Plasticizers for Concrete – Principle, Types & Advantages

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Introduction:
Depending on the case, you may need to be more or less practical. Deep beams, thin water-holding structures with a lot of steel support, connections between columns and beams, pouring concrete, pumping concrete, and working in hot weather all require a high level of workability in the concrete. Adding water is the most common form of abuse, usually done without any engineering on the spot. Adding water to concrete makes it more flexible, but it needs to be easier to work with. It won’t make a mixture more even or regular. Instead, it makes it more likely that people will fight and die. Plasticizers make concrete stronger and last longer by reducing the amount of water and cement needed to reach a certain level of workability. Since the heat of hydration of mass concrete goes down when the cement weight goes down, plasticizers can do this.

Fig: Plasticizers for Concrete
Courtesy: kingsunconcreteadmixtures.com

What is Plasticizer?
Plasticizers and water reducers are chemical admixtures used to make concrete more workable. Unless the mixture is “starved” of water, increasing the w/c ratio reduces the concrete’s strength. An increase in durability is achieved by decreasing the water content (without “starving” the concrete). Concrete is made more manageable and less time-consuming to mix by adding plasticizers, water reducers, superplasticizers, or dispersants.

Plasticizers are frequently used in conjunction with pozzolanic ash while making concrete. This mix proportioning method is typically utilized when making high-strength or fiber-reinforced concrete. One to two percent by weight of plasticizer added to the cement is usually all that is needed. Avoid using plasticizers altogether because doing so can lead to concrete separation. Adding too much plasticizer can slow down the process for some chemicals.

The Action of Plasticizer in Concrete:
Plasticizers make things more flexible because they have polymer molecules inside of them. When these molecules are added to concrete, they stick to the outside of the grains and make ionic groups that radiate outward. The crystals of cement would soon get a negative charge because of this. Cement particles that have a negative charge push against each other. The particles in the water and cement system push against each other, which breaks up the flocs of particles.

In addition to the fact that cement grains naturally don’t like each other, a sheath of aligned water molecules will circle each particle and keep them from getting too close. Because of this, the concrete paste is smoother and easier to work with than ever before.

Materials Used as Plasticizers:
i) Polyglycerol esters are made from hydroxylated carboxylic acids and their derivatives and changes.

ii) Lingo sulfates and their derived products and modifications are salts of sulphonates of hydrocarbons.

iii) Carbohydrates:Plasticizers are used in amounts that range from 0.1% to 0.4% by weight of cement. At the same level of workability, adding 0.1 to 0.4% of a plasticizer can reduce the amount of mixing water by 5 to 15%, naturally makings the material stronger. At the same water-to-cement ratio, the workability increase can be anywhere from 30 to 150 mm, depending on the concrete’s initial slump, the cement type, the amount of cement, and the amount of plasticizer.

A good plasticizer makes concrete or mortar flow in a way that is different from how an air-entraining agent does it. But some plasticizers also add air to the material, making it easier to work. A good plasticizer should add 1% to 2% of the air to concrete at most because adding air to concrete makes it less strong.

Types of Plasticizers in Concrete:
1. Hydrophilic plasticizer:
The primary purpose of hydrophilic plasticizers is to improve the concrete’s plastic and flow properties, as evidenced by their increased wet ability.

2. Hydrophobizing Plasticizers:
This plasticizer makes a lot of air get into the concrete mix. It is possible to lower the tension of the water in the solution and make the concrete more flexible.

Purpose and Usage of Plasticizers:

• Plasticizers turn hard plastic into soft, flexible, and elastic.
• It makes resin flexible and cuts down on film cracking.
• It increases how flexible the mixture is to make it less thick.
• Plasticizers are also used to hold air in place.
• It lowers the amount of water in cement and makes it strong.
• It makes it easier to work with the mix.

Advantages of Plasticizers:

• Plasticizers make it possible to change the shape of concrete without adding more water.
• Adding more cement makes the concrete stronger.
• The strength of the finished concrete base goes up by 25% because of the plasticizers.
• Without the use of vibrators, compacting can be done with plasticizers.
• Plasticizers make something easier to work with and help it stick better to surfaces.
• High-density concrete can be made with the help of plasticizers.
• When added to concrete, plasticizers reduce the water in the mix, making it less likely to crack
  and more resistant to cold.

Conclusion:
A plasticizer is an additive used in concrete to improve its workability, performance, and durability. Plasticizers are typically added to concrete mixes to make pouring, shaping, and finishing easier. They can also help to increase the strength and reduce the permeability of the hardened concrete. Several types of plasticizers can be used in concrete, including water-reducing plasticizers, superplasticizers, and retarding plasticizers. Water-reducing plasticizers reduce the amount of water needed in the concrete mix, while superplasticizers can increase the workability of the concrete without increasing the water content. Retarding plasticizers slows down the setting time of the concrete, which can be useful in hot or dry weather conditions.

It’s important to note that using plasticizers in concrete can have environmental implications, as some plasticizers may harm human health or the environment. As such, it’s important to consider the use of plasticizers in concrete carefully and to choose materials that are safe and effective.

References:
1. Plasticizers: Materials, Action, and Uses | Admixtures | Concrete Technology. (2017, December 18). Engineering Notes India. https://www.engineeringenotes.com/concrete-technology/plasticizers/plasticizers-materials-action-and-uses-admixtures-concrete-technology/32128
2. Editorial, B. (2021, July 23). Top Applications of a Concrete Plasticizer. BOSS Magazine. https://thebossmagazine.com/concrete-plasticizer/
3. Plasticizers for Concrete – Principle, Types & Advantages. (2021, July 23). PRODYOGI. https://www.prodyogi.com/2021/07/plasticizers-for-concrete-principle.html
4. Types of Plasticizers in Concrete | How Do Plasticizers Work In Concrete? (n.d.). Types of Plasticizers in Concrete | How Do Plasticizers Work in Concrete? https://www.constructioncost.co/types-of-plasticizers-in-concrete.html
5. Concrete Plasticizer: Achieve Workable Concrete with Less Water Content! (2017, December 20). Concrete Plasticizer: Achieve Workable Concrete With Less Water Content! https://gharpedia.com/blog/concrete-plasticizer/

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