom, where good waterproofing is of utmost importance. It must be noted that these admixtures also act as accelerators, thereby making it necessary to also add retarding admixtures if a slower setting time is desirable.
4. Best Admixture To Improve Durability
Air-entraining admixtures are used when enhanced durability is desirable in the project. These are relatively new admixtures, which when added to the concrete mixture, form tiny air bubbles which improve the workability of the mixture. Furthermore, the aerated mixture results in a lightweight structure with an improved modulus of elasticity, thereby improving the durability of the structure in freezing and thawing conditions. Some of the commonly used air-entering admixtures consist of Teepol, darex, vinsol resin, etc.
5. Best Admixture To Inhabit Corrosion
Corrosion-inhibiting admixtures (CIAs) are used in concrete to reduce the rate of corrosion of steel reinforcement. There are different types of CIAs available in the market, and the selection of the best one depends on various factors such as the severity of the corrosive environment, the type of reinforcement used, and the required service life of the concrete structure.
Calcium nitrite and Calcium nitrate are two of the most commonly used corrosion-inhibiting admixtures. While calcium nitrite is suitable for projects located in an alkaline environment, such as coastal regions, calcium nitrate is suitable for acidic environments.
Apart from these, there are various other types of admixtures that can be used based on your requirement. You can also mix multiple admixtures to impart the desired properties and improve the overall quality of the project.
Final Thoughts
Selecting the best admixture primarily depends on your project’s requirements. Therefore, it is important to analyze your requirement and select the right admixtures that impart the required properties to the concrete mix. You can also select multiple admixtures to get the best results. L&T-SuFin is the leading marketplace in India that provides a wide range of admixtures to choose from. They provide detailed specifications of each product to help you select the right one for your project.