Difference Between Plasticizer and Superplasticizer

Main Difference – Plasticizer vs Superplasticizer

Plasticizers, as represented by the name, are chemical components that are added to substances to increase the plasticity of that substance. Therefore, plasticizers are additives. Increasing the plasticity is equal to softening the substance. It makes the substance flexible and durable. Superplasticizers are polymers that are used to prevent particle segregation of suspensions. Both plasticizers and Superplasticizers are known as dispersants. A dispersant is a chemical compound that is added to a suspension in order to improve the separation of particles. Both these compounds are used as additives for concrete mixtures to reduce the water requirement for the concrete mixture. Therefore, plasticizers and superplasticizers are different from each other depending on the reduction of water requirement for concrete mixtures.  The main difference between plasticizers and superplasticizers is that plasticizers can reduce the need for water by 5-15% whereas superplasticizers can reduce the need for water by 30%.

Key Areas Covered

1. What is a Plasticizer
     – Definition, Applications in Polymers, Applications in Concrete Mixtures
2. What is Superplasticizer
     – Definition, Application in Concrete Mixtures
3. What is the Difference Between Plasticizer and Superplasticizer
     – Comparison of Key Differences

Key Terms: Concrete, Durability, Plasticity, Plasticizers, Plasticizing, Phthalate, Polymer Chains, PVC, Segregation, Superplasticizer, Suspension, Volatility

What is a Plasticizer

A plasticizer is an additive used to improve the plasticity of a certain substance. Usually, plasticizers are added to PVC to alter the physical properties. This addition improves the flexibility and durability of PVC. Plasticizers are colorless and odorless esters (most of the times, phthalate esters).

Addition of plasticizes to PVC soften the polymer material. Therefore, PVC becomes bendable. This is very useful in producing different PVC products. Plasticizers can be either liquid or solids. They make polymers more flexible by decreasing the attraction between polymer chains. In addition to PVC, plasticizers are used in concrete, clay products, rubber products, paints, adhesives, etc.  

Examples of plasticizers that have been used from early times include water and oil. But phthalates and adipates are commonly used in the present. Plasticizers are added after heating the material. When heated, the distance between polymer chains in the polymer material widen. This makes the material soft. When plasticizers are added at this stage, they position themselves between the polymer chains and helps to keep the distance between the polymer chains. Thus, even when the material is cooled down the material is still soft.

Figure 1: Bis(2-ethylhexyl)phthalate is a compound used as a plasticizer.

The process of increasing plasticity by plasticizers is known as plasticizing. PVC polymer chains have positive and negative charges. Plasticizer compounds also have positive and negative charges. Hence, these compounds can retain between polymer chains due to electrostatic attraction forces. But in order to add a plasticizer to a material, it should be compatible with the material. Plasticizers should also possess a low volatility and low migration (not easily washed with water or not turned into vapor at lower temperatures).

Plasticizers are also called water reducers. Plasticizers are added to concrete mixtures as water reducers. It is useful in reducing the water: cement ratio used for concrete production. But this reduction does not alter the workability of concrete. Addition of plasticizers increase the strength of concrete and the cost is reduced as well. Plasticizers are added to 0.1-0.5% of the weight of cement. The reduction of water requirement is about 5-15%. But sometimes, the addition of plasticizers may cause air to entrap in the concrete mixture, reducing the strength. Therefore, well-mixing is required.

What is Superplasticizer

Superplasticizer is a water-reducing admixture capable of producing large water reduction or great flowability without causing undue set retardation or entrainment of air in mortar or concrete. An admixture is a mixture of two or more components.

The main aim of using superplasticizer is to avoid particles from segregating. Segregation is the action or state of setting someone or something apart from others. Superplasticizers are used to improve the quality of concrete mixtures. The weak characteristics of concrete are improved by superplasticizers. Addition of these compounds reduce the amount of water needed for the mixture of concrete, i.e., reduce the water to cement ratio. But it does not alter the workability of concrete. Segregation of different particles in a concrete mixture can also be avoided by adding superplasticizers.

Figure 2: A Concrete Mixture

Superplasticizers are improved chemical compounds when compared to plasticizers. The reduction of water can be around 30%. We can add 0.5-3% of superplasticizers (by weight of cement) to a concrete mixture. Some superplasticizers are derived from natural sources whereas others are synthetic.

Difference Between Plasticizer and Superplasticizer

Definition

Plasticizer: A plasticizer is an additive used to improve the plasticity of a certain substance.

Superplasticizer: Superplasticizer is a water-reducing admixture capable of producing large water reduction or great flowability without causing undue set retardation or entrainment of air in mortar or concrete.

Major Applications

Plasticizer: Plasticizers are used to increase the plasticity of polymer materials such as PVC and as a water reducer in concrete mixtures.

Superplasticizer: Superplasticizers are used to further increase the water requirement for concrete mixtures, increasing the strength and durability of concrete.

Other Names

Plasticizer: Plasticizers are also called water reducers.

Superplasticizer: Superplasticizers are also called high range water reducers.

Water Reduction

Plasticizer: Plasticizers can reduce the need for water by 5-15%.

Superplasticizer: Superplasticizer can reduce the need for water by 30%.

Amount Added to Concrete

Plasticizer: Plasticizers are added 0.1-0.5% by weight of cement.

Superplasticizer: Superplasticizers are added 0.5-3% by weight of cement.

Conclusion

Plasticizers and superplasticizer are added to concrete mixtures in order to reduce the water: cement ratio, thereby, reduces the water requirement in the production of concrete. The main difference between plasticizers and superplasticizers is that plasticizers can reduce the need for water by 5-15% whereas superplasticizers can reduce the need for water by 30%.

References:

1. “Plasticizers – Benefits, Trends, Health, and Environmental Issues.”, ChemistryViews, Available here.
2. “Plasticising.” The Free Dictionary, Farlex, Available here.
3. “Superplasticizer.” Wikipedia, Wikimedia Foundation, 21 Oct. 2017, Available here.

Image Courtesy:

1. “Bis(2-ethylhexyl)phthalate” (Public Domain) via Commons Wikimedia
2. “Small-transit-mixer” (CC BY 3.0) via Commons Wikimedia